A method for preparing an isobenzofuran-1(3H)-one based compound of the following formula I is provided. R1, R2 and p are defined in the specification. ##STR00001##

Provided is a free-polyunsaturated-fatty-acid-containing composition that has a total metal content of 0.1 ppm or less and that comprises at least one free polyunsaturated fatty acid having 20 or more carbon atoms, in an amount that is at least 80.0% of the amount of fatty acids in the composition; and a method for manufacturing a free-polyunsaturated-fatty-acid-containing composition, comprising: providing a raw material composition containing at least one polyunsaturated fatty acid having 20 or more carbon atoms; performing a hydrolysis treatment on a reaction solution prepared by combining the provided raw material composition, a lower alcohol, water having a total metal content of 0.01 ppm or less, and an alkali catalyst; and limiting the contact between the reaction composition and the metal after the hydrolysis treatment so that the product T [cm.sup.2days] of the contact surface area [cm.sup.2] per 1 g and the contact time [days] between the composition and the metal is 100 or less.

Provided is a free-polyunsaturated-fatty-acid-containing composition that has a total metal content of 0.1 ppm or less and that comprises at least one free polyunsaturated fatty acid having 20 or more carbon atoms, in an amount that is at least 80.0% of the amount of fatty acids in the composition; and a method for manufacturing a free-polyunsaturated-fatty-acid-containing composition, comprising: providing a raw material composition containing at least one polyunsaturated fatty acid having 20 or more carbon atoms; performing a hydrolysis treatment on a reaction solution prepared by combining the provided raw material composition, a lower alcohol, water having a total metal content of 0.01 ppm or less, and an alkali catalyst; and limiting the contact between the reaction composition and the metal after the hydrolysis treatment so that the product T [cm.sup.2days] of the contact surface area [cm.sup.2] per 1 g and the contact time [days] between the composition and the metal is 100 or less.

The present invention relates to a process for producing succinic anhydride by maleic anhydride hydrogenation, comprising (1) feeding a maleic anhydride solution and a hydrogen raw material respectively to a first-stage hydrogenation reactor from an upper liquid-phase feed port and a top gas-phase feed port of the first-stage hydrogenation reactor for a first-stage hydrogenation reaction to obtain a first-stage hydrogenation product; (2) feeding the first-stage hydrogenation product to a second-stage hydrogenation reactor for a second-stage hydrogenation reaction to obtain a second-stage hydrogenation product, optionally, before entering the second-stage hydrogenation reactor, subjecting the first-stage hydrogenation product to a first-stage gas-liquid separation to obtain a first-stage gas phase and a first-stage liquid phase, and then feeding the first-stage gas phase and the first-stage liquid phase respectively from a top gas-phase feed port and an upper liquid-phase feed port of the second-stage hydrogenation reactor; and (3) subjecting the second-stage hydrogenation product to a second-stage gas-liquid separation to obtain a second-stage gas phase and a second-stage liquid phase, returning a part of the second-stage liquid phase to step (1) to be mixed with the maleic anhydride solution for the first-stage hydrogenation reaction, and optionally, using part or all of the second-stage gas phase as a circulating hydrogen. The present invention also relates to a process for producing succinic acid comprising such process, a liquid-phase hydrogenation reaction system, and a system for producing succinic acid comprising such system.

The present invention relates to a process for producing succinic anhydride by maleic anhydride hydrogenation, comprising (1) feeding a maleic anhydride solution and a hydrogen raw material respectively to a first-stage hydrogenation reactor from an upper liquid-phase feed port and a top gas-phase feed port of the first-stage hydrogenation reactor for a first-stage hydrogenation reaction to obtain a first-stage hydrogenation product; (2) feeding the first-stage hydrogenation product to a second-stage hydrogenation reactor for a second-stage hydrogenation reaction to obtain a second-stage hydrogenation product, optionally, before entering the second-stage hydrogenation reactor, subjecting the first-stage hydrogenation product to a first-stage gas-liquid separation to obtain a first-stage gas phase and a first-stage liquid phase, and then feeding the first-stage gas phase and the first-stage liquid phase respectively from a top gas-phase feed port and an upper liquid-phase feed port of the second-stage hydrogenation reactor; and (3) subjecting the second-stage hydrogenation product to a second-stage gas-liquid separation to obtain a second-stage gas phase and a second-stage liquid phase, returning a part of the second-stage liquid phase to step (1) to be mixed with the maleic anhydride solution for the first-stage hydrogenation reaction, and optionally, using part or all of the second-stage gas phase as a circulating hydrogen. The present invention also relates to a process for producing succinic acid comprising such process, a liquid-phase hydrogenation reaction system, and a system for producing succinic acid comprising such system.

Processes for purifying acetic acid by distilling a process in a column in which acetic anhydride is formed in the lower portion of the column. The product stream withdrawn from the column comprises acetic acid, water at a concentration of no more than 0.2 wt. %, and acetic anhydride at a concentration of no more than 600 wppm. The process further comprises hydrating the acetic anhydride in the product stream to form a purified acetic acid product comprising acetic anhydride at a concentration of no more than 50 wppm.

Processes for purifying acetic acid by distilling a process in a column in which acetic anhydride is formed in the lower portion of the column. The product stream withdrawn from the column comprises acetic acid, water at a concentration of no more than 0.2 wt. %, and acetic anhydride at a concentration of no more than 600 wppm. The process further comprises hydrating the acetic anhydride in the product stream to form a purified acetic acid product comprising acetic anhydride at a concentration of no more than 50 wppm.

A process for the preparation of an aromatic product is disclosed which includes a step b) of contacting one or more intermediate compounds with a further acid to form the aromatic product. The intermediate compounds can be obtained in step a) that includes contacting a 7-oxabicyclo[2.2.1]hept-2-ene core structure with an acidic mixture. The amount of acid in step b) is higher than the amount of acid in step a).

A process for the preparation of an aromatic product is disclosed which includes a step b) of contacting one or more intermediate compounds with a further acid to form the aromatic product. The intermediate compounds can be obtained in step a) that includes contacting a 7-oxabicyclo[2.2.1]hept-2-ene core structure with an acidic mixture. The amount of acid in step b) is higher than the amount of acid in step a).

A process for the preparation of an aromatic product is disclosed which includes a step b) of contacting one or more intermediate compounds with a further acid to form the aromatic product. The intermediate compounds can be obtained in step a) that includes contacting a 7-oxabicyclo[2.2.1]hept-2-ene core structure with an acidic mixture. The amount of acid in step b) is higher than the amount of acid in step a).