Sciencemadness Discussion Board

Oxidizing the methyl groups in caffeine

Jmap science - 24-10-2013 at 15:11

Could I oxidize the methyl groups of a caffeine to make a organic acid. Caffonic acid I guess.

:P

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Nicodem - 25-10-2013 at 05:42

Formal oxidation of any of those methyl groups would give a carbamic acid or an N-cabamoylcarbamic acid. These cannot exist as such, because they decarboxylate immediately. So, such an oxidation would give theophylline, theobromine, paraxanthine, then the three N-methylxanthines, or ultimately xanthine itself by complete demethylation.
The oxidative demethylation of caffeine occurs in vivo from the cytochrome P450 oxidase. However, it does not necessarily take the complete oxidation to a COOH group to cleave the methyl groups.

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Jmap science - 25-10-2013 at 16:56

I was going to use KmnO4 and caffeine, what would that yield?

Nicodem - 26-10-2013 at 09:59

Probably a mixture of several compounds, depending on the conditions and stoichiometry. The imidazole ring can be oxidized and/or ring opening can occur. I already posted references for preparative synthesis of caffeine oxidation products (with HCl/H2O2 or HNO3) in another thread. I suggest you to start by reading those articles. You can additionally check the literature for oxidations with KMnO4.