Abstract: The invention relates to a method for the separation of ascorbic acid from a mixture containing ascorbic acid and 2-keto-L-gulonic acid in a polar, preferably aqueous solvent, by means of liquid/liquid extraction using an amide. The method preferably also comprises steps for the back-extraction of the ascorbic acid, recycling of the extraction solvent and/or the back extraction solvent and for isolation of the ascorbic acid from the back extraction solvent. The invention further relates to a method for the production of ascorbic acid from KGA and isolation of the ascorbic acid so produced.

Abstract: A method for the production of C1-C10-alkyl 2-keto-L-gulonates by esterification of 2-keto-L-gulonic acid anhydrate with an anhydrous C1-C10-alkyl alcohol in the presence of an acidic homogeneous catalyst in a reactor cascade comprising at least two reactors, one of these reactors being a tubular reactor, without the water forming in the esterification being removed from the reaction space.

Abstract: The invention relates to a method for producing 2-keto-L-gulonic acid-C4–C10 alkyl ester by esterifying 2-keto-L-gulonic acid (KGS) with an unsaturated, branched or unbranched C4–C10 alcohol. The inventive method is characterized by the fact that an aqueous KGS solution is reacted with a C4–C10 alcohol up to an esterification degree of 20 to 70 percent in a pre-esterification process carried out under acidic catalysis conditions; and the obtained product is dehydrogenated with an unsaturated, branched or unbranched C4–C10 alcohol in a continuous rectification device, whereby the esterification reaction continues, n-butanol preferably being used as the alkyl alcohol. In a preferred embodiment, the aqueous KGS solution is concentrated up to or beyond the limit of solubility prior to the esterification process, preferably by catalyzing a homogeneous or heterogeneous catalyst, especially sulfonic acid, at temperatures of 50 to 120° C.

Abstract: In a process for the single-stage preparation of polytetrahydrofuran and/or tetrahydrofuran copolymers having a mean molecular weight of from 650 to 5000 dalton by polymerization of tetrahydrofuran over an acid catalyst in the presence of at least one telogen and/or comonomer, the telogen and/or comonomer is added at at least two addition points in different segments of the polymerization apparatus.

Abstract: The present invention relates to a process for extracting 2-keto-L-gulonic acid (KGA) from a polar, preferably aqueous, solvent, preferably from a solvent which comprises a mixture of ascorbic acid and 2-keto-L-gulonic acid, by means of liquid/liquid extraction using an extractant which comprises a tertiary amine and a polar organic diluent. The process of the invention preferably also comprises steps for back-extraction of the KGA and recycling of the extractant. The present invention likewise relates to a process for preparing ascorbic acid from KGA and isolating the prepared ascorbic acid.

Abstract: The invention relates to a method for producing 2-keto-L-gulonic acid-C4-C10 alkyl ester by esterifying 2-keto-L-gulonic acid (KGS) with an unsaturated, branched or unbranched C4-C10 alcohol. The inventive method is characterized by the fact that an aqueous KGS solution is reacted with a C4-C10 alcohol up to an esterification degree of 20 to 70 percent in a pre-esterification process carried out under acidic catalysis conditions; and the obtained product is dehydrogenated with an unsaturated, branched or unbranched C4-C10 alcohol in a continuous rectification device, whereby the esterification reaction continues, n-butanol preferably being used as the alkyl alcohol. In a preferred embodiment, the aqueous KGS solution is concentrated up to or beyond the limit of solubility prior to the esterification process, preferably by catalyzing a homogeneous or heterogeneous catalyst, especially sulfonic acid, at temperatures of 50 to 120 ° C.

Abstract: The invention relates to a method for the separation of ascorbic acid from a mixture containing ascorbic acid and 2-keto-L-gulonic acid in a polar, preferably aqueous solvent, by means of liquid/liquid extraction using an amide. The method preferably also comprises steps for the back-extraction of the ascorbic acid, recycling of the extraction solvent and/or the back extraction solvent and for isolation of the ascorbic acid from the back extraction solvent. The invention further relates to a method for the production of ascorbic acid from KGA and isolation of the ascorbic acid so produced.

Abstract: A process for the isolation of salts of organic acids from an aqeuous solution, in particular from a fermentation discharge, by partial evaporative crystallization and subsequent or simultaneous displacement precipitation of its salts, and for the liberation of the organic acid from the crystals, preferably by means of an electromembrane process, is described.

Abstract: In a process for the single-stage preparation of polytetrahydrofuran and/or tetrahydrofuran copolymers having a mean molecular weight of from 650 to 5000 dalton by polymerization of tetrahydrofuran over an acid catalyst in the presence of at least one telogen and/or comonomer, the telogen and/or comonomer is added at at least two addition points in different segments of the polymerization apparatus.

Abstract: A process for the single-stage preparation of polytetrahydrofuran and/or tetrahydrofuran copolymers having a mean molecular weight of from 650 to 5000 dalton by polymerization of tetrahydrofuran over a heterogeneous acid catalyst in the presence of at least one telogen and/or comonomer selected from the group consisting of alpha,omega-diols, water, polytetrahydrofuran having a molecular weight of from 200 to 700 dalton and cyclic ethers comprises a) separating off the catalyst and/or downstream products of the catalyst suspended and/or dissolved in the output from the polymerization, b) fractionating the resulting catalyst-free output from the polymerization in at least one distillation step to give a distillation residue comprising the polymerization product and at least one tetrahydrofuran fraction and returning at least part of the tetrahydrofuran fraction to the polymerization and c) separating low molecular weight polytetrahydrofuran and/or tetrahydrofuran copolymers having a mean molecular weight of

Abstract: The invention provides a microstructured, self-cleaning, catalytically active surface with elevations and depressions, comprising a catalytically active material in the depressions.

Abstract: A process for the single-stage preparation of polytetrahydrofuran and/or tetrahydrofuran copolymers having a mean molecular weight of from 650 to 5000 dalton by polymerization of tetrahydrofuran over a heterogeneous acid catalyst in the presence of at least one telogen and/or comonomer selected from the group consisting of alpha,omega-diols, water, polytetrahydrofuran having a molecular weight of from 200 to 700 dalton and cyclic ethers comprises

Abstract: The invention provides an evaporator having a heatable heat exchange surface, which has a self-cleaning microstructured surface with elevations and depressions.

Abstract: A process for the thermal treatment of incombustible liquids in a combustion space of a combustion apparatus by contacting the incombustible liquid with a supplementary fuel in the combustion space in the presence of at least one reactive gas. The process of the invention comprises feeding the incombustible liquid and the supplementary fuel into the combustion space (1) at different points, mixing the incombustible liquid with at least one reactive gas and the supplementary fuel with at least one inert gas prior to the contacting, and vaporizing the incombustible liquid and supplementary fuel prior to the contacting in the combustion space. The advantage of this invention is that environmentally harmful waste waters in particular are disposed of by burning these using a supplementary fuel. The required amounts of supplementary fuel are minimal in the process and only small amounts of nitrogen oxides, carbon monoxide and soot are generated.

Abstract: In a process for the preparation of crystalline N-methylol(meth)acrylamide from (meth)acryamide and paraformaldehyde, the reaction of the solid reactants to give a product melt and the subsequent crystallization thereof in a reactor while subjecting the reaction mixture to mechanical shear load is preferably carried out in a self-purging screw reactor or a disk reactor. The reaction of the reactants and the crystallization of the product melt are preferably carried out without added solvent. A catalyst, in particular an alkali metal carbonate or a trialkylamine, can be used for the reaction of the reactants.