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Nucleophilic addition

In organic chemistry, a nucleophilic addition (AN) reaction is an addition reaction where a chemical compound with an electrophilic double or triple bond reacts with a nucleophile, such that the double or triple bond is broken. Nucleophilic additions differ from electrophilic additions in that the former reactions involve the group to which atoms are added accepting electron pairs, whereas the latter reactions involve the group donating electron pairs.

Addition to carbon–heteroatom double bonds
Nucleophilic addition reactions of nucleophiles with electrophilic double or triple bond (π bonds) create a new carbon center with two additional single, or σ, bonds. Addition of a nucleophile to carbon–heteroatom double or triple bonds such as >C=O or -C≡N show great variety. These types of bonds are polar (have a large difference in electronegativity between the two atoms); consequently, their carbon atoms carries a partial positive charge. This makes the molecule an electrophile, and the carbon atom the electrophilic center; this atom is the primary target for the nucleophile. Chemists have developed a geometric system to describe the approach of the nucleophile to the electrophilic center, using two angles, the Bürgi–Dunitz and the Flippin–Lodge angles after scientists that first studied and described them.
 * [[Image:NucleophilicAdditionsToCarbonyls.svg|300px|Nucleophilic addition to a carbonyl]]

This type of reaction is also called a 1,2-nucleophilic addition. The stereochemistry of this type of nucleophilic attack is not an issue, when both alkyl substituents are dissimilar and there are not any other controlling issues such as chelation with a Lewis acid, the reaction product is a racemate. Addition reactions of this type are numerous. When the addition reaction is accompanied by an elimination the reaction type is nucleophilic acyl substitution or an addition-elimination reaction.

Addition to carbonyl groups
With a carbonyl compound as an electrophile, the nucleophile can be:
 * water in hydration to a geminal diol (hydrate)
 * an alcohol in acetalisation to an acetal
 * a hydride in reduction to an alcohol
 * an amine with formaldehyde and a carbonyl compound in the Mannich reaction
 * an enolate ion in an aldol reaction or Baylis–Hillman reaction
 * an organometallic nucleophile in the Grignard reaction or the related Barbier reaction or a Reformatskii reaction
 * ylides such as a Wittig reagent or the Corey–Chaykovsky reagent or α-silyl carbanions in the Peterson olefination
 * a phosphonate carbanion in the Horner–Wadsworth–Emmons reaction
 * a pyridine zwitterion in the Hammick reaction
 * an acetylide in alkynylation reactions.
 * a cyanide ion in cyanohydrin reactions

In many nucleophilic reactions, addition to the carbonyl group is very important. In some cases, the C=O double bond is reduced to a C-O single bond when the nucleophile bonds with carbon. For example, in the cyanohydrin reaction a cyanide ion forms a C-C bond by breaking the carbonyl's double bond to form a cyanohydrin.

Addition to nitriles
With nitrile electrophiles, nucleophilic addition take place by:
 * hydrolysis of a nitrile to form an amide or a carboxylic acid
 * organozinc nucleophiles in the Blaise reaction
 * alcohols in the Pinner reaction.
 * the (same) nitrile α-carbon in the Thorpe reaction. The intramolecular version is called the Thorpe–Ziegler reaction.
 * Grignard reagents to form imines. The route affords ketones following hydrolysis or primary amines following imine reduction.

Addition to carbon–carbon double bonds
When a nucleophile X− adds to an alkene, the driving force is the transfer of negative charge from X to the electron-poor unsaturated -C=C- system. This occurs through the formation of a covalent bond between X and one carbon atom, concomitant with the transfer of electron density from the pi bond onto the other carbon atom (step 1). During a telescoped second reaction or workup (step 2), the resulting negatively charged carbanion combines with an electrophilic Y to form the second covalent bond.

 * [[Image:NucleophilicAdditionGeneral.svg|300px|Nucleophilic addition to an alkene]]

Unsubstituted and unstrained alkenes are typically insufficiently polar to admit nucleophilic addition, but a few exceptions are known.

The strain energy in fullerenes weakens their double-bonds; addition thereto is the Bingel reaction.

Bonds adjacent to an electron-withdrawing substituent (e.g. a carbonyl group, nitrile, or fluoride) readily admit nucleophilic addition. In this process, conjugate addition, the nucleophile X adds β to the substituent, because then said substituent inductively stabilizes the product's negative charge. Aromatic substituents, although typically electrophilic, can also sometimes stabilize negative charge; for example, styrene reacts in toluene with sodium to give 1,3-diphenylpropane:

title: Nucleophilic addition


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User talk:Weatherdragon

AfD nomination of Taulmaril
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Nomination of Wulfgar (Forgotten Realms) for deletion
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Nomination of Wulfgar (Forgotten Realms) for deletion
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The redirect [//en.wikipedia.org/w/index.php?title=Taulmaril&redirect=no Taulmaril] has been listed at redirects for discussion to determine whether its use and function meets the redirect guidelines. Anyone, including you, is welcome to comment on this redirect at  until a consensus is reached. 1234qwer1234qwer4 17:21, 24 April 2023 (UTC)

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: User talk:Weatherdragon


text:
Talk:Hafenstraße

Untitled
I just edited this entry but I must confess I don't know anything about the subject (despite having been a squatter once!). I just felt it could read a bit better - my guess is that the initial article was written by a German speaker, judging by the phraseology. Anyway, my point is that my rewrite could have introduced factual inaccuracies, so if someone wants to check that would be great. Lancevortex 16:36, 11 Mar 2004 (UTC)

title: Talk:Hafenstraße


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Timeline of Cassini–Huygens

This article provides a timeline of the Cassini–Huygens mission (commonly called Cassini). Cassini was a collaboration between the United States' NASA, the European Space Agency ("ESA"), and the Italian Space Agency ("ASI") to send a probe to study the Saturnian system, including the planet, its rings, and its natural satellites. The Flagship-class uncrewed robotic spacecraft comprised both NASA's Cassini probe, and ESA's Huygens lander which was designed to land on Saturn's largest moon, Titan. Cassini was the fourth space probe to visit Saturn and the first to enter its orbit. The craft were named after astronomers Giovanni Cassini and Christiaan Huygens.

Launched aboard a Titan IVB/Centaur on 15 October 1997, Cassini had a nearly 20-year life span, with 13 of these years spent orbiting Saturn. The voyage to Saturn included flybys of Venus (April 1998 and June 1999), Earth (August 1999), the asteroid 2685 Masursky, and Jupiter (December 2000). The probes entered orbit on 1 July 2004, and the mission ended on 15 September 2017, when Cassini flew into Saturn's upper atmosphere in order to prevent any risk of contaminating Saturn's moons, some of which have active environments that could potentially bear life. The mission is widely perceived to have succeeded beyond expectations. Cassini-Huygens has been described by NASA's Planetary Science Division Director as a "mission of firsts", that has revolutionized human understanding of the Saturnian system, including its moons and rings, and our understanding of where life might be found in the Solar System.

Cassini's primary mission lasted for four years, from June 2004 to May 2008. The mission was extended for another two years until September 2010, under the name of Cassini Equinox Mission. The mission was extended a second and final time with the Cassini Solstice Mission, lasting until the spacecraft's destruction in September 2017.

The Huygens module traveled with Cassini until its separation from the probe on 25 December 2004; it was successfully landed by parachute on Titan on 14 January 2005. It successfully returned data to Earth for around 90 minutes, using the orbiter as a relay. This was the first landing ever accomplished in the outer Solar System and the first landing on a moon other than our own.

At the end of its mission, the Cassini spacecraft executed the "Grand Finale" of its mission: several risky passes through the gaps between Saturn and Saturn's inner rings. The purpose of this phase was to maximize Cassini scientific outcome before the spacecraft was destroyed. The atmospheric entry of Cassini effectively ended the mission, although data analysis and production is still ongoing.

Launch and cruise phase (1997–2003)
15 October 1997 01:43 Pacific Daylight Time (PDT) – Cassini launched at 08:43 UTC inside Titan IVB/Centaur rocket at Cape Canaveral.

26 April 1998 06:52 PDT – Gravity-assisted flyby of Venus at 284 km, receiving a boost in speed of about 7 kilometers per second.

3 December 1998 22:06 PST – Cassini fired its main rocket engine for 90 minutes, setting the spacecraft on course for its second Venus flyby in 1999. The engine burn slowed the spacecraft by close to 450 meters per second (about 1,006 miles per hour) relative to the Sun. Cassini's speed went from 67,860 kilometers per hour (42,168 miles per hour) at the start of the maneuver to 66,240 kilometers per hour (41,161 miles per hour) at the end of the engine firing.

