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Gas‐phase thermolysis of t ‐butylsulfenamides: N , N ‐dimethyl t ‐butylsulfenamide, 2,6‐dimethylpiperidinyl t ‐butylsulfenamide, and N ‐ t ‐butyl t ‐butylsulfenamide
Author(s) -
Martin Gonzalo,
Ascanio Julian,
Rodriguez Jesus
Publication year - 1996
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/(sici)1097-4601(1996)28:5<353::aid-kin4>3.0.co;2-u
Subject(s) - chemistry , dimethylamine , toluene , thermal decomposition , arrhenius equation , gas phase , torr , medicinal chemistry , organic chemistry , thermodynamics , activation energy , physics
The amide derivatives of t ‐butylsulfenic acid mentioned in the title have been thermolyzed in a stirred‐flow reactor at temperatures of 273–390°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: $$k(s^{-1})=10^{14.45\pm 0.46}\exp(-175\pm 5 {\rm kJ/mol}\,{\bf RT})$$ 2,6-dimethylpiperidyl t-butylsulfenamide: $$k(s^{-1})=10^{14.38\pm 0.26}\exp(-161\pm 3 {\rm kJ/mol}\,{\bf RT})$$ N-t-butyl t-butylsulfenamide: $$k(s^{-1})=10^{14.75\pm 0.37}\exp(-184\pm 7 {\rm kJ/mol}\,{\bf RT})$$ 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°C forming free sulfur and dimethylamine, 2,6‐dimethylpiperidine, and t ‐butylamine, respectively. © 1996 John Wiley & Sons, Inc.