Gas-phase thermolysis oft-butylsulfenamides:N, N-dimethylt-butylsulfenamide, 2,6-dimethylpiperidinylt-butylsulfenamide, andN-t-butylt-butylsulfenamide
作者:Gonzalo Martin、Julian Ascanio、Jesus Rodriguez
DOI:10.1002/(sici)1097-4601(1996)28:5<353::aid-kin4>3.0.co;2-u
日期:——
The amide derivatives of t-butylsulfenic acid mentioned in the title have been thermolyzed in a stirred-flow reactor at temperatures of 273-390 degrees C and pressures of 7- 15 torr, using toluene as carrier gas, at residence times of 0.4-2 s. Isobutene formed in 95-99% yields, through order one reactions, following the Arrhenius equations: N,N-dimethyl t-butylsulfenamide:k(s(-1)) = 10(14.45+/-0.46) exp(-175 +/- 5 kj/molRT)2,6-dimethylpiperidyl t-butylsulfenamide:k(s(-1)) = 10(14.38+/-0.26) exp(-161 +/- 3 kj/molRT)N-t-butyl t-butylsulfenamide:k(s(-1)) = 10(14.75+/-0.37) exp(-184 +/- 7 kj/molRT)These thermolyses are considered to take place through unimolecular, four-center cyclic transition-state reaction mechanisms, giving rise to isobutene plus the corresponding S-unsubstituted thiohydroxylamines. The latter decompose outside the reactor at temperatures above -78 degrees C forming free sulfur and dimethylamine. 2,6-dimethylpiperidine, and t-butylamine, respectively. (C) 1996 John Wiley & Sons, Inc.