Abstract: A process for rectificatively separating fluids including (meth)acrylic monomers in a rectification column by directly cooling the vapor including (meth)acrylic monomers rising to the top of the rectification column to form top condensate including (meth)acrylic monomers, the condensation space at the top of the column being separated from the region of the rectification column containing the separating internals only by at least one chimney tray from which the top condensate formed is removed from the rectification column, which includes effecting the direct cooling of the vapor in the condensation space in at least two spray zones which are spatially successive and are flowed through by vapor by spraying supercooled top condensate including added polymerization inhibitor, and the temperature of the sprayed supercooled top condensate becoming lower from spray zone to spray zone in the flown direction of the vapor.

Abstract: In a thermal separating process between at least one gaseous and at least one liquid stream, of which at least one comprises (meth)acrylic monomers, in a separating column containing sieve trays as separating internals, at least some of the sieve trays are operated above an entrainment fraction of 10% by weight.

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: 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: In a thermal separating process between at least one gaseous and at least one liquid stream, of which at least one comprises (meth)acrylic monomers, in a separating column containing sieve trays as separating internals, at least some of the sieve trays are operated above an entrainment fraction of 10% by weight.

Abstract: A process for rectificatively separating fluids comprising (meth)acrylic monomers in a rectification column by directly cooling the vapor comprising (meth)acrylic monomers rising to the top of the rectification column to form top condensate comprising (meth)acrylic monomers, the condensation space at the top of the column being separated from the region of the rectification column containing the separating internals only by at least one chimney tray from which the top condensate formed is removed from the rectification column, which comprises effecting the direct cooling of the vapor in the condensation space in at least two spray zones which are spatially successive and are flowed through by vapor by spraying supercooled top condensate comprising added polymerization inhibitor, and the temperature of the sprayed supercooled top condensate becoming lower from spray zone to spray zone in the flow direction of the vapor.

Abstract: The process for the esterification of (meth)acrylic acid with an alkanol in the presence of an esterification catalyst, in which unconverted starting compounds and the (meth)acrylate to be formed are separated off by distillation and an oxyester-containing bottom product is formed and is separated off, and (a) in the bottom product separated off, the oxyesters present are cleaved, if required after the addition of (meth)acrylic acid and/or oligomeric (meth)acrylic acid, directly in the presence of acid catalysts differing from (meth)acrylic acid and/or oligomeric (meth)acrylic acid, and the cleavage products are removed, a cleavage residue remaining, or (b) the oxyesters are first removed by distillation from the cleavage product separated off, a distillation residue remaining, and the oxyesters removed are cleaved, if required after addition of (meth)acrylic acid and/or oligomeric (meth)acrylic acid, in the presence of acid catalysts differing from (meth)acrylic acid and/or oligomeric (meth)acrylic acid, a

Abstract: A process is described for preparing (meth)acrylic esters by reacting (meth)acrylic acid with C4-C12-alkanols in the presence of sulfuric acid or a mono-C4-C12-alkyl sulfate as catalyst, where the catalyst is regenerated by extraction with water from the reaction mixture and the aqueous catalyst solution is recycled back to the esterification, the concentration of unreacted alkanol in the reaction mixture to be extracted being not more than 5% by weight, based on the reaction mixture to be extracted.

Abstract: A process for isolating acrylic acid forward during catalytic gas phase oxidation of propene, which entails separating acrylic acid from the gas phase oxidation reaction using an absorbent containing biphenyl, diphenyl ether or dimethyl phthalate; and extracting acrylic acid from acid water of the gas phase reaction with a solvent containing biphenyl, diphenyl ether or dimethyl phthalate.

Abstract: In a process and an apparatus for the continuous preparation of alkyl esters of (meth)acrylic acid by reacting (meth)acrylic acid with alkanols having from 1 to 5 carbon atoms in a homogeneous, liquid, solvent-free phase at elevated temperature and in the presence of an acid esterification catalyst, in which the (meth)acrylic acid, the alkanol and the catalyst are fed to a reaction zone, the water formed is removed by rectification during a residence time as constituent of a mixture comprising alkanol in a rectification unit superposed on the reaction zone, the distillate thus obtained is separated into an organic phase comprising alkanol and an aqueous phase comprising water, the organic phase is returned to the rectification unit, the reaction mixture is discharged from the reaction zone and conveyed into a distillative separation zone comprising further rectification units and in the latter the alkyl (meth)acrylate formed is separated off.

