The '1.1' dicarboxylic acid is prepared from ethylene dibromide and sodio-malonic ester.
The cis 1.2-cyclo-propane dicarboxylic acid is formed by eliminating carbon dioxide from cyclo-propane tricarboxylic acid -1.2.3 (from 43-dibrompropionic ester and sodio-malonic ester).
The a-acid is diphenyl-2.4-cyclo-butane dicarboxylic acid -1.3; and the /3-acid diphenyl-3.4-cyclo-butane dicarboxylic acid -1.2.
When digested with fuming hydrochloric acid for some time it is converted into ad furfurane dicarboxylic acid (see Furfurane); while on heating with barium sulphide it is transformed into a - thiophene carboxylic acid (see Thiophene).
