Abstract: Basic (meth)acrylates IV are prepared by transesterification of alkyl (meth)acrylates I in the presence of a catalyst and working-up of the reaction mixture by distillation, by a process in which a gas or gas mixture which is inert under the reaction conditions is passed through the reaction zone and/or heat exchanger.

Abstract: The invention relates to a method for producing (meth)acrylic acid esters IV by means of transesterification of a (meth)acrylic acid ester I with an alcohol R2OH comprising at least one more carbon atom than the alcohol constituents (R1O—) in the (meth)acrylic acid ester I to be subjected to transesterification, in the presence of a catalyst or a catalyst mixture. Either essentially the (meth)acrylic acid ester I is separated and then the catalyst used is separated by distillation (catalyst separation), or the catalyst used is separated by distillation first (catalyst separation), and then essentially the (meth)acrylic acid ester I is separated, from the reaction product of the transesterification. Constituents from the mixture obtained, which have a lower boiling point than the (meth)acrylic acid ester IV, are essentially separated by distillation (separation of constituents at low boiling point), and the (meth)acrylic acid ester IV is then purified by distillation (purification by distillation).

Abstract: Higher (meth)acrylates IV are prepared by transesterification of a lower (meth)acrylate I with a higher alcohol R2OH in the presence of a stabilizer or stabilizer mixture and of a catalyst or catalyst mixture, by a process in which the liberated lower alkanol R1OH is separated off and is fed at least partly to the preparation of the lower (meth)acrylate I.

Abstract: The tert-butyl ester of an aliphatic C1-C4-carboxylic acid is prepared by reacting the carboxylic acid with isobutene in the liquid phase in the presence of an acidic catalyst by a continuous process in which the reaction is carried out in a reactor divided into a plurality of sections, the carboxylic acid, the isoolefin and the catalyst are fed into the first section of the reactor, the reaction mixture obtained is removed from the last section of the reactor and the ester is isolated therefrom, the reaction temperature in the reactor being controlled so that it is from 10 to 40° C. and is highest in the first section of the reactor.

Abstract: The tert-butyl ester of an aliphatic C1-C4-carboxylic acid is prepared by reacting the carboxylic acid with isobutene in the liquid phase in the presence of an acidic catalyst by a continuous process in which the reaction is carried out in a reactor divided into a plurality of sections, the carboxylic acid, the isoolefin and the catalyst are fed into the first section of the reactor, the reaction mixture obtained is removed from the last section of the reactor and the ester is isolated therefrom, the reaction temperature in the reactor being controlled so that it is from 10 to 40° C. and is highest in the first section of the reactor. The novel process permits the technically simple, economical and environmentally friendly preparation of tertiary butyl esters of saturated and unsaturated C1-C4-carboxylic acids.

Abstract: A process for preparing acrylic acid and/or acrylates which comprises the following stage A and, if desired, B and C: A: cooling a gaseous reaction mixture which comprises acrylic acid and is obtained in the gas-phase oxidation to prepare acrylic acid, using oligomeric acrylic acid or a mixture of acrylic acid and oligomeric acrylic acid, to give a gaseous mixture comprising acrylic acid and a quench bottom product which comprises oligomeric acrylic acid; B: separating the gaseous mixture comprising acrylic acid, to give a low-boiling fraction, a crude acrylic acid, and a bottom product, which comprises oligomeric acrylic acid; C: esterifying the crude acrylic acid obtained in stage B by means of one or more alkanols.

Abstract: In a process for quenching a hot gas mixture comprising (meth)acrylic acid by direct cooling by means of a cooling liquid in a spray cooler, the cooling liquid is atomized in the spray cooler by means of an impingement atomizer.

Abstract: The invention relates to a method for producing (meth)acrylic acid esters by transesterification of the (meth)acrylic acid with an alkanol in the presence of an acid catalyst, a polymerization inhibitor and an organic solvent that forms an azeotropic mixture with water. The reaction mixture is heated to the boiling point of the mixture in a reactor that comprises a distillation unit with a column and a condenser. The azeotropic mixture is distilled off, the organic solvent is returned to the column as reflux and at least a part of the column reflux is contacted with copper or a copper-containing material. The inventive method is advantageous in that substantially no polymerizate is produced in the distillation column.

Abstract: The invention relates to a method for producing (meth)acrylic acid esters by transesterification of the (meth)acrylic acid with a higher alkanol in the presence of an acid catalyst, at least one polymerization inhibitor and one organic solvent that forms an azeotropic mixture with water. The reaction mixture is heated to the boiling point of the mixture in a reactor that comprises a distillation unit with a column and a condenser. The content of the reactor is recirculated via an external evaporator and heated to the boiling point, and the azeotropic mixture is distilled off. The organic solvent forms a reflux and at least a part of the solvent reflux is recirculated between the reactor and the evaporator. The inventive method allows for the production of higher (meth)acrylic acid esters in a reactor with a circulation evaporator without using copper salts as the polymerization inhibitors.