Abstract: In a process and an apparatus for the continuous preparation of alkyl esters of (meth)acrylic acid by reacting (meth)acrylic acid and monohydric alkanols of 1 to 8 carbon atoms in the homogeneous, liquid, solvent-free phase at elevated temperatures and in the presence of an acidic esterification catalyst, by feeding the (meth)acrylic acid, the alkanol and the acid catalyst continuously to a reaction zone, the reaction zone consists of a cascade of at least two reaction regions connected in series, and the discharge stream of one reaction region forms a feed stream of a downstream reaction region. The cascade may have from two to four reaction regions is spatially separated from one another.

Abstract: In the process for the continuous preparation of alkyl esters of (meth)acrylic acid by reacting (meth)acrylic acid with monohydric alkanols having from 1 to 8 carbon atoms in the presence of an acid esterification catalyst in a reaction zone, there is discharged from the reaction zone a product mixture which comprises the alkyl (meth)acrylate formed, the catalyst and the by-products formed during the course of the esterification having boiling points higher than that of the alkyl (meth)acrylate, and from which the alkyl (meth)acrylate is separated by distillation in a separation zone. The product mixture discharged from the reaction zone is fed to a rectification unit (I), in this unit the product mixture discharged is separated by rectification into at least one product (I) comprising the alkyl ester of (meth)acrylic acid and a product (II) comprising the catalyst, the product (I) is fed to a further rectification unit (II) and in this the alkyl ester of (meth)acrylic acid is separated off by rectification.

Abstract: Acrylic acid or methacrylic acid is purified by(a) subjecting a mixture comprising the acrylic acid or methacrylic acid to a sharply defined separation process essentially in the absence of an organic solvent, with the composition of the phase in which the acrylic acid or methacrylic acid accumulates remaining essentially constant when the composition of the other phases participating in the mass transfer changes, then taking off this phase and(b) subjecting at least a part of the remaining phase from stage(a) to a less sharply defined separation process and(c) feeding one of the phases formed in stage (b) to the sharply defined separation process in stage (a).In addition, the invention provides a process for preparing acrylic acid or methacrylic acid which includes the abovementioned purification process.

Abstract: In a process and an apparatus for the continuous preparation of alkyl esters of (meth)acrylic acid by reacting (meth)acrylic acid and monohydric alkanols of 1 to 8 carbon atoms in the homogeneous, liquid, solvent-free phase at elevated temperatures and in the presence of an acidic esterification catalyst, by feeding the (meth)acrylic acid, the alkanol and the acid catalyst continuously to a reaction zone, the reaction zone consists of a cascade of at least two reaction regions connected in series, and the discharge stream of one reaction region forms a feed stream of a downstream reaction region. The cascade may have from two to four reaction regions spatially separated from one another.

Abstract: Reaction mixtures obtained in addition reactions of OH-- or NH-- carrying compounds with acetylene or propyne in the presence of alkali metal alcoholates or alkali metal amides are worked up by distilling off the vaporizable components from the reaction mixture in a thin-film evaporator. Before removal of the vaporizable components from the reaction mixture, a particularly defined polyether is added thereto.

Abstract: N-Vinyllactams of the general formula I ##STR1## where n is from 1 to 3, are prepared by a process which comprises reaction of a lactam of the general formula II ##STR2## where n is from 1 to 3, with from 10 to 90 percent by weight of an aqueous alkali metal hydroxide solution with distillation at from 50.degree. to 250.degree. C. and from 1 to 100 mbar and with a residence time of from 0.1 to 5 hours and subsequent reaction with acetylene at from 60.degree. to 250.degree. C. and from 1 to 100 bar.