24 June 1999 13:30 PDT – Gravity-assisted flyby of Venus at 623 km.

18 August 1999 03:28 UTC − Gravity-assisted flyby of Earth. An hour 20 minutes before closest approach, Cassini made the closest approach to the Moon at 377,000 km, and took a series of calibration images. The spacecraft flew past Earth at a distance of 1,171 km, passing most closely above the eastern South Pacific at -23.5°N, -128.5°W. Cassini received a 5.5-kilometer-per-second (about 12,000-mile-per-hour) boost in velocity.

23 January 2000 – flyby of Asteroid 2685 Masursky around 10:00 UTC. Cassini took images 5 to 7 hours before at 1.6 million km distance and estimated a diameter of 15 to 20 km.

30 December 2000 10:05 UTC − Gravity-assisted flyby of Jupiter. Cassini was at its closest point (9.7 million kilometres, 137 Jovian radii) to Jupiter at this date, and performed many scientific measurements. It also produced the most detailed global color portrait of Jupiter ever produced (seen on the right); the smallest visible features are approximately 60 km across.

30 May 2001 – During the coast phase between Jupiter and Saturn, it was noticed that "haze" became visible in the pictures taken by the narrow-angle camera of Cassini. This was first seen when a picture of the star Maia in the Pleiades was taken after a routine heating period.

23 July 2002 – In late January, a test was performed to remove the "haze" from the narrow-angle camera lens by heating it. Warming the camera to 4 degrees Celsius (39 degrees Fahrenheit) for eight days produced positive results. Later, the heating was extended to 60 days, and a picture of the star Spica showed an improvement of more than 90 percent compared to before the heating period. On 9 July, a picture showed that the removal procedure was completed successfully, which was announced on 23 July.

10 October 2003 – The Cassini science team announced the results of a test of Einstein's theory of gravity, using radio signals from the Cassini probe. The researchers observed a frequency shift in the radio waves to and from the space craft, as those signals traveled close to the Sun. Past tests were in agreement with the theoretical predictions with an accuracy of one part in one thousand. The Cassini experiment improved this to about 20 parts in a million, with the data still supporting Einstein's theory.

Primary mission (2004–2008)
27 February 2004 – A new, high-resolution picture of Saturn taken by Cassini on 9 February was released, and it was noted that mission scientists were puzzled by the fact that no "spokes" in Saturn's ring are visible. These dark structures in the "B" section of the ring had been discovered in pictures taken by the Voyager probe in 1981. Another picture, in infrared light, taken on 16 February shows cloud height differences and the same disturbance visible throughout the 1990s in Hubble Space Telescope images.

12 March 2004 – Pictures taken on 23 February do show a feature discovered by Voyager: Clumps in the outer "F"-ring. What could not be ascertained at the time was the exact lifetime of these clumps, and it is hoped that Cassini will provide conclusive data about this question. The first set of pictures shows a set of "clumps" moving along the "F" ring.

26 March 2004 – The Cassini science team published the first sequence of pictures of Saturn showing clouds moving at high speed around the planet. Using a filter to better see water haze on top of the dense cloud cover, motions in the equatorial and southern regions are clearly visible. The pictures were taken during the days from 15 to 19 February.

8 April 2004 – The first "long-term" observation of cloud dynamics in Saturn's atmosphere were published by mission scientists. A set of pictures shows two storms in the southern latitudes merge during a period from 19 to 20 March. Both storms had a diameter of about 1,000 km before they merged.

15 April 2004 – NASA announced that two moons discovered by Voyager 1 were sighted again by Cassini in pictures taken on 10 March: Prometheus and Pandora. These are no ordinary moons, but their gravitational effects on the "F" ring led scientists to call them "shepherd moons". They fascinate all researchers interested in the dynamics of the ring system, because their orbits are close enough that they interact with each other in a chaotic manner. They have a history of defying predictions of their orbits. One of Cassini's missions will be to monitor the movements of these bodies closely.

18 May 2004 – Cassini entered the Saturn system. The gravitational pull of Saturn began to overtake the influence of the Sun.

20 May 2004 – The first picture of Titan with better resolution than any Earth-based observation was released. It was taken 5 May from a distance of 29.3 million kilometers (18.2 million miles).

27 May 2004 – TCM-20, the Phoebe approach TCM (Trajectory Correction Maneuver) was executed at 22:26:00 UTC. This was a 5-minute and 56 second burn of the main engine, which was not used since December 1998. It therefore doubled as a "dress rehearsal" for the 96 minute burn during "Saturn Orbit Insertion" (SOI). However, TCM-20 was mainly designed to change Cassini's velocity by 34.7 m/s (78 mph), setting up a flyby of the moon Phoebe 11 June.

11 June 2004 – Cassini flew by the moon Phoebe at 19:33 UT in Spacecraft Event Time at 2068 kilometers distance. All of the eleven onboard instruments operated as expected and all data was acquired. Scientists plan to use the data to create global maps of the cratered moon, and to determine Phoebe's composition, mass and density. It took scientists several days to pore over the data to make more concrete conclusions.

16 June 2004 – TCM-21 took place with a 38-second main engine burn. It was planned as the last correction of the trajectory of Cassini before SOI. A few days later the final TCM-22 tentatively scheduled for 21 June was canceled.

1 July 2004 – The Saturn Orbit Insertion burn was successfully executed. At 7:11 p.m. PDT (10:11 p.m. EDT), Cassini crossed the ring plane between Saturn's F and G rings. Its antenna was oriented forward acting as a shield against small ring particles. At 7:36 p.m. PDT (10:36 p.m. EDT), the spacecraft began a critical 96-minute main engine burn to cut its velocity by 626 meters per second and permit a 0.02 x 9 million kilometer Saturn orbit. Right after that burn, pictures of the rings were taken and sent back to mission scientist as the spacecraft approached within 19,980 kilometers (12,400 miles) from the cloud tops. Scientists were surprised by the clarity and detail of the pictures and will be poring over them for quite some time. "We won't see the whole puzzle, only pieces, but what we are seeing is dramatic," said Dr. Carolyn Porco, Cassini imaging team leader, Space Science Institute, Boulder, Colo. "The images are mind-boggling, just mind-boggling. I've been working on this mission for 14 years and I shouldn't be surprised, but it is remarkable how startling it is to see these images for the first time."

2 July 2004 – Cassini's first flyby of Titan was executed and first close up pictures were sent back to Earth. Due to the planning of the initial orbit, Cassini was passing over the south pole of the moon and from a larger distance than in later flybys. However, during a press conference on 3 June, mission scientist presented pictures that are already forcing them to rethink previous theories. It now seems that the darker and brighter albedo features on the surface do represent different materials. But in contrast to expectation, the icy regions seem to be darker than the areas where other (possibly organic) matter is mixed in with the ice.

16 August 2004 – Mission scientists announce the discovery of two new moons of Saturn, and with it the successful start of one of the programs of Cassini: Locating small and yet unknown moons. Later named "Methone" (S/2004 S 1) and "Pallene" (S/2004 S 2), these objects are small compared to other moons and they orbit between Mimas and Enceladus.

23 August 2004 – At a distance of 9 million kilometers from Saturn, the last major firing of the main engine took place to adjust the next closest approach and avoid the particles in the ring system. The 51 minute burn increased the velocity of the probe by 325 meters per second, moving the orbital periapsis point about 300,000 km farther away from Saturn than its smallest distance during SOI. At the same time, the new course will bring Cassini very close to Titan on its next flyby.

14 September 2004 – Final checkout of the Huygens lander was completed successfully. The separation of the probe stays scheduled for 25 December, with the landing anticipated on 14 January 2005.

26 October 2004 – The second flyby of Titan (called "Titan-A") was successfully executed. Data started to arrive at the JPL mission center at 01:30 UTC, 27 October, and included the highest resolution pictures ever taken of the surface of that moon. Also, first high-resolution infra-red spectra and pictures were taken from the atmosphere and surface. The spacecraft successfully skimmed the hazy, smoggy atmosphere of Titan, coming within 1,176 kilometers of Titan's surface. The flyby was the closest that any spacecraft has ever come to Titan. The pictures, spectra, and radar data revealed a complex, puzzling surface. Analysis of all data is on-going. The only glitch during the "Titan-A" event involved the CIRS instrument. During playback, the instrument team observed corrupted data. A decision was made to power the instrument off to reboot it. CIRS was powered back on within 24 hours and returned to its nominal state.

23 November 2004 – The last in-flight checkout of the Huygens probe before separation was completed successfully. All systems are ready for an on-time deployment of the probe.

