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Encyclopedia Britannica - Main :: MAL-MAR |
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MALONE , a village
York
York
village
CC12:CH000C2H5 + Ag2O + H20= 2AgC1 + HOOCCH2COOC2H5. It crystallizes in monoclinic tables, and is readily soluble in water, alcohol and ether. The acid melts at 132 C., and at a higher temperature it rapidly decomposes into acetic acid and carbon dioxide. When heated with bromine and water to rod C. it forms tribromacetic acid, some bromoform being produced at the same time. Malonic acid, as well as its esters, is characterized by the large number of condensation products it can form. In the presence of a dehydrating agent (such as acetic anhydride), it combines with aldehydes to form compounds of the type R CH: C(COOH)2, or their decomposition products (formed by loss of CO2) R CH : CH COOH. Many salts of the acid are known and, with the exception of those of the alkali metals, they are difficultly soluble in water. Many esters of malonic acid have been prepared, the most important being the diethyl ester (malonic ester), CH2(000C2H5)2, which is obtained by dissolving monochloracetic acid in water, neutralizing the solution with potassium carbonate, and then adding potassium cyanide and warming the mixture until the reaction begins. When the reaction has finished, the whole is evaporated and heated to about 130`-140 C. and then allowed to cool. The mass is then covered with two-thirds of its weight
heating
scheme of reactions is shown thus:R'I CH2(COOR)2- CHNa(COOR)2-.CHR'(COOR)2 1NaOH End of Article: MALONE If you wish, you can link directly to this article.
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