Virginie Boutueil

Gaele Lesteven
email: gaele.lesteven@enpc.fr

The role of ICT-based innovations in transforming intermediate transport in African cities The cases of Cape Town, Nairobi, and Addis Ababa

Keywords: ICT-based innovations, paratransit, urban mobility, Africa

Over recent decades, intermediate modes of transport (also known as paratransit, which includes taxis, mototaxis, collective taxis, ride-hailing services, etc.) have gained momentum in the fast-expanding cities of the developing world. They now commonly are a significant, though often informal, component of mobility systems in these cities. On top of rapid demographic growth, cities in South and East Africa are enjoying higher levels of economic growth and political stability than cities in other Sub-Saharan countries. Such trends translate into a dynamic development of heavy infrastructures, private motorisation as well as mobility innovations of various sorts. Paratransit services -with their intrinsic qualities of innovation-readiness (besides flexibility and labourintensiveness)-could remain a key element of future, more sustainable urban mobility systems. The main assumption underlying this research is that mobility innovations using Information and Communication Technologies (ICTs) could play a significant role in this consolidation process. The paper first presents an overview of the mobility systems of three cities in South and East Africa and their respective ICT background: Cape Town, South Africa (3.7 million residents), Nairobi, Kenya (3.1 million residents), and Addis Ababa, Ethiopia (3.3 million residents). It then analyses the place of intermediate transport modes in each of the three cities. Finally, it presents a set of ICT-based innovations developing in these cities and discusses the role of such innovations in the modernisation, upgrade and expansion of paratransit services. This study combines an extensive review of academic and grey literature with the insights gained from 32 indepth stakeholder interviews carried out by the authors during a field trip in March-April 2017.

Introduction

As of 2017, 1.3 billion people live in Africa. This represents 17 per cent of the world population. More than half of the world population growth by 2050 is expected to occur in Africa, meaning the African population would double and would represent 26 per cent of the world population by then (UN, 2017). Africa is also set to be the fastest urbanising region in the coming decades. In 1990, one third of Africa's population was urban. By 2050, the figure is projected to reach 56 per cent. Today, 60 per cent of the population is under 25 and 41 per cent under 15. Africa appears as a region of massive changes, not only in terms of demography and urban development, but also regarding the adoption and use of Information and Communication Technologies (ICTs). At the end of 2016, there were 420 million unique mobile subscribers in Sub-Saharan Africa, a penetration rate of 43%. The rate was 27% in 2010. Only 6 years later, Sub-Saharan Africa almost reached the 2010 global average penetration rate (46%, which rose to 66% in 2016). Smartphone connections in Sub-Saharan Africa have doubled over the past two years to nearly 200 million, accounting for a quarter of mobile connections in 2016 (GSMA, 2017).

Intermediate transport refers to all means of transport between the individual use of the private car and mass transit. Intermediate transport services, also called paratransit, are heterogeneous, ranging from licensed minibus services operated on a prescribed route by a formalised company to illegal motorbike services run by informal one-person businesses. They also have seen the recent addition of shared mobility services proposed by fastgrowing transportation network companies (TNCs), such as Uber. In many African cities, paratransit services now commonly are a significant component of the mobility system. As motorisation rates are still low and road networks are highly congested and dangerous for cyclists and pedestrians (Sietchiping et al., 2012), they are often the only means for many urban dwellers to travel. They are often subject to vehement criticism related to their reckless driving of overloaded vehicles, even armed violence, and collusion with corrupt police (Pirie, 2014). Nevertheless, thanks to their intrinsic qualities -flexibility, labour-intensiveness, and innovation-readiness (Lesteven and Boutueil, 2017)-, paratransit services are a key asset for urban mobility systems to be able to cope with fast-increasing demand on the short term.

The aim of our project is to discuss the role of ICT-based innovations in the modernisation, upgrade and expansion of paratransit services. Our main assumption is paratransit services -with their intrinsic qualities of innovation-readiness besides flexibility and labour-intensiveness-could remain a key element of future, more sustainable urban mobility systems, with the help of the current boom in ICT-based mobility innovations. On top of rapid demographic growth, cities from South and East Africa are enjoying higher levels of economic growth and political stability than cities in other Sub-Saharan countries. Such trends translate into a dynamic development of heavy infrastructures, private motorisation as well as mobility innovations of various sorts. For this study, we selected three cities of similar size but presenting different national and local political settings: Nairobi, Kenya; Cape Town, South Africa, and Addis Ababa, Ethiopia. The diverse levels of maturity of the three cities regarding ICT infrastructure and services helps provide a broad view of possible barriers to, and enablers of, the transformation by ICTs of the industry(ies) of intermediate transport in Africa.

The paper is organised as follows. The next section presents the methodology and provides background information on the urban, transport and ICT contexts in the three cities. Section 3 discusses the role of paratransit services in the cities. Section 4 provides an overview of ICT-based innovations in the urban mobility systems considered. The final section discusses their impacts on the paratransit sector, as vectors for a more sustainable mobility, and offers some concluding remarks.

Methodology and general background

Methodology

This study combines an extensive review of literature with the insights gained from 32 in-depth stakeholder interviews carried out by the authors during a field study in March-April 2017 in Nairobi, Kenya, Cape Town, South Africa, and Addis Ababa, Ethiopia. Interviewees included representatives of public authorities (5 interviews), transport operators (4 interviews), international development agencies (3 interviews), consultancies (2 interviews), NGOs (2 interviews), IT start-ups (8 interviews), and researchers (8 interviews). The recruitment was not exhaustive but diverse enough to collect different positions on the debate. The interviews were all transcribed. The survey findings were complemented by field observations and an extensive literature review of scientific papers, policy documents, and local newspapers (for lack of better sources).

Three Sub-Saharan cities

Nairobi, Cape Town and Addis Ababa have approximately the same population size (between 3 and 4 million inhabitants). All three cities have been shaped by the development of railways in the 19 th century. If spatial segregation is a common historical feature in Nairobi and Cape Town, it is a more recent development in the case of Addis Ababa. The capital of Kenya, Nairobi, is located in the fertile central highlands. The city has been created by the British as a commercial place on the Uganda-Mombasa railway. Since Independence in 1963, population has grown to reach 3.1 million people in the Nairobi City County. The Western side of the city, that is the former colonial city, remains a wealthy area. Low-income populations live in the eastern and southern part of the city and jobs are mainly located in the CBD. The racial segregation of early Nairobi has evolved into the current social segregation pattern (Klopp, 2012).

Cape Town is older than Nairobi. Created three centuries ago, it is located in a spectacular setting in the southwestern part of South Africa. The building of a railway line to the Southern suburbs during the 19th century shaped the urban growth of the city. Accelerated urbanisation occurred in the 1940s and resulted in large informal settlements populated by Black African populations in the peripheries. The 1960s and 1970s were marked by low-density suburban expansion along the city's freeways. The city proved very attractive, with a population growth of 30% over the last decade, reaching 3.7 million inhabitants (TCT, 2015). The current structure of the city still reflects the legacy of Apartheid and the associated policies of deliberate segregation.

Like Nairobi, Addis Ababa is a capital city. Located in the central highlands of Ethiopia, the second most populated country in Africa, it is its principal commercial centre. Addis Ababa is also an important regional and international transportation hub as the Addis Ababa-Djibouti Railway has been influential in the development of the city and Ethiopian Airlines has established itself as the largest airline in Eastern Africa. The population of the city has almost doubled every decade since the 1980s. It has reached 3.3 million. The city has experienced rapid sprawl, due to informal squatter settlements and forced relocation of population in the peripheries.

Urban mobility systems

The three cities are contrasted in terms of infrastructure development, motorisation rate, and modal share. In Nairobi, 30% of households own a car. The modal share of private cars is 14%, and 5% for motorised twowheelers (JICA, 2014). Traffic congestion is heavy as all road traffic converges towards the CBD and by-roads have not been completed yet. The car culture is more strongly established in Cape Town where more than half of households own a car. The city counts 306 cars per 1,000 inhabitants. The private car has a 37% modal share (TCT, 2015). Congestion occurs at peak hours on the intra-urban freeway system built in the 1960s and 1970s (Wilkinson, 2000). Car ownership in Addis Ababa is lower than in Cape Town and even Nairobi. But the city has lately seen a rapid increase in car ownership with 130 vehicles per 1,000 people in 2015 against 65 in 2012 (World Bank, 2016a and 2014). Addis Ababa City Roads Authority (AACRA) initiated in 1998 the construction of a ring road to alleviate congestion on the city's roads.

