M-Trisulfonated Triphenylphosphine

Abstract

[63995-70-0] C18H12Na3O9PS3 (MW 568.40) InChI = 1S/C18H15O9PS3.3Na/c19-29(20,21)16-7-1-4-13(10-16)28(14-5-2-8-17(11-14)30(22,23)24)15-6-3-9-18(12-15)31(25,26)27;;;/h1-12H,(H,19,20,21)(H,22,23,24)(H,25,26,27);;;/q;3*+1/p-3 InChIKey = MYAJTCUQMQREFZ-UHFFFAOYSA-K (the title reagent, among all the water-soluble ligands, is most widely used for carbon-carbon, carbon-hydrogen, and carbon-heteroatom formations3) Alternate Name: TPPTS, trisodium salt of 3,3′,3′′-phosphanetriylbenzenesulfonic acid, tris(3-sulfonatophenyl)phosphine sodium salt, triphenylphosphine-3,3′,3′′-trisulfonic acid trisodium salt. Solubility: soluble in H2O (1100 g/L). Form Supplied in: white powder. Analysis of Reagent Purity: TPPTS ligand is supplied in the presence of a variable amount of TPPTS oxide. 31P{1H} NMR (D2O, 200 MHz, 25 °C) δ = −4.8 ppm (δ = 34.2 ppm for oxide), 1H NMR (D2O, 200 MHz, 25 °C) δ = 7.86 (m, 3*2H), 7.54 (m, 3*2H) ppm (same signals at 8.14 and 7.78 ppm for oxide). Preparative Methods: TPPTS is synthesized by sulfonation of triphenylphosphine with oleum (i.e., concentrated H2SO4 and SO3). Various parameters (triphenylphosphine/oleum ratio,wt % of SO3, time, temperature, and agitation speed) have been studied and modified to suppress the formation of by-products such as phosphines with a low degree of sulfonation and phosphine oxides.1 One particularly attractive method employs orthoboric acid B(OH)3, concentrated H2SO4, and a controlled SO3 concentration and cleanly affords either disulfonated ligand (TPPDS) or TPPTS with negligible oxidation and no by-products.2 Purification: the purification of TPPTS is based on its higher solubility in water compared to mono- and disulfonated phosphines and lower solubility in methanol/water than the phosphine oxides. The resulting acid solution may be neutralized with NaOH, Na2SO4 is then separated by adding methanol, and an optimal purity is reached via repeated precipitation from water/methanol mixtures.1 Another process employs the extraction of the sulfonic acids with triisooctylamine in toluene followed by extraction with an aqueous NaOH solution, neutralization, and evaporation under vacuum.2 TPPTS oxide, present in variable amount in commercially available lot, may be eliminated by extraction with acetone/methanol/water (10:5:1).1b Handling, Storage, and Precautions: solid TPPTS is substantially stable to air, but bottles of TPPTS should be flushed with N2 or Ar and kept tightly closed for prolonged storage. TPPTS is slowly oxidized to the phosphine oxide in solution, therefore oxygen-free solvents are preferred.