Hi Christiaan, you picked a challenging reaction mechanism!  My understanding is that the mechanism of the Fries rearrangement is still unresolved but undoubtably much is known that I am not aware of.  Aluminum chloride can form a complex with acid chlorides in Friedel-Crafts applications, for example, which can subsequently give AlCl4- and RCO+ , so perhaps something like this occurs in the Fries reaction as well.  There have been many studies of crossover Fries reactions to try to determine whether the mechanism is inter- or intramolecular but results have varied.  HCl and AlCl3 can form H+, AlCl4- in carbon monoxide formylations ArH + CO + HCl  -->  ArCHO in the presence of AlCl3, yielding the electrophile HCO+, AlCl4- so perhaps the HCl and AlCl3 are involved in a protonation step somehow in the Fries reaction you are doing.  Another reaction which I vaguely recall is an acylation reaction similar to Friedel-Crafts acylations, but using an acid anhydride in the presence of AlCl3,  Ar + CH3CO-O-COCH3 + AlCl3  -->   Ar-COCH3.  This reaction may be of interest in the exploration of carbonyl - AlCl3 chemistry also.

 

I found a site ( http://www.tlchm.bris.ac.uk/org/research/hartres.htm ), a Dr. L. S. Hart's research description, in which he states, "In the case of the Fries Rearrangement, we believe we now have a reasonably detailed picture of the mechanisms involved under particular reaction conditions".  His references may be a good starting point for a literature search on recent studies of the Fries mechanism.  Good luck!

 

Steve

Thanks Christiaan, I would be glad to add the organic sites you like to my list here, as  I do not have many links to good organic sites here yet.  Hope you have some luck with the mysterious Fries reaction!

 

Steve