C3H404 MALONIC

ACID  or CH2(000H)2, occurs in the form of its calcium salt in the sugar beet . It was first prepared in 1858 by V . Dessaignes, who obtained it by oxidizing malic acid (Ann., 1858, 107, p . 251) . It may also be obtained by oxidizing allylene and propylene with cold potassium permanganate solution, by the hydrolysis of barbituric acid (malonyl urea) with alkalis (A . Baeyer, Ann., 1864, 130, p . 143) ; by the hydrolysis of cyanacetic acid (H . Kolbe, Ann., 1864, 131, p . 349; H . Muller, Ann., 1864, 131, p . 352), and by the action of silver oxide on 13-di-chloracrylic ester at 125° C . (O .

Wallach, Ann., 1878, 193, p . 25) The

half nitrile of malonic acid is cyanacetic acid, CN•CH•2 COOH, which, in the form of its ester, may be obtained by the action of a solution of potassium cyanide on monochloracetic acid . The solution obtained is neutralized, concentrated on the water-bath, acidified by sulphuric acid and extracted with ether . It is then converted into the lead salt, which is decomposed by sulphuretted hydrogen and the solution is carefully concentrated (Th . Nieves, Ann., 1867, 143, p . 201) . It melts at 70° C.and at higher temperatures decomposes, with evolution of carbon dioxide and formation of aceto-nitrile, CH3.CN . The true nitrile of malonic acid is methylene cyanide, CH2 (CN)2, which is obtained by distilling a mixture of cyanacetamide and phosphorus pentoxide . It is a crystalline solid, which melts at 29°—30' C. and boils at 218°-219° C., and is readily soluble in alcohol and ether .