Abstract: The present invention relates to an improved method for preparing (meth)acrylic anhydride (A(M)A2O) by transanhydrification between (meth)acrylic acid and acetic anhydride in the presence of at least one polymerization inhibitor, in which reaction to the point of partial conversion of the reagents is carried out, followed by continuous distillation. With the method according to the invention, it is possible to produce I1A(M)A2O of very high purity under improved productivity conditions compared to existing methods while eliminating problems of reactor fouling.

Abstract: The present invention provides a process for preparing crystalline parahydroxybenzoic acid anhydride, comprising the step of precipitating and isolating parahydroxybenzoic acid in an aqueous solvent at a temperature equal to or above the transition temperature of parahydroxybenzoic acid.

Abstract: According to the present invention there is provided a process for producing an acid anhydride by reacting a carboxylic acid, preferably a carboxylic acid having a polymerizable group, with a sulfonyl halide compound in the presence of a tertiary amine or in the presence of a tertiary amine and an inorganic base, wherein the tertiary amine or the tertiary amine and the inorganic base are used in an amount of 0.9 to 1.2 equivalents relative to the acid generated from the sulfonyl halide compound.

Abstract: This process for the manufacture of isobutyric anhydride by reacting acetic anhydride with isobutyric acid, distilling the acetic acid generated as it is formed, is characterized in that the reactor is initially loaded with at least a portion of one of the reagents and a portion of the other such that the reagents are in an excess molar ratio relative to the stoichiometry of one of the reagents, and the reaction is carried out while adding the remainder of the reagents as the reaction progresses and according to the place left free in the reactor by the distillation of the acetic acid produced by the reaction, until the desired overall molar ratio of the reagents is reached.

Abstract: There is provided a process for producing high molecular weight polymer comprising the step of reacting one or more preformed linear polymers with one or more cores (as hereinbefore defined) to form high molecular weight polymers, wherein the preformed linear polymers are at a temperature in the range from the melting point of the preformed linear polymers to 330° C.

Abstract: The present invention relates to a novel process for the preparation of citraconic anhydride. More precisely, the invention relates to a process for the preparation of citraconic anhydride from a starting material comprising itaconic acid.The process for the preparation of citraconic anhydride may be performed continuously starting from itaconic acid, or continuously or in a batchwise manner starting directly from a fermentation broth of itaconic acid or of by-products from the manufacture of itaconic acid.

Abstract: The process for carbonylating olefins with carbon monoxide in the presence of water, an alcohol or a carboxylic acid and a halogen-free catalyst comprises using a catalyst comprising nickel or a nickel compound and at least one of the metals of the group consisting of chromium, molybdenum, tungsten, rhenium, ruthenium, osmium, rhodium, iridium, palladium, platinum, silver and gold, or a compound of these metals.

Abstract: This invention relates to novel anhydrides of general formula (I), ##STR1## wherein Ar is an aryl radical, and either R.sub.1 is C.sub.6 H.sub.5 --CO or (CH.sub.3).sub.3 C--O--CO, R.sub.2 is a hydrogen atom and R.sub.3 is a hydroxy function protective grouping, or R.sub.1 is (CH.sub.3).sub.3 C--O--CO and R.sub.2 together form a saturated 5 or 6-membered heterocyclic ring; preparation thereof; and uses thereof for preparing taxane derivatives having general formula (III), ##STR2## wherein R=H, acetyl; R.sub.1 is C.sub.6 --H.sub.5 --CO or (CH.sub.3).sub.3 C--O--CO), and having antitumoral properties.

Abstract: A concentrated catalyst solution provided in the carbonylation reaction in which methyl acetate or dimethyl ether is chemically bonded with carbon monoxide in the presence of a catalyst system comprising a rhodium compound and an alkali metal iodide to produce acetic anhydride is subjected to a carbonylation treatment with carbon monoxide or a mixture of carbon monoxide and hydrogen before it is applied to a process for separating the tar contained in the catalyst solution, thereby increasing the iodide ion content of the catalyst solution, thus enabling the rhodium compound to be stabilized.When the concentration of the iodide ion in the concentrated catalyst solution is increased by this method, there is no possibility of the balances between the rhodium concentration and, the alkali metal concentration and the iodine concentration of the carbonylation reaction system being disturbed even when the catalyst solution as reprocessed is returned to the carbonylation reaction system.

Abstract: A fast, three-stage, low temperature process for the conversion of fatty acids into food grade-anhydrides is disclosed. The process comprises as a first step the reaction of a higher fatty acid with a dehydrating agent under mild conditions. A second process step comprises the further conversion of mixed anhydrides to symmetrical anhydrides by continuous removal of the dehydrating agent and by-product acid from the reaction mixture under vacuum. In a third process step, the symmetrical anhydrides are purified under mild conditions, preferably using thin-film short path evaporation. The resulting anhydrides have minimal by-products and good color and odor.

Abstract: Solid-phase copolymers of 4-vinylpyridine or 4-vinylpyridine 1-oxide may be employed as catalysts in the formation of acid anhydrides. A water soluble polymer of 4-vinylpyridine 1-oxide may also be employed as a catalyst in the formation of acid anhydrides.