O-Carboxycinnamic acid

A. o-Carboxycinnamic acid. Eighty-eight grams (78 ml., 0.46 mole of peracid) of 40% peracetic acid (Note 1) is placed in a 250-ml. Erlenmeyer flask which is immersed in a water bath maintained at 25-30°. A 150-ml. dropping funnel is mounted so that the stem enters the flask to within about 4 cm. of the liquid surface. With mechanical stirring (Note 2), a cold solution of... 

The filtrate, either on concentration under reduced pressure or upon dilution with water, fails to yield more o-carboxycinnamic acid, but a crystalline by-product, presumably 4-(o-carboxy-phenyl)-5,6-benzocoumarin,2 may be encountered in small yield. 

On melting, o-carboxycinnamic acid cyclizes to give the lactone of /3-hydroxy-j3-(0-carboxyphenyl)propionic acid (phtha-lideacetic acid), m.p. 153°. If the melting point is taken too slowly, or if the diacid is not washed completely free of mineral acid, it may therefore melt considerably below 200°. The re-... 

Using less than 50 g. of the alloy results in the same yield of final product, which, however, contains small amounts of unchanged o-carboxycinnamic acid. Equally good results are obtained when proportionately smaller quantities of reactants are used. 

Page and TarbelP oxidized /8-naphthol to o-carboxycinnamic acid with 1.1 times the theoretical amount of 40% Becco peracetic acid without addition of sodium acetate. The peracid (0.14 mole) was stirred in a bath at 25-30°, and a solution of 0.14 mole of /3-naphthol in 100 ml. of acetic acid was added in 4 hrs. (temperature 5H. XOjH... 

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