Oxalyl chloride

Greetings,

you can find the mechanism proposed for the transformation of
carboxylates into acyl chlorides in the March's textbook.
If you don't have the book, in this link you could find the mechanism
[Only registered users see links. ]
In a few words the carboxylate attacks the oxalyl chloride to carry out
a acylic nuckeofilic substitution to give an anhydride, and then the
eliminated chloride attacs the anhydride to give the acyl chloride and
CO2.