Preparation of n-hydrocarbylthiophosphoric triamides

Abstract

Continuously fed to and mixed in a first reactor are (i) a preformed mixture of primary hydrocarbyl monoamine, tertiary amine and liquid inert organic solvent, and (ii) thiophosphoryl chloride while removing heat of reaction to maintain the reaction temperature in the range of about -20.degree. C. to about +50.degree. C. A reaction mixture containing N-hydrocarbylaminothiophosphoryl dichloride is formed. Ammonia and an effluent stream from the first reactor are continuously fed to and mixed in a second reactor in proportions of at least about 16 moles, of ammonia per mole of N-hydrocarbylaminothiophosphoryl dichloride that produce a reaction mixture containing N-hydrocarbylthiophosphoric triamide, and that keep in solution ammonium chloride co-product formed in the reaction. Heat of reaction is removed so that the temperature is high enough to keep ammonium chloride-ammonia complex from forming a solid phase in this reaction mixture, but low enough to avoid significant reduction in yield of N-hydrocarbylthiophosphoric triamide being formed. Effluent is withdrawn from the second reactor so as to maintain a substantially constant volume of reaction mixture in the second reactor. The process eliminates a difficult filtration of the co-product ammonium chloride formed in the second reaction. Also, it possible to accomplish this in a continuous process, with improved efficiency in large scale production of the N-hydrocarbylthiophosphoric triamides. Moreover, the ammonium chloride can be readily converted in the process to an industrially useful liquid co-product mixture.