Dramatic Effect of Atmosphere on Product Distribution from Steady-State Photolysis of Triarylphosphines

作者：Yasui Shinro^*; Ogawa Yuya; Shioji Kosei; Mishima Masaaki; Yamazaki Shoko

来源：Bulletin of the Chemical Society of Japan, 2014, 87(9): 988-996.

DOI：10.1246/bcsj.20140100

The steady-state photolysis of triarylphosphines using a xenon lamp was carried out under various conditions. Product analysis by gas-chromatography and gas-chromatography mass spectrometry as well as H-1 and P-31 NMR spectroscopies showed that the irradiation of light (%26gt;310 nm) in air results in oxidation of triarylphosphine to triarylphosphine oxide in moderate to quantitative yield. In sharp contrast, photolysis under deoxygenated conditions, in which air was replaced by argon gas, gave products resulting from homolytic cleavage of a P-C bond in the triarylphosphine, namely, diaryl(cyanomethyl)phosphine (from the photolysis in acetonitrile) and 1,1,2,2-tetraaryldiphosphine, except for the photolysis of triphenylphosphine where triarylphosphine oxide was formed quantitatively. Dependence of the conversion of triarylphosphine on the wavelength of the irradiating light demonstrates that the reaction is initiated by photoexcitation of triarylphosphine to the singlet excited state, which, directly or after intersystem crossing to the triplet state, undergoes the homolytic cleavage of a P-C bond. Meanwhile, in the presence of oxygen, electron transfer from the phosphine in the excited state to O-2 in the ground state is dominant, the resulting triarylphosphine radical cation undergoing radical coupling with O-2 to eventually afford the phosphine oxide.

• 出版日期2014-9-15