[baseball07]

Hello everyone.  I was just wondering if it is possible to obtain a carboxylic acid from an epoxy or vicinal diol.  I know you can convert the vicinal diol to an aldehyde by sodium periodate oxidation then oxidize the aldehyde to get a carboxylic acid, but I was wondering if anywhere in between I can get a carboxylic acid.  Thank you for your help.

Rob

[seanifred]

ways to make a carboxylic acid:

primary alcohol + Na₂Cr₂O₇/H₂so₄ --> carboxylic acid

alkene + concentrated KMnO₄ --> carboxylic acid

alkyne + concentrated KMnO₄ --> 2 carboxylic acids

methyl ketone + (1)Cl₂, ^-OH/(2)H⁺ --> carboxylic acid

[movies]

Ruthenium tetraoxide (RuO₄) is a good one too!

[Shaun]

There are a number of ways to do this that go through the aldehyde as an intermediate and then further oxidize to the carboxylic acid.

In general vicinal diols are in equilibrium with the corresponding aldehyde (although the aldehyde form usually predominates).  Many oxidations of aldehydes to carboxylic acids go through vicinal diol intermediates anyway so all of those will work.

Jones' reagent is a good example.

It will also work on acetals (-CH(OR)2) if the acetal is readily hydrolyzed under acidic aqueous conditions (they usually are).

[ultrashogun]

Any phenylalkane with permanganate always gives benzoic acid.

[limpet chicken]

Not so ultrashogun, not so, in cold, dilute solution, KMnO4 will oxidise the likes of ephedrine to the beta-keto derivative (called methcathinone), but its a pretty sensitive reaction, yields aren't particularly good, as KMnO4 is such a strong oxidant its very likely to lead as you said, to the carboxylic acid.

[HP]

Also possible path: R-OH + CBr4 + P(Ph)3 = R-Br
then Grignard R-Br + Mg = RMgBr
then RMgBr + CO2 = R-COOH