The thermal dissociation of tertiary butyl peroxide in presence of nitric oxide

Abstract

In the presence of nitric oxide the decomposition of gaseous tertiary butyl peroxide has been shown to follow essentially the course: (i) (CH 3 ) 3 COOC(CH 3 ) 3 → k 1 2(CH 3 ) 3 CO, (ii) (CH 3 ) 3 CO → k 2 (CH 3 ) 2 CO + CH 3 , (iii) 2CH 3 → k 3 C 2 H 6 , (iv) (CH 3 ) 3 CO + NO → k 4 (CH 3 ) 3 CONO, (v) CH 3 + NO → k 5 CH 3 NO → other products. Rates of reaction have been measured by observation of pressure changes and mass-spectrometric analysis for peroxide, acetone, ethane, nitric oxide and tertiary butyl nitrite at various stages. The ratio k 4 / k 2 at 160°C, determined from the rate of formation of acetone in presence of nitric oxide, is approximztely 0⋅7 (with concentrations expressed in mm Hg). If the ‘collision yield' or 'steric factor’ for the union of methyl radicals is near unity, that for the combination of methyl radicals and nitric oxide is about 7 x 10 -5 , from experiments on the rate of ethane formation. If the rate constants for the combination of nitric oxide with methyl and tertiary butoxy radicals respectively are assumed equal, k 2 is estimated to be about 10 3 s -1 at 160°C. A rough estimate for the corresponding activation energy ( E 2 ) gives 13⋅2 ± 2⋅4 kcal/mole for the decomposition of the tertiary butoxy radical, compared with a (redetermined) value of 38 kcal/mole for that of the peroxide itself.

The Reaction of Methyl Radicals With Formaldehyde

“…I . This leads to a rate constant, kl = 2.5XlOl6 exp(-38,70O/RT) sec-', in excellent agreement with those previously determined (3,4,5,6,7,8 …”

“…The ratio of acetaldehyde/CO in these experin~ents was approximately 0.25. This is not, however, a reliable measure of the relative rates of reactions [8] and [9], as acetaldehyde might also be produced in the decomposition of methyl radical -formaldehyde addition compounds.…”

Kinetics and mechanism for the formation of oxygenated products from the photolysis of hexafluoroacetone–methane system

“…Because ~ the stability of these radicals is sensitive to such low temperatures, the activation energies for their decoin-I position are likely to be rather low. In fact, the 1 decomposition of tert-butoxyl radicals has been / studied (19,20): the activation energy is in the range between I I to 13 kcal inol-' which is consistent with available in the literature. However, it is well known that the tert-butoxyl radical needs a much lower activation energy for H-abstraction than does a inethyl radical (21).…”