Perkin’s reaction

Cinnamic Acid. CeH5CH CH COOH. (Perkin s Reaction.)... 

Cinnamic acid is usually prepared by Perkin s reaction, benzaldehyde being heated with sodium acetate in the presence of acetic anhydride. It is probable that the benzaldehyde and the acetic anhydride combine under the catalytic action of the sodium acetate, and the product then readily loses water to give mono-benzylidene acetic anhydride (. ). The latter, when subsequently... 

Cinnamic Acid.—The reaction, which takes place when an aldehyde (aliphatic or aromatic) acts on the sodium salt of an aliphatic acid in presence of the anhychide, is known as Perkin s reaction, and has a ery wide application. Accoid-ing to the result of Fittig s researches on the properties of the unsaturated acids described below, the reaction occurs in two steps. The aldeh) de forms first an additive compound with the acid, the aldehyde caibon attaching itself to the n-carbon ii.e.i nevt the carbovyl) of the acid. A saturated hydiOKy-acid is formed, which is stable, if the a-carbon is attached to only one atom of hydrogen, as in the case of isobutync acid,... 

Other reactions involving the addition of carbanions are reactions like Perkin s reaction, Claisen condensation, benzilic acid rearrangement and Michael addition. 

The methylene groups of hippuric acid and malonic acid are much more reactive than that of acetic acid. They may be caused, therefore, to condense with aldehydes under much milder conditions, e.g. by the action of pyridine. The use of malonic acid forms an extension of Perkin s reaction to the aliphatic series (Doebner), e.g. 

When benzaldehyde is condensed with hippuric acid in the presence of acetic anhydride a Perkin s reaction takes place and benzoyl-a-amido-cinnamic acid is formed —... 

Am. Soc., 1,313.)—This is an extension of Perkin s reaction, and depends on the fact that when benzaldehyde and phenyl-acetic acid are condensed in the usual way, the unsaturated acid thus formed is unstable, and loses carbon dioxide, giving stilbene. 

Cinnamic Acid by Perkin s Reaction.—Cinnamic acid has the constitution assigned to it above as is proven by the following synthesis from benzaldehyde by condensation with sodium acetate in the presence of acetic anhydride. 

Oxidation. Aromatic amines can undergo a variety of oxidation reactions, depending on the oxidizing agent and the reaction conditions. For example, oxidation of aniline can lead to formation of phenyUiydroxylamine, nitrosobenzene, nitrobenzene, azobenzene, azoxybenzene or -benzoquinone. Oxidation was of great importance in the early stages of the development of aniline and the manufacture of synthetic dyes, such as aniline black and Perkin s mauve. 

This series of ten alkaloids may appropriately be called the cryptopine sub-group, since the characteristic nuclear structure of the type was first made clear by Perkin s investigation of cryptopine. They are closely related to the profoberberines, with which they are interconvertible by two characteristic reactions, which have been of great value in their investigation. The two alkaloids formerly known as )S- and y-homochelidonines have now been renamed a- and -ofiocryptopines respectively to distin-... 

While Robinson was completing his thesis work under Perkin s direction, on the chemistry of brazilin and the structure of alkaloids, he discovered that Lapworth had a highly personal and successful method of deciding whether a reaction would "go" or not it turned out to be the scheme of alternating... 

Derivatives of Menthene.— The most important alcohols and ketones derived from the menthene unsaturated group of terpenes are terpineol, di-hydro carveol, di-hydro carvone and pulegone. The first one, the alcohol terpineol, occurs in its dextro form in cardamon oil and marjoram oil, in its leoo form in neroU oil and in its inactive form in cajeput oil. The constitution is proven by Perkin s synthesis from As-tetra-hydro para-toluic acid by means of the Grignard reaction. 

Bowden, K., Battah, S. Reactions of carbonyl compounds in basic solutions. Part 32. The Perkin rearrangement. J. Chem. Soc., Perkin Trans. 21998, 1603-1606. 

B champ s discovery in 1854 that nitro compounds could be reduced in the presence of iron and acetic acid and Perkin s subsequent application in 1857 of the reaction in the commercial production of aniline were events of great significance in the development of the dye industry, and thus in the birth of industrial synthetic organic chemistry. Technical progress in the application of this reaction was first made by substituting hydrochloric acid for the acetic acid originally employed. Subsequently, it was discovered that the ferrous salt functions in such a way that reduction can be carried out with far less than the theoretical quantity of acid. 

Tyrosine has been prepared by a number of interesting methods one of these involves the condensation of p-hydroxy-benzaldehyde and hippuric acid, C6H5CO.NH.CH2COOH, by a reaction similar to that which takes place in Perkin s synthesis. 

It was not long after Perkin s original feat that Kekule and his structural formulas supplied organic chemists with a map of the territory, so to speak. Using that map, they could work out logical schemes of reaction, reasonable methods for altering a struc-... 

Often the reactions worked out received the name of the discoverer. A method for adding two carbon atoms to a molecule, discovered by Perkin, is called the Perkin reaction, for instance a method for breaking an atom ring containing a nitrogen atom, discovered by Perkin s teacher, is the Hofmann degradation,... 

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