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Topic: Caffeine: reducing the keto-groups to alkanes  (Read 1513 times)

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Offline naalya

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Caffeine: reducing the keto-groups to alkanes
« on: December 01, 2022, 02:06:44 AM »
Hi,
i'm wondering if you could reduce both keto-groups in caffeine to their alkanes.
the reduction method i'm thinking of is mainly used to reduce secondary alcohols to alkanes, but i found some rather 'not properly reliant' information on the internet, that it will also reduce ketones to alkanes (using hydroiodic acid, generated in situ using two elements in the presence of water. i'm not sure if it's allowed to specify this procedure, since it's often used by hobby 'chemists' to get an illegal product).

if it works and both keto-groups would be reduced, the product should be 1,3,7-trimethyl-3,7-dihydro-1H-purine (see attachment). it should be less water soluble than caffeine. i found information about 6-methylpurine, but nothing on (hydrated) (tri)methylpurines.

my questions are:
1. has anyone ever tried reducing the keto-groups of caffeine?
2. has anyone ever come upon the proposed product?
3. can anyone with access to SciFinder try a quick search, if it has been mentioned in literature anywhere?
(4. are i am allowed to post the procedure i would use (i think some people here will know which one i mean)?)

Offline rolnor

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Re: Caffeine: reducing the keto-groups to alkanes
« Reply #1 on: December 26, 2022, 01:20:55 AM »
I would try first sulfurisation with P2S5 to make the di-thio caffeine and then use Raney-nickel for desulfurisation.

Offline spirochete

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Re: Caffeine: reducing the keto-groups to alkanes
« Reply #2 on: December 29, 2022, 06:21:38 PM »
If the only thing you can think of is the the reduction of the secondary alcohol method, it makes me think your background in chemistry is not the most academic. Also, mentioning it in this case seems pretty out of context. How would the secondary alcohol be obtained? Wouldn't it be an unstable hemi-aminal at that point? There is no ketone here. More like special amides/lactams. But they are also part of a ring with aromatic character. And one of carbonyl groups has two nitrogen lone pairs conjugated with it. Basically it is specialized heterocycle chemistry.

But LiAlH4 seems like a reasonable option. I don't know if it will work the same as a regular amide because the 6 membered ring has aromatic character. Amide + LiAlH4 is standard reaction. Caffeine + LiAlH4 is not a standard reaction.

Also both what I am suggesting and what Rolnor is suggesting involve serious reagents that can start large fires for various reasons. Possibly being exposed to water, maybe even just air, looking at them funny, etc.

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