Organic chemistry is a huge field for research and experimentation. The number of reactions and methods for producing the same substance can sometimes be amazing. It is not surprising that among this chaos, the most important is noted by the names of the scientists who made the discovery. Therefore, in chemistry there are a lot of so-called nominal reactions - named after their researchers. They will be discussed.
History of Organic Synthesis
Previously, a very long time ago, it was believed that all chemistry was divided into two parts - “living” and “nonliving”. Now this classification approximately coincides with the division into organic and inorganic, but then they also believed that compounds of "living" chemistry could not be obtained in the laboratory, but could only be isolated from the natural materials in which they were contained. The point is the mysterious manpower, which in a special way regulates all processes in the "living" chemistry.
Friedrich Wöhler refuted these beliefs in 1824 by obtaining urea from living chemistry from inanimate ammonia and carbon dioxide. The reaction was carried out at high temperature and pressure, but without the participation of any "living forces". Later, Veler’s student Adolf Kolbe synthesized trichloroacetic acid. It was a long chain of reactions, but at the very beginning it was only coal. And from trichloroacetic acid he received acetic acid .
Berthelot's reactions
The previous evidence was convincing, but there was still very little of it. And here the French chemist Marseille Berthelot entered the game. He synthesized methane - the basis of all organics - using hydrogen sulfide and carbon disulfide. When these gases were passed over a copper catalyst, the desired compound was obtained. Berthelot's next experiment was the reaction of producing formic acid from sodium alkali and carbon monoxide. Then they synthesized acetylene - Berthelot used hydrogen electrolysis on carbon electrodes, Weler hydrolyzed carbide.
In addition to these two hydrocarbons (methane and acetylene), Berthelot received many more complex ones - benzene, ethylene and their derivatives. Ethanol was obtained from ethylene and water in the presence of sulfuric acid - this Berthelot reaction served as yet another refutation of the “life force” that was supposed to participate in the formation of the same ethanol fermentation, the previous method of preparation.
All the same Berthelot managed to get natural fats from glycerol and fatty acids. All these reactions in the aggregate nevertheless completely refuted the notion of "inanimate force", and thus the foundation was laid for the chemistry of organic synthesis - the study of methods for producing various organic compounds.
Laboratory reactions
The most popular reaction, one of the few known to anyone other than chemists, is the Tollens test , or the reaction of a silver mirror. It consists in the oxidation of aldehyde, formic acid (and a number of other less popular compounds) and the simultaneous reduction of silver, which is deposited on a smooth surface in the form of a continuous shiny layer - that same mirror.
Another well-known nominal reaction in organic chemistry is the Kucherov reaction - hydration of alkynes with the help of mercury salts in an acidic medium. As a result, enol is first formed - unsaturated alcohol, which then regroups into a carbonyl compound (aldehyde or ketone).
Of interest is also the Diels-Alder reaction. It is difficult enough to explain with words and very simply with a picture.
First, the conjugated diene enters the reaction (for such a diene, double bonds are located through one), and secondly, the dienophile, which has a double bond, and not a simple one, but with a lower electron density - therefore, the dienophile has a multiple bond next to it there is an electron-withdrawing group (carbonyl, carboxyl or some other), which draws this density onto itself. Then the diene is attached to the dienophile multiple bond, forming a six-membered cycle.
Industrial synthesis
One of the most significant reactions, especially for Russian science, is the synthesis of butadiene - the basis for the production of synthetic rubber. It is called the reaction of Lebedev. Ethyl alcohol is passed over a complex catalyst - aluminum oxide, zinc oxide and a temperature of 400-500 o C. The process takes place in one stage and this is beneficial; it was thanks to him that the USSR in 1926 received the raw materials necessary for the production of one of the most important industrial polymers - synthetic rubber, that is, rubber.
The Fischer-Tropsch process is also of great importance. It consists in obtaining various liquid hydrocarbons from synthesis gas (a mixture of carbon monoxide and hydrogen) with catalysts from iron or cobalt. From the synthesis products, you can continue to make fuel - gasoline or diesel (the main directions of the use of the process). Also, the composition of the synthesis products can be changed by selecting certain catalysts: the process can be directed to the production of methane, branched chain hydrocarbons, higher paraffins, methanol and others.
Discrepancies
Often in the scientific literature in different languages, the name of the same reaction may differ. For example, the reaction of mild oxidation of alkenes to dihydric alcohols - glycols - is called the Wagner reaction in all Russian-language literature , but remains nameless in the rest of the world.
There is also a reaction in which the silver salts of carboxylic acids react with halogens to form halogenated hydrocarbons. During the reaction, the carboxyl group leaves, therefore, the halogen-substituted hydrocarbon chain contains one less carbon atom. We usually call it the Borodin- Hundisker reaction, but in German and English scientific literature it is usually known as the Hundisker reaction.
And where, in fact, is the reaction with the name of Berthelot?
In Russian-language organic chemistry, a nominal reaction, wholly and completely owned by Berthelot, does not exist. The production of benzene by trimerization of acetylene at 600 ° C is a reaction of Zelinsky, or Berthelot-Zelinsky. Do not confuse the Bertlo-Zelinsky reaction with the Zelinsky-Kazan reaction: in both cases, benzene is obtained, only in the first - from acetylene, and in the second - from cyclohexane. However, there is the so-called Berthelot method, which is used to detect ammonia. The Berthelot reagent participating in this reaction — a solution of phenol with sodium hypochlorite in an alkaline medium — reacts with ammonia to form blue-colored indophenol.
The method is widely used in analytical chemistry (in particular, for the detection of phenol in urine or for the detection of urea itself, which decomposes into ammonia and carbon dioxide).