Castro-Stephens reaction
Synthesis of arylacetylenes (by analogy with the Chodkiewicz-Kadio method):
C6H5-X + Cu-C?CR > C6H5-C?CR + CuX
C6H5-C?C-X + Cu-C?CR > C6H5-C?C-C?C-R + CuX
Kizhner-Wolf reaction
The reaction of complete reduction of the keto group using hydrazine and a strong base (most often potassium hydroxide).
Clemmensen reaction
Opened in 1913. The reaction involves the reduction of the carbonyl group in aromatic and fatty aromatic ketones using amalgamated zinc and hydrochloric acid. makes it possible to obtain alkylbenzenes with a primary alkyl group, which are inaccessible by the Friedel-Crafts reaction. The mechanism has not been established in detail.
Claisen condensation
A chemical addition-fragmentation reaction in which carbonyl and activated methylene groups take part (in the presence of a base that abstracts a proton from the methylene group).
Here is an example of this type of reaction: the condensation of phenylacetic acid and ethyl acetate in ethanol in the presence of a catalytic amount of sodium ethoxide. The reaction mechanism is as follows: phenylacetic acid acts as an electrophile, nucleophilic sodium ethoxide (which can be considered as an ethylate anion) abstracts a proton from the methylene group, the resulting anion reacts with the electrophilic carbonyl ethyl acetate. Subsequently, the compound (β-keto acid) can be decarboxylated in an acidic environment to form a compound (which, however, no longer applies to condensation and is given for the sake of completeness of the reaction).
According to Clemmensen), reduction of the carbonyl group of aldehydes and ketones to methylene (deoxygenation) under the influence of Zn in hydrochloric acid:
The reaction is carried out by boiling the carbonyl compound. and Zn/Hg with excess HCl present. org. r-ritel or without it; yields 50 80%. Sterically hindered conn. are restored with lower yields. In K. r. aliphatic, fatty-aromatic. and aromatic. If there is one or more in a molecule. functional groups (COOH, COOR, OAlk, OH, etc.), the latter remain unchanged, for example: 
In the conditions of K. r. there is a restoration of C=C bonds conjugated with the carbonyl group, heterocyclic. nuclei, as well as replacing the halogen in the a-position to the carbonyl group with . By-products include the formation of pinacones, olefins and resinous products. Mechanism of K. r. not fully studied. It has been established that it is split off in the form of H 2 O from the partially reduced intermediate associated with Zn. Numerous are known. variants of K. r., differing in the nature of the solution and the method of amalgamation of Zn. Solvents that do not mix with water and HCl are often used. Thus, to remove the original substance and the product from the acidic zone of the solution, boiling water is often used (Martin’s modification); product yield approx. 90%. K.r. mainly used for the production of hydrocarbons from fatty aromatics. ketones. The district was opened by E. Clemmensen in 1913. Lit. Martin E.. in the book. Organic reactions, trans. from English, vol. 1. M.. 1948, p. 194 296; Fizer L., Fizer M.. Reagents for organic synthesis, trans. from English. t 4, M., 1971. p. 202; right there. t 5. p. 548; General, per. from English. t. 1, M.. 1981. p. 132; right there. t 2, M.. 1982. p. 506; Vedeis ED "Organic reactions", 1975, v. 22, p. 401 -22. K. V. Vatsuro.
Chemical encyclopedia. - M.: Soviet Encyclopedia. Ed. I. L. Knunyants. 1988 .
See what "CLEMMENSEN REACTION" is in other dictionaries:
Replacement of an oxygen atom of an aldehyde or ketone group with two hydrogen atoms under the action of amalgamated zinc and hydrochloric acid: K. r. used in laboratory organic synthesis most widely for... ...
Reduction of a carbonyl group (>C=O) into a methylene group (>CH2). To do this, the aldehyde or ketone is converted to hydrazone, which is decomposed by heating under pressure in the presence of bases: Ketone Hydrazine... ... Great Soviet Encyclopedia
Reduction of the carbonyl group of aldehydes or ketones into the methylene group by converting them into hydrazones and decomposing the latter into the presence. strong bases: The decomposition of hydrazones can be carried out in an alcohol environment under pressure at 180-200 °C in ... ... Chemical encyclopedia
Scientific career
Together with his wife, Pirquet committed double suicide on February 28, 1929, by taking potassium cyanide.
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Excerpt characterizing Pirquet, Clemens
“Sans aucun doute, sire, [Without any doubt, sir,” answered Rapp.Napoleon looked at him.
“Vous rappelez vous, Sire, ce que vous m"avez fait l"honneur de dire a Smolensk,” said Rapp, “le vin est tire, il faut le boire.” [Do you remember, sir, those words that you deigned to say to me in Smolensk, the wine is uncorked, I must drink it.]
Napoleon frowned and sat silently for a long time, his head resting on his hand.
