Composition of CYANEX 301 by gas chromatography-mass spectrometry

The composition of the commercial reagent CYANEX 301 was investigated by gas chromatography coupled to mass spectrometry (GC-MS). CYANEX 301 was found to contain five compounds. Mass spectrometric studies of these compounds allowed the identification of four of them as bis(2,4,4-trimethylpentyl)dithiophosphinic acid, tris(2,4,4-trimethylpentyl)phosphine sulphide, bis(2,4,4-trimethylpentyl)monothiophosphinic acid and bis(2,4,4-tri-methylpentyl)phosphinic acid. The spectra of these compounds have some important differences depending on whether oxygen or sulphur is attached directly to the phosphor-us atom. Thus tris(2,4,4-trimethylpentyl)phosphine sulphide and the methyl esters of bis(2,4,4-trimethylpentyl)dithiophosphinic acid and bis(2,4,4-trimethylpentyl)monothiophosphinic acid give a base peak at the mass-to-charge ratio (m/z) = 57 attributed to the species [C4H9](+), whereas the methyl ester of bis(2,4,4-trimethylpentyl)phosphinic acid gives a base peak at m/z = 108 that can probably be assigned to [(CH3)(CH2)PO(CH3)OH](+.). The mass spectra of these compounds are discussed and some fragmentation processes are postulated.