Hemolytic decomposition of di-sec-butyl peroxide

Abstract

Rates and products have been determined for the thermal decomposition of sec-butyl peroxide at 110-150 "C in several solvents.The decomposition was shown to be unimolecular with energies of activation in toluene, benzene, arid cyclohexane of 35.5 & 1.0, 33.2 + 1.0, 33.8 + 1.0 kcal/mole respectively. The activation energy of thermal decomposition for the deuterated peroxide was found to be 37.2 + 1.0 kcal/mole in toluene.About 70-80% of the products could be explained by known reactions of free alkoxy radicals, and very little, if any, disproportionation of two sec-butoxy radicals in the solvent cage could be detected.The other 20-30% of the peroxide yielded Hz and methyl ethyl ketone. The yield of H z was unaffected by the nature or the viscosity of the solvent, but H z was not formed when s-BuZOZ was photolyzed in toluene at 35 "C nor when the peroxide was thermally decomposed in the gas phase.cc,a'-Dideutero-sec-butyl peroxide was prepared and decomposed in toluene at 110-150 "C. The yield of D, was about the same as the yield of H 2 from s-BuZ02, but the rate of decomposition (at 135 "C) was only '11.55 as fast.Mechanisms for hydrogen production are discussed, but none satisfactorily explains all the evidence.Canadian Journal of Chemistry, 48, 615 (1970) Introduction The decomposition of dialkyl peroxides has received less attention than that of other peroxidic species, partly, because being rather more stable, they have been less utilized for commercial purposes (i.e., initiation of free radical chain reactions); partly, because being less easily reduced, they are harder to analyze quantitatively. But perhaps too, because dialkyl peroxides have the reputation of being "well behaved" they have been regarded as uninteresting species. Dialkyl peroxides are commonly supposed to cleave on heating at the 0-0 bond by an exclusively homolytic process, relatively uncomplicated by other types of decomposition either radical or molecular in nature.

Ab initio study of the CH3O2 self‐reaction in gas phase: Elucidation of the CH3O2 CH3O2 → 2CH3O O2 pathway

“…Based on their observations, the following mechanism was suggested: This proposal is in agreement with the direct electron‐spin‐resonance (ESR) monitoring experiments of Bartlett and Guaraldi 9, who found convincing evidence for the existence of such intermediate. In addition, Hiatt and Szilagyi 10 observed that in the self‐oxidation of tertiary peroxyl radicals a tetraoxide intermediate is involved that leads to the production of alkoxy radicals and molecular oxygen. These radicals may in turn react with each other, or they can start the following chain of reactions due to diffusion: or …”

Electrocyclic versus homolytic decompositions of peroxides: Solvent and phase effects

“…Our own results [2] for s -B u~O~ a t 130°C, whether in the presence or absence of added toluene vapor, indicate only traces (4.03%) bas& on decomposed peroxides. For the same peroxide a t 10Oo-14O0C in the presence of nitric oxide, Walker and Phillips [21] found 0.1%0.2% H2; yields did not vary with temperature, but were sensitive to the pressure of NO (-0.1 % at 10-20 torr and 0.18%-0.20% a t 40-80 torr).…”

“…The fact that largish yields of H2 are linked to the presence of NO, and in at least one case [21] are demonstrably greater at higher NO concentrations suggests intimate involvement, perhaps via with NOH decomposing to H2 in some unspecified way.…”

Studies on allylic peroxides. II. Allyl-t-butyl peroxide

“…It's difficult to see why cage disportionation should not be a factor, particularly as the I-BuOe + alkyl radical reaction is well documented 48), but perhaps it is not. Some years ago (9) we found that the thermal decomposition of (MeEtCDO), in toluene yielded no MeEtCDOD. We were not wholly convinced at the time, nor are we now, but merely state our findings, to which as yet there has been no direct contradiction.…”