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: In a process for the continuous preparation of alkyl esters of (meth)acrylic acid by reacting (meth)acrylic acid with alkanols having from 1 to 8 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 acid catalyst are fed to a reaction zone, the water formed is removed by rectification during a residence time as constituent of a mixture comprising starting alkanol in a rectification unit (III) superposed on the reaction zone, the distillate obtained is separated into an organic phase comprising alkanol and an aqueous phase comprising water, the organic phase is essentially completely returned to the rectification unit (III), 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: 1,4-Dibenzothiazine-comprising crude acrylic acid is purified by crystallization by raising its diacrylic acid content to at least 1% by weight prior to the crystallization step.

Abstract: A process for the separation by rectification of (meth)acrylic acid from a mixture containing (meth)acrylic acid and an inert hydrophobic organic liquid having a boiling point higher than that of (meth)acrylic acid as main constituents and also lower aldehydes as secondary constituents, a primary amine and/or a salt thereof are added.

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 for preparing .omega.-hydroxyesters of .alpha.,.beta.-unsaturated carboxylic acids, a vinyloxy ester of the carboxylic acid is treated with a strong acid in the presence of an alcohol, in particular a 1,2-diol or 1,3-diol.

Abstract: In a process for esterifying (meth)acrylic acid with an alkanol in the presence of an acidic esterification catalyst, in which unconverted starting compounds and the (meth)acrylates to be formed are separated off by distillation and an oxyester-containing bottom product is formed, the bottom product is separated off and is heated in the presence of an acid to 150-250.degree. C. and the pressure is adjusted so that the cleavage products formed under the abovementioned conditions from the oxyesters contained in the bottom product evaporate directly. The process can be carried out in the presence of molecular oxygen. Mineral acids, for example sulfuric acid or phosphoric acid and/or alkanesulfonic or arylsulfonic acids, for example methanesulfonic acid or p-toluenesulfonic acid, can be added to the bottom product.

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: In a process for esterifying (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, the bottom product is first separated off, the oxyesters contained therein are then separated off by distillation and the resulting distillate is cleaved in the presence of acids at elevated temperatures. The process can be carried out in the presence of molecular oxygen. The distillate is cleaved at from 170.degree. to 250.degree. C., preferably from 180.degree. to 230.degree. C.

Abstract: A diester of (meth)acrylic acid with a C.sub.4 -C.sub.6 -alkanediol is separated from a mixture which essentially consists of the C.sub.4 -C.sub.6 -alkanediol, the monoester of (meth)acrylic acid with the C.sub.4 -C.sub.6 -alkanediol and the diester of (meth)acrylic acid with the C.sub.4 -C.sub.6 -alkanediol by extraction with an organic solvent in the presence of water, by a process in which the diester-containing mixture is added continuously in the middle section of an extraction column and in addition water and the organic extracting agent are passed continuously countercurrent in the extraction column.

Abstract: A process for the fractional separation of (meth)acrylic acid from a mixture containing (meth)acrylic acid, in which (meth)acrylic acid is tapped off from the rectifying column at a point above the level at which the liquid mixture containing (meth)acrylic acid enters the rectifying column, and at at least one point of the rectifying column the reflux liquid descending therein is tapped off from the rectifying column, oligomerized and/or polymerized (meth)acrylic acid present therein is separated and the reflux liquid is subsequently recycled to the rectifying column.

Abstract: 1,4-butanediol mono(meth)acrylate is prepared by esterification of (meth)acrylic acid with 1,4-butanediol, by a process in which an aqueous solution of unconverted 1,4-butanediol is obtained, wherein the 1,4-butanediol present in the aqueous solution is converted into readily volatile tetrahydrofuran in the presence of a catalytic amount of a strong acid and the tetrahydrofuran is separated off from the aqueous solution.

Abstract: A process for the separation of a mono(meth)acrylate of a C.sub.4 -C.sub.6 alkanediol from an aqueous solution containing a mono(meth)acrylate of a C.sub.4 -C.sub.6 alkanediol and the said C.sub.4 -C.sub.6 alkanediol, by extraction with an organic solvent, in which the extracting agent used is an organic solvent selected from the group comprising esters of C.sub.1 -C.sub.4 alkanecarboxylic acids and C.sub.1 -C.sub.5 alkanols, single and mixed dialkyl ethers having from 4 to 8 C atoms, and mixtures of such organic solvents.

