Abstract: A continuous process can be used for preparing methacrylic acid by catalytic hydrolysis of methyl methacrylate that has been prepared proceeding from C-2, C-3, or C-4 raw materials. In this process, methyl methacrylate of high purity is reacted with water in the presence of a Brønsted catalyst to give a reaction mixture containing the reactants and products and worked up in a distillation column. In the distillation column, a condensate containing an azeotrope of MMA with methanol is produced at the top, a vapour condensate containing methacrylic acid of high purity is produced in the middle part of the column, and a substance mixture containing high-boiling by-products and a small amount of methacrylic acid is obtained in the bottom of the column.

Abstract: The invention relates to a process for distillative removal of a unsaturated carboxylic anhydride of the general formula (I) R—C(O)—O—C—(O)—R in which R is an unsaturated organic radical having 2 to 12 carbon atoms, wherein said unsaturated carboxylic anhydride is discharged in gaseous form from a sidestream take-off and is condensed in an atomized liquid circulating stream of said unsaturated carboxylic anhydride.

Abstract: A process for continuous dissolution of a solid in a reaction medium includes: (a) providing a liquid by withdrawal of a portion of the reaction medium from a first reaction vessel; (b) contacting the liquid provided in (a) with the solid in a second reaction vessel to form a solution of the solid; and (c) recycling the solution formed in step b) into the first reaction vessel. The solid in the second reaction vessel is present in the form of a fixed bed which is traversed by the liquid.

Abstract: A process for continuous dissolution of a solid in a reaction medium includes: (a) providing a liquid by withdrawal of a portion of the reaction medium from a first reaction vessel; (b) contacting the liquid provided in (a) with the solid in a second reaction vessel to form a solution of the solid; and (c) recycling the solution formed in step b) into the first reaction vessel. The solid in the second reaction vessel is present in the form of a fixed bed which is traversed by the liquid.

Abstract: The invention relates to a process for preparing N-alkyl(meth)acrylamides by reacting (meth)acrylic anhydride with corresponding alkylamines.

Abstract: The present invention relates to a process for purifying monomers, by evaporating at least a portion of the monomers present in a starting composition and then condensing it, which is characterized in that at least a portion of the starting composition is evaporated in a short-path evaporator, the mass flow density of the vapors {dot over (m)} being selected according to the relation (I) m . ? 1800 ? kg · K mbar · m 2 · h · kg kmol · p i · ( M ~ T ) 0.5 ( I ) in which {tilde over (M)} is the average molar mass of the vapors in the short-path evaporator in kg/kmol T is the temperature of the vapors in K pi is the pressure in the short-path evaporator in mbar {dot over (m)} is the mass flow density of the vapors in kg/(m2·h). A further aspect of the present invention is a plant for performing the process.

Abstract: The invention relates to a process for preparing N-alkyl(meth)acrylamides by reacting (meth)acrylic anhydride with corresponding alkylamines.

Abstract: The present invention relates to a process for preparing methacrylic acid based on the hydrolysis of methacrylic esters.

Abstract: The invention relates to a process for continuously preparing N-alkyl(meth)acrylamides by reacting alkyl(meth)acrylates with high-boiling amines. A catalyst activation and specific workup technique achieve product qualities which have not been achieved to date. In addition, very high space-time yields and overall yields can be achieved.

Abstract: The present invention relates to a process for preparing methacrylic acid based on the hydrolysis of methacrylic esters.

Abstract: Process for distillatively purifying polymerizable compounds using a high-boiling, inert, thermally long-term-stable substance as a boiling oil, characterized in that the boiling oil is disposed in the bottom of a rectification column.

Abstract: The present invention relates to a process for purifying monomers, by evaporating at least a portion of the monomers present in a starting composition and then condensing it, which is characterized in that at least a portion of the starting composition is evaporated in a short-path evaporator, the mass flow density of the vapours {dot over (m)} being selected according to the relation (I) m . ? 1800 ? kg · K mbar · m 2 · h · kg kmol · p i · ( M ~ T ) 0.5 ( I ) in which {tilde over (M)} is the average molar mass of the vapours in the short-path evaporator in kg/kmol T is the temperature of the vapours in K pi is the pressure in the short-path evaporator in mbar {dot over (m)} is the mass flow density of the vapours in kg/(m2·h). A further aspect of the present invention is a plant for performing the process.

