| 摘要 |
<p>The invention provides an improved process for preparing unsaturated carboxylic anhydrides of the general formula I R—C(O)—O—C(O)—R (I) in which R is an unsaturated organic radical having 2 to 12 carbon atoms by transanhydridizing an aliphatic carboxylic anhydride with a carboxylic acid of the general formula II R—COOH (II) in which R is as defined above, in an apparatus consisting of a reaction region and a rectification column, characterized in that a) the reactants are fed into a reaction region in stoichiometric ratios, b) the carboxylic acid formed as a by-product is removed from the reaction mixture, c) the carboxylic anhydride of the formula I is subsequently drawn off, d) the unconverted reactants are recycled into the reaction region, e) the reaction region comprises a heterogeneous catalyst and f) one or more polymerization inhibitors are added.</p> |
