Phosphonium salts. I. The alkaline hydrolysis of some bis-phosphonium salts
JJ Brophy and MJ Gallagher
Australian Journal of Chemistry
22(7) 1385 - 1398
Published: 1969
Abstract
Ethane- and ethene-1,2-bisphosphonium salts are cleaved by alkali into a phosphine and a phosphine oxide with loss of the two-carbon bridge. When the phosphorus atom carries benzyl substituents, loss of the benzyl groups is competitive with loss of the bridge. Based on a kinetic study, a synchronous mechanism, analogous to the alkaline hydrolysis of acyclic monophosphonium salts, is proposed to account for the fragmentation. With 6-membered 1,4-diphosphonio heterocyclic salts the nature of the products is dependent on whether alkali or phosphonium salt is present in excess. With an excess of alkali a synchronous mechanism again appears to operate, while with an excess of salt the reaction proceeds stepwise and without loss of the bridge. A partial explanation of these facts is advanced in terms of non-bonded interactions in the intermediate phosphoranes. The synchronous reaction appears to be favoured by coplanarity of the P-C-C-P system.https://doi.org/10.1071/CH9691385
© CSIRO 1969