Abstract: An expandable styrene polymer comprisinga) from 0 to 90% by weight of a styrene polymer or styrene copolymer other than b) contains at least 50% by weight of copolymerized styrene,b) from 10 to 100% by weight of a styrene/methacrylamide copolymer comprising from 0.5 to 50% by weight of at least one copolymerized N-substituted methacrylamide of the formula I ##STR1## where R.sup.1 and R.sup.2 are identical or different and are hydrogen, C.sub.1 - to C.sub.15 -alkyl, C.sub.6 - to C.sub.16 -cycloalkyl or C.sub.6 - to C.sub.20 -aryl, it being possible, if R.sup.1 and R.sup.2 contain at least 2 carbon atoms, for at least 2 carbon atoms to be linked via hetero atoms, andc) from 1 to 15% by weight, based on the sum of a) and b), of an aliphatic C.sub.3 - to C.sub.9 -hydrocarbon and/or carbon dioxide as blowing agent.

Abstract: In a process for purifying crude (meth)acrylic acid, the crude (meth)acrylic acid is worked up by distillation after addition of an organic carboxylic acid hydrazide and, if desired, an organic sulfonic acid.

Abstract: An expandable styrene polymer comprisinga) from 0 to 90% by weight of a styrene polymer or styrene copolymer other than b) contains at least 50% by weight of copolymerized styrene,b) from 10 to 100% by weight of a styrene/methacrylamide copolymer comprising from 0.5 to 50% by weight of at least one copolymerized N-substituted methacrylamide of the formula I ##STR1## where R.sup.1 and R.sup.2 are identical or different and are hydrogen, C.sub.1 - to C.sub.15 -alkyl, C.sub.6 - to C.sub.16 -cycloalkyl or C.sub.6 - to C.sub.20 -aryl, it being possible, if R.sup.1 and R.sup.2 contain at least 2 carbon atoms, for at least 2 carbon atoms to be linked via hetero atoms, andc) from 1 to 15% by weight, based on the sum of a) and b), of an aliphatic C.sub.3 - to C.sub.9 -hydrocarbon and/or carbon dioxide as blowing agent.

Abstract: Monoethylenically unsaturated carboxylates are prepared by a process in which, following esterification,a) the product mixture is extracted in a first extraction stage with from 5 to 30% v/v of water, based on the product mixture, at a temperature of from 10.degree. to 40.degree. C., andb) the aqueous phase from the first extraction stage is extracted, in a second extraction stage, with from one to four times its weight of the alkanol to be esterified, at a temperature of from 10.degree. to 30.degree. C.

Abstract: Materials which are cross-linkable by ultraviolet radiation under atmospheric oxygen and are based on (meth)acrylate copolymers having a K value of from 10 to 100 are obtained by free radical polymerization, in the presence or absence of a solvent, ofa) from 5% to 97.4% by weight of isoamyl acrylate and/or isoamyl methacrylate,b) from 9% to 89.9% by weight of (methacrylates whose homopolymers have a glass transition temperature below -30.degree. C.,c) from 2.5% to 30% by weight of .alpha.,.beta.-monoolefinically unsaturated compounds whose homopolymers have a glass transition temperature above -30.degree. C.,d) from 0% to 10% by weight of monoolefinically unsaturated acids and/or their anhydrides ande) from 0% to 20% by weight of further olefinically unsaturated monomers having one or more of the following functional groups: hydroxyl, amide, epoxide, ether, ester, urethane, urea, primary, secondary and tertiary amine and ether groups, andf) from 0.

Abstract: Acrylates or methacrylates I ##STR1## (A and B=C.sub.2 -C.sub.5 -alkylene, R.sup.1 =H, CH.sub.3) are prepared by reacting an acrylate or methacrylate II ##STR2## (R.sup.2 =C.sub.1 -C.sub.4 -alkyl) with a heterocycle III ##STR3## in the presence of titanium alcoholates chelate compounds of the metals titanium, zirconium, iron and zinc with 1,3-dicarbonyl compounds.

Abstract: Alkyl esters of .alpha.,.beta.-monoolefinically unsaturated monocarboxylic acids are prepared by esterifying the monocarboxylic acid with an alcohol of 6 to 20 carbon atoms in the presence of from 0.1 to 5% by weight, based on the reaction mixture, of a strong acid and in the presence of a polymerization inhibitor and an oxygen-containing gas, at from 80.degree. to 150.degree. C., by a process in which the molar ratio of the monocarboxylic acid to the alcohol is from 1:0.8 to 1:1.2, and the water of reaction is separated off from the reaction mixture while passing an inert gas containing from 1 to 20% by volume of oxygen through the reaction mixture.