Description
Triphenylphosphine: a member of tertiary phosphines
Triphenylphosphine (TPP) is a member of tertiary phosphines, which is phosphane, in which the three hydrogens are replaced by phenyl groups. It has a role as a reducing agent and an NMR chemical shift reference compound. It is a crucial ligand utilized in the Wittig reaction for alkene synthesis. This reaction involves the formation of alkyliden-etriphenylphosphoranes from the action of butyllithium or another base on the quarternary halide. Triphenylphosphine is used to synthesise organic compounds due to its nucleophilicity and reducing character.
Purification Methods
It crystallises from hexane, MeOH, diethyl ether, CH2Cl2/hexane or 95% EtOH. Dry it at 65o/<1mm over CaSO4 or P2O5. Chromatograph it through alumina using (4:1) *benzene/CHCl3 as eluent. [Blau & Espenson et al. J Am Chem Soc 108 1962 1986, Buchanan et al. J Am Chem Soc 108 1537 1986, Randolph & Wrighton J Am Chem Soc 108 3366 1986, Asali et al. J Am Chem Soc 109 5386 1987.] It has also been crystallised twice from pet ether and 5 times from Et2O/EtOH to give m 80.5o. Alternatively, dissolve it in conc HCl, and upon dilution with H2O it separates because it is weakly basic, it is then crystallised from EtOH/Et2O. It recrystallises unchanged from AcOH. [Forward et al. J Chem Soc Suppl. p121 1949, Muller et al. J Am Chem Soc 78 3557 1956.] 3Ph3P.4HCl crystallises out when HCl gas is bubbled through an Et2O solution, it has m 70-73o, but recrystallises very slowly and is deliquescent. The hydriodide, made by adding Ph3P to hydriodic acid, is not hygroscopic and decomposes at ~100o. The chlorate (1:1) salt has m 165-167o, but decomposes slowly at 100o. All salts hydrolyse in H2O to give Ph3P [IR, UV: Sheldon & Tyree J Am Chem Soc 80 2117 1958, pK: Henderson & Streuli J Am Chem Soc 82 5791 1960, Kosolapoff, Organophosphorus Compounds, Wiley 1950]. [Beilstein 16 IV 951.] § Available commercially on a polystyrene or polyethyleneglycol support.
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