{HEAD ~ Carbonylation products} such as alkanoic anhydrides, e.g., acetic anhydrides, are produced by {TAIL ~ carbonylation} of esters and ethers in the presence of a rhodium or iridium catalyst and an iodine moiety in a reaction zone wherein the reaction mixture is in a continuous boiling state 
are produced by
{ HEAD ~ Carbonylation products } such as alkanoic anhydrides , e.g. , acetic anhydrides , are produced by { TAIL ~ carbonylation } of esters and ethers in the presence of a rhodium or iridium catalyst and an iodine moiety in a reaction zone wherein the reaction mixture is in a continuous boiling state
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