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Abstract

A process for the carbonylation of allylic butenol or butenyl ester of a carboxylic acid (e.g., crotyl acetate, 3-acetoxybutene-1 and mixtures thereof) in an anhydrous carboxylic acid solvent and production of beta-gamma unsaturated carboxylic acid anhydride (e.g., 3-pentenoic acid anhydride) utilizing a rhodium-containing catalyst (e.g., dicarbonylacetylacetonate rhodium(I)) promoted with a metal iodide (e.g., dicarbonylacetylacetonate rhodium(I), or the like). The following representative reaction showing a crotyl ester (i.e., a carboxylic acid ester of 2-buten-1-ol) as the reactant producing a corresponding pentenoic acid anhydride is illustrative of the overall carbonylation. ##STR1## Suitable allylic compounds are of the form ##STR2## where one of the groups R.sup.1, R.sup.2, and R.sup.3 is methyl and the other two groups are H and wherein R.sub.4 is selected from the group consisting of H and ##STR3## wherein R.sup.5 is selected from the group consisting of a C.sub.1 to C.sub.10 alkyl. Such a process is particularly useful in the production of beta-gamma unsaturated carboxylic acid anhydride without promoting the back reaction producing butadiene and a carboxylic acid.

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