Decomposition of lauroyl, decanoyl, and octanoyl peroxides in solution

Abstract

The thermal decomposition from 50 to 250" of lauroyl, decanoyl, and octanoyl peroxides in solution in a high molecular weight hydrocarbon was studied. These peroxides are convenient sources of C-11, C-9, and C-7 straight-chain aliphatic free radicals, whose reactions may be considered as models for the higher molecular weight radicals formed during thermal cracking of polyolefins.The ratio of disproportionation to combination for these radicals is about 0.2, which is very similar to the values obtained for lower alkyl radicals in the gas phase. This ratio appears to be relatively independent of temperature. Intramolecular chain transfer, which results in the isomerization of the radical, occurs at the higher temperatures, and the process has an apparent activation energy of about 2 kcal per mole.The product distribution indicates that at reaction temperatures up to 250" a statistically random distribution of alkyl radicals is never achieved in solution. Since the radicals are formed in pairs, they tend to react with each other rather than with radicals formed from other peroxide molecules. This is demonstrated by the near absence of cross-combination products when two different peroxides are decomposed in the same solution simultaneously at 70". At 250", some cross-product is formed but less than one-fifth of the amount expected if the radicals were uniformly distributed in the solution. The activation energy for the formation of cross-product is of the same order as that for diffusion. The significance of these results in terms of the classical picture of "cage reactions" is discussed.

Exceptionally high decarboxylation rate of a primary aliphatic acyloxy radical determined by radical product yield analysis and quantitative 1H‐CIDNP spectroscopy

“…The average decomposition rate for all peroxides was 1.6 ± 0.6 × 10 −4 s −1 between 80 and 83 °C. Since the decomposition of these peroxides presumably involves a common O–O bond homolysis step, these rate constants are identical to 1.4 × 10 −4 s −1 obtained previously for 2 under identical conditions 46–48. The sensitivity of rate to structure of the R group, for example, primary, sec, tertiary, benzyl, etc.…”

Alkylation of Cyclododecanone with Allyl Acetate in the Presence of Solid Radical Initiators

“…UV light irradiation might also induce undesired side reactions. Transition metal oxides or salts in which the metal species can easily switch between the oxidation state of n +1 and n by accepting a single electron are also known as suitable radical chain initiators . Such compounds can be removed, reoxidized and reused in a radical reaction representing more sustainable initiators.…”

“…The C-C coupling between cycloalkanones and terminal alkenes via radical alkylation can be initiated either by organic peroxides or other radical chain initiators [1][2][3][4][5] or by UV light irradiation in the presence of photocatalysts. [6,7] A disadvantage in case of organic initiators is the impossibility to recycle them.…”

“…Transition metal oxides or salts in which the metal species can easily switch between the oxidation state of n+1 and n by accepting a single electron are also known as suitable radical chain initiators. [3][4][5][6][7][8][9] Such compounds can be removed, reoxidized and reused in a radical reaction representing more sustainable initiators. Hájek and Málek [1] reported the alkylation of cyclic C 5 -and C 6 -ketones with 1-olefins in the presence of Ag 2 O and AgO as radical initiators in a batch procedure to produce alkylated ketones.…”

Solvent interactions with polysulfone

“…The use of gas chromatography for this purpose was initiated by Smidsrad and Guillet (19). Since the poineering work of Smidsrad and Guillet, many workers have used gas chromatography to determine solvent-polymer interactions and solvent activity coefficients in molten polymers (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30).…”