13 December 2004 – The "Titan-B" flyby was executed successfully and the collected data are analyzed by mission scientists.

25 December 2004 – Huygens probe separated from Cassini orbiter at 02:00 UTC.

27 December – NASA published a picture of Huygens taken from Cassini two days after release. It reported that the analysis of that picture shows that the probe is on the correct course within the expected error range. These checks were necessary in order to place the orbiter in the correct orientation to receive the data from the probe when it enters Titan's atmosphere.

28 December 2004 – OTM-10 was executed at 03:00 UTC in Spacecraft Event Time. This maneuver, also called the Orbit Deflection Maneuver (ODM), took Cassini off of a Titan-impacting trajectory and on to a flyby trajectory with the required altitude to receive data from the Huygens probe as it plunges into Titan.

31 December 2004 – Cassini's flyby of Iapetus occurred at 18:45:37 UTC at an altitude of 122645 kilometers. First raw pictures were available the next day.

14 January 2005 – Huygens entered Titan's atmosphere at 09:06 UTC and had landed softly on its surface about two hours later. This was confirmed by the reception of the carrier wave emitted by the probe during its descent and touchdown. At 16:19 UTC the Cassini orbiter started to relay to Earth the scientific data received from the probe. The first picture was released at 19:45 UTC, showing a view from about 16 km above the surface. A second picture taken from the probe at rest on the surface was released a short time later. Analysis of the data is ongoing.

15 February 2005 – Successful Titan flyby, with new regions of its surface scanned by radar. Cassini's mapping radar acquired a picture that shows a large crater on Titan, with an estimated diameter of 440 km.

17 February 2005 – The first close flyby of Enceladus was executed and first closeup images were sent back to Earth. The flyby distance was about 1180 km.

17 March 2005 – The Cassini probe reveals that Saturn's moon Enceladus has an atmosphere. It has been described as "substantial" by its discoverers.

16 April 2005 – The fifth planned flyby of Titan with a minimum distance of about 1,025 kilometers was executed at 19:12 UTC. This was the closest flyby up to this date, and provided the opportunity to obtain more detailed data on the constituents in the upper atmosphere of Titan. The first analysis of that data showed a large range of complex carbon molecules. On 25 April a mass plot was published that demonstrates the existence of these molecules.

3 May 2005 – Cassini begins Radio occultation experiments on Saturn's Rings, to determine ring particle size distribution, on the scale of centimetres.

10 May 2005 – At the beginning of a period of focussed observation of the ring system of Saturn, slated to take until September, mission scientists announced the discovery of a new moon in the "Keeler gap" inside the "A" ring. Provisionally named S/2005 S 1 and later named Daphnis, it was first seen in a time-lapse sequence of images taken on 1 May. Imaging scientists had predicted the new moon's presence and its orbital distance from Saturn after last July's sighting of a set of peculiar spiky and wispy features in the Keeler gap's outer edge.

14 July 2005 – The closest flyby of Enceladus with a distance of 175 km was executed successfully. First raw pictures were published.

7 September 2005 – Flyby of Titan at a distance of 1075 km, data gathered partially lost due to software problem.

26 September 2005 – Flyby of Hyperion at a distance of 1010 km, the closest flyby and only visit to the moon during the primary mission.

27 July 2006 – NASA confirms the presence of hydrocarbon lakes in Titan's northern polar region.

28 May 2008 – Cassini completed its 43rd flyby of Titan, ending its primary mission. Renamed Cassini Equinox mission, Cassini observed Saturn during its equinox crossing, or summertime.

Cassini Equinox mission (2008–2010)

9 August, 11 August, 9 October, and 31 October 2008 – With closest approach at 50, 25, and 200 km, respectively, Cassini's last three Enceladus flybys of 2008 utilized a new imaging technique named "skeet shooting" to successfully acquire very high resolution images. The flybys also allowed Cassini to directly sample Enceladus's cryovolcanic plumes.

3 November, 14 November, 5 December, and 21 December 2009 – Titan flybys 46 through 49 concentrated on radar, VIMS, and INMS sampling of Titan and its thick atmosphere. T47 involved high-resolution VIMS coverage of the Huygens landing site, while the other three flybys made use of radar and RSS. T49 allowed radar coverage of Ontario Lacus, one of the largest methane lakes on Titan.

June - October 2009 – Cassini observed Saturn during its equinox, or the time of Saturn's year where the sun is directly over its equator.

2 November 2010 – Cassini was triggered into a protective standby mode, or "safe mode", after a bit flip caused it to miss an important instruction. NASA announced the interruption in scientific processes on 8 November. However, by 8 November some of the craft's functionality had already been partly restored. Nominal scientific instrument sequencing events were successfully started on 10 November. Cassini was reactivated as scheduled on 24 November and has returned to perfect working order, in time for two scheduled close fly-bys with Enceladus. At this point there has been no public disclosure as to the data loss impact of the 11 November (T-73) flyby. However, no images were acquired on the 11 November polar flyby.

Cassini Solstice Mission (2010–2017)
On 3 February 2010, NASA announced that a second mission extension until May 2017, a few months past Saturn's summer solstice, had been funded. The schedule included an additional 155 orbits, with 54 flybys of Titan, 11 of Enceladus, 2 of Rhea, and 3 of Dione. One of the flybys of Titan dipped below the ionosphere.

Grand Finale (2017)

On 15 September 2017, Cassini was deliberately disposed of by a controlled fall into Saturn's atmosphere, ending its nearly two-decade-long mission. The last signal was received at 11:55:46 UTC.

Detailed timeline of Huygens mission
All times given after 2005-Jan-14 09:11 UTC are expected event times and may differ from actual event times. This page will be updated after descent has occurred with corrections if they are necessary.

The data used in this section has been slightly out of date, an updated version of ephemeris from ESA was available 2005 January 6.

Fly-bys
Following is a list of close fly-bys of Saturn's moons (at less than 5000 km). The closest approach for each moon is bolded.

Solstice mission
The second extended mission was scheduled from 2010 October 12 through the Saturnian summer solstice in May 2017, followed by two dozen proximal orbits of Saturn and the rings. Cassini's final optical navigation image of the mission was taken on 20 September 2016. The Cassini mission ended on 15 September 2017, when the craft disintegrated in Saturn's atmosphere.

 * Proximal orbits

title: Timeline of Cassini–Huygens


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Talk:Body language

Wikipedia Ambassador Program course assignment
This article is the subject of an educational assignment at Lewis University supported by WikiProject Psychology and the Wikipedia Ambassador Program during the 2011 Q3 term. Further details are available on the course page.

The above message was substituted from by PrimeBOT (talk) on 15:51, 2 January 2023 (UTC)

body language
Body language is a type of communication in which physical behaviors, as opposed to words, are used to express or convey information. Such behavior includes facial expressions, body posture, gestures, eye movement, touch and the use of space. The term body language is usually applied in regard to people but may also be applied to animals.[1] The study of body language is also known as kinesics.[2] 117.222.128.212 (talk) 12:29, 30 May 2023 (UTC)

title: Talk:Body language


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Luis de Requesens y Zúñiga

Luis de Requesens y Zúñiga (25 August 1528 – 5 March 1576) was a Spanish general, sailor, diplomat and politician. He served as governor of the Duchy of Milan (1572–1573) and as governor of the Spanish Netherlands (1573–1576).

Biography
Luis de Requesens y Zúñiga was born at Molins de Rei, Spanish Empire. He, and his brother Juan de Zúñiga y Requesens (Viceroy of Naples in 1579–1582), were the sons of Juan de Zúñiga, a tutor of King Philip II, and Estefanía de Requesens. He married Gerónima Esterlich y Gralla, the daughter of Francisco Gralla, "Maestre Racional" or Finances Head Controller in Catalonia.

His early career was that of a government official and diplomat. In 1563 he gained the king's confidence as his representative at Rome. In 1568 he was appointed lieutenant-general to John of Austria during the suppression of the Morisco Revolt in the Alpujarras, and he also accompanied John during the Lepanto campaign, his function being to watch and control his nominal commander-in-chief, whose excitable temperament was distrusted by the king.

In 1572 Philip named him Governor of the Duchy of Milan, a post usually given to a great noble. Requesens was only a gentleman, though by the king's favour he was grand commander of the military order of Santiago in Castile. He was credited with having shown moderation at Milan, but he came into sharp collision with the archbishop, Charles Borromeo, who took up the cause of his flock.

