摘要:
A process for preparing halogen-free, reactive polyisobutene having a terminal double bond content of more than 60 mol % and an average molecular weight Mn of 800-3000 dalton by cationic polymerization in the liquid phase of isobutene over an acidic, essentially halogen-free heterogeneous catalyst, where a) a hydrocarbon mixture of essentially C4-hydrocarbons comprising isobutene in an amount of from 10 to 80% by weight is used as the starting material and b) polymerization is carried out continuously at from −30 to 0° C. with average starting material residence times of one hour or less, where the temperature and the residence time are selected such that the isobutene conversion is less than 60% and, after separation from the resulting polyisobutene, the isobutene is either enriched in the partially converted hydrocarbon mixture and returned to the polymerization or passed to another isobutene reaction coupled with the polymerization.
摘要:
In a process for preparing alcohols by gas phase hydrogenation of carboxylic acids or esters thereof at elevated temperature and elevated pressure in the presence of catalysts consisting of or comprising, as hydrogenating components, oxides of main group VI and/or subgroup IV, the hydrogenation is carried outa) at from 250.degree. C. to 400.degree. C. and from 5 bar to 100 bar in the presence ofb) primary or secondary alcohols, the molar hydrogen/alcohol ratio being at most 800.
摘要:
A process for the separation by distillation of a mixture of 1,4-butanediol and at least one 4-hydroxybutyraldehyde, its cyclic hemiacetal and its cyclic full acetals with at least one further alcohol by carrying out the distillation in the presence of an alkaline compound. The mixture to be separated preferably contains a cyclic full acetal of 4-hydroxybutyraldehyde with a further alcohol which has a lower boiling point than butanediol and also the further alcohol in free form. The process is particularly suitable for the separation by distillation of mixtures formed in the hydrogenation of maleic acid derivatives.
摘要:
A process for preparing cyclopentanone and cyclopentene-1-carboxylic acid or an ester thereof of the formula I where R is hydrogen or an aliphatic radical having 1-6 carbon atoms or a cycloaliphatic, araliphatic or aromatic radical having 6-12 carbon atoms comprises heating a compound of the formula II X—(CH2)4—COOR II where X is formyl or hydroxymethyl and R is defined as above, and/or a compound which is converted into a compound of the formula II by reaction with water or alcohols ROH under the reaction conditions to from 200 to 450° C. in the gas or liquid phase in the presence of a heterogeneous oxidic catalyst.
摘要:
In a process for preparing THF (tetrahydrofuran) by reaction of a 1,4-butanediol-containing reaction mixture over an acid catalyst, the reaction mixture comprises further alcohols different from 1,4-butanediol and is essentially free of water.
摘要:
A process for preparing cyclopentanone by reacting adipic esters of the formula R1OOC—(CH2)4—COOR2 I where R1 and R2 are each alkyl having from 1 to 12 carbon atoms, cycloalkyl having 5 or 6 carbon atoms, aralkyl or aryl and R2 may additionally be hydrogen, in the presence of oxidic catalysts comprises reacting adipic esters of the formula I having less than 5% by weight of by-products other than adipic esters in the gas phase in the presence of water, a carrier gas and a) from 0.01 to 10% by weight of at least one metal oxide selected from the first or second main group of the periodic table or from the group of the rare earth metals on titanium dioxide or zirconium dioxide as catalyst support, or b) from 0.01 to 50% by weight of at least one metal oxide selected from the second main group of the periodic table on zink oxide as catalyst support.
摘要:
Optically active amines of the formula I where R1 and R2 are different and R1, R2, R3 are alkyl, cycloalkyl, arylalkyl, aryl, heteroaryl and heterocyclic radicals and R3 may also be hydrogen (H), with the radicals being able to bear substituents selected from the group consisting of alkyl, cycloalkyl, alkoxy, aryloxy, amino, alkylamino and dialkylamino, are racemized by reacting the optically active amine I in the presence of hydrogen and a hydrogenation or dehydrogenation catalyst at elevated temperature, wherein the catalyst comprises the active components copper and zinc oxide and a support material.
摘要:
A process for the hydrogenation of an organic compound containing at least one carbonyl group comprises bringing the organic compound in the presence of hydrogen into contact with a shaped body which can be produced by a process in which (i) an oxidic material comprising copper oxide, zinc oxide and aluminum oxide is made available, (ii) pulverulent metallic copper or pulverulent cement or a mixture thereof is added to the oxidic material, and (iii) the mixture resulting from (ii) is shaped to form a shaped body.
摘要:
The present invention provides a process for preparing 2-cyclopentenones of the general formula: where R1 to R4 are each hydrogen atoms or are alkyl or alkenyl radicals having from 1 to 12 carbon atoms, cycloalkyl or cycloalkenyl radicals having from 5 to 7 carbon atoms, aralkylene or aryl radicals, by converting hexenedioic acids and/or their esters of the general formulae where R1 to R4 are each as defined above and R5 and R6 are each hydrogen atoms or are alkyl radicals having from 1 to 12 carbon atoms, cycloalkyl radicals having 5 or 6 carbon atoms, aralkyl or aryl radicals, at temperatures of from 150 to 450° C., over solid, oxidic catalysts, wherein the catalysts on an oxidic support material comprise from 0.01 to 5% by weight of at least one alkali metal oxide.
摘要:
Optically active amines of the formula I where R1 and R2 are different and R1, R2, R3 are alkyl, cycloalkyl, arylalkyl, aryl, heteroaryl and heterocyclic radicals and R3 may also be hydrogen (H), with the radicals being able to bear substituents selected from the group consisting of alkyl, cycloalkyl, alkoxy, aryloxy, amino, alkylamino and dialkylamino, are racemized by reacting the optically active amine I in the presence of hydrogen and a hydrogenation or dehydrogenation catalyst at elevated temperature, wherein the catalyst comprises the active components copper and zinc oxide and a support material.