CH2 CHz?CU; CO CH 3 CO CH2 from sodio-malonic ester and 0-unsaturated ketones or ketonic esters: /CH, CO (R02C)2CH2+ Ph CH :CH /CH:>; CH(C02R) C07 from aceto-acetic ester and esters of a$-unsaturated acids, followed by elimination of the carboxyl group: CH2 CR', CH 3 CO CH 2.
Acids may be prepared by the action of dihalogen paraffins on sodio-malonic ester, or sodio-aceto-acetic ester (W.
The esters of the acids may also be obtained by condensing sodio-malonic ester with a-halogen derivatives of unsaturated acids: CH H?
The '1.1' dicarboxylic acid is prepared from ethylene dibromide and sodio-malonic ester.
When sodio-malonic ester is condensed with trimethylene bromide the chief product is ethyl pentane tetracarboxylate, tetramethylene dicarboxylic ester being also formed, and from this the free acid may be obtained on hydrolysis.