Patent ID: 6348626
Filing Date: 2002-02-19
Classification: C07C

Abstract:
A process for producing oxamide comprising the step of:(a) melting a starting material consisting essentially of 70 to 100% by weight of an oxalic acid diester of an aliphatic alcohol and 0 to 30% by weight of the same aliphatic alcohol as mentioned above; (b) feed-mixing an ammonia-containing gas to the resulting melt of the starting material, while stirring, to start a reaction of the oxalic acid diester of the aliphatic alcohol with ammonia to produce oxamide and a by-product consisting of the aliphatic alcohol; (c) continuing the feed-mixing procedure of the ammonia-containing gas under reaction conditions sufficient to convert said diester to oxamide and, while stirring, controlling the feed rate of ammonia, and evaporating and removing the aliphatic alcohol by-product from the reaction mixture to an extent such that the content of the aliphatic alcohol in the reaction mixture is maintained at a level of 5 to 40% by weight to produce a reaction product mixture containing the resulting oxamide and the aliphatic alcohol substantially free of oxalic acid monoestermonoamide, and wherein said reaction product mixture is in the state of a wetted solid without filtering it; and (d) directly drying the reaction product mixture in the state of a wetted solid to remove the aliphatic alcohol from said wetted solid and recover said oxamide.