B-Dimethyl-hydrocinnamic acid

348 grains of methyl ethyl glycolic acid, and 450 grams of acetic anhydride are heated together for 4 hours on an oil bath at 150° C. The acetic acid is subsequently distilled off. 250 grams of dimethyl acrylic acid are isolated from the distillation residue (84% of the theoretical yield) of dimethylacrylic acid. 

30 grams of dimethylacrylic acid (dissolved in 220 grams of thiophene-free, dry benzene) and 100 grams of finely powdered anhydrous aluminum chloride are allowed to stand for 1 week at 40-45° C. Ice and concentrated hydrochloric acid are added to the reaction mixture. The benzene and aqueous layers are thereafter separated and, after evaporation the benzene, 30 grams (56% of theoretical yield) of an acid boiling at 129-132° C. can be isolated from the residue by vacuum distillation at 5 mm. pressure. After one recrystalization from petroleum ether and benzene the melting point is 132° C. 

Analysis gave a carbon content of 74.3% and a hydrogen content of 7.95%. For a/p/ia-b-dimethylcinnamic acid the carbon content is calculated to be 74.2 % and the hydrogen content 7.88%. 

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The aZp/ia,l3-dimethyl-cinnamic acid is hydrogenated by dissolving the acid in an equivalent amount of alkali and then hydrogenating it with colloidal palladium according to Paal and Skite. a/p/ia,B-dimethyl hydrocinnamic acid, which can be recrystallized. 

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