mr.crow - 6-4-2011 at 11:53
Is it possible to react phthalic anhydride with dry HCl to produce a mono-chlorinated acid? I haven't found much information on this compound.
I am thinking this could be a precursor to other more volatile acid chlorides. Or maybe just beating a dead horse
ScienceSquirrel - 7-4-2011 at 03:50
Breaking the five membered ring is going to be tough and chloride is only weakly nucleophilic.
I think the anhydride would be more stable than the monochloride, phthalic acid itself dehydrates on heating, so you might be pushing your dead horse
uphill 
I think you can use the anhydride to do everything that you could use the monochloride for anyway eg heating with one equivalent of methanol yields
the monomethyl ester.