Iodination Help

[Mercedes Benzene]

I need to synthesize 4-iodoresorcinol (a).

This should be simple, but it hasn't been. My first inclination was to simply iodinate resorcinol (:singer:, but I've never done an iodination before. I have only performed chloro and bromo halogenations previously, and since I wanted to maximize yield, I didn't want to deal with the diiodo moiety.

 

So, I decided to use a procedure that has worked for me in the past (with bromination), using 2,4-dihydroxybenzoic acid ©. I used Iodine monochloride (1 equivalent), quenched, and decarboxylated. But either the iodination failed, or something went wrong during decarboxylation.

 

Any ideas?

 

[UncleAl]

Water, resorcinol, an equivalent of iodine as triodide, progressively add base (sodium carbonate, slowly). Acidify, extract. Seems like that ought to do it - certainly worth a half gram-scale diddle. Phase transfer of iodine from toluene into water with resorcinol and base next. Keep oxygen out in all cases. HOI ought to iodinate resorcinol and especially its anion. I2 ought to do its anion. The 2-iodo isomer should be disinclined by steric hindrance plus statistics.

[Mercedes Benzene]

Thanks Al! I think I'll give it a shot when I get back to the lab. :)