Organophosphorus Intermediates. IX. The Cleavage of α,ω-Bisdiphenylphosphinoalkanes With Lithium. A ¹³P N.M.R. Study

Abstract

The title phosphines, Ph₂P(CH₂).PPh₂ (n = 2-5), react with lithium in tetrahydrofuran to give the corresponding 1, n-dilithio-1, n-di(phenylphosphines) directly with little or no intermediacy of the 1-lithio- 1-phenyl- n- diphenylphosphinoalkanes which can, however, be obtained by arylation of the diphosphides. Methylenebisdiphenylphosphine and 1,4-diphenyl-1,4-diphosphinane undergo exclusive phosphorus-alkyl carbon cleavage. The chemistry and ³¹P n.m.r. spectroscopy of the diphosphides are described and the mechanism of the cleavage reaction is discussed. Some cleavage reactions in liquid ammonia are described.