Abstract: Process for continuously preparing unsaturated carboxylic anhydrides of the general formula I R—C(O)—O—C(O)—R??(I) in which R is an unsaturated organic radical having 2 to 12 carbon atoms by transanhydridization of an aliphatic carboxylic anhydride with a carboxylic acid of the general formula II R—COOH??(II) in which R is as defined above in a rectification column having an upper, middle and lower region, characterized in that f) an inert boiling oil is initially charged in the bottom of the column, g) the reactants are fed into a reaction region in stoichiometric ratios, h) the carboxylic acid formed as the by-product is withdrawn at the top of the column, i) the unconverted reactants are recycled into the reaction region and j) the product of the formula I is obtained via a side draw, preferably between the middle and lower column region.

Abstract: The invention relates to a process for continuously preparing N-alkyl(meth)acrylamides by reacting alkyl (meth)acrylates with high-boiling amines. A catalyst activation and specific workup technique achieve product qualities which have not been achieved to date. In addition, very high space-time yields and overall yields can be achieved.

Abstract: The present invention relates to a composition which comprises at least one hydroxyalkyl(meth)acrylate and has been stabilized for a purification, which comprises hydroquinone monomethyl ether and 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxyl. The present invention additionally describes processes for purifying and for preparing hydroxyalkyl(meth)acrylates. A further aspect of the present invention is a composition which is obtainable by the processes mentioned.

Abstract: The invention relates to a method for the continuous production of unsaturated carboxylic acid anhydrides of general formula (I): R—C(O)—O—C(O)—R (I), wherein R is an unsaturated organic group with 2 to 12 C atoms, by reaction of a ketene with an unsaturated carboxylic acid of general formula (II): R—COOH (II), wherein R is defined as above, in an apparatus which has a reaction zone (1) for the reaction of a ketene with an unsaturated carboxylic acid of general formula (II), and a reaction zone (2) for the subsequent reaction of the crude anhydride mixture and a rectification column with an upper, a middle and a lower zone, in the sump of which an inert boiling oil is present.

Abstract: The invention provides an improved process for preparing unsaturated carboxylic anhydrides of the general formula I R—C(O)—O—C(O)—R??(I) in which R is an unsaturated organic radical having 2 to 12 carbon atoms by transanhydridizing an aliphatic carboxylic anhydride with a carboxylic acid of the general formula II R—COOH??(II) in which R is as defined above, in an apparatus consisting of a reaction region and a rectification column, characterized in that a) the reactants are fed into a reaction region in stoichiometric ratios, b) the carboxylic acid formed as a by-product is removed from the reaction mixture, c) the carboxylic anhydride of the formula I is subsequently drawn off, d) the unconverted reactants are recycled into the reaction region, e) the reaction region comprises a heterogeneous catalyst and f) one or more polymerization inhibitors are added.

Abstract: Process for continuously preparing unsaturated carboxylic anhydrides of the general formula I R—C(O)—O—C(O)—R??(I) in which R is an unsaturated organic radical having 2 to 12 carbon atoms by transanhydridization of an aliphatic carboxylic anhydride with a carboxylic acid of the general formula II R—COOH??(II) in which R is as defined above in a rectification column having an upper, middle and lower region, characterized in that f) an inert boiling oil is initially charged in the bottom of the column, g) the reactants are fed into a reaction region in stoichiometric ratios, h) the carboxylic acid formed as the by-product is withdrawn at the top of the column, i) the unconverted reactants are recycled into the reaction region and j) the product of the formula I is obtained via a side draw, preferably between the middle and lower column region.

Abstract: Process for distillatively purifying polymerizable compounds using a high-boiling, inert, thermally long-term-stable substance as a boiling oil, characterized in that the boiling oil is disposed in the bottom of a rectification column.

Abstract: The invention relates to a method for the continuous production of unsaturated carboxylic acid anhydrides of general formula (I): R—C(O)—O—C(O)—R (I), wherein R is an unsaturated organic group with 2 to 12 C atoms, by reaction of a ketene with an unsaturated carboxylic acid of general formula (II): R—COOH (II), wherein R is defined as above, in an apparatus which has a reaction zone (1) for the reaction of a ketene with an unsaturated carboxylic acid of general formula (II), and a reaction zone (2) for the subsequent reaction of the crude anhydride mixture and a rectification column with an upper, a middle and a lower zone, in the sump of which an inert boiling oil is present.