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: 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 supply system for feeding a fluid to a vessel (1) is described, which is provided with a feedline (10), having a reservoir which is filled with the fluid and a compressed-gas store (14) which can be brought into communication with this reservoir (13), in which system the reservoir (13) and the compressed-gas store (14) are arranged in immediate proximity to one another, and wherein the reservoir (13) can, when required, be brought into communication with the feedline (10) via connection pieces (11, 12).

Abstract: A method is described of stabilizing (meth)acrylic esters against unwanted free-radical polymerization, in which the mixture to be stabilized has added to it a polymerization inhibitor mixture comprising at least one nitroxyl radical and/or at least one organic compound having at least one nitroso group, and at least one p-phenylenediamine.

Abstract: Free radical polymerizations immediately terminated by a process comprising the addition of an inhibitor solution which contains phenothiazine and at least 50% (w/w) N-alkylpyrrolidone to a system undergoing free radical polymerization, wherein the inhibitor solution also contains p-methoxyphenol (MEHQ).

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 method of transporting and/or storing pure acrylic acid comprises ensuring by means of appropriate measures that the pure acrylic acid is partly crystalline during the entire duration of transport and/or storage.

Abstract: Plant parts which are used for the production or processing of (meth)acrylic esters are cleaned by

Abstract: A method of transporting and/or storing pure acrylic acid comprises ensuring by means of appropriate measures that the pure acrylic acid is partly crystalline during the entire duration of transport and/or storage.

Abstract: A process for preparing pure (meth)acrylic acid or a (meth)acrylate starting from a crude (meth)acrylic acid, which comprises the following stages: A: treating the crude (meth)acrylic acid with at least one compound which is able to remove aldehydes, to give an aldehyde-free crude (meth)acrylic acid; B: subjecting the aldehyde-free crude (meth)acrylic acid to imprecise distillation, to give a low-boiling fraction comprising (meth)acrylic acid and acetic acid and a high-boiling fraction comprising (meth)acrylic acid and high boilers; C: isolating a pure (meth)acrylic acid from the high-boiling fraction and, if desired, D: esterifying the low-boiling fraction comprising (meth)acrylic acid and acetic acid that is obtained in stage B by means of one or more alkanols, to give an esterification mixture comprising one or more (meth)acrylates, one or more acetic esters, and one or more alkanols.

Abstract: Pure acrylic acid is stored and/or transported by a process in which the pure acrylic acid is stored and/or transported as liquid aqueous solution at ≦15° C.

Abstract: A method for continuous production of (meth)acrylic alkyl esters by reacting (meth)acrylic acid with alkanols containing 1-8 C-atoms, whereby raw (meth)acrylic acid containing acetic acid is used as a starting compound and the alkyl acetate that is formed as a by-product is evacuated in an appropriate area.

Abstract: In a process for esterifying (meth)acrylic acid with an alkanol, oxy ester formed as a byproduct of the esterification is recleaved under acid catalysis with addition of monomeric and/or oligomeric (meth)acrylic acid and water.

Abstract: (Meth)acrylic esters are prepared by reacting (meth)acrylic acid with a C4-C12-alkanol in the presence of sulfuric acid or a mono-C4-C12-alkyl sulfate as catalyst, wherein a) the reaction is carried out in an esterification unit which comprises a first reactor and at least one further reactor, b) a mixture of (meth)acrylic acid, C4-C12-alkanol and catalyst which contains not more than 5% by weight of water, based on the sum of the starting materials, is introduced into the first reactor, c) the esterification in the first reactor is conducted without removing ester, alkanol or water to a (meth)acrylic acid conversion of at least 40%, but only so far that the mixture remains a single phase, and d) the esterification is continued in at least one further reactor with the water formed being removed by distillation.

Abstract: The disclosure is a process for preparing (meth)acrylic esters by reacting (meth)acrylic acid with C4-C6-alkanols in the presence of a strong inorganic acid or of a C4-C6-monoalkyl ester of a polybasic strong acid as catalyst, which comprises removing the unconverted alkanol from the resulting reaction mixture by distillation and thereafter removing the catalyst from the resulting mixture.

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 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 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.