In 1573 he was called by Philip II to succeed the Fernando Álvarez de Toledo, 3rd Duke of Alba as governor of the Spanish Netherlands, then in revolt against the Spaniards.

He was rather moderate in comparison to Alba, requesting Philip to grant a general amnesty to all, with the exception of persistent heretics, and to permit the emigration of those who would not comply.

The king wished to pursue a more conciliatory policy, without, however, yielding any one of the points in dispute between himself and the revolting Dutch. His situation was aggravated by the empty Spanish treasury. Requesens came to Brussels on 17 November 1573 and launched a new military campaign. In February 1574 the rebels had conquered the port of Middelburg, but Requesens's army obtained a victory against the troops of Louis of Nassau at the Battle of Mookerheyde, during which William the Silent's two brothers died.

However, at this point the money for funding his troops was exhausted; Requesens had to find an agreement with William the Silent, the leader of the Flemish opposition, with the mediation of the Emperor Maximilian II. The negotiations were held in Breda. Requesens declared himself ready to remove his troops from Flanders, but in exchange Catholicism was to be the only religion accepted. However, by now Protestantism had gained deep roots in the Netherlands, and therefore the proposal was rebuffed by the Dutch. Requesens restarted the military campaign and his troops occupied much of Zeeland, but when Philip II stopped payment to the Flemish troops, they mutinied and military operations were halted for one year.

Requesens died suddenly at Brussels in 1576, to be replaced in the now totally chaotic Netherlands by John of Austria, half-brother of King Philip II of Spain. His body was brought to Barcelona and buried in his family palace.

title: Luis de Requesens y Zúñiga


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User talk:Jhilsua

Can you please include more than just an external link in articles? When creating an article, the external link should be an add on to the main text, not the entirety of the article. Thank you. -- Graham :) 16:40, 11 Mar 2004 (UTC)

 * That last edit you made at Bank of New York was a clear copyright violation (it even said it in the text). Please read through Welcome newcomers before making any more edits Graham  :) 16:57, 11 Mar 2004 (UTC)

 * Stop adding copyrighted information to Bank of New York: I will block you if you do it again. Graham :) 17:02, 11 Mar 2004 (UTC)

I did not know that it is not ok to put copyrighted information even if you indicate the source of it. When is it ok to post information from other sources?

Thanks

 * See Copyrights for further info. Graham :) 17:24, 11 Mar 2004 (UTC)

What does UTC mean?

 * Coordinated Universal Time -- Graham :) 17:29, 11 Mar 2004 (UTC)

I see. Excuse my ignorance... how do I create a new page? I would like to create a page about my fermer university, Zamorano. The webpage is http://www.zamorano.edu

Thanks (JHILSUA)

Hi there, I saw your message on the new users log. Welcome to wikipedia. Here are a whole bunch of links to help you learn how to edit wikipedia, you can test these things out in the sandbox. :)

You might find these links helpful in creating new pages or editing existing articles: How to edit a page, How to write a great article, Naming conventions, Manual of Style. You should read our policies at some point too.

If you want to see what other users are doing at the moment, have a look at recent changes. This is a good way to find random articles you might be interested on working on, or you can simply enjoy reading what other wikipedians have to say. Every article has a Talk page (like this one) where you can raise questions or suggest a direction for an article to take. When you make edits to a page, it's a very good idea to add a few words to the summary field to let other users know what you just did (anything from typo to rewrote article)!

If you have any questions, see the help pages, add a question to the village pump or ask me on my talk page. I hope you enjoy editing here and being a Wikipedian!

 * If you made any edits before you got an account, you might be interested in assigning those to your username.

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Again, welcome! :) fabiform | talk 17:46, 11 Mar 2004 (UTC)

title: User talk:Jhilsua


text:
Graham County

Graham County is the name of three counties in the United States: Graham County is the name of the USS GRAHAM COUNTY LST-1176.
 * Graham County, Arizona
 * Graham County, Kansas
 * Graham County, North Carolina

title: Graham County


text:
Argenis

Argenis is a book by John Barclay. It is a work of historical allegory which tells the story of the religious conflict in France under Henry III of France and Henry IV of France, and also touches on more contemporary English events, such as the Overbury scandal. The tendency is royalist, anti-aristocratic; it is told from the angle of a king who reduces the landed aristocrats' power in the interest of the "country", the interest of which is identified with that of the king.

Jennifer Morrish describes Argenis as one of "the two most influential Neo-Latin novels", along with Thomas More's Utopia.

Some editions
Originally published in Latin in 1621, King James asked for it to be translated into English. The first such translation was undertaken by Ben Jonson, but his version was lost in a fire which also destroyed many of his other works. Later translations were made by Kingsmill Long (1625), and Robert Le Gruys (1628). Clara Reeve translated it as The Phoenix (1772).
 * 1621 - Paris, Nicolas Buon (Latin)
 * 1622 - London, Eliot's Court Press (Latin)
 * 1623 - Frankfurt, Danielis & Davidis Aubriorum & Clementis Schleichij (Latin)
 * 1625 - London, G. Purslowe for Henry Seile (First English edition)
 * 1626 - Johann Barclaÿens Argenis Deutsch gemacht durch Martin Opitzen. Breslau. (First German edition)
 * 1627 - Leiden, Elzevir (First printing by Elzevir)
 * 1629 - Venice, G. Salis, ad instantia di P. Frambotti (Italian translation by Francesco Pona)
 * 1630 - Elzevir (Second printing by Elzevir)
 * 1630 - Elzevir (Third printing by Elzevir)
 * 1636 - London, Syne of the Tygres Head (Second English edition)
 * 1644 - Amsterdam, J. Janssonius (Second German edition)
 * 1697 - Warszawa, Drukarnia OO. Pijarów, (Polish translation by Wacław Potocki)
 * 1995 - New York, (Fourth printing by Argenis Jimenez)(English edition)

title: Argenis


text:
Organolithium reagent

In organometallic chemistry, organolithium reagents are chemical compounds that contain carbon–lithium (C–Li) bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom to the substrates in synthetic steps, through nucleophilic addition or simple deprotonation. Organolithium reagents are used in industry as an initiator for anionic polymerization, which leads to the production of various elastomers. They have also been applied in asymmetric synthesis in the pharmaceutical industry. Due to the large difference in electronegativity between the carbon atom and the lithium atom, the C−Li bond is highly ionic. Owing to the polar nature of the C−Li bond, organolithium reagents are good nucleophiles and strong bases. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive, and are sometimes pyrophoric.

History and development
Studies of organolithium reagents began in the 1930s and were pioneered by Karl Ziegler, Georg Wittig, and Henry Gilman. In comparison with Grignard (magnesium) reagents, organolithium reagents can often perform the same reactions with increased rates and higher yields, such as in the case of metalation. Since then, organolithium reagents have overtaken Grignard reagents in common usage.

Structure
Although simple alkyllithium species are often represented as monomer RLi, they exist as aggregates (oligomers) or polymers. The degree of aggregation depends on the organic substituent and the presence of other ligands. These structures have been elucidated by a variety of methods, notably 6Li, 7Li, and 13C NMR spectroscopy and X-ray diffraction analysis. Computational chemistry supports these assignments.

Nature of carbon–lithium bond
The relative electronegativities of carbon and lithium suggest that the C−Li bond will be highly polar. However, certain organolithium compounds possess properties such as solubility in nonpolar solvents that complicate the issue. While most data suggest the C−Li bond to be essentially ionic, there has been debate as to how much covalent character exists in it. One estimate puts the percentage of ionic character of alkyllithium compounds at 80 to 88%.

In allyl lithium compounds, the lithium cation coordinates to the face of the carbon π bond in an η3 fashion instead of a localized, carbanionic center, thus, allyllithiums are often less aggregated than alkyllithiums. In aryllithium complexes, the lithium cation coordinates to a single carbanion center through a Li−C σ type bond.

Solid state structure

Like other species consisting of polar subunits, organolithium species aggregate. Formation of aggregates is influenced by electrostatic interactions, the coordination between lithium and surrounding solvent molecules or polar additives, and steric effects.

A basic building block toward constructing more complex structures is a carbanionic center interacting with a Li3 triangle in an η3- fashion. In simple alkyllithium reagents, these triangles aggregate to form tetrahedron or octahedron structures. For example, methyllithium, ethyllithium and tert-butyllithium all exist in the tetramer [RLi]4. Methyllithium exists as tetramers in a cubane-type cluster in the solid state, with four lithium centers forming a tetrahedron. Each methanide in the tetramer in methyllithium can have agostic interaction with lithium cations in adjacent tetramers. Ethyllithium and tert-butyllithium, on the other hand, do not exhibit this interaction, and are thus soluble in non-polar hydrocarbon solvents. Another class of alkyllithium adopts hexameric structures, such as n-butyllithium, isopropyllithium, and cyclohexanyllithium.

