Kinetics of thermal decomposition of n-alkyl-n?-methoxydiazene-n-oxides in the gas phase

Quantum chemical investigation of the 1‐methyl‐ and 1‐neopentyl‐2‐methoxydiazene‐1‐oxides thermal decomposition mechanisms

“…There are earlier quantum‐chemical calculations for compound 1 , including the calculation of the Z‐E isomerization barrier. [ 24 ] In this study, the authors verified the mechanisms of thermolysis 1 discussed in [ 18 ] by quantum‐chemical calculations at the B3LYP/6‐311G(d,p) and G3MP2B3 levels. It is worth mentioning historically the first quantum‐chemical calculations of the geometry of compound 1 .…”

“…In the original work [ 18 ] for the decomposition of compound 1 , a fairly reasonable mechanism with homolytic breaking of the weakest bond N–OCH 3 was proposed. The homolytic breaking of N–CH 3 bonds was also considered there but was rejected due to the comparative analysis of activation parameters.…”

“…These are model ADOs for which the kinetics of thermal decomposition in the gas phase has been well studied. [ 18 ]…”

“…The activation enthalpy of such transformation is 184 kJ/mol, [ 20 ] which corresponds well to the experiment. [ 18 ] N , O ‐dimethyl‐ N ‐nitrosohydroxylamine ( 3 ) formed by such a transfer of the CH 3 group is a well‐known compound. [ 21 ] According to experimental (nuclear magnetic resonance) and calculated (B3LYP/6‐31G*) data, [ 22 ] compound 3 exists at room temperature as a mixture of Z and E tautomeric forms, which easily transform into each other with an activation enthalpy about 60 kJ/mol.…”

“…Therefore, already at the initial stage of work with ADO in the Institute of Problems of Chemical Physics of the Russian Academy of Sciences, one of the authors of this article (I.N. Zyuzin in co‐authorship with colleagues) studied the kinetics of thermal decomposition in the gas phase of three model 1‐alkyl‐2‐methoxydiazene‐1‐oxides, [ 18 ] specially synthesized for this purpose. [ 19 ] Based on activation parameters and quantitative analysis of decomposition products, reaction mechanisms were proposed depending on the nature of the 1‐alkyl substituent.…”