Abstract: Higher (meth)acrylates are prepared by reacting (meth)acrylic acid and the alcohol in the presence of at least one acidic catalyst and at least one polymerization inhibitor and in the presence of a solvent which forms an azeotropic mixture with water and distilling off and condensing the azeotropic mixture, the condensate separating into an aqueous phase and an organic phase, by a process in which

Abstract: In a process for the fractional condensation of an acrylic acid-containing product gas mixture of a gas-phase partial oxidation of C3 precursors of acrylic acid with molecular oxygen under heterogeneous catalysis, the separation column used contains both dual-flow trays and hydraulically sealed cross-flow trays as baffles having separation activity.

Abstract: An ester of an &agr;,&bgr;-unsaturated carboxylic acid is prepared by reacting the carboxylic acid with a C6-C12-alkanol, cyclopentanol or cyclohexanol in the presence of an acidic esterification catalyst and of an entraining agent for removing the water of reaction formed in the esterification, by a process in which the entraining agent used is the olefin on which the alkanol is based.

Abstract: The tert-butyl ester of an aliphatic C1-C4-carboxylic acid is prepared by reacting the carboxylic acid with isobutene in the liquid phase in the presence of an acidic catalyst by a continuous process in which the reaction is carried out in a reactor divided into a plurality of sections, the carboxylic acid, the isoolefin and the catalyst are fed into the first section of the reactor, the reaction mixture obtained is removed from the last section of the reactor and the ester is isolated therefrom, the reaction temperature in the reactor being controlled so that it is from 10 to 40° C. and is highest in the first section of the reactor.

Abstract: In a process for esterifying (meth)acrylic acid with an alkanol in the presence of an esterification catalyst, in which unconverted starting compounds and (meth)acrylic ester to be formed are separated off by distillation and an oxyester-containing bottom product is formed, the bottom product is first separated off and then the oxyesters contained in it are cleaved in the presence of a relatively long-chain alkylbenzenesulfonic acid at elevated temperatures.

Abstract: In a process for preparing an ester of an unsaturated carboxylic acid by reacting an ester of the unsaturated carboxylic acid and a C1-C4-alkanol with an alcohol R3OH, where R3 is a C4-C20-alkyl radical, a C5-C7-cycloalkyl radical, a phenyl-C1-C4-alkyl radical or a C2-C12-alkyl radical substituted by at least one NR5R5 group or by from 1 to 3 hydroxyl groups or C1-C4-alkoxyl groups or interrupted by one or more oxygen atoms, where the radicals R5 are, independently of one another, C1-C6-alkyl or together with the nitrogen atom form a 5- to 7-membered heterocyclic ring which may contain a further nitrogen or oxygen atom, in the presence of a transesterification catalyst, the transesterification catalyst used is at least one metal alkanolate containing at least one OR1 group, where R1 is a 2,2,6,6-tetraalkyl-1-oxylpiperidin-4-yl radical.

Abstract: A tert-C4-C8-alkyl (meth)acrylate is prepared by reacting (meth)acrylic acid with an olefin of the formula 1

Abstract: Plant parts which are used for the production or processing of (meth)acrylic esters are cleaned by (a) emptying the plant parts, (b) flushing the plant parts with aqueous 5 to 50% strength by weight alkali metal hydroxide solution, (c) removing the alkali metal hydroxide solution from the plant parts, (d) if required, washing the plant parts with water and (e) if required, drying the plant parts.

Abstract: A process for preparing acrylic acid and/or acrylates, which comprises stage A with or without stages B and C: A: cooling a gaseous reaction mixture which comprises acrylic acid and is obtained in the gas-phase oxidation to prepare acrylic acid, using an inert high-boiling solvent, to give a gaseous mixture comprising acrylic acid; B: separating the gaseous mixture comprising acrylic acid to give a low-boiling fraction, a crude acrylic acid, and a bottom product, and C: esterifying the crude acrylic acid obtained in stage B by means of one or more alkanols to give an esterification mixture comprising one or more acrylates and one or more acetic esters.

Abstract: Polymerizable compounds are prepared and/or worked up using at least one liquid ring pump by a process in which a working liquid which contains a material stream from the preparation and/or working-up of the polymerizable compound is used in a liquid ring pump.

Abstract: Pure (meth)acrylic acid and lower (meth)acrylates are prepared from crude (meth)acrylic acid by a process in which I) crude (meth)acrylic acid is separated by crystallization in at least one crystal batch A and at least one mother liquor B and II) at least a part of the crystal batch A is removed as pure (meth)acrylic acid and at least a part of the mother liquor B is used for the preparation of lower (meth)acrylates by esterifying (meth)acrylic acid with the corresponding alcohols in the presence of an acidic catalyst.