Common lithium amides, e.g. lithium bis(trimethylsilyl)amide and lithium diisopropylamide, are also subject to aggregation. Lithium amides adopt polymeric-ladder type structures in non-coordinating solvent in the solid state, and they generally exist as dimers in ethereal solvents. In the presence of strongly donating ligands, tri- or tetrameric lithium centers are formed. For example, LDA exists primarily as dimers in THF. The structures of common lithium amides, such as lithium diisopropylamide (LDA) and lithium hexamethyldisilazide (LiHMDS) have been extensively studied by Collum and coworkers using NMR spectroscopy. Another important class of reagents is silyllithiums, extensively used in the synthesis of organometallic complexes and polysilane dendrimers. In the solid state, in contrast with alkyllithium reagents, most silyllithiums tend to form monomeric structures coordinated with solvent molecules such as THF, and only a few silyllithiums have been characterized as higher aggregates. This difference can arise from the method of preparation of silyllithiums, the steric hindrance caused by the bulky alkyl substituents on silicon, and the less polarized nature of Si−Li bonds. The addition of strongly donating ligands, such as TMEDA and (-)-sparteine, can displace coordinating solvent molecules in silyllithiums.

Solution structure
It is possible for organolithium reagents adopt structures in solution that differ from the solid state. NMR spectroscopy has emerged as a powerful tool for the studies of organolithium aggregates in solution. For alkyllithium species, C−Li J coupling can often used to determine the number of lithium interacting with a carbanion center, and whether these interactions are static or dynamic. Separate NMR signals can also differentiate the presence of multiple aggregates from a common monomeric unit.

Organolithium compounds bind Lewis bases such as tetrahydrofuran (THF), diethyl ether (Et2O), tetramethylethylene diamine (TMEDA) or hexamethylphosphoramide (HMPA). Methyllithium is a special case: its tetrameric structure is unaffected by ether or even HMPA. On the other hand, THF deaggregates hexameric butyl lithium: the tetramer is the main species, and ΔG for interconversion between tetramer and dimer is around 11 kcal/mol. TMEDA can also chelate to the lithium cations in n-butyllithium and form solvated dimers such as [(TMEDA) LiBu-n)]2. Phenyllithium has been shown to exist as a distorted tetramer in the crystallized ether solvate, and as a mixture of dimer and tetramer in ether solution.

Structure and reactivity
As the structures of organolithium reagents change according to their chemical environment, so do their reactivity and selectivity. One question surrounding the structure-reactivity relationship is whether there exists a correlation between the degree of aggregation and the reactivity of organolithium reagents. It was originally proposed that lower aggregates such as monomers are more reactive in alkyllithiums. However, reaction pathways in which dimer or other oligomers are the reactive species have also been discovered, and for lithium amides such as LDA, dimer-based reactions are common. A series of solution kinetics studies of LDA-mediated reactions suggest that lower aggregates of enolates do not necessarily lead to higher reactivity.

Also, some Lewis bases increase reactivity of organolithium compounds. However, whether these additives function as strong chelating ligands, and how the observed increase in reactivity relates to structural changes in aggregates caused by these additives are not always clear. For example, TMEDA increases rates and efficiencies in many reactions involving organolithium reagents. Toward alkyllithium reagents, TMEDA functions as a donor ligand, reduces the degree of aggregation, and increases the nucleophilicity of these species. However, TMEDA does not always function as a donor ligand to lithium cation, especially in the presence of anionic oxygen and nitrogen centers. For example, it only weakly interacts with LDA and LiHMDS even in hydrocarbon solvents with no competing donor ligands. In imine lithiation, while THF acts as a strong donating ligand to LiHMDS, the weakly coordinating TMEDA readily dissociates from LiHMDS, leading to the formation of LiHMDS dimers that is the more reactive species. Thus, in the case of LiHMDS, TMEDA does not increase reactivity by reducing aggregation state. Also, as opposed to simple alkyllithium compounds, TMEDA does not deaggregate lithio-acetophenolate in THF solution. The addition of HMPA to lithium amides such as LiHMDS and LDA often results in a mixture of dimer/monomer aggregates in THF. However, the ratio of dimer/monomer species does not change with increased concentration of HMPA, thus, the observed increase in reactivity is not the result of deaggregation. The mechanism of how these additives increase reactivity is still being researched.

Reactivity and applications
The C−Li bond in organolithium reagents is highly polarized. As a result, the carbon attracts most of the electron density in the bond and resembles a carbanion. Thus, organolithium reagents are strongly basic and nucleophilic. Some of the most common applications of organolithium reagents in synthesis include their use as nucleophiles, strong bases for deprotonation, initiator for polymerization, and starting material for the preparation of other organometallic compounds.

Carbolithiation reactions
As nucleophiles, organolithium reagents undergo carbolithiation reactions, whereby the carbon-lithium bond adds across a carbon–carbon double or triple bond, forming new organolithium species. This reaction is the most widely employed reaction of organolithium compounds. Carbolithiation is key in anionic polymerization processes, and n-butyllithium is used as a catalyst to initiate the polymerization of styrene, butadiene, or isoprene or mixtures thereof.

 * Anionic polymerization of styrene initiated by sec-BuLi.png

Another application that takes advantage of this reactivity is the formation of carbocyclic and heterocyclic compounds by intramolecular carbolithiation. As a form of anionic cyclization, intramolecular carbolithiation reactions offer several advantages over radical cyclization. First, it is possible for the product cyclic organolithium species to react with electrophiles, whereas it is often difficult to trap a radical intermediate of the corresponding structure. Secondly, anionic cyclizations are often more regio- and stereospecific than radical cyclization, particularly in the case of 5-hexenyllithiums. Intramolecular carbolithiation allows addition of the alkyl-, vinyllithium to triple bonds and mono-alkyl substituted double bonds. Aryllithiums can also undergo addition if a 5-membered ring is formed. The limitations of intramolecular carbolithiation include difficulty of forming 3 or 4-membered rings, as the intermediate cyclic organolithium species often tend to undergo ring-openings. Below is an example of intramolecular carbolithiation reaction. The lithium species derived from the lithium–halogen exchange cyclized to form the vinyllithium through 5-exo-trig ring closure. The vinyllithium species further reacts with electrophiles and produce functionalized cyclopentylidene compounds.

 * Intramolecular carbolithiation'.png

Addition to carbonyl compounds
Nucleophilic organolithium reagents can add to electrophilic carbonyl double bonds to form carbon–carbon bonds. They can react with aldehydes and ketones to produce alcohols. The addition proceeds mainly via polar addition, in which the nucleophilic organolithium species attacks from the equatorial direction, and produces the axial alcohol. Addition of lithium salts such as LiClO4 can improve the stereoselectivity of the reaction.

 * LiClO4 increase selectivity.png

When the ketone is sterically hindered, using Grignard reagents often leads to reduction of the carbonyl group instead of addition. However, alkyllithium reagents are less likely to reduce the ketone, and may be used to synthesize substituted alcohols. Below is an example of ethyllithium addition to adamantone to produce tertiary alcohol.

 * Li add to adamantone.png

Organolithium reagents are also better than Grignard reagents in their ability to react with carboxylic acids to form ketones. This reaction can be optimized by carefully controlling the amount of organolithium reagent addition, or using trimethylsilyl chloride to quench excess lithium reagent. A more common way to synthesize ketones is through the addition of organolithium reagents to Weinreb amides (N-methoxy-N-methyl amides). This reaction provides ketones when the organolithium reagents is used in excess, due to chelation of the lithium ion between the N-methoxy oxygen and the carbonyl oxygen, which forms a tetrahedral intermediate that collapses upon acidic work up.

 * Li add to weinreb.png

Organolithium reagents also react with carbon dioxide to form, after workup, carboxylic acids.

In the case of enone substrates, where two sites of nucleophilic addition are possible (1,2 addition to the carbonyl carbon or 1,4 conjugate addition to the β carbon), most highly reactive organolithium species favor the 1,2 addition, however, there are several ways to propel organolithium reagents to undergo conjugate addition. First, since the 1,4 adduct is the likely to be the more thermodynamically favorable species, conjugate addition can be achieved through equilibration (isomerization of the two product), especially when the lithium nucleophile is weak and 1,2 addition is reversible. Secondly, adding donor ligands to the reaction forms heteroatom-stabilized lithium species which favors 1,4 conjugate addition. In one example, addition of low-level of HMPA to the solvent favors the 1,4 addition. In the absence of donor ligand, lithium cation is closely coordinated to the oxygen atom, however, when the lithium cation is solvated by HMPA, the coordination between carbonyl oxygen and lithium ion is weakened. This method generally cannot be used to affect the regioselectivity of alkyl- and aryllithium reagents.

