摘要:
In a process for preparing water-absorbent resins based on acrylic acid, crude acrylic acid is firstly isolated from the reaction gases from the catalytic gas-phase oxidation of propane, propylene and/or acrolein. This is treated with an aldehyde scavenger and pure acrylic acid is separated by distillation from the treated crude acrylic acid, and this pure acrylic acid can be subjected directly to a free-radical polymerization.
摘要:
A process prepares an aqueous alkali metal acrylate solution by distillatively removing acrylic acid from a mixture as vapors and taking up the vapors immediately from the gas phase into an aqueous alkali solution.
摘要:
A process prepares an aqueous alkali metal acrylate solution by distillatively removing acrylic acid from a mixture as vapors and taking up the vapors immediately from the gas phase into an aqueous alkali solution.
摘要:
A process for preparing caprolactam by reacting 6-aminocapronitrile with water in the presence of catalysts comprises using a starting mixture of 6-aminocapronitrile and the tetrahydroazepine derivative of the formula and conducting the reaction in liquid phase in the presence of a heterogeneous catalyst. Also describes a process for preparing said tetrahydroazepine derivative I and its use for preparing caprolactam and polycaprolactam.
摘要:
In a process for producing polyamides by polymerization of lactams in the presence of metal oxides as heterogeneous catalysts, the metal oxides are used in a form which permits mechanical removal from the reaction mixture and are removed from the reaction mixture in the course of or on completion of the polymerization.
摘要:
Crude capronitrile is purified by hydrogenation, subsequent treatment in an acidic medium and subsequent distillation in an alkaline medium, by a process in which(a) 6-aminocapronitrile is converted into crude caprolactam by reaction with water,(b) high boilers and low boilers are separated off from the crude caprolactam from step (a),(c) the crude caprolactam from step (b) is treated with hydrogen at from 50.degree. to 150.degree. C. and from 1.5 to 250 bar in the presence of a hydrogenation catalyst and, if desired, of a solvent to give a mixture A,(d1) mixture A in a solvent is passed, at from 30.degree. to 80.degree. C. and from 1 to 5 bar, over an ion exchanger containing terminal acid groups to give a mixture B1, or(d2) mixture A is distilled in the presence of sulfuric acid, any solvent present being removed before the addition of the sulfuric acid, to give a mixture B2, and(e) mixture B1 or mixture B2 is distilled in the presence of a base to give pure caprolactam.
摘要:
A process for preparing a secondary or tertiary 2-methyl-1,5-pen-tanediamine of the formula I where R1 and R2 are H, C1-C20-alkyl, C3-C8-cycloalkyl, aryl, C7-C20-arylalkyl, where the radicals R1 and R2 may bear substituents selected from the group consisting of C1-C20-alkyl, C1-C20-alkoxy, C6-C20-aryloxy and hydroxy, and R1 and R2 are not simultaneously hydrogen, or R1 and R2 are together an unsubstituted or C1-C20-alkyl- and/or C1-C20-alkoxy-substituted C3-C7-alkylene chain which may, if desired, be interrupted by one or two O or NR3 groups, where R3 is H or C1-C20-alkyl comprises reacting 2-methylglutarodinitrile with a primary or secondary amine of the formula R1R2NH and hydrogen at from 50 to 250° C. and pressures of from 0.5 to 35 MPa in the presence of an oxidic supported catalyst comprising one or more noble metals which has been treated with hydrogen at from 50 to 300° C. for at least 0.5 hour before use. The compound 1,5-bis(dimethylamino)-2-methylpentane is also claimed.
摘要:
A process for hydrogenating a compound in the group of the imines or enamines I to an amine II in the presence of a nitrile III, said nitrile III being essentially not hydrogenated comprises reacting a mixture comprising a compound I and a nitrile III with a gas comprising molecular hydrogen in the presence of a catalyst IV.
摘要:
Cyclic lactams are prepared by reacting an aminocarboxylic acid compound of the formula IH.sub.2 N--(CH.sub.2).sub.m --COR.sup.1 Iwhere R.sup.1 is --OH, --O--C.sub.1 -C.sub.12 -alkyl or --NR.sup.2 R.sup.3 and R.sup.2 and R.sup.3, independently of one another, are each hydrogen, C.sub.1 -C.sub.12 -alkyl or C.sub.5 -C.sub.8 -cycloalkyl and m is an integer from 3 to 12, with water by a process in which the reaction is carried out in the liquid phase using a heterogeneous catalyst.