In all three cities, the urban organisation is inadequately compensated by the public transport system, especially as far as the mobility needs of the poorest portions of the populations are concerned. Nairobi mainly relies on its minibus services, called 'matatus', as the public bus services failed in the 1980s. Besides matatu services, 'bodaboda' motorbike-taxi services are expanding, and so are TNC services. Uber and its local competitor LittleCab respectively operate about 4,000 and 5,000 for-hire vehicles in the capital [interview with an operator]. Matatus account for 28% of daily trips, as compared with 12% for buses (JICA, 2014). A commuter train operates but its use remains marginal. The creation of the long-awaited Nairobi Metropolitan Area Transport Authority in 2017 may help materialise the plans for implementing BRT corridors. The modal share of paratransit in Cape Town (in the form of minibus taxis) is relatively low compared to other South-African cities (15%, as compared with 70% in Johannesburg). Minibus taxis are increasingly taking market share from the historical transport mode of the poorest, namely the commuter rail (11% modal share) (TCT,2015), owing to persistent problems of underinvestment in railway infrastructure, decaying rolling stock, inadequate policing and vandalism (Pirie, 2014). Buses, public or otherwise, hold a 15% market share in Cape Town. MyCiti BRT, the latest addition to public transit services in Cape Town, started in 2011 and progressively opened new routes. Though emblematic as an urban project, the BRT has had a limited impact on demand (<1% modal share) so far. Uber started operating in Cape Town in 2015. Contrary to Kenya, there are no moto-taxi services in South Africa. Finally, in Addis Ababa, the transit and paratransit fleet is diversified. It includes 8,500 Saloon taxis, 7,500 blue and white minibus taxis, 1,800 buses (private and public, standard and express), and 22 trains to address the mobility needs of 2.5 million persons [START_REF] Fortune | Road Maintenance Divides Addis Residents[END_REF][START_REF] Fortune | Mass Transportation Mess: The Poor Traffic Management in Addis Ababa[END_REF]. Minibus taxis had a 34% modal share in Addis Ababa in 2006, as compared with only 6% for buses and 6% for taxis (Addis Ababa city government, 2012). The latest additions to the public transport system in Addis Ababa are two Light-Rail Transit (LRT) lines. Launched in 2015 as an emblematic project for the city, they have not yet reached their expected full capacity of 15,000 passengers per hour per direction, which will require completing the purchase of the 41 trains as originally planned. Non-motorised transport (NMT) in Nairobi and Addis Ababa respectively accounts for 42% and 44% of daily trips (in Nairobi, NMT is involved in 70% of road accidents). The situation differs in Cape Town, where the modal share of NMT is half what it is in the other two cities.

The ICT background

Mobile networks cover more than 90% of the African population, with more than half also covered by highspeed mobile broadband networks (GSMA, 2017). The transition to mobile broadband is driven by network deployment and expansion, more attractive prices for data transfers, and greater availability and affordability of smartphones. Numbers of subscribers will continue to increase as the population is still very young, and fewer women than men currently own a mobile phone. South Africa is among the top five countries of Sub-Saharan Africa for mobile penetration (all with a penetration rate of 68%-69%): 37.5 million inhabitants are unique mobile subscribers. Kenya ranks 11 th on the subcontinent, with a rate of 59% (28.3 million subscribers) and Ethiopia ranks 34 th with a rate of 34% (34.7 million subscribers) (GSMA, 2017). In South Africa, 52% of the population use Internet versus 47% in Kenya and only 12% in Ethiopia. Telecommunications are an open market in South Africa and Kenya where the main operators are respectively Vodacom, MTN and Cell C; Safaricom, Airtel, and Telkom. In Ethiopia, the industry consists in a monopoly, Ethio-telecom. The Ethiopian government has shut down mobile Internet repeatedly in 2016-2017, to quell anti-government sentiment.

Mobile technology is the only available platform for the majority of the population in Sub-Saharan countries to get online. Therefore, ICT-enabled service innovations mostly rely on mobile technology. Among these services, mobile money is very popular, especially in Kenya. M-Pesa, the very popular mobile money platform of Safaricom contributed 27% of the company's service revenues in 2016 (GSMA, 2017). M-Pesa is still largely used via SMS and USSD, which is driving engagement levels among non-smartphone users.

Parallel to mobile network infrastructures, Africa is also developing tech hubs, i.e. spaces mainly focused on developing a digital entrepreneurship ecosystem, and tech incubators. The World Bank's mapping project for tech hubs and incubators in Africa registered 173 entities as of June 2016, with the greatest contributors being South Africa (32), Kenya (16) and Nigeria (15) (World Bank, 2016b). Depending on the cases, initiatives such as tech hubs and tech incubators can be led by government, civil society, academia, or a combination of them. Through the Kenya Vision 2030 (released in 2007) and the Kenya National ICT Master Plan 2014-2017 documents, the national government has set a clear framework and direction for the ICT industry to develop fast and for the economy to reap the benefits of such development. Nairobi concentrates the vast majority of tech hubs and incubators in the country (World Bank, 2016b), and universities are involved in several of them [interview with a researcher]. In South Africa, the National Integrated ICT Policy White Paper (released in 2016) sets the framework for government support to digital technology hubs nationwide but local initiatives were one step ahead and the civil society has developed several functional tech hubs in Cape Town in particular. In Ethiopia, progress has been slower, but 2 tech hubs have developed, partly supported and funded by the diaspora, that seem to get things moving forward, despite the current restrictions on Internet access [interview with a startup; interview with an NGO].

Intermediate transport services as a key component of urban mobility systems

Paratransit services present common features in the three cities examined here. First of all, the size of the paratransit fleet is comparable among all three cities: about 10,000 minibuses for a 4-million city (see Table 1). Interestingly, the same ratio holds for the 'daladala' minibuses in Dar-es-Salaam, Tanzania, 4 million inhabitants (Rizzo, 2014). Yet, as already mentioned, the modal share of paratransit varies from 15% to 30% in the three cities. This section provides an overview of the history of paratransit services development in the three cities and discusses two of the most prominent common features of paratransit services, namely: their flexibility and their labour-intensiveness.

To the origins of large paratransit fleets

In South Africa and Kenya as in Tanzania, paratransit emerged to address the unmet travel needs of the indigenous population. After independence, the Kenyan government allowed 'private taxis' to operate, first informally then as registered Public Service Vehicles (PSVs) from the 1980s onwards. At the time, the bus and commuter train services, with dated technologies and management, were unable to handle increasing passenger demand. These services eventually collapsed in the 1990s, in a context of structural adjustment programmes, reduced government budgets and privatisation [interview with an operator] (Klopp and Mitullah, 2016). In Cape Town, the minibus-taxi industry developed during Apartheid mostly to carry poor people living in the townships to workplaces in the CBD. It started operating, illegally, to compensate bad commuter train services. Following transport deregulation in 1987, the industry rapidly expanded and overcapacity led to 'taxi wars' (Dugard, 2001;Lomme, 2008). The situation became less violent in the post-Apartheid era. The industry became regulated but the quality of service decreased. Like in Cape Town, attempts at regulating the industry in Nairobi have reduced the violence and the number of cartels and gangs have declined since 2010 (McCormick et al., 2016).

The situation in Addis Ababa is somehow different judging by the historical process, but not so much by the outcome. Because the Italian occupation of Ethiopia was short-lived (1936)(1937)(1938)(1939)(1940)(1941), Addis-Ababa was not moulded by colonial segregation considerations to the same extent as other cities on the continent (Ouallet and Giorghis, 2005). Besides, the city has managed to preserve its public large-bus company, Anbessa, owing to strong public support. Yet, paratransit services in the form of minibus taxis, locally known as 'wuyeyet' (Voukas and Palmer, 2012), have developed alongside public transport to absorb the fast demographic growth of the city.

Flexible transport services to address a diverse demand

The fundamental asset of paratransit services is their essential flexibility. Notwithstanding regulation, paratransit services are, to a greater or lesser extent, flexible in time (no schedule, adaptability to peak and off-peak hours) and in space (no fixed routes, or no fixed stops along routes, adaptable routing in peak/off-peak hours, capacity to reach city outskirts and informal settlements). Depending on the context, on the choice of vehicle, on the fare structure, etc., paratransit is also adaptable to different categories of users, from very poor to middle-income classes. This 'gap-filler' (Cervero and Golub, 2011) provides accessibility to demand segments that are not addressed otherwise.

Matatus in Nairobi are privately run and demand-driven services. They receive no subsidies from public authorities. Fares vary according to the route, the condition and aspect of the vehicle and even the weather [interview with a researcher]. On rainy days, fares could triple on a given journey. This fare structure excludes the very poor from using the minibus services and occasionally encourages the shift of wealthier users to TNC services. Mostly operated by young men, boba-boda moto-taxi services target matatu users who would want to escape traffic jams as well as lower-income customers (as they are cheaper). As their income increases, middleclass users usually switch to private cars or TNCs. Regulations on matatu registration (to be filed through a matatu association) and routes allocation (to link each vehicle licence to a specific route) were made more stringent in 2010 with a view to improving the organisation and quality of service. The National Transport and Safety Authority is currently implementing electronic licensing [interview with an operator].

In Cape Town, local authorities saw in the planning of BRT services an opportunity to replace paratransit services by a trunk-and-feeder network in which all remaining operators would be formal bus companies [START_REF] Behrens | An evaluation of policy approaches to upgrading and integrating paratransit in African[END_REF]. Although some would argue that the current BRT system is a success story -as it is considered the first reliable bus system, with a cost recovery close to 50%, and much appreciated too by some portions of the population [interview with a consultant]-, others criticise it as both over expensive for users and costlier than anticipated for public authorities, as well as inadequate to actual travel needs of the target population. It is inflexible with regards to stops for pick-up and drop-off, not serving some of the poorest, most populated areas, and using very rigid, high-tech ticketing (based on Europay-Mastercard-Visa cards) [interview with a researcher x2]. For these reasons, the minibus-taxi services are still operating on feeder lines for the BRT. The City of Cape Town has recently been operating a shift in perspective, and is now considering the integration of paratransit services into the BRT project [interview with a consultant].

In Addis Ababa, minibus taxi fares are controlled by the city government, and so is the route allocation process. Besides minibus taxis, Higer midi-buses (27 seats) have operated on 24 designated main routes since 2007. They qualify as paratransit as they can flexibly choose their stops along the way (Voukas and Palmer, 2012). With the delays in BRT implementation so far (World Bank, 2014), and the rapid expansion of the city (including major settlement projects far beyond the reach of the LRT system) (Meshesha Fenta, 2014), minibus taxis and other forms of intermediate transport services -such as 'bajaj' auto-rickshaws in the peripheries-play a major role in the supply of transport services in many areas of the city [interview with a researcher]. Besides, congestion on the LRT is already very high and safety (theft) and health (lice) issues have arisen on board the trains, which are reflected in the preference of many passengers for paratransit over LRT [interview with an international institution; interview with a researcher].