 * 1,4vs1,2_addition1.svg

Organolithium reagents can also perform enantioselective nucleophilic addition to carbonyl and its derivatives, often in the presence of chiral ligands. This reactivity is widely applied in the industrial syntheses of pharmaceutical compounds. An example is the Merck and Dupont synthesis of Efavirenz, a potent HIV reverse transcriptase inhibitor. Lithium acetylide is added to a prochiral ketone to yield a chiral alcohol product. The structure of the active reaction intermediate was determined by NMR spectroscopy studies in the solution state and X-ray crystallography of the solid state to be a cubic 2:2 tetramer.

 * Merck synthesis of Efavirenz.png

SN2 type reactions
Organolithium reagents can serve as nucleophiles and carry out SN2 type reactions with alkyl or allylic halides. Although they are considered more reactive than Grignard reagents in alkylation, their use is still limited due to competing side reactions such as radical reactions or metal–halogen exchange. Most organolithium reagents used in alkylations are more stabilized, less basic, and less aggregated, such as heteroatom stabilized, aryl- or allyllithium reagents. HMPA has been shown to increase reaction rate and product yields, and the reactivity of aryllithium reagents is often enhanced by the addition of potassium alkoxides. Organolithium reagents can also carry out nucleophilic attacks with epoxides to form alcohols.

 * SN2 inversion with benzyllithium.png

As base
Organolithium reagents provide a wide range of basicity. tert-Butyllithium, with three weakly electron donating alkyl groups, is the strongest base commercially available (pKa = 53). As a result, the acidic protons on −OH, −NH and −SH are often protected in the presence of organolithium reagents. Some commonly used lithium bases are alkyllithium species such as n-butyllithium and lithium dialkylamides (LiNR2). Reagents with bulky R groups such as lithium diisopropylamide (LDA) and lithium bis(trimethylsilyl)amide (LiHMDS) are often sterically hindered for nucleophilic addition, and are thus more selective toward deprotonation. Lithium dialkylamides (LiNR2) are widely used in enolate formation and aldol reaction. The reactivity and selectivity of these bases are also influenced by solvents and other counter ions.

Metalation
Metalation with organolithium reagents, also known as lithiation or lithium-hydrogen exchange, is achieved when an organolithium reagent, most commonly an alkyllithium, abstracts a proton and forms a new organolithium species.

Common metalation reagents are the butyllithiums. tert-Butyllithium and sec-butyllithium are generally more reactive and have better selectivity than n-butyllithium, however, they are also more expensive and difficult to handle. Metalation is a common way of preparing versatile organolithium reagents. The position of metalation is mostly controlled by the acidity of the C-H bond. Lithiation often occurs at a position α to electron withdrawing groups, since they are good at stabilizing the electron-density of the anion. Directing groups on aromatic compounds and heterocycles provide regioselective sites of metalation; directed ortho metalation is an important class of metalation reactions. Metalated sulfones, acyl groups and α-metalated amides are important intermediates in chemistry synthesis. Metalation of allyl ether with alkyllithium or LDA forms an anion α to the oxygen, and can proceed to 2,3-Wittig rearrangement. Addition of donor ligands such as TMEDA and HMPA can increase metalation rate and broaden substrate scope. Chiral organolithium reagents can be accessed through asymmetric metalation.

 * Directed ortho metalation2.png

Directed ortho metalation is an important tool in the synthesis of regiospecific substituted aromatic compounds. This approach to lithiation and subsequent quenching of the intermediate lithium species with electrophile is often better than the electrophilic aromatic substitution due to its high regioselectivity. This reaction proceeds through deprotonation by organolithium reagents at the positions α to the direct metalation group (DMG) on the aromatic ring. The DMG is often a functional group containing a heteroatom that is Lewis basic, and can coordinate to the Lewis-acidic lithium cation. This generates a complex-induced proximity effect, which directs deprotonation at the α position to form an aryllithium species that can further react with electrophiles. Some of the most effective DMGs are amides, carbamates, sulfones and sulfonamides. They are strong electron-withdrawing groups that increase the acidity of alpha-protons on the aromatic ring. In the presence of two DMGs, metalation often occurs ortho to the stronger directing group, though mixed products are also observed. A number of heterocycles that contain acidic protons can also undergo ortho-metalation. However, for electron-poor heterocycles, lithium amide bases such as LDA are generally used, since alkyllithium has been observed to perform addition to the electron-poor heterocycles rather than deprotonation. In certain transition metal-arene complexes, such as ferrocene, the transition metal attracts electron-density from the arene, thus rendering the aromatic protons more acidic, and ready for ortho-metalation.

Superbases
Addition of potassium alkoxide to alkyllithium greatly increases the basicity of organolithium species. The most common "superbase" can be formed by addition of KOtBu to butyllithium, often abbreviated as "LiCKOR" reagents. These "superbases" are highly reactive and often stereoselective reagents. In the example below, the LiCKOR base generates a stereospecific crotylboronate species through metalation and subsequent lithium-metalloid exchange.

 * Superbase;.png

Asymmetric metalation
Enantioenriched organolithium species can be obtained through asymmetric metalation of prochiral substrates. Asymmetric induction requires the presence of a chiral ligand such as (-)-sparteine. The enantiomeric ratio of the chiral lithium species is often influenced by the differences in rates of deprotonation. In the example below, treatment of N-Boc-N-benzylamine with n-butyllithium in the presence of (-)-sparteine affords one enantiomer of the product with high enantiomeric excess. Transmetalation with trimethyltinchloride affords the opposite enantiomer.

 * Asymmetric synthesis with nBuLi and (-)-sparteine.png

Enolate formation
Lithium enolates are formed through deprotonation of a C−H bond α to the carbonyl group by an organolithium species. Lithium enolates are widely used as nucleophiles in carbon–carbon bond formation reactions such as aldol condensation and alkylation. They are also an important intermediate in the formation of silyl enol ether.

 * Li enolate 2.png

Lithium enolate formation can be generalized as an acid–base reaction, in which the relatively acidic proton α to the carbonyl group (pK =20-28 in DMSO) reacts with organolithium base. Generally, strong, non-nucleophilic bases, especially lithium amides such LDA, LiHMDS and LiTMP are used. THF and DMSO are common solvents in lithium enolate reactions.

The stereochemistry and mechanism of enolate formation have gained much interest in the chemistry community. Many factors influence the outcome of enolate stereochemistry, such as steric effects, solvent, polar additives, and types of organolithium bases. Among the many models used to explain and predict the selectivity in stereochemistry of lithium enolates is the Ireland model.

In this assumption, a monomeric LDA reacts with the carbonyl substrate and form a cyclic Zimmerman–Traxler type transition state. The (E)-enolate is favored due to an unfavorable syn-pentane interaction in the (Z)-enolate transition state.

 * Ireland model enolate1.svg

Addition of polar additives such as HMPA or DMPU favors the formation of (Z) enolates. The Ireland model argues that these donor ligands coordinate to the lithium cations, as a result, carbonyl oxygen and lithium interaction is reduced, and the transition state is not as tightly bound as a six-membered chair. The percentage of (Z) enolates also increases when lithium bases with bulkier side chains (such as LiHMDS) are used. However, the mechanism of how these additives reverse stereoselectivity is still being debated.

There have been some challenges to the Ireland model, as it depicts the lithium species as a monomer in the transition state. In reality, a variety of lithium aggregates are often observed in solutions of lithium enolates, and depending on specific substrate, solvent and reaction conditions, it can be difficult to determine which aggregate is the actual reactive species in solution.

Lithium–halogen exchange
Lithium–halogen exchange involves heteroatom exchange between an organohalide and organolithium species.

Lithium–halogen exchange is very useful in preparing new organolithium reagents. The application of lithium–halogen exchange is illustrated by the Parham cyclization.

 * Parham cyclization in MitoSpin'.png

Transmetalation
Organolithium reagents are often used to prepare other organometallic compounds by transmetalation. Organocopper, organotin, organosilicon, organoboron, organophosphorus, organocerium and organosulfur compounds are frequently prepared by reacting organolithium reagents with appropriate electrophiles.

