TRIS(TRIMETHYLSILYL)PHOSPHINE

Chemical properties

Colorless to light yellow liqui

Physical properties

mp 24 °C; bp 243–244 °C; d 0.863 g cm?3; n20 D 1.501–1.503.

The Uses of TRIS(TRIMETHYLSILYL)PHOSPHINE

Tris(trimethylsilyl)phosphine is a more stable analog of phosphine, but retains high reactivity due to the presence of the weak polar Si–P bond. It is nucleophilic and readily reacts with a range of electrophiles. Reaction with alkylating agents provides substituted phosphines, with acid chlorides phosphaalkenes can be obtained, and phosphabenzenes can be synthesized upon reaction with pyrylium salts. It can be used as user-friendly phosphorus source and alternative to phosphine gas, precursor of (Me3Si)2PLi, covalent synthon for the anion P3?).

The Uses of TRIS(TRIMETHYLSILYL)PHOSPHINE

It is used as the intermediate in organic synthesis.

Preparation

several preparative methods are known. These include the following: reaction of alkali metal phosphides (NaPH2, KPH2, Li3P, usually prepared by reaction of metal and phosphine gas or via metal alkyl derivative) with chlorotrimethylsilane or fluorotrimethylsilane in 1,2-dimethoxyethane or diethyl ether; reaction of sodium–potassium alloy with white or red phosphorus in refluxing 1,2- dimethoxyethane for 24 h followed by addition of chlorotrimethylsilane and heating at reflux for 72 h (good stirring is necessary for high yield of product), evaporation of the solvent, and vacuum distillation (75% yield); reaction of piperidinodichlorophosphine with lithium powder and chlorotrimethylsilane in refluxing tetrahydrofuran (71% yield); reaction of phosphine with excess of trimethylsilyl triflate in the presence of a tertiary amine in an inert solvent (Et2O) at low temperature (90% yield); reaction of phosphorus trichloride, magnesium, and chlorotrimethylsilane (62% yield). The last method is considered to be the most cost effective and also the safest approach.

Synthesis

Tris(trimethylsilyl)phosphine is prepared by treating trimethylsilyl chloride, white phosphorus, and sodium-potassium alloy: 1/4 P4 + 3 Me3SiCl+ 3 K → P(SiMe3)3 + 3 KCl