Job providers

Local socio-political conditions are considered to have an influence on the development of transport services (Rizzo, 2015). In the type of cities considered here, employment is a major concern and paratransit, being highly labour-intensive, is a valuable source of income to tens of thousands of people locally. Depending on the context, it provides jobs to 'drop-outs' but also graduates (cf. the minibus-taxi industry in Nairobi) [interview with an operator], to township residents as well as immigrants (cf. respectively the minibus-taxi industry and the TNC industry in Cape Town) [interview with a researcher], and thereby contributes to alleviating poverty and empowering low-income populations. The opportunity to 'run their own business' is even the main argument made by Uber in Cape Town and Nairobi to recruit 'driver partners' [interview with an operator].

Contrasting with the common description of a demand-driven, flexible model, some experts would go as far as describing intermediate transport as a 'supply model', where 'the basis of the business is employment' [interview with a consultant]. One particular aspect of this model is the 'target system' -still in use in Cape Town and Nairobi, like in many other contexts (for daladala minibuses in Dar-es-Salaam, see: Jerven and Johnston, 2015; for rickshaw runners in Calcutta, see: Breman, 2003)-, whereby a fixed income amount (target) has to be paid to the owner by the crew daily. Increasing competition for expansion leading to increasing misbehaviour on competitive routes, minimal standards of safety and quality of service have been difficult to uphold. In its shift to integrate paratransit to the BRT system, the City of Cape Town, with support from the University of Cape Town, has organised training sessions for managerial capacity building with minibus-taxi operators, helping them create a reliable service for non-scheduled operations (Schalekamp, 2015). In Nairobi, while there is high compliance with regulations concerning registration, routes, and payments for use of terminals, the matatu industry shows low compliance with regulations related to labour and is reluctant to abandon the 'target system'. The National Transport and Safety Authority plans surprise inspections to control drivers and improve road safety, and offers some support for mechanical training, but no management training yet [interview with a researcher x2].

Major issues are yet to be dealt with for paratransit to remain a key component in future, more sustainable urban mobility systems, including, but not limited to, reckless driver behaviour, poor vehicle maintenance practices, poor management capabilities (Behrens et al., 2016;Pirie, 2014). The following section discusses the role that ICT-based innovations may play in supporting the modernisation, upgrade and expansion of paratransit services in fast-evolving urban mobility systems.

ICT-based innovations

ICTs are now widely acknowledged to be major contributors to the ongoing changes in mobility systems and to offer significant opportunities for further improvement in the overall performance of said systems (TRB Committee for Review of Innovative Urban Mobility Services, 2015). Due to the rapid diffusion of mobile ICTs in the developing world, it has also become a common topic of research over the last decade to explore whether these technologies could 'bridge and connect what is conceptualised as 'North' and 'South'' (Pfaff, 2010).

From the demand-side perspective, ICTs can help individuals make more informed choices, access a greater number of mobility options, be more flexible in their choices of options, have greater trust in the reliability of services, become actors of the supply and quality of service of mobility services, etc. From the supply-side perspective, ICTs can trigger the development of new services, improve the performance of existing services and facilitate the integration among services and modes. Finally, from the regulatory-side perspective, ICTs pose many challenges to regulators by way of the development of new mobility services half-way between public and private (e.g. in terms of infrastructure planning and appraisal, or in terms of right of access to road and parking infrastructure), the rise of a largely informal sharing economy (e.g. in terms of safety regulation, or in terms of tax policy), and the development of unprecedented massive data bases (e.g. in terms of privacy protection, intellectual property and data ownership, dynamic traffic regulation, real-time transport planning).

It can be argued that innovation-readiness is another main asset of paratransit's, besides flexibility and labourintensiveness, in the context of cities in the developing world. This section analyses a wide set of ICT-based initiatives in the paratransit industry in the three cities examined here, to illustrate the role of ICTs in the modernisation, upgrade and possible expansion of the industry.

Mapping networks and tracking operations with ICTs

Because most paratransit services have remained informal for a long time (they sometimes still are) and because they do not operate along precisely-fixed routes or schedules, information about the service provided in a given city by the industry as a whole has long remained impossible to consolidate (e.g. in the form of network maps, or planning tools for multi-legged journeys). Paratransit users would then have to rely on their own expertise or on the expertise of relatives to plan multi-legged journeys. Under such circumstances, it is probable that even public authorities would base regulations on partial data complemented by experience and hearsay.

Most famous of all the paratransit mapping projects, Digital Matatus, an initiative led by a team at MIT, University of Nairobi, Columbia University, and the consulting firm Groupshot, achieved in 2014 the first consolidated visualisation of over a hundred matatu routes serving the city of Nairobi. This project demonstrated the possibility to use cell phones to develop an open source database on non-traditional transit in an adapted version of GTFS (General Transit Feed Specifications) format. The expectation was that, based on the data collected, new technology and services, e.g. transit routing apps, could in turn develop. The collection method involved the creation of a community of users in the field (mostly students), which was also an important result of the project (Williams et al., 2015).

Around the same time the Digital Matatus project was launched, the private company TaxiMap was created in 2013 and started mapping minibus-taxi routes in Cape Town and Durban (more than 600 routes on the website for the two cities). An app was used for data collection, but no crowdsourcing was involved (the founders rode the taxis themselves). The website provides user-oriented information on operating hours, fares, variability of routes (during peak / off-peak hours), exact origin and destination locations (including street view pictures), etc. Update of the information is a challenge, but operations are quite steady over time and user feedback can be used in the process [interview with a start-up].

Following in the footsteps of Digital Matatus, the Cape Town-based company WhereIsMyTransport shifted its business model from developing ICT-based apps (e.g. routing app FindMyWay) to developing an open, integrated platform for transport data (including transit and paratransit) that would serve as a common tool (in the form of an Application Programming Interface) for various stakeholders. The consolidation of data collected from transit operators and from a dedicated collector team (for minibus taxis) enabled the first visualisation of 137 minibus-taxi routes alongside rail and bus networks in Cape Town in early 2017. For minibus taxis, data was proactively collected and later formatted on end-to-end routes, fares and frequencies for weekends, and for peak and off-peak hours on weekdays. Information on route deviation during off-peak hours, as well as common places to get on/off (beyond the rare designated stops), was also collected [interview with a start-up].

Another Cape Town-based start-up, GoMetro, is developing a 'Flexible Mobility Platform', that allows mapping of various kinds of transport services, but is more oriented towards tracking and optimising operations. Data is collected from minibus taxis' clipboard counts and through full-day on-board surveys (using a dedicated app), focusing on boarding / alighting locations, real-time revenue, seat turnover, etc. Data is cleaned and analysed by the platform and can be delivered to the client in different formats [interview with a start-up].

The ride-hailing revolution brought by ICTs

E-hailing platforms have been developing in Africa over the last few years. As of mid-2017, Uber was present in 16 cities, including 13 in Sub-Saharan Africa (Cape Town, Durban, Johannesburg, Pretoria and Port Elizabeth in South Africa; Nairobi and Mombasa in Kenya). After working for 2 years with the authorities at national level to adapt the metered-taxi regulations to e-hailing operations (no requirement of link to an association, no stipulation of the place of origin), Uber started operating in Cape Town in 2015. Uber 'driver partners' in South Africa must have a Professional Driving Permit (PDP), pass a driving evaluation (specifically in Cape Town and Johannesburg), and vehicle documentation must include an operator's permit from the Department of Transport. Yet, in a little over 2 years, Uber had about 7,800 drivers registered on the platform in South Africa. Uber brought much change to the traditional metered-taxi industry in Cape Town, offering a cheaper service, together with upfront information on the fare to be paid, cashless payment and driver rating [interview with an operator].

The same kind of development took place in Kenya, where Uber vehicles must be registered as Public Service Vehicles (PSVs), vehicle documentation must include a business permit, and drivers must hold a PSV driving license. Uber started operating in Nairobi in 2015 (Mombasa in 2016) and two years later had about 4,000 drivers registered on the platform. Smartphone access being a very low barrier to entry in Kenya, Uber chose not to introduce the USSD feature that exists in other developing countries. On the other hand, Nairobi was one of the first pilot cities around the world for Uber to test cash payment, when Uber realised that only allowing credit card payment prevented growth. Mobile payment to the driver (via m-pesa) is feasible, but there is no m-pesa plug-in into the app. Direct payment to the drivers (via cash or m-pesa) make up the vast majority (80%-90%) of transactions, which raises some new challenges for Uber to collect its service fee. Minimum fare as of mid-2017 was 200 KES (1.7 EUR), and 1 in 4 or 5 trips on average were minimum fare. Uber's main competitors locally, beyond the 1,000 metered taxis, is the Kenyan e-hailing platform LittleCab which launched in 2016, and had 5,000 drivers registered as of mid-2017, a mobile payment option (m-pesa is a shareholder) and a portfolio of vehicle options including moto-taxis. Other competitors have developed locally (Taxi5, MondoRide), all displaying only small variations from the Uber app [interview with an operator].

The reasons why Uber does not operate in Addis Ababa are twofold: i) the ICT context is still inadequate (low smartphone penetration, low bandwidth, and more recently mobile Internet shutdown under the 'state of emergency'); ii) national laws do not allow international payments (thereby preventing the automatic payment of the 25% service fee to Uber BV in the Netherlands, as is the platform's model) [interview with an operator]. Yet, two local e-hailing platforms have launched in the Ethiopian capital: ZayRide (500 drivers by mid-2017) and ETTA (close to 100 drivers by mid-2017). One of the challenges, beyond limited Internet access (implying adapted content, e.g. low-resolution pictures), is to find alternatives to credit card payment (low penetration and high cost of swiping devices) and USSD payment (high cost of USSD codes and basic telecommunications due to the monopolistic situation). ETTA has developed a partnership with Wegagen Bank for a prepaid card (the first one specifically made for e-hailing). Another challenge is to seal partnerships with the 'right' taxis or taxi associations, possibly taking advantage of the ongoing renewal of the taxi fleet in the capital. Both companies had to set up conventional call centres after the Internet access was shut down under the 'state of emergency', and as of mid-2017 were hoping to negotiate the reopening of their apps [interview with an operator x2].