Common types of transmetalation include Li/Sn, Li/Hg, and Li/Te exchange, which are fast at low temperature. The advantage of Li/Sn exchange is that the tri-alkylstannane precursors undergo few side reactions, as the resulting n-Bu3Sn byproducts are unreactive toward alkyllithium reagents. In the following example, vinylstannane, obtained by hydrostannylation of a terminal alkyne, forms vinyllithium through transmetalation with n-BuLi.

 * Li Sn exchange.png

Organolithium can also be used in to prepare organozinc compounds through transmetalation with zinc salts.

 * Organozincfrom li.png

Lithium diorganocuprates can be formed by reacting alkyl lithium species with copper(I) halide. The resulting organocuprates are generally less reactive toward aldehydes and ketones than organolithium reagents or Grignard reagents.

 * 1,4 cuprate addition.png

Preparation
Most simple alkyllithium reagents, and common lithium amides are commercially available in a variety of solvents and concentrations. Organolithium reagents can also be prepared in the laboratory. Below are some common methods for preparing organolithium reagents.

Reaction with lithium metal
Reduction of alkyl halide with metallic lithium can afford simple alkyl and aryl organolithium reagents.

Industrial preparation of organolithium reagents is achieved using this method by treating the alkyl chloride with metal lithium containing 0.5–2% sodium. The conversion is highly exothermic. The sodium initiates the radical pathway and increases the rate. The reduction proceeds via a radical pathway. Below is an example of the preparation of a functionalized lithium reagent using reduction with lithium metal. Sometimes, lithium metal in the form of fine powders are used in the reaction with certain catalysts such as naphthalene or 4,4’-di-t-butylbiphenyl (DTBB). Another substrate that can be reduced with lithium metal to generate alkyllithium reagents is sulfides. Reduction of sulfides is useful in the formation of functionalized organolithium reagents such as alpha-lithio ethers, sulfides, and silanes.

 * Reduction with li metal.png

Metalation
A second method of preparing organolithium reagents is a metalation (lithium hydrogen exchange). The relative acidity of hydrogen atoms controls the position of lithiation.

This is the most common method for preparing alkynyllithium reagents, because the terminal hydrogen bound to the sp carbon is very acidic and easily deprotonated. For aromatic compounds, the position of lithiation is also determined by the directing effect of substituent groups. Some of the most effective directing substituent groups are alkoxy, amido, sulfoxide, sulfonyl. Metalation often occurs at the position ortho to these substituents. In heteroaromatic compounds, metalation usually occurs at the position ortho to the heteroatom.

 * Organolithium Reagents Prepared Metalation.svg

Lithium–halogen exchange
See lithium–halogen exchange (under Reactivity and applications)

A third method to prepare organolithium reagents is through lithium halogen exchange.

tert-butyllithium or n-butyllithium are the most commonly used reagents for generating new organolithium species through lithium halogen exchange. Lithium–halogen exchange is mostly used to convert aryl and alkenyl iodides and bromides with sp2 carbons to the corresponding organolithium compounds. The reaction is extremely fast, and often proceed at −60 to −120 °C.

Transmetalation
The fourth method to prepare organolithium reagents is through transmetalation. This method can be used for preparing vinyllithium.

Shapiro reaction
In the Shapiro reaction, two equivalents of strong alkyllithium base react with p-tosylhydrazone compounds to produce the vinyllithium, or upon quenching, the olefin product.

Handling
Organolithium compounds are highly reactive species and require specialized handling techniques. They are often corrosive, flammable, and sometimes pyrophoric (spontaneous ignition when exposed to air or moisture). Alkyllithium reagents can also undergo thermal decomposition to form the corresponding alkyl species and lithium hydride. Organolithium reagents are typically stored below 10 °C. Reactions are conducted using air-free techniques. The concentration of alkyllithium reagents is often determined by titration.

Organolithium reagents react, often slowly, with ethers, which nonetheless are often used as solvents.

title: Organolithium reagent


text:
Crop Circles

Crop circles are patterns created by flattening a crop.

Crop Circles may also refer to:

 * Crop Circles (album), by Dean Brody, 2013
 * "Crop Circles", a 2019 song by Jon Bellion
 * "Crop Circles", a song by Tash Sultana from the 2021 album Terra Firma

Other uses

 * Crop Circles: Quest for Truth, a 2002 documentary by William Gazecki

title: Crop Circles


text:
Catholic Youth Organization

Catholic Youth Organization (CYO) is an international Catholic youth movement founded by Bishop Bernard Sheil in Chicago in 1930. It became a major factor in the development of race relations in the US Catholic Church following World War II.

History
The first CYO was initiated by prison chaplain and auxiliary bishop Bernard J. Sheil in Chicago in 1930 during the Great Depression. The first CYO was conceptualized as an athletic association. Its aim was to offer young males, especially from the working class, a community and constructive leisure activity in the hope to dissuade them from taking part in criminal activities.

The first CYOs adopted structures similar to the older Protestant youth movement, the YMCA. However, unlike the YMCA, the CYO used Catholic social teachings and New Deal ideology. Furthermore, under the patronage of archbishop George Cardinal Mundelein, it became a core principle of CYO not to discriminate on the basis of race, religion, or gender—as was common in other youth organizations of the time.

CYOs operate around the world in the 21st century.

Aims
The organization's main purposes are guiding the young Catholics to live a Christian life from a young age, developing trust between peers, and living a happy life in a positive manner.

Activities
Usually each group uses the church for meeting and gathering, although some have their own premises. Activities vary in accordance with local culture but often includes prayer, singing, charity, sales, sports and visiting the sick. In the United States, CYO is mainly known for its organized sports programs, notably boxing, basketball, baseball, track and field, and volleyball, as well as drum corps. Its athletic contests are often so competitive that CYO has been jokingly described as "Crush Your Opponents."

United States
CYO operates in many dioceses in the United States, following much the same model as in the time of its founding. CYO youth sports leagues are the most recognizable feature, and teams are typically connected to individual parishes.

Ghana
CYO Ghana is a Catholic youth organization in Ghana. At international level CYO Ghana is a full member of the Catholic umbrella of youth organizations Fimcap.

CYO Nigeria

CYO Nigeria is a Catholic youth organization in Nigeria. At international level CYO Nigeria is a full member of the Catholic umbrella of youth organizations Fimcap.

Sierra Leone
CYO Sierra Leone is a Catholic youth organization in Sierra Leone. At international level CYO Sierra Leone is a full member of the Catholic umbrella of youth organizations Fimcap.

Philippines
There are also active units of this organization in the Philippines. Most units are choirs of their parishes, and they also organize various activities under sports, spiritual, social, cultural, formation, ways and means, and membership committees. All of these projects have helped in nurturing the faith of the Filipino Catholic youth, their holistic growth, leadership capabilities, cultural and artistic talents, love for the family, and for the community. CYO in the Philippines was founded by Fr. George J. Willman in the year 1938, with Loreto Parish in Sampaloc, Manila as the pilot unit. Its National Chaplain, Emeritus is Msgr. Francisco Tantoco, and Fr. Jerome Cruz as National Chaplain. CYO's Founder's Day is celebrated every 29 June, which is also Fr. George J. Willman's birthday.

Australia
The Catholic Youth Organisation was established in Sydney in 1945 and had a peak membership of 20,000 in the 1950s.

title: Catholic Youth Organization


text:
Talk:Risk analysis (psychology)

This text appears to come originally from, a US fed gov't (and therefore public domain) source. -- Seth Ilys 16:45, 11 Mar 2004 (UTC)

The text seems to be more related to computer science than psychology.

title: Talk:Risk analysis (psychology)


text:
Talk:Boil

note
Isn't this more of a dictionary definition than an encyclopedia article?Average Earthman 16:46, 11 Mar 2004 (UTC)

from VfD
On 10 Feb 2005, this article was nominated for deletion. See Votes for deletion/Boil (disambiguation) for a record of the discussion.

