Pressure dependence of the reaction of 1-butanethiol with hydrogen atoms

The reaction of 1-butanethiol with hydrogen atoms was investigated at room temperature under pressures of 133, 266, 532, 2660, and 5320 Pa, using two types of fast-flow discharge reactors; the main products were n-butane and 1-butene with total yields of more than 90%. In the reaction of 1-butanethiol and deuterium atoms, monodeuterated 1-butanethiol was observed by a photo-ionizing mass spectrometer. The relative rate of the two initial reactions of 1-butanethiol with hydrogen atoms was 0.272 (k₁,/k₂). The n-butane and 1-butene are considered to be produced via chemically activated 1-butanethiol on the basis of the pressure dependence of the two main products. 1-C₄H₉SH + H → 1-C₄H₉^̇ + H₂S (1) 1-C₄H₉SH + H → 1-C₄H₉S^̇ + H₂ (2) 1-C₄H₉S^̇ + H → 1-C₄H₉SH* (3) Relative rates of molecular elimination of hydrogen sulfide and C - S bond fission for the chemically activated 1-butanethiol, k₅/k₄ and k₆/k₄, were 0.114 and 0.0552 under 532 Pa of pressure at room temperature. Activation energies of the two reactions were calculated to be 228 [kJ/mol] and 297 [kJ/mol], respectively, by use of RRKM on the base of estimated A factors. 1-C₄H₉SH* + M → 1-C₄H₉SH (4) 1-C₄H₉SH* → 1-C₄H₈ + H₂S (5) 1-C₄H₉SH* → 1-C₄H₉^̇ + HS^̇ (6)