C([O-])(=O)/C=C\C([O-])=O.[Ca+2].[O:10]1[CH:15]([C:16]([O-:18])=[O:17])[CH:11]1[C:12]([O-:14])=[O:13].[Ca+2].[Ca].S(=O)(=O)(O)O>CC(C)=O>[O:10]1[CH:15]([C:16]([OH:18])=[O:17])[CH:11]1[C:12]([OH:14])=[O:13]
The epoxidation of acid calcium maleate was effected in accordance with Example 1. 50 g. of the calcium epoxysuccinate attained in this manner (calcium content 11.9% by weight) were suspended, with stirring, in 400 g. of 50% aqueous acetone. 15 g. of concentrated sulphuric acid were then added and the suspension was kept for 2 hours at 20° C. If the suspension is made in acetone alone, a corresponding amount of dilute sulphuric acid may be added instead of concentrated sulphuric acid. The suspension was then heated to 50° C. and, after being kept for 2 hours at this temperature, the calcium sulphate was filtered off and washed with water. The acetone was removed by distillation from the mixture of acetone and water, and the remaining aqueous epoxysuccinic acid solution was subjected directly to hydrolysis. From two moles of acid calcium epoxysuccinate, 512 g. of free epoxysuccinic acid were obtained, corresponding to a yield of 97% of the theoretical.
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