| 摘要 |
Dicarboxylic acids of the formula <FORM:1115039/C2/1> in which A is a polymethylene radical containing at least 3 carbon atoms, or the anhydrides or diesters thereof are prepared by (a) reacting at room temperature two molecular proportions of halogen with one molecular proportion of a b -keto-ester of formula <FORM:1115039/C2/2> in which R is C1-C4 alkyl; (b) reacting the di-halo compound obtained with an alkali metal carbonate or bicarbonate in a C1-C4 alkanol, and, if desired, (c) converting the dicarboxylic ester obtained into the corresponding acid or anhydride. Examples are given of the preparation of (a) cycloundec-1-ene-1,2-dicarboxylic acid (which is claimed per se) its anhydride and its mixed methyl ethyl ester; (b) cyclohept-1-ene-1,2-dicarboxylic acid and its ethyl ester; and (c) cyclopent-1-ene-1,2-dicarboxylic acid and its ethyl ester. |