“Cette pauvre armee,” he said suddenly, “elle a bien diminue depuis Smolensk.” La fortune est une franche courtisane, Rapp; je le disais toujours, et je commence a l "eprouver. Mais la garde, Rapp, la garde est intacte? [Poor army! It has greatly diminished since Smolensk. Fortune is a real harlot, Rapp. I have always said this and am beginning to experience it. But the guard, Rapp, are the guards intact?] – he said questioningly.
“Oui, Sire, [Yes, sir.],” answered Rapp.
Napoleon took the lozenge, put it in his mouth and looked at his watch. He didn’t want to sleep; morning was still far away; and in order to kill time, no orders could be made anymore, because everything had been done and was now being carried out.
– A t on distribue les biscuits et le riz aux regiments de la garde? [Did they distribute crackers and rice to the guards?] - Napoleon asked sternly.
– Oui, Sire. [Yes, sir.]
– Mais le riz? [But rice?]
Rapp replied that he had conveyed the sovereign’s orders about rice, but Napoleon shook his head with displeasure, as if he did not believe that his order would be carried out. The servant came in with punch. Napoleon ordered another glass to be brought to Rapp and silently took sips from his own.
“I have neither taste nor smell,” he said, sniffing the glass. “I’m tired of this runny nose.” They talk about medicine. What kind of medicine is there when they cannot cure a runny nose? Corvisar gave me these lozenges, but they don't help. What can they treat? It cannot be treated. Notre corps est une machine a vivre. Il est organise pour cela, c"est sa nature; laissez y la vie a son aise, qu"elle s"y defende elle meme: elle fera plus que si vous la paralysiez en l"encombrant de remedes. Notre corps est comme une montre parfaite qui doit aller un certain temps; l"horloger n"a pas la faculte de l"ouvrir, il ne peut la manier qu"a tatons et les yeux bandes. Notre corps est une machine a vivre, voila tout. [Our body is a machine for life. This is what it is designed for. Leave the life in him alone, let her defend herself, she will do more on her own than when you interfere with her with medications. Our body is like a clock that must run for a certain time; The watchmaker cannot open them and can only operate them by touch and blindfolded. Our body is a machine for life. That's all.] - And as if having embarked on the path of definitions, definitions that Napoleon loved, he suddenly made a new definition. – Do you know, Rapp, what the art of war is? - he asked. – The art of being stronger than the enemy at a certain moment. Voila tout. [That's all.]
Dozens of scientists made history in the diagnosis and treatment of tuberculosis. One of the most famous fighters against this dangerous disease was the Austrian pediatrician Clemens von Pirquet. In the first half of the last century, the Pirquet test (wrist scratch) found widespread use throughout the world. Other original ideas of this doctor contributed to the treatment of asthma and eczema. And it was thanks to him that the term “allergy” was established in medicine, which translated from Greek means “reaction to something foreign.”
Clemens von Pirquet was born on May 12, 1874 in a suburb of Vienna into a wealthy family of a member of parliament. All doors were open to the young aristocrat; he could have mastered any profession and taken any position, but he chose medicine. True, he didn’t come to her right away.
At first he was attracted to theology, and in 1892 Clemens went to Innsbruck to study this science. But the young man quickly realized that being a priest was not his calling and transferred to the Faculty of Philosophy. And again it’s not the same! After two semesters, he plunged headlong into the study of psychiatry and decided to connect his life with medicine. Pirke changed not only sciences, but also several universities: he studied in Vienna, Konigsberg and Graz. In 1900, the young man finally decided on the future profile of his research work and moved to the Department of Pediatrics at the Faculty of Medicine in Berlin. Pirquet's outstanding abilities were obvious even during his studies, so already in 1903 he was entrusted with lecturing students on the theory of vaccination.
The most brilliant works that brought him world fame belong to the first Viennese period of Pirquet's life. In 1905, a report of serum sickness appeared; in 1906, after a long study of skin reactions to various irritants, Pirquet introduced the concept of allergy (Greek Αλλεργία), which translated from Greek means “reaction to something foreign.” Apparently, the choice of such a capacious and precise name was facilitated by training at the Faculty of Philosophy. In 1907, after the first works on vaccination and the effects of tuberculin on the skin appeared in print, Pirquet proposed a new way to diagnose one of the most terrible diseases - tuberculosis. Like all ingenious things, the method was simple. The scientist found that upon contact with the vaccine, the skin of sick and healthy children exhibited different reactions.
This technique (for greater clarity, Pirquet made a small incision on the patient's forearm and rubbed the reagent there) was first demonstrated on May 8, 1907 at the Berlin Medical Society. After enthusiastic recognition by colleagues of the scientist’s many years of work, the method was adopted by doctors. The reaction demonstrated by Pirquet quickly became widespread. Its enormous diagnostic value and role in identifying the general infection of the population, especially early childhood, have undoubtedly been established.
