| 摘要 |
Carboxylic acids of formula (I) are prepd. by reacting a mercaptan of formula (II) with an unsatd. carboxylic acid of formula (III) or its anhydride in a strongly acidic medium. - X = S or NH; each R is independently H, alkyl, haloalkyl, alkoxy, alkylthio, alkylsulphonyl, phenyl, alkylphenyl, phenylalkyl, cycloalkyl, halogen, NO2, CN, COOH, alkoxycarbonyl, OH or a prim., sec. or tert. amino or carbamoyl gp.; R1-R4 = H, alkyl, haloalkyl, hydroxyalkyl, alkoxyalkyl, carboxyalkyl, COOH or opt. substd. aryl or aralkyl, or R1+R2 is a bond or an alkylene gp. opt. substd. by 1 or 2 COOH gps.
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