Abstract:
A process for preparing cyclohexanol from benzene by a) preparing cyclohexene by hydrogenating benzene in the presence of a catalyst and b) preparing cyclohexanol by hydrating the cyclohexene in the presence of a catalyst, comprises carrying out steps a) and b) in a reaction facility which has a bottom region at the lower end, a top region at the upper end and a reaction zone between the top region and the bottom region which contains the catalyst according to steps a) and b), evaporating a portion of the benzene using the heat of reaction in the reaction zone, condensing it in the top region and returning it to the reaction zone, and withdrawing a reaction mixture containing cyclohexanol in the bottom region.
Abstract:
A process for distillative removal of 6-aminocapronitrile from mixtures (I) comprising 6-aminocapronitrile and an imine (II) comprises conducting the distillation in the presence of carbon dioxide.
Abstract:
The invention relates to a process for reducing the dimerization of piperidines of the formula I ##STR1## where R.sup.1 to R.sup.4 are C.sub.1 - to C.sub.6 -alkyl, R.sup.1 and R.sup.2 and/or R.sup.3 and R.sup.4 together are a CH.sub.2 chain having 2 to 5 carbon atoms, which comprises adding to the piperidine from 0.001 to 0.2% by weight of a reducing agent of the formula MXH.sub.4-m Y.sub.m, where M is an alkali metal, NR.sub.4, where R are identical or different C.sub.1 -C.sub.4 -alkyl groups, or an equivalent of an alkaline earth metal or an equivalent of zinc, X is boron or aluminum, Y is H or CN and m is 0 or 1. The invention also relates to a mixture of piperidines of the formula I, from 0.001 to 0.2% by weight of a reducing agent and from 1 to 1000 ppm of dimers of the piperidines of the formula I, and to the preparation of hindered amine light stabilizers therefrom.
Abstract:
1,6-Hexanediol is prepared from a carboxylic acid mixture comprising adipic acid, 6-hydroxycaproic acid and small amounts of 1,4-cyclohexanediols which is obtained as a by-product in the oxidation of cyclohexane to cyclohexanone/cyclohexanol by water extraction of the reaction mixture, by esterification of the acids and hydrogenation whereina) the monocarboxylic and dicarboxylic acids present in the aqueous dicarboxylic acid mixture are reacted with a low molecular weight alcohol to give the corresponding carboxylic esters,b) the resulting esterification mixture is freed of excess alcohol and low boilers in a first distillation stage,c) the bottoms are fractionated in a second distillation stage to give an ester fraction essentially free of 1,4-cyclohexanediols and a fraction comprising at least the major part of the 1,4-cyclohexanediols,d) the ester fraction essentially free of 1,4-cyclohexanediols is catalytically hydrogenated ande) in a pure distillation stage, 1,6-hexanediol is isolated from the hydrogenation product in a manner known per se.
Abstract:
Vinyl formate containing formic acid, acetaldehyde and water following synthesis is separated from formic acid and water in a first distillation stage and from acetaldehyde in a second stage to give pure vinyl formate.
Abstract:
A process for the separation of 1,4-butanediol from mixtures obtained by the catalytic hydrogenation of maleates, fumarates, and/or succinates, which also contain tetrahydrofuran, water, C.sub.1 -C.sub.4 alcohols, succinic diesters, hydroxybutyrates, alkylhydroxyalkyl succinates, gamma-butyrolactone and butyrates, in addition to 1,4-butanediol, comprising the following steps:a) separating, in a first column having an actual number of plates of from 20 to 70 and operated at a top pressure of from 50 to 1100 mbar and preferably from 50 to 500 mbar and a top temperature of from 40.degree. to 120.degree. C., alcohol, water and tetrahydrofuran, as overhead product,b) feeding the bottom product of the first column into a second column having an actual number of plates of from 30 to 90 and withdrawing the overhead product consisting of alcohol and butyrate and obtained at a top pressure of from 45 to 250 mbar and a top temperature of from 45.degree. to 120.degree. C., and withdrawing gamma-butyrolactone and butyrates through a side outlet, and feeding the bottom product to a phase separator,c) feeding the 1,4-butanediol-enriched bottom phase of the liquid two-phase mixture coming from the phase separator to a third column having an actual number of plates of from 30 to 90, alcohol being distilled off as overhead product at a top pressure of from 45 to 250 mbar and a top temperature of from 45.degree. to 120.degree. C., and the azeotrope comprising 1,4 -butanediol and succinic diester is withdrawn as a sidestream and recycled to the phase separator, whilst 1,4-butanediol is removed together with alkyl-hydroxyalkyl succinate, butyl hydroxybutyrate, and high-boiling fractions as bottoms, andd) separating the succinate-enriched top phase in the phase separator.
Abstract:
A planetary roller extruder with planetary spindles and stop ring. The abstract of the disclosure is submitted herewith as required by 37 C.F.R. § 1.72(b). As stated in 37 C.F.R. § 1.72(b): A brief abstract of the technical disclosure in the specification must commence on a separate sheet, preferably following the claims, under the heading “Abstract of the Disclosure.” The purpose of the abstract is to enable the Patent and Trademark Office and the public generally to determine quickly from a cursory inspection the nature and gist of the technical disclosure. The abstract shall not be used for interpreting the scope of the claims. Therefore, any statements made relating to the abstract are not intended to limit the claims in any manner and should not be interpreted as limiting the claims in any manner.
Abstract:
The invention relates to a process for purifying an ionic liquid, which comprises the steps (a) partial crystallization of the ionic liquid from its melt and (b) separation of the crystals from the residual melt.
Abstract:
The present invention relates to a process for purifying a composition (I) comprising at least one cyclic ketone having from 7 to 16 carbon atoms, which comprises thermal treatment of the composition (I) with a catalyst comprising at least one transition metal and further purification by means of a process selected from the group consisting of distillation, extraction and crystallization. Furthermore, the present invention relates to a process for preparing cyclododecanone, which comprises such a purification, and the use of at least one catalyst comprising at least one transition metal for purifying a composition (I) comprising at least one cyclic ketone having from 7 to 16 carbon atoms by thermal treatment of the composition (I) with a catalyst comprising at least one transition metal.
Abstract:
The present application relates to a process for reacting a composition I comprising at least one aldehyde with hydrogen in the presence of a catalyst in at least one main reactor and at least one postreactor, wherein at least 50% of the fresh hydrogen fed to the reaction system is fed into at least one postreactor. In a preferred embodiment, composition I comprises at least one further organic compound.