A method of production of malic acid includes treating a first intermediate product to form a second intermediate product. The treating includes substantially removing impurities from the first intermediate product to obtain a treated intermediate product by gas stripping the crude maleic anhydride, or subjecting a mixture of one or more of the crude maleic acid, the crude fumaric acid, and the vent gas scrubber solution obtained from a phthalic anhydride production process or a maleic anhydride production process to crystallization, passing an aqueous solution of the treated intermediate product through a carbon column to substantially remove retained impurities to form the second intermediate product, obtaining a feed that includes the second intermediate product, and causing the feed to undergo hydration reaction in a tubular reactor or a continuous stirred tank reactor to produce malic acid.

A method of production of malic acid includes treating a first intermediate product to form a second intermediate product. The treating includes substantially removing impurities from the first intermediate product to obtain a treated intermediate product by gas stripping the crude maleic anhydride, or subjecting a mixture of one or more of the crude maleic acid, the crude fumaric acid, and the vent gas scrubber solution obtained from a phthalic anhydride production process or a maleic anhydride production process to crystallization, passing an aqueous solution of the treated intermediate product through a carbon column to substantially remove retained impurities to form the second intermediate product, obtaining a feed that includes the second intermediate product, and causing the feed to undergo hydration reaction in a tubular reactor or a continuous stirred tank reactor to produce malic acid.

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.

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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##

A method for producing acetic acid includes subjecting an acetic acid solution to an acetic anhydride decreasing treatment. The acetic acid solution is present typically in, or downstream from, a distillation column (5) of acetic acid production equipment (X), includes acetic acid in a concentration of 90 mass percent or more, acetic anhydride, and water, and is in such a state that an equilibrium concentration of acetic anhydride is higher than an acetic anhydride concentration. The acetic anhydride decreasing treatment includes at least one of water concentration increasing and temperature lowering so as to bring the acetic acid solution into such a state that the equilibrium concentration of acetic anhydride is lower than the acetic anhydride concentration. The acetic acid production method is suitable for yielding a high-purity acetic acid product.

A method for producing acetic acid includes subjecting an acetic acid solution to an acetic anhydride decreasing treatment. The acetic acid solution is present typically in, or downstream from, a distillation column (5) of acetic acid production equipment (X), includes acetic acid in a concentration of 90 mass percent or more, acetic anhydride, and water, and is in such a state that an equilibrium concentration of acetic anhydride is higher than an acetic anhydride concentration. The acetic anhydride decreasing treatment includes at least one of water concentration increasing and temperature lowering so as to bring the acetic acid solution into such a state that the equilibrium concentration of acetic anhydride is lower than the acetic anhydride concentration. The acetic acid production method is suitable for yielding a high-purity acetic acid product.

A process for production of malic acid includes obtaining a feed that includes one or more of crude maleic anhydride, pure maleic anhydride, crude maleic acid, crude fumaric acid, pure maleic acid, pure fumaric acid, vent gas scrubber solutions from production of maleic anhydride, and vent gas scrubber solutions from production of phthalic anhydride. The feed is passed in a tubular reactor assembly to obtain a first product stream, which includes unreacted feed and malic acid. The feed is made to undergo hydration reaction in the tubular reactor assembly for a first predetermined time period, and further hydration of the first product stream is caused in a stirred tank reactor assembly for a second predetermined time period to obtain a final product stream, which includes the malic acid.

A process for production of malic acid includes obtaining a feed that includes one or more of crude maleic anhydride, pure maleic anhydride, crude maleic acid, crude fumaric acid, pure maleic acid, pure fumaric acid, vent gas scrubber solutions from production of maleic anhydride, and vent gas scrubber solutions from production of phthalic anhydride. The feed is passed in a tubular reactor assembly to obtain a first product stream, which includes unreacted feed and malic acid. The feed is made to undergo hydration reaction in the tubular reactor assembly for a first predetermined time period, and further hydration of the first product stream is caused in a stirred tank reactor assembly for a second predetermined time period to obtain a final product stream, which includes the malic acid.

A process for production of malic acid includes obtaining a feed that includes one or more of crude maleic anhydride, pure maleic anhydride, crude maleic acid, crude fumaric acid, pure maleic acid, pure fumaric acid, vent gas scrubber solutions from production of maleic anhydride, and vent gas scrubber solutions from production of phthalic anhydride. The feed is passed in a tubular reactor assembly to obtain a first product stream, which includes unreacted feed and malic acid. The feed is made to undergo hydration reaction in the tubular reactor assembly for a first predetermined time period, and further hydration of the first product stream is caused in a stirred tank reactor assembly for a second predetermined time period to obtain a final product stream, which includes the malic acid.

A method for producing acetic acid includes subjecting an acetic acid solution to an acetic anhydride decreasing treatment. The acetic acid solution is present typically in, or downstream from, a distillation column (5) of acetic acid production equipment (X), includes acetic acid in a concentration of 90 mass percent or more, acetic anhydride, and water, and is in such a state that an equilibrium concentration of acetic anhydride is higher than an acetic anhydride concentration. The acetic anhydride decreasing treatment includes at least one of water concentration increasing and temperature lowering so as to bring the acetic acid solution into such a state that the equilibrium concentration of acetic anhydride is lower than the acetic anhydride concentration. The acetic acid production method is suitable for yielding a high-purity acetic acid product.