Sciencemadness Discussion Board

Friedel-Crafts Alkylation using iodine

CRUSTY - 15-7-2016 at 17:34

Hello all, bit of a beginner question. I was wondering, would it be possible to do a successful FC alkylation of benzene using iodine, despite the low electronegativity of iodine relative to carbon. I'm mostly asking this because of the lower toxicity and higher melting/boiling points of iodine compared to other halogens. I won't be surprised if the answer to all of this is no, but I couldn't find anything mentioning this on the search engine.

[Edited on 16-7-2016 by CRUSTY]

AvBaeyer - 15-7-2016 at 18:40

I am unaware of iodine catalyzed "alkylations" in the F-C sense. However, acylations to give ketones (acetic anhydride + iodine) were shown to be possible if the aromatic substrate is reactive enough. Anisole, furan, and thiophene are known to give the acyl derivatives. I do not have the references immediately at hand but the work was done in the 1950's. I know that one of the investigators was RM Dodson so you could track that down if you are interested. I have tried some of these iodine catalyzed acylations and they are a real mess with multiple products. They seem to be quite sensitive to a broad range of reaction conditions. Perhaps that is why interest quickly withered.

AvB

CRUSTY - 15-7-2016 at 18:58

Quote: Originally posted by AvBaeyer  
However, acylations to give ketones (acetic anhydride + iodine) were shown to be possible if the aromatic substrate is reactive enough. Anisole, furan, and thiophene are known to give the acyl derivatives. I do not have the references immediately at hand but the work was done in the 1950's.
AvB


I've actually seen this one before. I found it at JACS vol. 68, 2639 (1946). I've yet to do anything iodine-catalyzed of this nature, I'm glad someone here has tried it.

[Edited on 16-7-2016 by CRUSTY]