Phosphonium salts. I. The alkaline hydrolysis of some bis-phosphonium salts

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.

2-Pyridyl-phosphine and -diphosphine complexes of nickel(0), their reactivity (including aqueous solution chemistry), and some related, incidental methylphosphonium iodides

“…This precipitation behavior is known for ditertiary diphosphines, and has been exploited for selective formation of the diphosphine monoxides (versus bisoxides) by alkaline hydrolysis of the insoluble monophosphonium salt -see Eq. (7) [53]; under these same conditions [54], the bisphosphonium cation [Ph 3 P(CH 2 ) 2 PPh 3 ] 2+ decomposes further to a complex mixture containing OPPh 3 , PPh 3 , C 2 H 4 , and C 6 H 6 .…”

Stability of ionic liquids in Brønsted-basic media

“…129 Brophy and Gallagher later confirmed these findings. 130 Independent decomposition of the two centers would yield two equivalents of phosphine oxide (or a bis(phosphine oxide)) and one or two equivalents of alkane, and this behavior is indeed observed for methylene-bridged and trimethylene-linked phosphonium dications. 130,131 Ethylene-bridged phosphonium dications, however, yielded one equivalent of phosphine oxide and one equivalent of phosphine, with the loss of one equivalent of ethylene gas being inferred.…”

“…130 Independent decomposition of the two centers would yield two equivalents of phosphine oxide (or a bis(phosphine oxide)) and one or two equivalents of alkane, and this behavior is indeed observed for methylene-bridged and trimethylene-linked phosphonium dications. 130,131 Ethylene-bridged phosphonium dications, however, yielded one equivalent of phosphine oxide and one equivalent of phosphine, with the loss of one equivalent of ethylene gas being inferred. 130 This behavior was studied extensively by Brophy and Gallagher, who proposed a mechanism involving concerted formation of the phosphine oxide and elimination of the phosphine from an anti-periplanar transition state (Fig.…”

“…130,131 Ethylene-bridged phosphonium dications, however, yielded one equivalent of phosphine oxide and one equivalent of phosphine, with the loss of one equivalent of ethylene gas being inferred. 130 This behavior was studied extensively by Brophy and Gallagher, who proposed a mechanism involving concerted formation of the phosphine oxide and elimination of the phosphine from an anti-periplanar transition state (Fig. 27a).…”

Basic hydrolysis of l,4-bis(triphenylphosphonio)buta-1,3-diene dihalides

“…This is also evidenced by the data on the basic hydrolysis of 1,4 bis(triphenylphosphonio)but 2 ene di halides under different conditions. 4, 7 In contrast to salt 1a, the hydrolysis of related 1,4 bis (tributylphosphonio)buta 1,3 diene dibromide (6) with 10% aqueous NaOH was accompanied by strong resini fication. Only tributylphosphine (28%) and tributylphos phine oxide (43%) were isolated from the reaction mixture and identified.…”