Purification Methods
All operations should be carried out in an efficient fume cupboard because it is flammable, toxic and has a foul odour. Purify the phosphine by fractional distillation at atmospheric pressure in a stream of dry N2, as it is oxidised by air to the oxide. In 300% excess of CS2 it forms Et3PCS2 (m 118-120o crystallising from MeOH) which decomposes in CCl4 to give Et3PS as a white solid m 94o when recrystallised from EtOH. [Sorettas & Isbell J Org Chem 27 273 1962, Henderson & Streuli J Am Chem Soc 82 5791 1960, pK: Henderson & Streuli J Am Chem Soc 82 5791 1960, see also trimethylphosphine.] Store it in sealed vials under N2. Alternatively, dissolve it in Et2O and shake it with a solution of AgI and KI to form the insoluble complex. Filter off the complex, dry it over P2O5 and the Et3P is regenerated by heating the complex in a tube attached to a vacuum system. [Hewitt & Holliday J Chem Soc 530 1953, Schettas & Isbell J Org Chem 27 2573 1962, Kosolapoff Organophosphorus Compounds, Wiley p 31 1950, Beilstein 4 IV 3431.]
