The present invention relates to a process for recovering acrylic acid which is obtained by catalytic gas phase oxidation of propene, wherein, in an absorption stage (K2), the acrylic acid is absorbed from the reaction mixture (1) from the gas phase oxidation with a first solvent (3) and is drawn off for distillative purification, and a gas mixture from the absorption stage (K2) is passed onward to a condensation stage, wherein, in the condensation stage, the gas mixture is condensed, and a condensed phase of the gas mixture is drawn off as acid water (4) and is subjected to a phase separation operation in a phase separation vessel (B1), comprising the steps of a) feeding the aqueous phase (4*) of the acid water (4) drawn off from the condensation stage that has been obtained in the phase separation vessel (B1) to an extraction stage (K7) in which acrylic acid present in the acid water (4) is extracted with a second solvent (5), b) feeding the acrylic acid-comprising extract (6) to a stripping column (K8) in which the acrylic acid is removed from the second solvent (5) with cycle gas (8), wherein the second solvent (5) removed is fed back again after the acrylic acid has been stripped out in the extraction stage (K7), c) feeding the acrylic acid-laden cycle gas (9) to a stripping cycle gas scrubber (K5) in which the acrylic acid is removed from the cycle gas with the first solvent stream (10) fed to the stripping gas scrubber (K5) and transferred into the first solvent (3), and d) feeding a first portion of the acrylic acid-laden first solvent (3) back to the absorption stage (K2).

The present invention further relates to a corresponding plant for recovery of acrylic acid.

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Disclosed is a method for preparing compound Formula S-1, comprising resolving compound Formula rac-2 with a compound of Formula 3 wherein R.sup.1.Math.R.sup.4, m and n are as defined in the disclosure.

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Disclosed is a method for preparing compound Formula S-1, comprising resolving compound Formula rac-2 with a compound of Formula 3 wherein R.sup.1.Math.R.sup.4, m and n are as defined in the disclosure.

A refining method according to the present invention is a refining method for crystallizing a compound with at least one crystal form, including setting, as a target wavelength and a target temperature, a specific infrared wavelength and a specific temperature at which a specific crystal form precipitates from a solution of the compound dissolved in a solvent, and using an infrared radiation apparatus capable of emitting infrared radiation including the target wavelength to evaporate the solvent and precipitate the specific crystal form while irradiating the solution with infrared radiation including the target wavelength and adjusting a temperature of the solution to the target temperature.

A refining method according to the present invention is a refining method for crystallizing a compound with at least one crystal form, including setting, as a target wavelength and a target temperature, a specific infrared wavelength and a specific temperature at which a specific crystal form precipitates from a solution of the compound dissolved in a solvent, and using an infrared radiation apparatus capable of emitting infrared radiation including the target wavelength to evaporate the solvent and precipitate the specific crystal form while irradiating the solution with infrared radiation including the target wavelength and adjusting a temperature of the solution to the target temperature.

A refining method according to the present invention is a refining method for crystallizing a compound with at least one crystal form, including setting, as a target wavelength and a target temperature, a specific infrared wavelength and a specific temperature at which a specific crystal form precipitates from a solution of the compound dissolved in a solvent, and using an infrared radiation apparatus capable of emitting infrared radiation including the target wavelength to evaporate the solvent and precipitate the specific crystal form while irradiating the solution with infrared radiation including the target wavelength and adjusting a temperature of the solution to the target temperature.

A catalytic process for preparing an α,β-ethylenically unsaturated carboxylic acid salt, comprising a) contacting an alkene and carbon dioxide with a carboxylation catalyst, an organic solvent, and an alkoxide having a secondary or tertiary carbon atom directly bound to an [O.sup.−] group, to obtain a crude reaction product comprising the α,β-ethylenically unsaturated carboxylic acid salt and an alcohol by-product which is the conjugate acid of the alkoxide, b) allowing the α,β-ethylenically unsaturated carboxylic acid salt to precipitate out from the crude reaction product; and c) subjecting at least part of the crude reaction product to a mechanical separation step while maintaining the alcohol by-product in liquid form to obtain a solid phase comprising the α,β-ethylenically unsaturated carboxylic acid salt and a liquid phase comprising the carboxylation catalyst, the organic solvent and the alcohol by-product. The process allows for easy separation of the α,β-ethylenically unsaturated carboxylic acid salt by a mechanical separation operation.

A catalytic process for preparing an α,β-ethylenically unsaturated carboxylic acid salt, comprising a) contacting an alkene and carbon dioxide with a carboxylation catalyst, an organic solvent, and an alkoxide having a secondary or tertiary carbon atom directly bound to an [O.sup.−] group, to obtain a crude reaction product comprising the α,β-ethylenically unsaturated carboxylic acid salt and an alcohol by-product which is the conjugate acid of the alkoxide, b) allowing the α,β-ethylenically unsaturated carboxylic acid salt to precipitate out from the crude reaction product; and c) subjecting at least part of the crude reaction product to a mechanical separation step while maintaining the alcohol by-product in liquid form to obtain a solid phase comprising the α,β-ethylenically unsaturated carboxylic acid salt and a liquid phase comprising the carboxylation catalyst, the organic solvent and the alcohol by-product. The process allows for easy separation of the α,β-ethylenically unsaturated carboxylic acid salt by a mechanical separation operation.

Disclosed is a method for preparing compound S-1 (S-1) comprising resolving compound rac-2 (rac-2) with a compound of Formula 3 wherein R.sup.1, R.sup.4, m and n are as defined in the disclosure.

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Disclosed is a method for preparing compound S-1 (S-1) comprising resolving compound rac-2 (rac-2) with a compound of Formula 3 wherein R.sup.1, R.sup.4, m and n are as defined in the disclosure.

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