摘要:
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 from 200 to 700 dalton from the distillation residue from work-up step b) and isolating polytetrahydrofuran and/or tetrahydrofuran copolymers having a mean molecular weight of from 650 to 5000 dalton.
摘要:
A process is provided for the preparation of cyclic lactams of formula (II): in which n and m can each have the values 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 and the sum of n+m is at least 3, preferably at least 4, and R1 and R2 are C1-C6-alkyl, C5-C7-cycloalkyl or C6-C12-aryl groups, by reacting a compound (I) of the formula in which R1, R2, m and n are as defined above and R are [sic] nitrile, carboxamide and carboxylic acid groups, with steam in the gas phase.
摘要:
A process is provided for the preparation of caprolactam from a compound of formula (I): NC—(CH2)5—CO—R (I) in which R is a carboxamide, carboxylic acid or carboxylic acid ester group, wherein a) a compound (I) or a mixture of such compounds, in the presence of ammonia and optionally a liquid diluent (VI), is hydrogenated with hydrogen in the presence of a catalyst (II) to give a mixture (III), b) the hydrogen and the catalyst (II) are separated from the mixture (III) to give a mixture (IV), and c) the mixture (IV), optionally in the presence of a liquid diluent (VII), is converted to caprolactam in the presence of a catalyst (V).
摘要:
A process for the coproduction of 6-aminocapronitrile (ACN) and hexamethylenediamine (HMD) by treatment of adiponitrile (ADN) with hydrogen in the presence of a nickel-containing catalyst at temperatures not below room temperature and elevated hydrogen partial pressure in the presence or absence of a solvent comprises, after the conversion based on ADN and/or the selectivity based on ACN has or have dropped below a defined value (a) interrupting the treatment of ADN with hydrogen by stopping the feed of ADN and of the solvent, if used, (b) treating the catalyst at from 150.degree. to 400.degree. C. with hydrogen using a hydrogen pressure within the range from 0.1 to 30 MPa and a treatment time within the range from 2 to 48 h, and (c) then continuing the hydrogenation of ADN with the treated catalyst of stage (b).
摘要:
The present invention relates to a process for preparing diols by hydrogenating a mixture comprising carboxylic acid, carboxylic anhydrides and/or carboxylic esters/lactones by means of a cobalt-comprising catalyst, wherein alkali metal and/or alkaline earth metal ions are added to the hydrogenation feed, excluding alkali metal and/or alkaline earth metal ions of mineral acids.
摘要:
The disclosure relates to a process for purifying crude caprolactam. The process involves converting a first mixture of 6-amino capronitrile and water to a second mixture of caprolactam ammonia, water, high boilers and low boilers using a catalyst. The ammonia is removed from the second mixture to obtain a third mixture. Water is removed from the third mixture to give crude caprolactam, high boiler and low boilers. Purified caprolactam is then obtained by a series of distillation steps.
摘要:
The invention relates to a process for preparing optically active 2-amino-, 2-chloro-, 2-hydroxy- or 2-alkoxy-1-alcohols by catalytically hydrogenating appropriate optically active 2-amino-, 2-chloro-, 2-hydroxy- and 2-alkoxycarboxylic acids or their acid derivatives in the presence of catalysts comprising palladium and rhenium or platinum and rhenium.
摘要:
The present invention provides a process for preparing 1,6-hexanediol having a purity of ≧99.5% by weight by catalytically dimerizing acrylic esters and catalytically hydrogenating the hexenedioic diesters obtained in this way to 1,6-hexanediol by a) dimerizing C1- to C8-acrylic esters in the presence of at least one rhodium compound to give mixtures of predominantly 2- and 3-hexenedioic diesters, b) hydrogenating the resulting dimerizing effluent in the presence of chromium-free catalysts comprising predominantly copper as the hydrogenation component and c) purifying the crude 1,6-hexanediol obtained in this way by fractional distillation.
摘要:
The invention relates to a method for removing, by distillation, 6-aminocapronitrile from mixtures that contain 6-aminocapronitrile, adipodinitrile and hexamethylenediamine, by a) removing the hexamethylenediamine from the mixture while obtaining a mixture (I) that has a hexamethylenediamine content of less than 1 wt. -%, b) removing completely or partially the 6-aminocapronitrile from mixture (I) while obtaining a mixture (II) whose content in substances that have a higher boiling point as 6-aminocapronitrile under distillation conditions and that cannot be formed by dimerization reactions when 6-aminocapronitrile is thermally treated is less than 1 wt. -%, and c) completely or partially removing from mixture (II) the hexamethylenediamine that might be present while obtaining a mixture (IV) whose hexamethylenediamine content is higher than that of mixture (II), and a mixture (V) whose hexamethylenediamine content is lower than that of mixture (II).
摘要:
A process is provided for the regeneration of a heterogeneous catalyst used for the preparation of compounds containing NH2 groups by the hydrogenation, with hydrogen, of compounds containing at least one unsaturated carbon-nitrogen bond, wherein a) the feed of the compound to be hydrogenated is stopped and b) the heterogeneous catalyst is treated with a compound of the formula R1R2N—CO—R3 (I), in which R1 is hydrogen or C1-C4 alkyl and R2, R3 independently of one another are each hydrogen or C1-C4 alkyl or together are a C3-C6 alkylene group, or mixtures of such compounds, at a pressure ranging from 0.1 to 30 MPa and a temperature ranging from 100 to 300° C., with the proviso that the compound of formula (I) is in liquid form during the treatment.