Synthesis and Reactivity of Phosphorus Iris (isocyanate)

Abstract

Synthesis and reactivity of phosphorus tris(isocyanate), P(NCO)₃, were investigated. The compound was prepared from the reaction of phosphorus trichloride (PCl₃) with sodium cyanate (NaOCN) in the presence of several additives in benzene. It was found that the reaction was accelerated remarkably by the presence of an additive which facilitates dissolution of NaOCN in benzene, such as acetonitrile and succinonitrile.
P(NCO)₃ reacted with primary alcohols in a molar ratio of 1: 1 and 1: 2 to give the corresponding P(NCO)₂(OR) and phosphorus compounds bearing triazine skeleton [(NXCO)₃: X=H, -P(NCO)(NHCO₂R), -P(NHCO₂R)₂]. The reaction with a large excess of such al cohols provided the corresponding carbamates and allophanates, P(OR)₃, and phosphorus compounds containing -NCO, -OR, -NHCO₂R, and -NHCONHCO₂R group. On the other hand, the reaction of P(NCO)₃ with t-BuOH afforded phosphorus compounds having triazine skeleton [(NXCO)₃: X=-P(NC0)(NHCO₂But)], together with 1-butene formed by dehydration of t-BuOH and compounds containing>P-H and>P(O)H bonds. Mechanism of the reaction leading to these products is also discussed.