Providing real-time information to users with ICTs

With safety and reliability (including time reliability) being two of the major issues facing the users of paratransit services, the provision of real-time information through ICT innovations offers promising prospects to improve the perceived quality of service. To reach the greatest possible number of users, such innovations face the challenge of choosing the adequate support for disseminating the information. The Nairobi-based startup Ma3Route is a spin-off of the Digital Matatus project. They run a crowd-based community that uses very simple phones and performs a real-time information service for matatu users, reporting on traffic conditions and accidents in three different languages through something close to a Twitter feed (using a light-data app). A partnership with NTSA and the Nairobi City Council allows for real-time reporting on bad driving behaviour from matatus as users send the information to Ma3Route [interview with a start-up].

As illustrated by various real-time information initiatives using USSD (e.g. transit traffic information in Cape Town by WhereIsMyTransport), or by the rise of prepaid cards (e.g. for electricity, water, in many cities), lowcost ICT solutions offer major perspectives for improving the perceived quality of service among paratransit users in cities where the cost of smartphones or the cost of data is still sensitive [interview with a start-up].

Discussion and conclusion

Surely enough, ICT-based modernisation of paratransit services in the cities examined here has its challenges, as illustrated by the decision of ride-hailing start-ups ZayRide and ETTA in Addis-Ababa to set up conventional call centres after the Internet shutdown under the 'state of emergency' [interview with an operator x2], or by the decision of Uber to introduce cash payment in Nairobi (despite the widespread use of m-pesa mobile payment) [interview with an operator], or yet by the postponed implementation of the cashless fare collection requirement for minibus-taxi licenses in Cape Town (Behrens et al., 2017). The adaptation of ICT-based solutions for mobility to local contexts -taking into account the penetration of mobile Internet, the types of mobile used, the quality of Internet access, the cost of voice, text and data communications, etc.-, is a crucial challenge for their development and massive adoption in cities of developing economies. Yet, the portfolio of innovations is so diverse, and the potential for performance improvement in paratransit so great (both from an operator perspective and from a user perspective), that it seems a fair assumption that ICT-based innovations will contribute to the modernisation, upgrade and expansion of paratransit services. Which forms of paratransit services will most benefit, what type of customers the upgraded services will serve, and what kind of economic, social and environmental benefits will be derived from such developments, are questions yet to be answered.

From a social perspective, under certain conditions of design, ICT-based innovations can foster the empowerment of both, users -through increased participation in the production of the service, including its safety and reliability features-and drivers -through increased productivity (and revenues) allowed by the facilitation of customer access and navigation (Eskenazi and Boutueil, 2016). Again depending on design options, ICT-based innovations can even enable the creation of communities around particular services. Some consideration should however be given by policy makers to the type of labour organisation (i.e. employment model, wage structure, contractual relations, etc.) that the ICT-based solutions will help promote. Additional concerns have been voiced that ICT-based mobility solutions in the form of TNC services would mostly serve in developing countries the needs of a growing middle and upper-class market (Schechtner and Hanson, 2017).

From an environmental perspective, the benefits to be expected from a consolidation or an expansion of paratransit services, will depend on both, the types of services concerned and the operational options taken by said services. Efficient paratransit services in cities of developing countries could help contain the rise in private car ownership and use (with a modal share currently ranging from 10% to 30%, as compared with 80% in cities of developed countries). On the other hand, uncontrolled development of some paratransit services could prove detrimental to more traditional transit modes (bus, light rail or metro) if they ended up competing for the same market and the same urban space without an adequate framework to effectively account for the respective merits and externalities of all modes. Besides, the renewal of paratransit service fleets (mostly second-hand, imported vehicles, some even at end-of-life) has a part to play in the overall sustainability performance of the industry. It is worth noting that vehicle-scrapping policies in several countries or cities in the developing world have targeted taxi and collective taxi fleets (e.g. in Morocco, Cairo, Egypt or Dakar, Senegal). In this direction, international lenders would seem positively inclined towards dealing with paratransit services.

Table 1 .

 1 Key data on the three cities For Nairobi: Kenya National Bureau of Statistics -Census 2009 & Nairobi City County Statistical Abstract 2015, JICA, 2014 (2013 modal share); for Cape Town: Transport for Cape Town, 2015 (2013 modal share); For Addis Ababa: Addis Ababa city government 2012 (2006 modal share), World Bank, 2016, Addis Fortune, 2015 and 2017.

		Nairobi	Cape Town	Addis Ababa
	Perimeter	Nairobi City County	City of Cape Town	City of Addis Ababa
	Population (million inh.)	3.1	3.7	3.3
	Area	696 km 2	2,445 km 2	540 km 2
	Mini/midi bus fleet	~10,000	7,576	~10,400
	Metered Taxi/TNCs fleet	> 9,000	n.a.	> 6,500
	Trips/day/person	2.34	2.37	1.02
	Public transport share	40%	41%	46%
	Incl. Mini/midibus share	28%	15%	34%
	Private mode share	19%	37%	9%
	NMT share	42%	21%	44%
	Sources:

Acknowledgements

This research was funded by the Sustainable Mobility Institute Renault-ParisTech (IMD), as part of the NexMob research project undertaken by LVMT (City Mobility Transport Lab) on car-based mobility in the service era. The authors are very grateful to the researchers and representatives of local authorities, transport operators, NGOs, consultancies, and start-ups, who contributed their knowledge to this project. All responsibility for the content of this publication is assumed by the authors.

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Vincent Escande

Alicia Velati

Claire Garel

Brice-Loïc Renard

Eddy Petit

Claude Grison
email: claude.grison@cnrs.fr

Phytoextracted mining wastes for Ecocatalysis: Eco-Mn ® , an efficient and eco-friendly plant-based catalyst for reductive amination of ketones

The rehabilitation of contaminated soils from phytoextraction technologies and the chemical recovery of subsequent biomass constitute a new strategy for the recycling of vital minerals required by industrial chemistry. Plant wastes derived from phytoextraction constituted the raw material for the preparation of eco-friendly catalysts for organic synthesis, namely Ecocatalysis. Eco-Mn ® was thus prepared starting from native plants used for rehabilitation of New Caledonian mining sites. Eco-Mn ® revealed an original polymetallic composition resulting in marked Brønsted and Lewis acidities and displayed superior catalytic performances than classical Mn salts, as highlighted by infrared study of pyridine desorption and model test reactions. The performances of Eco-Mn ® were illustrated by the reductive amination of ketones, in solvent-free conditions, with the easily prepared and safe Hantzsch ester (HEH) as reducing agent. A beneficial influence of water was observed with a model MnCl 2 -catalyzed reaction. Investigation of this effect revealed that water was specifically involved in the second step of the reaction, by activating both the imine substrate and the reducing agent. Finally, the Eco-Mn ® /HEH methodology was applied to the reductive amination of various ketones and amines, giving good yields of products (up to 99%), including two precursors of pharmaceutical compounds.

Introduction

The sustainable access to elemental supply has become a growing concern in recent years. The global increasing of living standards and the continuous growth of the world population lead to a rapid decreasing of the available reserves of many mineral resources, which will be exhausted in less than 50 years. [START_REF] Hunt | Element Recovery and Sustainability[END_REF][START_REF] Salazar | Mineral Commodity Summaries 2013[END_REF] This situation is particularly critical for some transition metals, such as zinc, nickel, manganese and platinum group elements (PGE), frequently used in industrial processes as catalysts with unique chemical properties. [START_REF] Lloyd | Handbook of industrial catalysts[END_REF] Chemical requirements for these non-renewable resources are increasing steadily, which explains the diminishing exploitable availability. Because of this phenomenon, elements become notably dispersed in the environment, which results in pollution issues and is a supplementary problem. [START_REF] Kabata-Pendias | Trace elements in soils and plants[END_REF][START_REF] Widmer | [END_REF] In several countries, governmental authorities have decided to develop innovative technologies of recycling, in order to tackle this increasing concern. Numerous efforts are thus devoted to the elaboration of large-scale recycling processes, adapted to low concentrations of elements, present in complex and varied environments. [START_REF] Graedel | Recycling Rates of Metals -A Status Report, A Report of the Working Group on the Global Metal Flows to the International Resource Panel[END_REF] Promising research areas have recently emerged, such as biomining, a technology that uses microbes to recover metallic elements from ores or wastes. [START_REF] Schippers | Geobiotechnology I[END_REF][START_REF] Brandl | [END_REF] Another example is the recovery of metals from electronic wastes, in particular through the use of plasma technology. 9,10 As regards the recovery of metallic elements dispersed in soils, phytoextraction is an effective phytotechnology which relies on the use of so-called metal-hyperaccumulating plants, able to extract metallic elements from the soil and concentrate them in their leaves. [START_REF] Raskin | Phytoremediation of toxic metals: using plants to clean up the environment[END_REF][START_REF] Anderson | Element Recovery and Sustainability[END_REF] Phytoextraction is well appropriate to the treatment of large surfaces of soils where the concentration in metallic trace elements (TE) is too low to be recovered by the classical mining processes in a cost-effective fashion. [START_REF] Losfeld | [END_REF][14][15] Moreover, phytoextraction is among the less costly technologies of soils remediation and has a good public acceptance. 16 It leads to develop a vegetative cover, which forms a protection against wind and water erosion of TE. However, TE concentration is high enough to cause environmental problems and to generate new wastes. 17 Previous works of our group have led to the emergence of the new concept of Ecocatalysis, which lies on the recovery of metal-hyperaccumulating plants, growing on contaminated and degraded soils, as raw material for the preparation of innovative metallic catalysts for organic synthesis. [18][19][20][21] The concept of Ecocatalysis is thus a novel way of recycling of metallic elements dispersed in soils due to past or present industrial activity, such as mining. Ecocatalysis allows the valorization of problematic and toxic wastes into a novel metallic resource for organic chemistry, being thus an opportunity for green chemistry and for the development of a new circular economy (Fig. 1). As Ecocatalysis enables the exploitation of a new resource of metals while contributing to the rehabilitation of polluted and degraded sites, this approach fits fully with the objectives of green chemistry by not only preventing environmental problems, but solving current pollution problems. This concept answers thus to a challenge proposed by P. Anastas and J. C. Warner, since the beginnings of green chemistry. [START_REF] Anastas | Green Chemistry: Theory and Practice[END_REF]

