359-65-9Relevant academic research and scientific papers
Bis(trifluoromethyl)phosphinous acid (CF3)2P-O-H: An example of a thermally stable phosphinous acid - Synthesis, gas-phase structure, and rotational isomers
Hoge, Berthold,Garcia, Placido,Willner, Helge,Oberhammer, Heinz
, p. 3567 - 3574 (2006)
The bis(trifluoromethyl)-phosphinous acid, (CF3):P-O-H, is the only known example of a thermally stable phosphinous acid. Although this compound has been known since 1960, little is known about the chemistry of this extraordinary compound: this might be due to the tedious, and in some part risky, synthesis that was originally published. An improved, simple, and safe synthesis that is based on the treatment of the easily accessible (CF 3)2PNEt2 with at least three equivalents of p-toluene sulfonic acid, is presented. The reaction results in a complete conversion to the phosphinous acid, which is isolated in almost 90% yield. The compound exists in an equilibrium of two P-OH rotational isomers, a fact which is supported by quantum chemical calculations. The relative enthalpy difference of 6.4 kJ mol-1, calculated at the B3PW91/ 6-311G(3d,p) level, is in excellent agreement with the experimental value of 5.9 kJ mol-1, which was determined from the temperature dependence of the v(OH) bands of the two rotational isomers. The complete experimental vibrational spectra of both rotamers, their predicted vibrational spectra obtained by using quantum chemical calculations, and an attempt at photoinduced isomerization of matrix-isolated (CF3)2POH is presented. The experimental structure, obtained from an electron-diffraction study in the gas phase, is reproduced very well by ab initio and density functional theory (DFT) methods.
Stable phosphinous acids
Hoge, Berthold,Neufeind, Stefan,Hettel, Sonja,Wiebe, Waldemar,Th?sen, Christoph
, p. 2382 - 2387 (2007/10/03)
The electronic properties of organyl element compounds are strongly influenced by the electronic characteristics of the organic substituents. The bonding of two CF3 groups to a phosphorus atom effects a drastically decreased basicity. That is the phosphorus atom is the least basic centre in the compound (CF3)2POH. This compound, synthesized in 1960 by Burg and Griffiths, is the only known example of a phosphinous acid, although there should be a general interest in this class of compounds. However, only a few investigations have been reported which may be explained by the tedious and risky synthesis. In this paper a safe one step and high yield synthesis of (CF3)2POH is described. The compound (C6F 5)2POH, originally claimed as a phosphinous acid, is proved to exist at room temperature exclusively in the tautomeric oxide form. (C6F5)2P(O)H crystallizes in the triclinic space group P1? (no. 2) with a 992.9(1) pm; b 1501.9(2) pm; c 1539.4(2) pm; α 117.48(1)°; β 100.39(1)°; γ 96.02(1)° and Z 6. Quantum chemical investigations prove the electron withdrawing effect of s-triazinyl groups (1,3,5-triazin-4-yl derivatives) to be much stronger than that of pentafluorophenyl groups. Quantum chemical calculations at the B3PW91/6-311G(3d,p) level of theory predict for the bis(s-triazinyl) derivative (C3N3H2)2POH the phosphinous acid isomer to be favored by ΔEZP = 22 kJ/mol in relation to the corresponding phosphane oxide isomer. The phosphinous acid (CF3) 2POH (Cs symmetry) is favored at the same level of theory by about ΔEZP = 14 kJ/mol compared with the phosphane oxide structure (Cs symmetry).
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
Cavell, Ronald G.,Pinkerton, A. Alan,Sim, William,Tomlinson, Adrian J.
, p. 2901 - 2908 (2007/10/12)
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.
