Isopropanol → Tetrakis(hydroxymethyl)phosphonium chloride

Participants

Reaction Steps

Tris(hydroxymethyl)phosphine (THP) was prepared from tetrakis-(hydroxymethyl)phosphonium chloride (THPC) as follows. Eighteen milliliters (corresponding to 19.3 grams anhydrous, or 101.5 mmol) 80% THPC was mixed with 100 milliliters isopropanol and 50 milliliters toluene. The mixture was evaporated to dryness on a Rotavap (bath temperature 80-90° C.), and the azeotropic distillation was repeated for 2 more times to provide a semi-solid mass of anhydrous THPC. The dried residue was dissolved in 60 milliliters of isopropanol, to which was added 40 milliliters dry triethylamine (TEA) under ice-cooling. After the exothermic reaction had subsided, the mixture was set in a freezer (−10° C.) for 1 hour to ensure that the precipitation of TEA.HCl was completed. The TEA salt was filtered off, and the filtrate was allowed to evaporate to dryness. Heating under reduced pressure on the Rotavap (bath temperature 80-90° C.) was continued for 4 hours to give a clear viscous liquid. The yield of THP was 11.8 grams (94% of theoretical). EIMS (electron ionization mass spectroscopy, direct inlet) exhibited a molecular ion at m/z 124 together with fragments at m/z 106, 94, 76, 64, 61, 46, and 31, formed due to successive loss of H2O, and CH2O from the molecular ion. Infrared absorptions occur at 3224 (broad), 2815, 1589, 1420, 1125 (strong), and 1030 (strong) cm−1. The THP thus prepared is pure enough for use in crosslinking. It is relatively stable and can be stored in freezer for up to 8 weeks without noticeable decomposition. Further purification of THP by distillation is not recommended due to thermal decomposition above 130° C. releasing PH3 gas in the process.

Provenance & Evidence