Facile Synthesis of a Monosulfonated Triphenylphosphane (TPPMS) Derived Ligand having Strong π‐Acceptor Character

Abstract

Two phenyl rings of triphenylphosphane have been modified by electron-withdrawing trifluoromethyl groups. A methoxy group has been introduced at the para-position of the third ring. Due to the activating effect of the methoxy group, the phosphane can be monosulfonated under mild conditions and with complete selectivity. The novel ligand, sodium 5-[bis-(4-trifluoromethylphenyl)-phosphanyl]-2-methoxybenzenesulfonate, has been obtained in quantitative yield, and it has an outstanding p-acceptor capacity among the known sulfonated triarylphosphanes. It is not soluble in water but soluble in light alcohols and ionic liquids. Its solubility properties allow facile catalyst separation without water.

Hydrophilic Ligands and Their Application in Aqueous-Phase Metal-Catalyzed Reactions

“…Incorporation of the sterically demanding tert -butyl groups apparently prevents sulfonation of the more electron-rich tert -butyl-substituted rings. Alternatively, incorporation of electron withdrawing groups will cause selective sulfonation of the unfunctionalized phenyl rings ( L4 ) . Dibenzofuranylphosphines are readily sulfonated in 95% sulfuric acid to give L6 due to the activating oxygen of the furan ring .…”

Strong π-acceptor sulfonated phosphines in biphasic rhodium-catalyzed hydroformylation of polar alkenes

“…However, the presence of the methoxy substituent, required for SUHSDULQJ WKLV OLJDQG VKRXOG GHFUHDVH WKH OE-acidity of this phosphine. 10 In the present work, we report the synthesis of a new series of phosphines containing no other substituents than sulfonated and trifluoromethylated groups (Figure 1). …”

High‐Yield Synthesis and Crystal Structure Determination of Sodium Triphenylphosphane Monosulfonate (TPPMSNa)

“…Since this first appearance of TPPMS Na in the literature, many similar preparation methods have been proposed. [2][3][4][5] Slow addition of triphenylphosphane and heating of the reaction mixture as described by Chatt were not questioned over the years. Purification steps like extraction of the sulfonated product with triisooctylamine in toluene or the intermediate isolation of the ammonium salt of TPPMS have been introduced to isolate TPPMS Na free of impurities.…”