Some reactions of bis(trifluoromethyl)phosphines, -phosphine oxides, and -phosphine sulfides with alcohols and mercaptans. Preparation, characterization, and NMR spectra of a homologous series of esters and thioesters

Article abstract of DOI:10.1021/ic50200a055

The esters (CF₃)₂POR and thioesters (CF₃)₂PSR (R = CH₃, C₂H₅, CH(CH₃)₂, and C(CH₃)₃) of trivalent phosphorus have been synthesized. Previously unknown esters in the series have been characterized and NMR parameters of all the above esters recorded. Synthesis of phosphinous esters and thioesters is aided by the presence of amine which is mandatory in the case of the reaction of tert-butyl alcohol with (CF₃)₂PCl. In the absence of amine, (CF₃)₂PCl reacted with tert-butyl alcohol to give (CF₃)₂P(O)C(CH₃)₃ and HCl. Separate reactions showed that (CF₃)₂POC(CH₃)₃ reacted with HCl to yield (CF₃)₂POH and (CH₃)₃CCl and that (CF₃)₂POH and (CH₃)₃CCl reacted to form (CF₃)₂P(O)C(CH₃)₃ and HCl. These reactions provide a basis for the detailed understanding of the reaction of (CF₃)₂PCl and related systems with tert-butyl alcohol. The oxy- and thioesters of pentavalent phosphorus, (CF₃)₂P(O)OR, (CF₃)₂P(O)SR, (CF₃)₂P(S)OR, and (CF₃)₂P(S)SR (R = CH₃, C₂H₅, CH(CH₃)₂), were prepared by reactions analogous to those used to prepare the phosphinous esters; however, the competitive reaction of salt formation with amines in the case of the tert-butyl and, to a lesser extent, methyl esters requires use of alternate synthetic routes. In the case of tert-butyl esters, isobutene was also obtained in addition to the amine salt due to the instability of the tert-butylammonium salt. The tert-butyl thioester (CF₃)₂P(S)SC(CH₃)₃ was obtained from tert-butyl iodide and the appropriate phosphorus acid salt, (CF₃)₂PS₂^-. In contrast the dioxo and oxythioesters could not be prepared in this way. NMR parameters are recorded for all esters of pentavalent phosphorus and the new esters of pentavalent phosphorus have been characterized. Separate reaction of the esters of pentavalent phosphorus with trimethylamine gave R′(CH₃)₃N⁺(CF₃) ₂PXY^- (X, Y = O, S) salts. In the case of esters of trivalent phosphorus, only (CF₃)₂POCH₃ formed a 1:1 adduct with trimethylamine which may be the salt (CH₃)₄N⁺(CF₃)₂PO ^- NMR parameters of the tert-butylphosphine oxide (CF₃)₂P(O)C₄H₄ are also given.