GB713144A - Improved method for the production of diethyl isonitrosomalonate and diethyl acetamidomalonate - Google Patents

Abstract

Diethyl isonitrosomalonate is prepared by dissolving diethyl malonate in from one-third to 3 times its volume of a water-immiscible inert solvent which is separable by distillation from the final product, suspending in said solution at least as many mols. of sodium nitrite as the number of mols. of diethyl malonate present, e.g. 1.25 mols. of sodium nitrite per mol. of diethyl malonate, and from 1 to 10 per cent by weight of water based on the weight of sodium nitrite, and adding glacial acetic acid gradually to the suspension while the latter is maintained at a temperature between 30 DEG and 70 DEG C. until the nitrosation of the ester is complete. The diethyl isonitrosomalonate may be isolated by washing the final solution with water to remove sodium acetate and concentrating the solution to precipitate the desired compound. The final solution may be treated with hydrogen in the presence of palladium on charcoal to convert the diethyl isonitrosomalonate into diethyl aminomalonate solution, and then adding acetic anhydride to form diethyl acetamidomalonate which is isolated by concentrating the solution and adding water. A large number of inert solvents are referred to, toluene being the preferred inert solvent. The catalyst may be recovered after the hydrogenation step and reactivated for further use by washing with acetic acid. In the examples, diethyl isonitrosomalonate and diethyl acetamidomalonate are prepared.