As you can see, Pirke’s long search for himself allowed him to accumulate a considerable amount of knowledge, thanks to which at the age of 32 he made a revolutionary discovery in medicine, recognized as one of the main achievements of science of the 20th century.
Many important observations, systematized by the logic of creative thought, led to the tuberculin skin test. It is characteristic that it was the result of simple everyday observations, which generations of doctors passed by indifferently.
In 1911 Pirquet returned to Vienna. The organization of a medical-pedagogical department, an exemplary tuberculosis department, a method of systematically using hygienic factors within the walls of the clinic, a nursing school for nurses and doctors, a system of protection against intra-hospital infections, giving the entire work of the clinic a medical and social character - all this, carefully developed, will soon became the property of the entire pediatric world.
Perke did not belong to the numerous category of scientists in the West who confined their interests to narrow, purely clinical work. In the last years of his life, he devoted himself to rationalizing children's nutrition, creating a special system. During the famine years, when the child population of Austria suffered incredible hardships from the consequences of the war, Pirke organized and brilliantly supervised the work of a number of American aid societies. In addition to medicine, Pirquet was acutely concerned about social problems. He fought for the well-being of the citizens of his country not only as a doctor, but also as a public figure.
His scientific and especially social work made him so popular that he considered it possible to stand as a candidate for the presidential election. Perke was considered the most likely contender for the position of Austrian president, but was still defeated.
Of course, Clemens von Pirquet could have made more than one brilliant discovery, but with his tragic death on February 28, 1929, Austria lost an outstanding doctor, public figure, philanthropist and politician.
And now about his mysterious death. The obituaries say that Pirke died tragically, committing suicide, by the way, together with his wife. It is assumed that this was somehow connected with his social work.
Pirquet's contribution to science was appreciated during his lifetime. He was nominated for the Nobel Prize five times, although he never received this high award. In June 2010, grateful descendants in the scientist’s homeland issued a commemorative 50 euro coin dedicated to the outstanding Austrian pediatrician. On one side there is an engraved portrait of a talented doctor, and on the other - the building of a children's university clinic, a nurse bending over a sick child, and a doctor at a microscope.
Pirquet, unlike, for example, the pure scientist Koch, was primarily a practitioner - a “health care organizer”, with a penchant for strange calculations and, in modern terminology, an “active life position”, which irritated many. Perhaps that is why Joseph Brodsky, in his farcical “History of the 20th Century,” portrayed him like this:
Man of the Year - Herr von Pirquet.
Stab, destroy, chop
with Hamlet's syringe in hand:
Too-B o note Too-B?
“Believe me, an allergy is not just a rash.
Colleagues, dear, someone else's beauty
It’s not a pity, but these spots are a sad sign:
you will go irrevocably into darkness tomorrow.
Now my new principle: with my needle
I inject, using a syringe, a completely different one,
and at the same time – a virus (no need for tears);
but if the virus grows - tuberculosis.
Although 86 years have passed since the death of Clemens von Pirquet, his name is still remembered in scientific circles.
Kira Lesnikova
(Clemmensen reduction), reduction of the carbonyl group of aldehydes and ketones to methylene (deoxygenation) under the influence of Zn amalgam in hydrochloric acid:
The reaction is carried out by boiling the carbonyl compound. and Zn/Hg with excess HCl present. org. r-ritel or without it; yields 50 80%. Sterically hindered conn. are restored with lower yields. In K. r. aliphatic, fatty-aromatic. and aromatic carbonyl compounds. If there is one or more in a molecule. functional groups (COOH, COOR, OAlk, OH, etc.), the latter remain unchanged, for example: 
In the conditions of K. r. there is a restoration of C=C bonds conjugated with the carbonyl group, heterocyclic. nuclei, as well as replacing the halogen in the a-position to the carbonyl group with hydrogen. By-products include the formation of pinacones, olefins and resinous products. Mechanism of K. r. not fully studied. It has been established that oxygen is eliminated in the form of H 2 O from the partially reduced intermediate associated with Zn. Numerous are known. variants of K. r., differing in the nature of the solution and the method of amalgamation of Zn. Solvents that do not mix with water and HCl are often used. Thus, boiling toluene (Martin’s modification) is often used to remove the initial substance and the product from the acidic zone of the river; product yield approx. 90%. K.r. mainly used for the production of hydrocarbons from fatty aromatics. ketones. The district was opened by E. Clemmensen in 1913. Lit. Martin E.. in the book. Organic reactions, trans. from English, vol. 1. M.. 1948, p. 194 296; Fizer L., Fizer M.. Reagents for organic synthesis, trans. from English. t 4, M., 1971. p. 202; right there. t 5. p. 548; General organic chemistry, trans. from English. t. 1, M.. 1981. p. 132; right there. t 2, M.. 1982. p. 506; Vedeis ED "Organic reactions", 1975, v. 22, p. 401 -22. K. V. Vatsuro.
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