Abstract: This invention relates to a method for preparing a cyclic anhydride such as succinic anhydride and methyl succinic anhydride from an unsaturated carboxylic acid such as acrylic acid or crotonic acid. This method can also be used in the manufacture of food additives, plasticisers, polymers of interest, in particular polyurethanes and elastanes, resins, coatings and pharmaceutical products.

Abstract: The present invention relates to a method for preparing cyclic anhydride, in particular succinic anhydride and methylsuccinic anhydride from a ?-lactone, in particular ?-propiolactone and ?-butyrolactone, respectively, in the presence of carbon monoxide, catalyzed by dicobalt octacarbonyl [Co2(CO)8], in an organic solvent. The invention also relates to the use of this method in the manufacture of food additives, plasticizers, polymers of interest in particular polyesters, polyurethanes and elastanes, resins, coatings, pharmaceutical products.

Abstract: A method is for preparing acrylic acid from ?-propiolactone and for using ?-propiolactone. The process is based on a specific reactivity of ?-propiolactone whereby acrylic acid is formed under operating conditions that are mild, especially in terms of temperature.