Uniting boil and abscess
This is basicly the same thing, I think, instead of deleting it we should join the two articles together. Boil is just a form of abscess. --Friðrik Bragi Dýrfjörð 18:54, 15 February 2006 (UTC)

 * A boil is an infection of a hair follicle, while it can progress into a skin abscess if intreated, they are not the same and should remain as separate articles. BSW-RMH (talk) 01:53, 18 July 2010 (UTC)

vandalism
Someone seems to have put in nonsense phrases into the article. (Test0zero 20:23, 15 November 2006 (UTC))

Apparent contradictions
The text says that boils are swellings of the hair follicles... that can occur on the lips, and are caused by tiny cuts allowing in bacteria. Because it's such an ancient word and condition there may be multiple, inconsistent definitions running around, so it will be important to carefully source and describe specific meanings. 70.15.116.59 17:41, 12 October 2007 (UTC)

Boils can occur anywhere not just in hair follicles. A Furuncle is the name for a boil that occurs within a hair follicle. See = http://www.medicinenet.com/boils/article.htm — Preceding unsigned comment added by 72.11.91.140 (talk) 03:26, 30 November 2013 (UTC)

Pores
If the pores still exist on the swelling, what's keeping the contents from coming out? Oil or skin plug? Surface tension? —Preceding unsigned comment added by 70.231.245.50 (talk) 08:15, 27 November 2007 (UTC)

Hair follicles go deeper under the skin than pores, so the pus wouldn't be able to escape through a pore. —Preceding unsigned comment added by 98.150.249.61 (talk) 09:03, 14 January 2009 (UTC) the swelling hurt's really bad —Preceding unsigned comment added by 99.130.172.31 (talk) 04:44, 30 June 2010 (UTC)

Treatment
I removed the following text as it appears to be a home remedy and lacks any citation "One known treatment that is successful is to warm a small glass of milk until hot, then taking a small piece of white bread and dunking it in the milk, then placing it over the surface of the boil and applying pressure until the area becomes warm and the milk drains from the bread. With several appliances throughout the day in the early stages of the infection, this treatment can stop the growth of a furuncle. In some cases, in a period of six hours or so, the boil has disappeared completely." Bfootdav (talk) 06:33, 4 January 2010 (UTC)

The part about intralesional steroid injections is 100% incorrect, and the citation provided does not support the claim made in the article. — Preceding unsigned comment added by 140.107.59.86 (talk) 20:04, 12 October 2015 (UTC)

External Review Comments
Hello, Boil article writers and editors. This article currently a priority article for the Wikipedia talk:WikiProject Medicine/Google Project. The goal of this project to is provide a useful list of suggested revisions to help promote the expansion and improvement of this article. I have added references throughout the article.

BSW-RMH (talk) 03:43, 18 July 2010 (UTC)

Sign & symptoms
I replaced the Dorland’s Medical Dictionary reference with MedlinePlus, an approved source in line with the Reliable sources (medicine-related articles) guidelines. I also added the Clinical Dermatology: A Color Guide to Diagnosis and Therapy and Fitzpatrick's Color Atlas & Synopsis of Clinical Dermatology references.

I removed the information about odor because I did not find this in my references.

I moved the risks information to the ‘causes’ section

BSW-RMH (talk) 03:43, 18 July 2010 (UTC)

Causes
I added the information about risks to this section and a reference (Tamir) for myiasis.

BSW-RMH (talk) 03:43, 18 July 2010 (UTC)

Complications
This article would benefit from addition of a section on complications. The most common complications are scarring and infection or abscess of the skin, spinal cord, brain, kidneys, or other organs. The infection may also spread to the bloodstream (sepsis) and quickly become life-threatening.

Habif, TP. Furuncles and carbuncles. In: Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 4th ed. Philadelphia, Pa.: Mosby Inc; 2004.

Wolf K, et al. Section 22. Bacterial infections involving the skin. In: Fitzpatrick's Color Atlas & Synopsis of Clinical Dermatology, 5th ed. McGraw-Hill Companies Inc; 2005.

BSW-RMH (talk) 03:43, 18 July 2010 (UTC)

This section was added BSW-RMH (talk) 04:16, 10 August 2010 (UTC)

Treatment
This section could be expanded.

All furuncles must drain in order to heal. Draining can be encourages by application of a cloth soaked in warm salt water. Washing and covering the furuncle with antibiotic cream or antiseptic tea tree oil and a bandage also promotes healing. Furuncles should never be squeezed or lanced without the oversight of a medical practitioner because it may spread the infection.

Furuncles at risk of leading to serious complications should be incised and drained by a medical practitioner. These include furuncles that are unusually large, last longer than two weeks, or are located in the middle of the face or near the spine.

Furuncle at MedlinePlus, http://www.nlm.nih.gov/medlineplus/ency/article/001474.htm

Wolf K, et al. Section 22. Bacterial infections involving the skin. In: Fitzpatrick's Color Atlas & Synopsis of Clinical Dermatology, 5th ed. McGraw-Hill Companies Inc; 2005.

Tree tea oil. Natural Medicines Comprehensive Database. http://www.naturaldatabase.com/(S(iyok1uyiw1fl112ek3ax2lu2))/nd/Search.aspx?cs=MAYO&s=ND&pt=100&id=113&fs=ND&searchid=11129198. Accessed 7-17-2010.

BSW-RMH (talk) 03:43, 18 July 2010 (UTC)

These changes were made. BSW-RMH (talk) 04:21, 10 August 2010 (UTC)

Soap
Regarding the statement "It was reported that frequent hand and body washing with water and antimicrobial soap solution decreases staphylococcus skin colonization" Who reported this, and why is 'antimicrobial' soap necessary? Regular soap kill Staph just fine and does not promote resistive strains like Antibacterial soap does. Compare to common soap if you wish to leave this in...

Msjayhawk (talk) 21:02, 2 November 2010 (UTC)

poor personal hygiene
The references to poor personal hygiene are important but become repetitive in the article. If too great an emphasis is placed on a single cause the explanation can appear a little one dimensional. Other more general causes could be mentioned such as general health for example. —Preceding unsigned comment added by 109.156.114.10 (talk) 20:52, 19 December 2010 (UTC)

MRSA?
abcess "A previous study reported that MRSA infection was significantly associated with poor personal hygiene."What has MRSA got to do with boils? Myrvin (talk) 20:47, 23 February 2011 (UTC)

 * MRSA is a kind of Staph, and speaking of someone who had a boil that became a abscess, which I lost a chunk of my back to, was a MRSA infection. It happens.  I inserted a couple of "citations needed" because MRSA isn't necessarily attributed to poor personal hygiene.  Apparently we all harbor either normal staphylococcus aureus or MRSA in our noses and the way to tell is to get a nose culture done. It is slowly becoming the dominant version. The anti-microbial soap thing needed a citation-needed too because alcohol based washes do a better job and don't selectively breed MRSA, or so I thought.  If someone could put in the cites, it would be helpful.

Hidradenitis Suppurativa
I think that this skin disease should be discussed within this article. I just would like to say that I have had boils from age 12 - 29 (current) they have progressively gotten worse so I finally went to a dermatologist who has diagnosed me with Hidradenitis Suppurativa. I come from caring parents who had adequete Health Insurance for me. I grew up in Washington, DC so of course like most Washingtonians I seen a pediatrician at George Washington University Medical Center. Their staff wasnt able to identify my Hidradenitis Suppurativa and just gave me antibiotics for 6 yrs straight! I stopped taking them after 2 yrs. I grew up, moved out on my own and was still having problems withthe boils so after a many of days of internet research I ran across a person with the exact same symptoms and they felt important to educate people with boils on Hidradenitis Suppurativa. After reading this I went to a dermatologist who was able to idnetify Hidradenitis Suppurativa. I apologize for posting in this area as I do not know how Wikipedia actually works, but I felt the same obligation to inform the internet readers about a condition of boils called Hidradenitis Suppurativa. —Preceding unsigned comment added by 207.108.136.244 (talk) 21:04, 30 March 2011 (UTC)

Reference?
"In contrast to common belief, boils do not need to be drained in order to heal; in fact opening the affected skin area can cause further infections.[12]" The Reference 12 doesn't support this statement, should it be removed? -- 141.20.6.74 (talk) 13:14, 16 September 2011 (UTC)

 * fixed to better reflect the mayo article — Preceding unsigned comment added by 72.195.128.195 (talk) 04:00, 14 August 2012 (UTC)

Image
I am thinking that we can present an image of the skin lesion if we contrasted the photo and tilted the patient's site about 30-45 degrees from the intersecting plane. The current image is not all the visually descriptive. The major aspects missing are contrast and depth of the lesion. I propose substituting the current image. 400 Lux (talk) 01:18, 10 April 2014 (UTC)

A good source to get
My dermatologist recommended me this website called for information about dermatology. On this website, search any dermatology-related things and a lot of pages in the website can show you some good information about dermatology. A reliable primary source.

This article could do with more improvement with the amount of information and THEN start using more secondary and tertiary sources. That is what I recommend.

Qwertyxp2000 (talk) 03:37, 22 October 2014 (UTC)

Hair follicles, gumboils, etc
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External links modified
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title: Talk:Boil


text:
Grand County

Grand County is the name of two counties in the United States:

 * Grand County, Colorado
 * Grand County, Utah

title: Grand County