Phosphorus(V) Isocyanates

Abstract

We assume that the AE, mechanism is concerned with cinesubstitution of ( I ) but not of (2). This is because the experimental points lie on a curve for the competition experiments with ( I ) but on a straight line for those with (2); in our experience -admittedly only for EA and AE, substitutionsa mixed mechanism is displayed by non-linear dependence of the molar proportions of the substitution products on the molar proportions of the competing bases, whereas a pure mechanism leads t o linear dependence [2*6,71. Further, reaction of ( I ) with piperidine to yield ( 7 a ) is not inhibited by ethanol whereas the corresponding reaction with (2) is wholly suppressed on addition of ethanol, facts which indicate participation of the AE, mechanism only in the competition experiments with ( I ) . The change from chloride (2) to bromide ( I ) apparently favors the AEa mechanism over the EA mechanism 181. The AEa mechanism was previously demonstrated only for the reaction of piperidine with (10/[9I. This reaction, in which intermediate (12) Recently we reportedrll a simple synthesis of diester isocyanates of phosphoric and thiophosphoric acid (2) by the action of oxalyl chloride on the corresponding diester amides ( I ) . The reaction is effected at 0 OC in an inert solvent such as carbon tetrachloride or benzene.We have now found that isocyanates (3) are also formed by the action of phosgene on diary1 thiophosphoramidates in boiling toluene or chlorobenzene 121.Diary1 phosphoramidates do not react under these conditions. Dialkyl phosphoramidates and thiophosphoramidates do react, even at O°C, but the isocyanates are then formed in only poor yield.Finally we have used organic bases byridine, triethylamine)as HCI acceptors in the reaction of phosphorus(v) amidesproceeding by way of (11) [cf. (S)]. The close resemblance to the "von Richter carboxylation reaction" [lo] (nucleophile: CNS; anionic leaving group: NO: ; hypothetical intermediate: (13); solvent: ethanol) should be pointed out.

Dichlorophosphanyl isocyanate – spectroscopy, conformation and molecular structure in the gas phase and the solid state

“…This is surprising, because they have been broadly used for the synthesis of phosphorylated urethanes and ureas as flame-retardant materials. 10 Unlike phosphorus(v) isocyanates, 11 phosphorus(III) isocyanates are generally more reactive due to the presence of a sterically active lone pair of electrons on the phosphorus atom. 12 To the best of our knowledge, difluorophosphanyl isocyanate, F 2 PNCO, is the only structurally characterized phosphorus(III) isocyanate; it has been studied by combining vibrational spectroscopy and gas electron diffraction (GED).…”