Malonic acid, as well as its esters, is characterized by the large number of condensation products it can form.
It is a most important synthetic reagent; with sodium or sodium ethylate it forms sodio-malonic ester, which reacts readily with alkyl halides, forming alkyl malonic esters, which are again capable of forming sodium derivatives, that by further treatment with alkyl halides yield the di-alkyl malonic esters.
Potassium bichromate oxidizes it to malonic acid; nitric acid oxidizes it to oxalic acid; and hydriodic acid reduces it to succinic acid.
Dibasic acids of the paraffin series of hydrocarbons have the general formula C n H 2 (000H) 2 "; malonic and succinic acids are important members.
Of foremost importance are the reactions termed the malonic acid and the aceto-acetic ester syntheses; these are discussed under their own headings.
It liquefies at 7° C. It is an exceedingly reactive compound, combining with water to form malonic acid, with hydrogen chloride to form malonyl chloride, and with ammonia to form malonamide.
It can be prepared by the reduction of phenyl propiolic acid with zinc and acetic acid, by heating benzal malonic acid, by the condensation of ethyl acetate with benzaldehyde in the presence of sodium ethylate or by the so-called "Perkin reaction"; the latter being the method commonly employed.
Crotonic acid, so named from the fact that it was erroneously supposed to be a saponification product of croton oil, may be prepared by the oxidation of croton-aldehyde, CH3 CH:CH CHO, obtained by dehydrating aldol, or by treating acetylene successively with sulphuric acid and water; by boiling allyl cyanide with caustic potash; by the distillation of 0-oxybutyric acid; by heating paraldehyde with malonic acid and acetic acid to, oo C. (T.
It crystallizes in prisms which melt at 121° C. It yields addition compounds with aniline and naphthalene, and combines directly with potassium methylate, sodio-malonic ester and hydrocyanic ester.
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.
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.
Riiber (Ber., 1902, 35, p. 2411; 1904, 37, P. 22 74), by oxidizing diphenyl-2.4-cyclo-butane-bismethylene malonic acid (fron cinnamic aldehyde and malonic acid in the presence of quinoline) with potassium permanganate.
The 1.4 compound also boils at 81-82° C. and on oxidation gives succinic and malonic acids.
It may be prepared synthetically by fusing its dicarboxylic ester (from malonic ester and sodio malonic ester at 145° C.) with potash (C. W.
Hexahydrobenzoic acid, C 6 H 11 CO 2 I-I, is obtained by the reduction of benzoic acid, or by the condensation of 1.5 dibrompentane with disodio-malonic ester.