Synthesis of Phosphino Alkane Sulfonates and their corresponding sulfonic acids by reaction of alkalimetal‐phosphides with sultones

Abstract

AbstractAlkalimetal salts of dialkyl‐ and diphenylphosphino alkane sulfonic acids (1–4, 6, 7) were prepared by reaction of alkalimetalphosphides with sultones at ambient temperature. The sulfonates can be converted into the free sulfonic acids by ion exchange. This method opens an access to water soluble phosphines (8, 9) which can be important as ligands in transition metal complexes for catalytic processes.The use of water soluble tertiary phosphines as ligands in catalytic active transition metal complexes seems to be an achievement of the last ten or twelve years [1]. An important aspect of application is the realization of two phase systems with the catalyst in the water phase acting in the interface. After the catalytic process the catalyst can be separated easily from the product and the recovery of the expensive transition metal is possible.Hydrophilicity of phosphines usually is achieved introducing highly polar hydroxy‐, amino‐, carboxylato‐, ammonium‐, sulfonato‐, and polyether‐groups, respectively, but only tetraalkylammonium‐, polyether‐ and sulfonato‐groups are suitable for a large pH‐range.Sulfonato groups can be introduced into phenylphosphines by sulfonation with sulfur trioxide in sulfuric acid leading to meta sulfonated products. Especially mono‐ and polysulfonation of triphenylphosphine was investigated by AHRLAND, CHATT et al. [2]. Monosulfonation occurs under mild conditions, but the selectivity of a multiple sulfonation is low, and there are some problems with the separation of reaction products [3]. Nevertheless, phenylphosphines with chiral substituents were sulfonated by this method and used as ligands in rhodium complexes for asymmetric syntheses [4]. A way to a triphenylphosphine sulfonated in the para position was given by SCHINDLBAUER [5], but his method seems to be less satisfactory with respect to yield and selectivity.