[snoopy91]

Hey all,

I'm doing a spot of revision for upcoming exams and thought I'd go over ozonolysis. The mechanism is all very clear to me (1,3-dipolar cycloaddition to the molozonide, then reverse, flip over the aldehyde, cycloaddition to the ozonide, and then opening with SMe2 or PPh3 to give two aldehydes, oxidising the nucleophile in the process), but my textbook also suggests that I can use hydrogen peroxide (instead of SMe2) to give carboxylic acids or sodium borohydride to give alcohols.

I can't for the life of me work out the mechanisms. Do these two nucleophiles replace SMe2 in the ozonide ring opening, or do they do something different?

Any pointers would be greatly appreciated!!!

[orgopete]

The additional reagents may not be effective by themselves. Though they may be. Sodium borohydride may reduce a peroxide or ozonide link to form the hydrate of a carbonyl compound. Perhaps someone may know this. Otherwise, borohydride may be used on a carbonyl intermediate to give an alcohol.

When dimethyl sulfide is used, it becomes oxidized and the O-O bond becomes reduced. If a simple acid hydrolysis were performed, then a dicarbonyl compound can be formed plus hydrogen peroxide. The hydrogen peroxide can react further with a carbonyl compound.

The different reagents may result in different products, but the chemistry will be consistent with their reactions.

[Dan]

Sodium borohydride may reduce a peroxide or ozonide link to form the hydrate of a carbonyl compound. Perhaps someone may know this.

NaBH₄ is well documented to reduce peroxides, so I think it would be reasonable to suggest that it reduces the ozonide O-O bond.

[orgopete]

Sodium borohydride may reduce a peroxide or ozonide link to form the hydrate of a carbonyl compound. Perhaps someone may know this.

NaBH₄ is well documented to reduce peroxides, so I think it would be reasonable to suggest that it reduces the ozonide O-O bond.

Yeh, I just wasn't sure about that. It isn't one of the methods that came to mind to destroy peroxides. That and generation of hydroxide or alkoxide from borohydride left me skeptical, so I asked for verification. Thanks.