Fig. 1 General concept of transformation of metal-enriched biomass into ecocatalysts

The diversity of metal hyperaccumulating plants and the specificity of phytoextracted metallic elements lead to the original compositions and properties of the ecocatalysts. The resulting ecocatalysts display unusual properties, and often higher than those of the corresponding "classical" metallic salts. [START_REF] Escande | [END_REF][24][25] In previous reports, we have highlighted the performances in terms of selectivity and efficiency of various ecocatalysts, named Eco-M ® (where M is the metal predominantly accumulated by the plant), such as Eco-Zn ® , Eco-Ni ® , Eco-Mn ® , Eco-Cu ® … 14,[26][27][28][29][30][31] These ecocatalysts, as polymetallic catalysts, are thus often active with low catalytic loadings thanks to synergy phenomena between their constitutive metallic elements, with high potential for green chemistry. 32 This is especially the case for the Eco-Mn ® catalyst, which has demonstrated substantially higher efficiency as catalyst for oxidation reactions and Lewis acid catalyzed reactions, than the commercial Mn simple salts. 27 This Eco-Mn ® catalyst is very promising for applications in green chemistry. The element manganese is non-toxic and among the most abundant transition metals in the Earth's crust. [START_REF] Greenwood | Chemistry of the elements[END_REF][START_REF] Gerber | [END_REF] Whereas manganese has been extensively studied for its properties in oxidation reactions, the activity of its derivatives in Lewis acidcatalyzed reactions has received paradoxically little attention. [START_REF] Arndt | Manganese compounds as oxidizing agents in organic chemistry[END_REF][START_REF] Browne | Modern oxidation methods[END_REF][START_REF] Lee | The Chemistry of Organomanganese Compounds[END_REF] In the course of our studies of Lewis acid properties of the Eco-Mn ® catalyst, we report here its high catalytic efficiency in promoting reductive amination reactions.

Reductive amination gives access to substituted amines by the condensation of a carbonyl compound and an amine, followed by the reduction of the formed imine or iminium. This reaction provides a practical and general way of synthesis of a broad range of building blocks for organic synthesis and of industrially important compounds, such as pharmaceuticals or agrochemicals. [START_REF] Gomez | [END_REF][39][40] Reductive amination requires the use of a reducing agent, which is a delicate question regarding the exigencies of green chemistry, as most of the classical reducing agents are associated with toxicity or safety issues. [START_REF] Abdel-Magid | Reductions in organic synthesis : recent advances and practical applications[END_REF][START_REF] Andersson | Modern reduction methods[END_REF] A typical example is sodium borohydride, widely used in various reduction reactions including reductive amination, [START_REF] Baxter | Reductive Aminations of Carbonyl Compounds with Borohydride and Borane Reducing Agents[END_REF] but which is highly toxic and generates sodium borate as by-product, whose reproductive and developmental toxicity is well documented. [START_REF] Moore | Expert Scientific Committee[END_REF]45 For such safety reasons, the European Chemicals Agency lists an increasing number of boron derivatives among the substances of very high concern requiring an authorization for their use in industrial processes, according to the European regulation REACH (Registration, Evaluation, Authorization and Restriction of Chemicals). [START_REF]Candidate List of Substances of Very High Concern for Authorisation[END_REF] In the context of evolution of chemistry toward sustainable processes, safe and non-polluting reduction methods are thus highly needed. Hydrogen is one of the greenest reducing agents, often described in reductive amination reactions. [START_REF] Gomez | [END_REF] However, its use is not only associated with safety issues but hydrogenation requires also catalysts predominantly based on precious metals such as Pd, Pt and Rh, which are rare and highly expensive. Boron hydrides alternative to NaBH 4 have also been proposed as reducing agents in reductive amination, such as NaBH 3 CN, [START_REF] Barney | [END_REF] NaBH(OAc) 3 , 48 Pyridine-BH 3 , 49 but they are equally associated with toxicity and safety issues. In recent years, greener reducing reagents have been proposed for reductive amination, such as silanes and formates, but they still need catalysts based on rare or toxic metals, or whose manipulation is hazardous. [50][51][52][53] Another method of reductive amination, inspired by biomimetic concepts, implies the use of 1,4dihydropyridines as reducing agents, more particularly the Hantzsch ester (HEH, also named ethidine or diludine), easily prepared in large quantities from affordable reagents. 54,[START_REF] Bechara | e-EROS Encyclopedia of Reagents for Organic Synthesis[END_REF] As the Hantzsch ester and its by-product have also the advantage of being non-toxic and safe to manipulate, an abundant literature has been devoted to reductive amination using this reagent with various catalysts, such as Mg(ClO 4 ) 2 , 56 ZrCl 4 , 57 Sc(OTf) 3 , 58 gold and silver complexes, 59 nucleotide model, 60 chiral phosphoric acids, [61][62][63][64] combined Brønsted acid and transition-metal 65 and thioureas. [66][67][68][69][70] Interestingly, in a recent paper researchers from GlaxoSmithKline selected the system HEH/Sc(OTf) 3 as one of the greener reductive amination method for industrial application. 71 However some of these catalysts were adapted only to the reductive amination of aldehydes. Moreover, regarding the green chemistry exigencies, such catalytic systems have still some limitations, such as their toxicity, their difficulty of preparation or the use of very expensive metals. We show here that Eco-Mn ® has a high potential in green reductive amination with HEH, as biosourced catalyst based on a non-toxic and abundant element, in solvent-free conditions, and that this methodology is adapted to the reductive amination of less reactive substrates such as ketones.

Results and discussion

Catalyst preparation and characterization

Eco-Mn ® was obtained by thermic treatment, followed by treatment with diluted hydrochloric acid, of leaves of Grevillea exul rubiginosa (Proteaceae) a native plant used for phytoremediation of contaminated mining sites in New Caledonia. As shown by ICP-MS study (Table 1), Eco-Mn ® , obtained under the form of powder, is a polymetallic catalyst with Mn as the major transition metal. The reproducibility of composition of similar ecocatalysts was studied in a previous article, and showed that the levels of transition elements are only slightly variable between samples derived from different plants of the same species. [START_REF] Escande | [END_REF] In particular, results show the necessity of considering leaves age in the design of sample collection to obtain a constant TE content in batches of Eco-Mn ® . 15 Eco-Mn ® was prepared from several batches of G. exul rubiginosa in order to homogenize the content and minimize possible variations in the composition. Updated data on Mn-hyperaccumulating and accumulating plants from New Caledonia have been presented in some recent papers of our group, aimed at producing Eco-Mn ® catalyst on industrial scale in view of its commercialization. [START_REF] Losfeld | [END_REF]72,73 XRD analysis of Eco-Mn ® (Fig. 2) was performed to investigate crystalline species present inside the catalyst. XRD showed unusual polymetallic complexes in Eco-Mn ® , mainly CaSO 4 (H 2 O) 0.5 , CaMg 2 Cl 6 (H 2 O) 12 and KMnCl 3 . KMnCl 3 is a masked form of MnCl 2 , which also indicates that Mn is present under the oxidation state Mn(II). XRD did not reveal the presence of molecules containing Fe or Al, which were detected by the elemental analysis. This was probably due to the non-crystalline nature of these species within the Eco-Mn ® catalyst. As regards the oxidation state of iron in Eco-Mn ® , a colorimetric test with ammonium thiocyanate demonstrated that iron was present under the oxidation state Fe(III) in the catalyst. 74

Fig. 2 XRD diffraction pattern of Eco-Mn

According to XRD analysis, Eco-Mn ® is made of several Lewis acid complexes, thus its Lewis acid properties might be unusual. Lewis acidity of Eco-Mn ® can be first characterized by its strength. A test reaction, the ene-cyclization of the monoterpene (+)-citronellal into isopulegol isomers, was used here to monitor the acidity of Eco-Mn ® catalyst and compare it with commercial manganese chloride catalysts, by discriminating these catalysts according to the strength of their Lewis acidity. Such insight is important to rationally design our ecocatalysts and has been previously applied in the literature to Cu catalysts via experimental and theoretical approaches. [START_REF] Alaerts | [END_REF]76 This reaction shows a complex selectivity pattern, as (+)-citronellal can be converted to four diastereomers, namely (-)-isopulegol, (+)-isoisopulegol, (+)-neo-isopulegol, and (+)-neoiso-isopulegol (see supporting information scheme S5). The synthesis of (-)-isopulegol as the major isomer in this reaction is well documented. With Lewis acids, high selectivities of (-)-isopulegol can be reached, especially when supported metal halides are used. 77 The carbonyl bond is activated by the Lewis acid, leading to a transition state which is similar to (-)-isopulegol, yielding the highest positive charge on the carbon of the carbonyl group and favoring therefore the nucleophilic attack of the C=C bond. With Brønsted acids, the ratio of (-)isopulegol to the other isomers is usually significantly lower than with Lewis acids, but (-)-isopulegol is still the most abundant isomer. 78,79 In a previous article on the development of Eco-Mn ® catalysis, our group has shown that this plant-based Mn(II) catalyst was a very efficient catalyst in the carbonyl-ene cyclization of (+)citronellal into isopulegol (95 % yield with 90 % of (-)-isopulegol with only 2 mol% of Mn in dichloromethane and in 0.5 h). 27 The selectivity is higher with Eco-Mn ® than those obtained with other transition metal chlorides described in the literature such as: ZnCl 2 supported 77 or not, FeCl 3 , AlCl 3 , SbCl 3, SnCl 4 , TiCl 4 , 80 CuCl 2 [START_REF] Alaerts | [END_REF] (see supporting information Table S5). As none of the multitude of articles related to the ene-cyclization of citronellal refers to manganese-based catalysts, the Lewis activity of Eco-Mn ® has been experimentally compared to those of commercial Mn catalysts, such as anhydrous MnCl 2 and MnCl 2 .4H 2 O. Whereas the reaction is complete in 0.5 h at room temperature with Eco-Mn ® , almost no conversion was observed with the classical Mn catalysts even when hard conditions were used (heating in toluene). So this strong Lewis activity of Eco-Mn ® should be due to its unusual polymetallic composition highlighted by ICP-MS analysis (Table 1). Supplementary studies appeared to be essential to evaluate and describe more specifically Lewis acid properties of Eco-Mn ® .

