REACTIONS OF ALKOXY RADICALS: V. PHOTOLYSIS OF DI-t-BUTYL PEROXIDE

Abstract

A B S T R A C T T h e photolysis o f di-1-butyl peroxide has been investigated over t h e teniperature range 25"t o 7g0 C. As reactio~l products were observed : acetone, t-butyl alcohol, methyl t-butyl ether, i-butylene oxide, ethane, methane, and carbon monoxide. T h e follo~ving reactions, involving t h e t-butoxy radical, have been studied:A n activation energy difference o f E ? -E 6 = 3 lccal has been obtained. I N T R O D U C T I O NPrevious work (1, 2, 3) on the photolysis of di-t-butyl peroxide has established that the primary process consists of the breakage of the 0--0 bond, thus producing two t-butoxy radicals. I t could also be sholvn that the t-butoxy radical is relatively unstable and decomposes according to reaction [2] :As most recent values for the activation energy of reaction [' I have been reported 11.2&2 (3) and 1 3 . 2~t 2 . 4 (4) ltcal.Such a value for E? ivould, however, indicate that especially a t low temperatures the t-butoxy radical might survive long enough to taltc part in abstraction and recombination reactions. While the formation of t-butyl alcohol through hydrogen abstraction b y t-butoxy radicals has been reported frequently (5, 6) no illformation was available regarding the activation energy for the abstraction of a hydrogen atom from di-t-butyl peroxide. In the photolysis of di-t-butyl peroxide a considerable amount of ethane is produced by recombination of methyl radicals, originating from reaction [2]. I t seemed, therefore, likely that especially a t low temperatures some methyl t-butyl ether might be produced via recombiilatioil reactions, although this compound had thus far not been reported among the reaction products. I n order to clear these questions the photolysis of di-t-butyl peroxide has been studied again.

The Thermochemistry And Reactivity Of Alkoxyl Radicals

“…Photolysis of ieri-butyl peroxide (185) produces ieri-butoxyl radicals and methyl radicals, which associate to give the ieri-butyl methyl ether.…”

Surface-Radical Mobility Test by Self-Sorted Recombination: Symmetrical Product upon Recombination (SPR)

“…The percent coverage of peroxide 2 on the nanoparticle surface was 0.87−13.8%, which compares favorably to De Mayo and coworker's radical combination to symmetrical products requiring 10−50% coverage of l-(4-methylphenyl)-3-(4methoxyphenyl)-2-propanone. 44,45 Alkoxy radicals tend not to react at the peroxide O−O bond, 46 whereas carbanions can attack the peroxide O−O bond to form ethers by electrophilic alkoxyl "RO + " transfer, 47 whereas ethers 48 or other downstream peroxide compounds are not observed in our case. (iv) The results from DFT calculations provide evidence that the O−O bond energy in symmetrical 3 is increased by 1.8 kcal/ mol upon exchange with unsymmetrical 2, which contributes to enriching to dimerize PhC(Me) 2 O • to 3 on the particle surface.…”

THE REACTION OF t-BUTYL ALCOHOL VAPOR WITH Hg 6(3P1) ATOMS

“…Considering first abstraction by CH3 radicals, AIchlillan (11) found in the photolysis of di-t-butyl peroxide that only ca. 3Yo of the methyl radicals formed resulted in methane.…”

“…For t-butoxy radicals, McAlillan and Wijnen (11) found that ca. 5% of this species resulted in t-butyl alcohol when the peroxide was photolyzed.…”