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 ( k 1 / k 2 ). 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. \scriptfont4=\seveni \scriptscriptfont4=\fivei \halign{\hfill $#$&$#$\hfill &$#$\hfill &\hfill\qquad\qquad #\cr\rm 1\hbox{‐}C_{4}H_{9}S&\rm H&\rm +H\longrightarrow 1\hbox{‐}C_{4}H_{9}\cdot +H_{2}S& (1)\cr \rm 1\hbox{‐}C_{4}H_{9}S&\rm H&\rm +H\longrightarrow 1\hbox{‐}C_{4}H_{9}S\cdot +H_{2}& (2)\cr\rm 1\hbox{‐}C_{4}H_{9}S&\rm \cdot &\rm +H\longrightarrow 1\hbox{‐}C_{4}H_{9}SH\ast & (3)\cr } \bigskip\rm{} Relative rates of molecular elimination of hydrogen sulfide and CS bond fission for the chemically activated 1‐butanethiol, k 5 / k 4 and k 6 / k 4 , 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. \scriptfont4=\seveni \scriptscriptfont4=\fivei \halign{\hfill $#$&$#$\hfill &$#$\hfill &\hfill\qquad\qquad #\cr\rm 1\hbox{‐}C_{4}H_{9}SH\ast +M&\rm \longrightarrow &\rm 1\hbox{‐}C_{4}H_{9}SH& (4)\cr \rm 1\hbox{‐}C_{4}H_{9}SH\ast &\rm \longrightarrow &\rm 1\hbox{‐}C_{4}H_{8}+H_{2}S& (5)\cr\rm 1\hbox{‐}C_{4}H_{9}SH\ast &\rm \longrightarrow &\rm 1\hbox{‐}C_{4}H_{9}\cdot +HS\cdot & (6)\cr } \bigskip\rm{} © 1998 John Wiley & Sons, Inc. Int. J. Chem Kinet 30: 923–932, 1998