Thus, these first results were completed by another method: the infrared characterization of adsorbed pyridine on catalysts. Pyridine is widely used as a probe to investigate Lewis and Brønsted acid properties by monitoring its infrared bands in the range of 1400-1660 cm -1 . 81,82 Infrared spectra of pyridine adsorbed on Eco-Mn ® and commercial anhydrous MnCl 2 recorded after outgassing at 25°C and at 150°C are presented in Figure 3 (a study after outgassing at higher temperatures than 150°C, did not give more useful information). Lewis acidity of Eco-Mn ® was evidenced here by the infrared band at 1446 cm -1 characteristic of pyridine strongly bonded to Lewis acid sites, 81,82 observed after outgassing at 25°C. However, the intensity of this band was strongly reduced after the outgassing at 150°C, while new infrared bands in the range of 1531-1537 cm -1 appeared, which are characteristic of pyridinium ion, as well as bands at 1630-1635 cm -1 (but these latter bands are ambiguous as they also might be attributed to pyridine bonded to Lewis acid sites). 82 This Brønsted acidity is due to the presence of CaMg 2 Cl 6 (H 2 O) 12 in Eco-Mn ® , highlighted by XRD analysis: water molecules might be responsible for the hydrolysis of Lewis acids in Eco-Mn ® , especially at high temperature, leading to protons formation and so to a Brønsted acid character. This was proved by comparing the infrared characterization of adsorbed pyridine on pure synthetic KMnCl 3 , CaSO 4 (H 2 O) 0.5 and CaMg 2 Cl 6 (H 2 O) 12 , the three salts identified by XRD, which are present in Eco-Mn ® (see supporting information Fig. S7). Only CaMg 2 Cl 6 (H 2 O) 12 displayed Brønsted acid character, and is thus responsible for the Brønsted acidity observed with Eco-Mn ® . Thus after outgassing at 150°C, the Lewis acids were mainly hydrolyzed and only pyridinium ion became visible. The infrared spectrum of adsorbed pyridine on the mixture of the three salts present in Eco-Mn ® was really closed to the spectrum observed with Eco-Mn ® (Fig. 3), which showed that these salts are mainly responsible for the Lewis and Brønsted acid properties of Eco-Mn ® .

Figure 3 IR spectra of pyridine adsorbed on Eco-Mn ® and on commercial or synthetic salts constitutive of Eco-Mn ® , recorded after outgassing at 25°C and 150°C

Conclusions obtained both with the synthesis of isopulegol and with the infrared characterization of adsorbed pyridine were supported and completed by using a third method, implemented and tested by Corma et al., 83,84 which consists in studying the rearrangement pathway of the cyclic acetal of α-bromopropiophenone in the presence of catalysts. By studying the selectivity of products, the hardness of the Lewis acidity (according to HSAB principle 85,86 ) of different catalysts can be assessed and compared. According to conversion rates (see supporting information Table S9), Eco-Mn ® is more active than commercial manganese chlorides on cyclic acetal, which well supports results obtained with the synthesis of isopulegol, about the strength of the Lewis acidity of Eco-Mn ® . The Brønsted acidity of Eco-Mn ® was also shown by this method, which confirmed the infrared study of adsorbed pyridine. The high selectivity of products from the Brønsted acid pathway indicated that commercial MnCl 2 .4H 2 O generates a stronger Brønsted acid character than anhydrous MnCl 2 in the reaction conditions. This corroborates the hypothesis formulated previously about the role of water molecules in hydrolysis of metal chlorides and in appearance of a Brønsted acid character. Finally, this method revealed that Lewis acidity of Eco-Mn ® is harder than the one of commercial manganese chlorides, which are considered as hard Lewis acids by HSAB theory. 87 The higher hardness of Lewis acid sites of Eco-Mn ® probably results from the presence of additional elements such as calcium or magnesium highlighted by ICP-MS analysis (Table 1), which are known to be hard Lewis acids. 87 2. Reductive amination with Hantzsch ester catalyzed by Eco-Mn ®

Reductive amination of ketones

The selected reducing agent, HEH was synthesized following a known procedure, by simply refluxing paraformaldehyde, ethyl acetoacetate and ammonium acetate in water for 2 hours, without the need for any catalyst. 88 HEH was thus obtained with 87% yield (Scheme 1). The product was collected by filtration and was of sufficient purity to be used without further purification. We however observed that it was preferable to prepare HEH in the dark, as this 1,4-dihydropyridine is somewhat light-sensitive.

Scheme 1 Chromatography-free preparation of HEH in water

We began our study by verifying that the reductive amination of aldehydes by HEH does not need any catalyst when performed in solvent-free conditions. However, when applied to ketones, the same reaction was sluggish and limited to the more reactive substrates, affording satisfactory yields only after 24 to 48 hours, at 150°C. 90 This was a clear indication that a catalyst was desirable to perform the solvent-free reductive amination of ketones with HEH, with moderate heating and in reasonable reaction time. Our first attempts involving cyclohexanone 1a and aniline 2a showed that Eco-Mn ® catalyst dramatically accelerated the reaction, as the product 3a was obtained in 96% yield, after only 1 hour at 80°C. Eco-Mn ® was remarkably efficient, as it was possible to lower the catalytic loading to 0.25 mol%, without affecting its performances (Table 2, entry 3). A blank test clearly indicated that the reaction was not possible without catalyst in the selected conditions (Table 2, entry 1). In order to place these results in context, a comparison was made with previously described methods of reductive amination on the same substrates (Table 2, entries 4-11). This overview of various reducing agents and catalysts highlighted the advantages of the proposed methodology, avoiding the use of toxic reagents and of rare and expensive metals as catalysts. Moreover, the high catalytic loadings, harmful conditions and long reaction times, often used whereas they are not compatible with green chemistry exigencies, are not necessary with the Eco-Mn ® /HEH methodology. The catalytic efficiency of the Eco-Mn ® catalyst was compared to classical Mn salts, under the form of chlorides, which are the majority anions in the plant-based Eco-Mn ® . In order to better highlight the differences between the catalysts, the reaction was performed on the less reactive 3-methyl-2-butanone 1b. Reaction conditions were adjusted to 1 mol% of Mn, 110°C, 4 h, to observe a sufficient conversion with all the tested Mn salts. In these conditions, fair yields of product 3b were obtained with commercial Mn chlorides, which confirmed that the activity of Eco-Mn ® was due to its Mn content (Table 3, entries 1-3). However, Eco-Mn ® conducted to significantly higher conversion than commercial Mn chlorides, illustrating the original properties of the polymetallic complexes in the plant-based catalyst. Our previous IR/pyridine study (section 1. "Catalyst preparation and characterization") of the synthetic mixture of KMnCl 3 , CaSO 4 (H 2 O) 0.5 and CaMg 2 Cl 6 (H 2 O) 12 showed nearly the same pattern than Eco-Mn ® , suggesting that the mixture should have the same catalytic properties. However, the synthetic mixture proved to be extremely hygroscopic and practically impossible to use in the same conditions than Eco-Mn ® . An attempt of reaction of reductive amination with the synthetic mixture did not give any results, probably for this reason. This extremely hygroscopic character may be attributed to CaMg 2 Cl 6 (H 2 O) 12 which is described in those terms in several papers. 91 As Eco-Mn ® did not display such properties and can be manipulated without anhydrous atmosphere, its stability may be due to particular structure of its constituents or to other species not identified yet. This was confirmed by a test with a "reconstituted" Eco-Mn ® , prepared by mixing commercial chlorides of K, Mg, Ca, Al, Mn, Fe and Ni, in the same proportions than in Eco-Mn ® , following its ICP-MS analysis (Table 1). The same yield than with sole MnCl 2 .4H 2 O was obtained (62%, Table 3, entries 3-4), which is slightly inferior to the value obtained with the plantbased Eco-Mn ® (67%, Table 3, entry 1). This showed that the catalytic performances of plant-based Eco-Mn ® are specific to its particular polymetallic associations, and cannot be explained by a simple sum of activities of classical metal chlorides. Interestingly, a noticeable difference in conversion was observed between anhydrous MnCl 2 (3b yield: 49%) and MnCl 2 .4H 2 O (3b yield: 62%), which indicated that the presence of water seemed beneficial for the reaction. This result was counter-intuitive since following the mechanism of reductive amination, the presence of water is unfavorable to the formation of the imine in the first step of the reaction. However, our previous characterization of the catalytic activity of MnCl 2 .4H 2 O in the rearrangement and hydrolysis of ethylene acetal of 2-bromopropiophenone indicated that this salt demonstrates a marked Brønsted acidity, probably because of a partial hydrolysis of MnCl 2 , forming Mn hydroxides and protons (see supporting information S9). Following this reasoning, the simultaneous presence of water and MnCl 2 could become an advantage, since the formed protons could catalyzed the formation of imine and, by protonating it, they could favored its reduction thanks to electrophilic activation. We tested this hypothesis by using as catalyst a mixture of anhydrous MnCl 2 and HCl (aq) (1 mol% of both species) in order to reproduce the simultaneous Lewis and Brønsted acidity assumed with MnCl 2 .4H 2 O (Table 3, entry 5). Interestingly, the conversion was indeed higher (55% yield) than with the sole anhydrous MnCl 2 (49% yield), whereas being slightly lower than with MnCl 2 .4H 2 O (62%). In order to determine if this difference can be explained by another effect of water on the reaction mechanism, we decided to investigate the influence of the amount of water, starting with anhydrous MnCl 2 . a Reaction conditions: 1 mmol 1b, 1 mmol 2a, 1.1 mmol HEH, neat, 110°C, 4 h. b Eco-Mn ® and "reconstituted" Eco-Mn ® loadings calculated in Mn mol%. c Yields determined by GC-MS after calibration with an internal standard. d In all cases, less than 5% of residual imine were detected. e "Reconstituted" Eco-Mn ® prepared by mixing commercial chlorides of K, Mg, Ca, Al, Mn, Fe and Ni, in the same proportions than in Eco-Mn ® , following its ICP-MS analysis. f 0.83 µL of 12 M HCl(aq) were added (1 mol% of HCl).

