MALONIC ACID crystallizes in large colourless plates, dis solving readily in water, alcohol or ether, and melts at 135.6° C. Although the sparingly soluble calcium malonate occurs in beet root, the acid itself, is generally produced by laboratory methods, such as the oxidation of malic acid (q.v.) or the hydrolysis of cyanoacetic acid, When care fully heated at 140-150° C, malonic acid partly decomposes into acetic acid and water, but 10-12% undergoes dehydration with formation of carbon suboxide, C302. (See CARBON COMPOUNDS.) The outstanding importance of malonic acid in systematic ch ethyl_ arises from the varied syntheses which can be with ts ethyl ester, diethyl malonate, or "malonic ester," CH2(CO2C 2H?)2. This ester, usually prepared by passing hydro gen chloride into i o a solution of cyanoacetic acid (obtained from chloroacetic acid) in absolute alcohol, is a colourless fragrant boiling at 198° C. Its very reactive methylene group,
i CH2, is instrumental in effecting syntheses of higher mono- and di-basic acids. (See HEMISTRY Organic.) The replacement of one hydrogen ofthis methylene group by sodium gives sodio malonic ester; this on heating at 145° C is condensed to a ben zenoid derivative, ethyl phloroglucinoltricarboxylate, which by alkali fusion yields the drug phloroglucinol. In the presence of sodium ethoxide the esters of malonic acid and diethylmalonic acid undergo condensation with urea to furnish respectively bar bituric and diethyl-barbituric acids, the latter being the well-known soporific drug, veronal (q v.). By a similar condensation with urea dipropylmalonic acid yields the drug proponal.