The carboxylate anion becomes methylated,thus generating the methyl ester,and nitrogen gas is evolved. Step 2:Nucleophilic attack on the methyl group displaces nitrogen 0 R-C- -g,CH,CN=N:→R-C -0-CH;+:N=N: Condensations of Acids with Amines (Amides) Although the acid chloride/amine reaction generates amides,it is also possible (and cheaper)to synthesize amides directly from carboxylic acids. The direct reaction of an amine and a carboxylic acid initially formed a carboxylate anion and an ammonium cation Normally the reaction would stop as this point since the carboxylate anion is a poor electrophile,but by heating the reaction to over 100C,the water can be driven off as steam,and amide products are formed. E.g QR-NH2 heat R-C-O-H 一R-C-ONHR R-C-NH-R +H2O This is an important commercial process. Ch20 Carboxylic Acids (landscape) Page 27Ch20 Carboxylic Acids (landscape) Page 27 The carboxylate anion becomes methylated, thus generating the methyl ester, and nitrogen gas is evolved. Condensations of Acids with Amines ( Amides) Although the acid chloride/amine reaction generates amides, it is also possible (and cheaper) to synthesize amides directly from carboxylic acids. The direct reaction of an amine and a carboxylic acid initially formed a carboxylate anion and an ammonium cation. Normally the reaction would stop as this point since the carboxylate anion is a poor electrophile, but by heating the reaction to over 100°C, the water can be driven off as steam, and amide products are formed. E.g. This is an important commercial process. R C O O-H R-NH2 R C O O -+NH3R heat R C O NH-R +H2O