Influence of water on the MnCl 2 /HEH reductive amination of ketones

The reaction was thus performed with anhydrous MnCl 2 with increasing amounts of water (Fig. 4). Starting with a yield of 49% in anhydrous conditions, an optimum was reached when 10 mol% of water was added, giving 59% yield. Higher amounts of water led to a marked decrease of the conversion, probably because the excess of water became too unfavorable for the imine formation. Characterization of MnCl 2 hydrated by controlled addition of water (in 1:10 proportions, following the optimized reaction conditions) was attempted by infrared study of pyridine desorption and model test reactions described above (section 1. "Catalyst preparation and characterization"). However, hydrated MnCl 2 in these conditions displayed only a slightly higher Brønsted acidity than anhydrous MnCl 2 (see supporting information S9). To better understand if the addition of water specifically favored the first step of imine synthesis or its reduction by HEH (the second step), we decided to study these two reactions separately. The influence of MnCl 2 and H 2 O was first examined on the formation of imine 4a, by reacting 3methyl-2-butanone 1b with aniline 2a, without addition of the reducing agent, HEH (Table 4). The obtained results showed that the addition of water seemed to have no overall effect on the imine formation, since the same yield of 4a (30%) was obtained with anhydrous MnCl 2 , MnCl 2 plus 10 mol% of water, and with Eco-Mn ® . Such observation can be the result of two opposite effects of the addition of water, which on the one side promoted the reaction thanks to the formation of protons by MnCl 2 hydrolysis, but on the other side, which also prevented the imine formation, since water is a product of the reaction. The overall observation suggested that these two effects canceled each other out. It is therefore likely that the beneficial effect of the addition of water relates to the second step of the reaction, namely the reduction of the formed imine. However, imine 4a proved to be quite unstable and difficult to isolate, therefore it was not possible to obtain experimental results demonstrating a definite effect of water on its reduction by HEH. We thus envisioned investigating the influence of water on the reduction step by following not the imine, but the transformation of the reducing agent. Indeed, previous studies reported that several reduction reactions using HEH or similar 1,4-dihydropyridines were significantly accelerated in presence of water. [98][99][100] The most frequent explanation proposed for this observation is an activation of the substrate by hydrogen bond formation, stabilizing the transition state. It was equally possible that the water addition contributed to increasing the reactivity of the reducing agent HEH, by favoring its oxidation and thus the substrate reduction, namely the imine. a Reaction conditions: 1 mmol 1b, 1 mmol 2a, 1 mol% Mn-catalyst, neat, 110°C, 1 h. b Eco-Mn ® loading calculated in Mn mol%. c Yields determined by GC-MS after calibration with an internal standard.

We thus studied the combined effect of water and Mn catalysts on HEH activation, whose oxidation was followed in the conditions of the reductive amination, but in contact with air as oxidizing reagent (Scheme 2 and Fig. 5). After heating HEH for 1 hour at 110°C in open reactor, only 16% of pyridine resulting of the oxidation was observed. The addition of 10 mol% of water slightly increased this proportion to 20%. A more marked effect was observed when anhydrous MnCl 2 or Eco-Mn ® were added, resulting respectively in 46% and 50% of oxidation product.

Scheme 2 Model oxidation of HEH by air, catalyzed by Mn-based catalysts in presence of water The maximum proportion of pyridine (58%) was obtained when HEH was heated in presence of MnCl 2 (1 mol%) and water (10 mol%), the same conditions that used for reductive amination. This result confirmed that the addition of water, in presence of Mn chloride, played a role in the activation of HEH, which became thus more reactive toward the substrate subjected to reduction. Water has thus probably a beneficial effect specifically on the reduction step of the reaction, for two reasons: first, probably by forming hydrogen bonds or by protonating the imine which thus become more electrophilic, and secondly by activating HEH, and thus fostering its oxidation by the preformed imine.

Since Eco-Mn ® demonstrated the higher efficiency in catalyzing the reductive amination of 3-methyl-2-butanone 1b and aniline 2a (67%, Table 3, entry 1), addition of water to Eco-Mn ® could have increased its efficiency, as revealed for MnCl 2 . However, such effect was not observed: the yield of 3b was quite unchanged, probably because Eco-Mn ® was already sufficiently hydrated, as shown by XRD (see Fig. 2) or by infrared characterization of the solid powder (an intense band at 3400 cm -1 , characteristic of water was observed for Eco-Mn ® ). Amount of water (mol%)

Yield of 3b (%)

Scope of the methodology

In order to prove the applicability of the Eco-Mn ® /HEH methodology, several ketones and amines were submitted to the previous reaction conditions (Table 5). The different ketones tested (aliphatic or cyclic ketones 1a-c and acetophenone 1d) provided good yields when reacted with aniline 2a (67-97%, Table 5, entries 1-2 and Table 3, entry 1). Aliphatic and cyclic amines 2b-c can also be reacted with these ketones, affording very good yields of products 3e-h (88-96%, Table 5, entries 3-6). Both anilines with electronwithdrawing and electron-donating groups afforded the desired products, in good yields with cyclic ketone 1a (95-99%, Table 5, entries 7, 9, 11), whereas the yields were moderate on aliphatic ketone 1b, less reactive (38-67%, Table 5, entries 8, 10, 12). a Reaction conditions: 1 mmol ketone, 1 mmol amine, 1.1 mmol HEH, 1 mol% Eco-Mn ® (calculated in Mn mol%), neat, 110°C, 4 h. b Yields determined by GC-MS after calibration with an internal standard. Values between parentheses are isolated yields (flash chromatography).

The presence of cations from Eco-Mn ® has been studied in the products of reaction, by ICP-MS analysis. This investigation showed that only traces of K, Mg, Ca and Al were detected in the final purified products, with contents inferior to 510 ppm (maximum detected value, for Ca). Other metallic elements were present in quantities inferior to 5 ppm (see supporting information S13).

Finally, it was of interest to apply the presented methodology to the preparation of compounds of known interest. We thus selected the synthesis of secondary amines deriving from 2-tetralone and 2indanone, as precursors of pharmaceutical compounds. Compound 3o has been signaled as a pharmacophore of antifungal agents, since it inhibits fungal CYP51, a member of the cytochrome P450 superfamily. 101 This compound was also reported to be the characteristic skeleton of dermal anesthetic drugs. 102 Aminoindane compounds such as 3p have been studied as precursors of cationic sodium channel blockers implied in the activity of nociceptor neurons, in treating pain. 103

Fig. 6 Application of the proposed methodology to the preparation of precursors of pharmaceutical compounds By applying the proposed Eco-Mn ® /HEH methodology, both compounds were synthesized on 1 g scale, in good yields (67 and 79%, Figure 6).

Conclusion

In conclusion, we have shown that pioneer plants used in the mining soil rehabilitation can be recovered as raw material for the production of ecocatalysts. This concept allows to turn wastes derived from phytoextraction into a mineral and sustainable resource for an eco-friendly and innovative organic synthesis. Eco-Mn ® was thus prepared from plants growing in New Caledonia, on Mn-rich degraded soils. The catalyst was successfully employed in the reductive amination of ketones, with HEH as an affordable, safe and easily prepared reducing agent, in a solvent-free methodology and in short reaction times (1-4 h). Eco-Mn ® showed a high catalytic efficiency, since a 96% yield of product can be obtained with only 0.25 mol% of catalyst, on the model reaction between cyclohexanone and aniline. Comparison with commercial chlorides of Mn and others elements present in Eco-Mn ® demonstrated that its activity was due to the original polymetallic complexes of the plantbased catalyst. Addition of small amounts of water (optimized to 10 mol%) to model salt MnCl 2 revealed to be beneficial for the reductive amination of ketones. Investigation showed that this effect was probably the result of hydrogen bonding or protonation of the pre-formed imine and of HEH activation, becoming more reactive toward the substrate. Finally, the methodology was extended to various starting ketones and amines, illustrating its potential and scope for the synthesis of substituted amines, including precursors of pharmaceutical compounds. Current studies are in progress to perform the reaction with solid supported Eco-Mn ® , allowing the recycling of the catalyst.

