It may be distinguished from the isomeric ethylene succinic acid by the fact that its sodium salt does not give a precipitate with ferric chloride.
This is true of the fatty acid series, and the corresponding ketones and alcohols, and also of the succinic acid series.
Ethylidene succinic acid or isosuccinic acid, CH3 CH(C02H)2, is produced by the hydrolysis of a-cyanpropionic acid and by the action of methyl iodide on sodio-malonic ester.
Of such syntheses we may notice: the condensation of sodium malonic ester to phloroglucin tricarboxylic ester, a substance which gives phloroglucin or trioxybenzene when fused with alkalis, and behaves both as a triketohexamethylene tricarboxylic ester and as a trioxybenzene tricarboxylic ester; the condensation of succinic ester, (CH2 C02C2H5)2, under the influence of sodium to succinosuccinic ester, a diketohexamethylene dicarboxylic ester, which readily yields dioxyterephthalic acid and hydroquinone (F.
Haitinger, Monats., 1882, 3, p. 228); and by boiling succinic dialdehyde with ammonia and glacial acetic acid (C. Harries, Ber., 1901, 34, p. 1 497).
Burmite and simetite agree also in being destitute of succinic acid.
Potassium bichromate oxidizes it to malonic acid; nitric acid oxidizes it to oxalic acid; and hydriodic acid reduces it to succinic acid.
Ethylene succinic acid occurs in amber, in various resins and lignites, in fossilized wood, in many members of the natural orders of Papaveraceae and Compositae, in unripe grapes, urine and blood.
Prominent among these are glycerin and succinic acid.
Hydriodic acid and phosphorus reduce it to maleic acid and finally to succinic acid.