Abstract
The carboxylation of nitromethane with carbon dioxide proceeded in the presence of potassium phenoxides in DMF, yielding dipotassium nitroacetate as a precipitate. This reaction proceeded well at 0°C. The substituent effect upon the carboxylation was investigated by using potassium phenoxides with various substituents (p-OCH3, p-CH3, H, p-Cl, m-Cl, p-COCH3, and p-NO2). The reaction was completed in 5 min at 0°C. The maximum yield of carboxylate was obtained when unsubstituted phenoxide was used ; the yield of carboxylate was low when potassium phenoxide with a substituent having a highly negative or highly positive σ value was used. The mechanism of the carboxylation is discussed. The formation of the carboxylate as a precipitate is considered to be an important factor. Methods for the effective transformation of dipotassium nitroacetate to methyl nitroacetate are briefly surveyed.
