Cis-Cinnamic acid

But catalytic reduction of the same phenyl propionic acid gives cis cinnamic acid. Therefore by adding hydrogen under various conditions, one can obtain a desired isomer. The conversion of acetylene into olefinic compounds has been carried out not only for the sake of obtaining the adduct, but Michael studied the various addition reactions for the sake of obtaining a desired product cis or trans. For example, he found that the addition of bromine to acetylene-dicarboxylic acid leads predominantly to the formation of trans isomer. 

Acetylenic aromatic acids having the triple bond Hanked by carboxyl and an aromatic ring were partially reduced to olefinic aromatic acids by chromous sulfate in aqueous dimethylformamide at room temperature in high yields. Phenylpropiolic acid afforded irani -cinnamic acid in 91% yield [195]. Its sodium salt in aqueous solution gave on catalytic hydrogenation over colloidal platinum at room temperature and atmospheric pressure 80% yield of cis-cinnamic acid if the reaction was stopped after absorption of 1 mol of hydrogen. Otherwise phenylpropanoic acid was obtained in 75-80% yield [992]. 

Bregman, J., K. Osaki, G. M. J. Schmidt, and F. I. Sonntag Topochem-istry. IV. The crystal chemistry of some cis-cinnamic acids. J. chem Soc. [London] 1964, 2021. 

The cis cinnamic acids as- 13B also isomerize to the tram acids under the same conditions but more slowly. What is the mechanism of this reaction ... 

C9H7N02 indole-6-carboxylic acid 1670-82-2 25.00 1.1330 2 16203 C9H802 cis-cinnamic acid 102-94-3 27.11 1.1523 2... 

A rare substitution hydroxylation is effected by Fusarium solani, which converts o-hydroxy-cis-cinnamic acid into 4-hydroxycoumarin (equation 473) [1089]. 

GA Reed, DR Dimmel, EW Malcolm. The Influence of Nucleophiles on the High Temperature Aqueous Isomerization of cis-Cinnamic Acid. J Org Chem 58 6364, 1993. 

Recall from Section 7.13 that a stereospecific reaction is one in which each stereoisomer of a particular starting material yields a different stereoisomeric form of the reaction product. In the examples shown, the product from Diels-Alder cycloaddition of 1,3-butadiene to cis-cinnamic acid is a stereoisomer of the product from trans-cinnamic acid. Each product, although chiral, is formed as a racemic mixture. 

Coumarins are quantitatively hydrolysed to give yellow solutions of the salts of the corresponding cis-cinnamic acids (coumarinic acids), which cannot be isolated, since acidification brings about immediate re-lactonisation prolonged alkali treatment leads to isomerisation and the formation of the trans- c A (coumaric acid) salt. 

An interesting method has been devised for estimating the approximate quantum yield for the photodimerization of solid trans-clnnamlc acid in crystalline films. It appears that cis-cinnamic acid formation occurs at defect sites. Photocylization of (5) helicene to dihydrobenzoperylene in Shpols ki matrices at 4.2 K... 

The fact that there is only one product formed indicates that the second step occurs faster than does rotation about the carbon-carbon single bonds in the diradical intermediate. The diradical intermediate has a free electron on carbon 3 (and not carbon 2) of cis-cinnamic acid because it can undergo resonance stabilization involving the phenyl group. A proposed ionic mechanism for the same Diels-Alder reaction is ... 

Fig. I. Molecular models of the cinnamic acids. Left froM -cinnamic acid benzene nucleus, unsaturated side-chain and carboxyl group in one plane. Right cis-cinnamic acid coplanarity as occurring in the trans-iorm is impossible because of steric hindrance the side-chain cannot pass the hydrogen atoms in 2- and 6-positions.

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