Experimental section

Reagents and methods

Reagents and solvents were purchased from Sigma-Aldrich, and were used without further purification. Flash column chromatography was performed using Chromagel Carlo Erba Reactifs SDS silica 60 A CC 35-70 µm. Reactions were monitored using Merck Kieselgel 60 F254 aluminum. TLCs were visualized by UV fluorescence (254 nm) then by immersion in one of the following dyeing reagents: KMnO 4 , vanillin, ninhydrin, phosphomolybdic acid solution, and phosphotungstic acid solution. NMR spectra were recorded on a Brüker Avance 300 spectrometer at room temperature, [START_REF] Hunt | Element Recovery and Sustainability[END_REF] H frequency is at 300 MHz and [START_REF] Losfeld | [END_REF] C frequency is at 75 MHz. IR spectra were recorded on a PerkinElmer Spectrum 100 FT-IR spectrometer, in ATR mode. GC-MS analyses were performed on a Shimadzu QP2010SE apparatus, equipped with a 30 m × 0.25 mm × 0.25 µm ZB-5MSi Guardian column (Phenomenex ® ) with hydrogen as carrier gas.

Preparation of Eco-Mn ®

Eco-Mn ® was prepared from harvested leaves of Grevillea exul rubiginosa, a manganese hyperaccumulating plant present in New Caledonia. Grevillea exul rubiginosa was collected before flowering, at Col de Mouriange, near Le Mont-Dore, in the Southern province of the subtropical Pacific island of New Caledonia. The leaves were air-dried and ground. The obtained solid (50 g) was calcined to 400 °C for 5 h and the resulting ashes (1.5 g) were added to 20 mL of a diluted solution of HCl (1M). The solution was stirred for 2 h at 60 °C. During the heating, the color of the mixture changed from black to dark green. The reaction mixture was then filtered on a pad of celite. The resulting dark-green solution, composed of different metal chlorides, was concentrated under vacuum, yielding the ecocatalyst Eco-Mn ® as a pale yellow powder (2.25 g). Eco-Mn ® was stored in a desiccator under vacuum.

General procedures

Cyclization of the monoterpene (+)-citronellal into isopulegol isomers

To a suspension of Mn catalyst (amount corresponding to 0.020 mmol of Mn, 2 mol%) in 5 mL of dichloromethane was added 180.4 µL of (+)-citronellal (1.0 mmol). After stirring for 0.5 h under reflux, the reaction mixture was filtered, washed with a saturated aqueous solution of NaHCO 3 . The organic layer was dried over Na 2 SO 4 , filtered and concentrated under reduced pressure. 95% of yield and 90% of (-)-isopulegol stereoselectivity were estimated by GC-MS analysis.

Fourier transform infrared spectroscopy characterization of adsorbed pyridine on catalysts FTIR measurements were carried out using pyridine as a probe. A PerkinElmer Spectrum100 FT-IR spectrometer was used for recording the spectra. Excess pyridine was adsorbed, then the samples were degassed for 15 min at 25 °C (4 mbar) and a first spectrum was recorded. The samples were then degassed for 40 min at 150 °C (4 mbar) to eliminate the physisorbed pyridine and a second spectrum was recorded.

Rearrangement of the ethylene acetal of 2-bromopropiophenone

A solution of the ethylene acetal of 2-bromopropiophenone (75.8 mg, 0.29 mmol) in 1,2-dichlorobenzene (3.29 mL) was poured onto catalyst (mass corresponding to 0.012 mmol of Mn, 4 mol%), with water (5.31 µL, 0.29 mmol). The resulting suspension was magnetically stirred at 180 °C for 20 h. The mixture reaction was analyzed by GC-MS analysis, with the following temperature program: 4 min isothermal at 80 °C, then increasing from 80°C to 270 °C at 20 °C.min -1 .

Synthesis of HEH

Paraformaldehyde (3.0 g, 100 mmol), ethyl acetoacetate (50.6 mL, 400 mmol) and ammonium acetate (15.4 g, 200 mmol) were added to 150 mL of degasified water. The mixture was vigorously stirred at reflux temperature, under argon atmosphere and away from light (flask protected with aluminum foil), for 2 h. A bright yellow solid precipitated and was collected by filtration after cooling to room temperature. The solid was washed with 20 mL of water twice and dried in a desiccator under vacuum, avoiding prolonged exposure to light. The obtained solid (22.1 g, 87% yield) was nearly pure and used in the next step without further purification.

Test reaction of HEH oxidation in presence of Mn(II) catalysts and water HEH (253 mg, 1.0 mmol), Mn(II) catalyst (Mn 1 mol%) and water (1.8 µL, 10 mol%) were introduced into a 4 mL vial, open to air through a needle. After homogenization with a vortex mixer, the reaction mixture was heated to 110°C, 1 h, under stirring. An aliquot was taken and analyzed in GC-MS after dilution in DCM to determine the proportions of HEH and corresponding pyridine formed by oxidation.

Reductive amination of ketones by Eco-Mn ® /HEH HEH (278 mg, 1.1 mmol), ketone (1.0 mmol), amine (1.0 mmol) and Eco-Mn ® (8.3 mg, 1 mol% Mn) were introduced in a 4 mL vial. The solid mixture was homogenized with a vortex mixer, and then the reaction mixture was stirred at 110°C for 4 h (the solid melted quickly on heating). After cooling to room temperature, an aliquot was taken and analyzed in GC-MS after dilution in DCM. GC-MS calibration was performed by analysis of known quantities of pure products and biphenyl as internal standard. Products were isolated by flash column chromatography on silica gel (toluene/ethyl acetate, 9:1).

Fig. 4

 4 Fig. 4 Influence of the amount of water on the MnCl 2 /HEH reductive amination of ketones

Fig. 5

 5 Fig.5 Comparison of GC-MS chromatograms obtained with various catalysts and water amounts, after heating of HEH to 110°C, 1 h, in contact with air.

Table 1

 1 ICP-MS analysis of Eco-Mn ®

	Element wt% (±sd)
	K	4.32 (±0.0076)
	Mg	5.26 (±0.086)
	Ca	10.44 (±0.17)
	Al	0.24 (±0.015)
	Mn	6.72 (±0.037)
	Fe	0.90 (±0.0075)
	Ni	0.040 (±0.00039)

  89

	O	O	O		water	EtO OC	COOEt
	2	+		+	NH 4 OAc
		OEt	H	H	reflux, 2 h	N
						H
						HEH, 87% yiel d

Table 2

 2 Reductive amination of cyclohexanone with aniline catalyzed Eco-Mn ® and comparison to previously published methods

	Entry	Catalyst	Catalyst	Reducing agent	Solvent	Time	Yield c	Reference
			loading			[h]	[%]
			[mol%]
	1 a	Eco-Mn ®	-	HEH (1.1 equiv)	Solvent-free	1	3	This work
	2 a	Eco-Mn ®	0.1 b	HEH (1.1 equiv)	Solvent-free	1	60	This work
	3 a	Eco-Mn ®	0.25 b	HEH (1.1 equiv)	Solvent-free	1	96	This work
	4	PS-Pd-NHC	0.15	H 2 (35 bar)	water	8	91	Bagal et al. 92
	5	(PPh 3 )AuCl/Ag OTf	1	HEH (1.25 equiv)	CH 2 Cl 2	3	90	Zhang et al. 59
	6	γ-Fe 2 O 3 @ HAP-SO 3 H	10	NaBH 4 (1 equiv)	EtOH	0.7	87	Deng et al. 93
	7	ZnCl 2	50	NaBH 3 CN (1 equiv)	MeOH	2	85	Kim et al. 94
	8	Cu(OAc) 2	2	H 2 (50 bar)	toluene	24	83	Werkmeister et al. 95
	9	Pd/C	0.47	Et 3 SiH (4 equiv)	EtOH	0.5	73	Mirza-Aghayan et al. 96
	10	InCl 3	14	NaBH 4 (1.5 equiv)	CH 3 CN	0.7	57	Ravi et al. 97
	11 d	Mg(ClO 4 ) 2	100	HEH (1 equiv)	THF	90	45	Steevens and Pandit 56

a Reaction conditions: 1 mmol 1a, 1 mmol 2a, 1.1 mmol HEH, neat, 80°C. b Eco-Mn ® loading calculated in Mn mol% c Yields reported with Eco-Mn ® were determined by GC-MS after calibration with an internal standard d Reaction performed on the pre-synthesized imine.

Table 3

 3 Comparison of Eco-Mn ® and classical Mn chlorides in the reaction

	Entry a Catalyst	Catalyst	Yield c,d
			loading b [mol%]	[%]
	1	Eco-Mn ®	1	67
	2	MnCl 2	1	49
	3	MnCl 2 .4H 2 O	1	62
	4 e	"reconstituted" Eco-Mn ®	1	62
	5	MnCl 2 /HCl (aq)	1 f	55

Table 4

 4 Influence of the addition of water on the first step of the reaction

	Entry a	Catalyst b	Added water	Yield c
			[mol%]	[%]
	1	MnCl 2	-	30
	2	MnCl 2	10	30
	3	Eco-Mn ®	-	30

Table 5

 5 Reductive amination of different ketones and amines by the Eco-Mn ® /HEH methodology

	Entry a	Ketone	Amine	Product	Yield
					[%] b
	1				97 (94)
		1c	2a	3c
	2		2a		67 (54)
		1d		3d
	3				96 (77)
		1a	2b	3e
	4		2b		88 (85)
		1b		3f
	5	1a			96 (86)
			2c	3g
	6	1b	2c		95 (83)
				3h

Acknowledgements

This work was supported by the Agence Nationale de la Recherche (ANR, programme 11ECOT01101), the Agence de l'Environnement et de la Maîtrise de l'Energie (ADEME), the Centre National de la Recherche Scientifique (CNRS) and the Fond Européen de Développement Régional (FEDER).