Gas-phase thermolysis ofN-methyl-N-phenyl-tert-butylsulfenamide and morpholinyl-tert-butylsulfenamide
摘要:
N-Methyl-N-phenyl-tert-butylsulfenamide (MPSA) and morpholinyl-tert-butylsulfenamide (MOSA) were thermolyzed in a stirred-flow reactor at temperatures of 340-390 degrees C and pressures of 7-13 Torr, using toluene as carrier gas, at residence times of 0.3-1.3 s. Isobutene was formed in 99% yield through first-order reactions having the following Arrhenius parameters (A,s(-1), E-a, kJ mol(-1)): MPSA, log A = 12.41 +/- 0.02, E-a = 158.8 +/- 0.2; MOSA, log A = 12.91 +/- 0.22, E-a = 159 +/- 3. It is proposed that the elimination of isobutene takes place by unimolecular reaction mechanisms involving polar, four-center cyclic transition states, forming S-unsubstituted thiohydroxylamines as coproducts. Thermochemical parameters, estimated by semiempirical AM1 calculations, are reported for the latter and for the parent molecules. (C) 1998 John Wiley & Sons, Ltd.
Gas-phase thermolysis ofN-methyl-N-phenyl-tert-butylsulfenamide and morpholinyl-tert-butylsulfenamide
摘要:
N-Methyl-N-phenyl-tert-butylsulfenamide (MPSA) and morpholinyl-tert-butylsulfenamide (MOSA) were thermolyzed in a stirred-flow reactor at temperatures of 340-390 degrees C and pressures of 7-13 Torr, using toluene as carrier gas, at residence times of 0.3-1.3 s. Isobutene was formed in 99% yield through first-order reactions having the following Arrhenius parameters (A,s(-1), E-a, kJ mol(-1)): MPSA, log A = 12.41 +/- 0.02, E-a = 158.8 +/- 0.2; MOSA, log A = 12.91 +/- 0.22, E-a = 159 +/- 3. It is proposed that the elimination of isobutene takes place by unimolecular reaction mechanisms involving polar, four-center cyclic transition states, forming S-unsubstituted thiohydroxylamines as coproducts. Thermochemical parameters, estimated by semiempirical AM1 calculations, are reported for the latter and for the parent molecules. (C) 1998 John Wiley & Sons, Ltd.
Traditional preparation of sulfenamides require the use of low oxidation state of sulfur reagent such as RSCl, (RS)2 or RSH, which are toxic, odorous and difficult to deal with due to the harsh reaction conditions. Here high oxidation state of sulfur reagent—aliphatic sulfinamide, were used for preparation of sulfenamide in one step efficiently. Different aromatic amines with all sorts of functional