Direction of cleavage of primary ozonides in the methanolic ozonolyses of styrene, propenylbenzene, and 2-methylpropenylbenzene

The direction of ozone cleavage of selected unsymmetrical olefins RlR2C=CR3R4 to give (a) RlR2C0 + R3R4CCOO-and (b) RIR,CCOO-+ R3R4C0 has been measured, with particular emphasis on the mode of participation of alkyl substituents in distributing the reaction paths a and b. The interpretation, in terms of substituent effects in stabilizing potential zwitterionic carbo-cations in the transition states corresponding to paths a and b, considers (i) the "hyperconjugative stabilization" of positive sites, where the stabilizing abilities of the substituents are in the order CH, > C2H5 > i-C3H7 > tert-C4H9, and (ii) the participation of inductive effects. The latter appear to be particularly important when the substituents on the two C atoms of the primary ozonide act in the same direction in favoring its electrocyclic cleavage. In the ozonolysis of monosubstituted ethylenes the inductive effects are predominant, i.e. the R-C+HOO-formation is favored by the R groups in the order tert-C4H9 > i-C3H7 > C2H: > .CH3, whereas in trans-and cis-l,2-disubstituted ethylenes "hyperconjugation" governs the dlrectlon of cleavage. The cleavage of selected 1,l-disubstituted, tri-, and tetrasubstituted ethylenes is also studied.

Section: (I) Monosubstituted Ethylenessupporting

confidence: 59%

mentioning

confidence: 99%

Quantitative investigation of the ozonolysis reaction. XIV. A simple carbonium ion stabilization approach to the ozone cleavage of unsymmetrical olefins

Fliszár¹,

Renard²

1970

“…It was unexpected that the corresponding di-(1-alkoxyalkyl) peroxides should be formed and could be isolated. An aromatic peroxide of analogous structure was reported as a by-product of the ozonolysis of stilbene in methanol (27). Acid hydrolysis of the di-(1-alkoxyalkyl) peroxides proceeds as follows (28,29).…”

Section: Discussionmentioning

confidence: 98%

Reactions of ozonides. VII. Isolation and oxidation of ozonolysis products from 1-decene

Diaper¹

1968

1-Decene ozonide (1) was isolated by column chromatography of the mixed products of ozonation of 1-decene (2) in several nonpolar solvents. 1-Methoxy- (3) and 1-tertiary butoxynonane-1-hydroperoxide (4) were similarly obtained. The thin-layer chromatographic separation of these products from each other and from other ozonation products was examined. Compounds 3 and 4 were smoothly oxidized to di-(1-alkoxyalkyl)peroxides by Ce(IV). The stoichiometry of this reaction, examined by isothermal calorimetry, was 1:1. Compounds 1,3, and 4 were oxidized by CF3CO3H and by other oxidizing agents to nonanoic acid with chain degradation loss of 2–30%.

“…It was assumed that this more persistent methoxyhydroperoxide is the methoxymethylhydroperoxide 10. The latter had been obtained and spectroscopically characterized previously in ozonolysis reactions of methylene-terminated olefins in methanol (2,3). To our knowledge, however, its elemental analysis has not yet been reported and its chemistry has not been studied to any extent.…”

Section: Ch3ohmentioning

confidence: 99%

Ozonolysis of vinyl chloride in methanol: a convenient entry to methoxymethylhydroperoxide and its chemistry

Meister¹,

Zwick²,

Griesbaum³

1983

Ozonolysis of vinyl chloride (7) in methanol at −78 °C afforded methoxymethylhydroperoxide (10) in high yield along with only trace amounts of methyl formate (14). The former (10) was converted into a mixture of methyl formate (14) as the major and dimethylformal (18) as the minor product by HCl-catalysis in methanol. Reduction of 10 with dimethylsulfide and subsequent treatment with HCl–methanol gave dimethylformal (18). Partial reduction of 10 with a deficient amount of triphenylphosphine gave formaldehyde hemiacetal (19) and methoxymethylhydroxymethylperoxide (20).