Phenyl propiolic acid

The trans cinnamic acid and phenyl propiolic acid data involve fits of essentially the same precision at o-, m-, and p- positions (SD =. 05 . 02). However, the RMS of these sets is quite low, and consequently, / values of. 200 prevail. The interpretation of these results is therefore uncertain. To the extent that the results of Table VII are meaningful, it is of particular interest that Kj =p°Ip =. 68 for the phenyl propiolic acid, whereas for the tram cinnamic acids, K° = 1.02. These results suggest that in contrast to the ortho substituted benzoic acids, the lines of field forces in the ortho substituted phenyl propiolic acids do (partly at least) penetrate regions of hi dielectric solvent. The results for the tram cinnamic acids would then indicate some (but not complete) exclusion of solvent resulting from the presence of the vinyl hydrogens. These interesting results from the application of eq. (1) clearly need to be confirmed by additional studies. 

Additions at the triple bond. The catalytic hydrogenation of acetylenes gives predominantly the cis isomer. The reason is obvious. Both the hydrogen atoms approach the double bond from the same side from the side of the catalyst. The hydrogenation of phenyl propiolic acid is an example. 

Similarly phenyl propiolic acid is first reduced to phenyl propargyl alcohol which then forms a complex with LiAlH4 and decomposition of the latter with water gives cinnamyl alcohol. 

Mononitro compounds could be selectively obtained in the nitration of phenyl-propiolic acid derivatives with HNO3-HSO3F at low temperature501 [Eq. (5.191)]. Addition of fluorosulfuric acid to the triple bond, however, may also take place with substituted derivatives. 

Diphenyl-diacetylene is the parent hydi ocarhon of indigo blue, and the dye itself can be prepared by means of tliis reaction, starting with o-nitro-phenyl-propiolic acid. By loss of carbon dioxide the acid becomes o-nitro-phenyl-acetylene, the copper derivative of which passes to di-ortho-nitrophenyl-diacety-lene ... 

It is necessary to prepare first, o-nitro-phenyl-propiolic acid, which is itself obtained from o-nitro-cinnamic acid. Cinnamic ester (50 gms.) is nitrated by pouring gradually into cooled nitric acid (sp. g. 1-5). 

Table 5. Solvent effects on regioselectivity in the additions of pyrollidine and n-propylamine to 2-furyl- and phenyl-propiolic acid derivatives, X—R—C=CCOY (equation 53) >...

Phenyl acetic acid. Hydro cinnamic acid. Cinnamic acid or Phenyl acrylic acid Phenyl propiolic acid. Phenyl vinyl acetic acid. 

This acid is the simplest aromatic acid with the carboxyl in the side chain. Its name, phenyl acetic acid, indicates the relation to the aliphatic acids as a phenyl derivative. The commonly used names for the side-chain carboxy acids are derived similarly, e.g. phenyl propiolic acid. It will be seen at once that phenyl acetic acid and the toluic acids are isomeric, the first being the result of the partial oxidation of ethyl benzene, the latter the result of the partial oxidation of the di-methyl benzenes or xylenes which are isomeric with ethyl benzene. In both cases the relationship to the hydrocarbon is that only one carbon group of the side chain is oxidized to carboxyl. 

Phenyl Propiolic Acid.—The acetylene unsaturated side chain hydrocarbon phenyl propine, CbHb—C = C—CH3, yields an acid known as phenyl propiolic acid, CeHs—C = C—COOH, which by loss of carbon dioxide yields phenyl acetylene, CeHs—C = CH. The acid is important in connection with the synthesis of indigo (p. 879). 

Benzaldehyde, ortho-Nitro Cinnamic Acid, ortho-Nitro Phenyl Propiolic Acid.—Later he started with benzaldehyde and obtained first benzal chloride which by condensation with sodium acetate yielded cinnamic acid salt. 

From the cinnamic acid salt by nitration he obtained ortho-nitro cinnamic acid. This yielded a di-bromide which by loss of two molecules of hydrogen bromide was converted into ortho-nitro phenyl propiolic acid (p. 700). 

Finally ortho-nitro phenyl propiolic acid when heated with alkali and glucose, the latter acting as a reducing agent, yielded indigo. He also converted ortho-miio phenyl propiolic acid into indigo by the following series of reactions. 

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