Polyfluoroalkoxy trimethylsilanes R f CH 2 OSi(CH 3 ) 3 (from the alcohols R f CH 2 OH and HMDS), react with Ph 3 PICl (from ICl and Ph 3 P) eliminating (CH 3 ) 3 SiCl. Pyrolysis of the residues gives Ph 3 PO and pure iodides R f CH 2 I. ... Triphenylphosphine, iodine