PrimoPyro (Hive Prodigy)
01-31-02 23:22
No 263414
      Selective Alkylation Problem: Please Help.  Bookmark   

What if a bee has certain phenolic carboxylic acids, like say: 3,4,5-trihydroxy-benzoic acid, 3,4-dihydroxy-benzoic acid, and 2,5-dihydroxy-benzoic acid, and this bee wants to alkylate those phenolic hydroxies, but wants to protect the carboxylic acid?

How do you solve this issue? Is there either a way to selectively alkylate the hydroxies, or can one just alkylate the fuck out of the molecule, then hydrolyze the alkyl ester produced of the carboxylic acid with alakai? Would this hydrolyze the phenol esters too?

Essentially SWIPP wants to: Ph(OH)x(COOH) --> Ph(OR)x(COOH) or Ph(OR)x(COOR) --> Ph(OR)x(COOH)

How can an evil bee chemist accomplish this? Anything special to it, or just alkylate like normal, and hydrolyze with KOH?

Thank you in advance guys. I appreciate your help and advice as always.


Vivent Longtemps la Ruche!
(Stoni's sexual toy)
01-31-02 23:55
No 263424
      Re: Selective Alkylation Problem: Please Help.  Bookmark   

Alkylation of the phenolic OHs will produce the ETHER, not ESTER. Ethers are stable, you need rather drastic conditions to cleave them.
When using dimethyl sulfate you will end up with the etherified benzoic acid methylester, which when treated with NaOH readily saponifies producing the etherified benzoic acid.
(Hive Prodigy)
02-01-02 00:11
No 263431
      Re: Selective Alkylation Problem: Please Help.  Bookmark   

Thank you Os. I meant what you said, I just had a brain fart on the ether vs. ester bit.

So it is stable.....thank you.


Vivent Longtemps la Ruche!
(Old P2P Cook)
02-01-02 03:54
No 263512
      Re: Selective Alkylation Problem: Please Help.  Bookmark   

IIRC, Organic Syntheses has a prep of trimethoxybenzoic acid from gallic acid using dimethylsulfate.

Here is the link to the Organic Syntheses prep.

trimethoxybenzoic acid: