Abstract: Preparation of cyclic, &agr;,&bgr;-unsaturated ketones of formula II by dehydrogenation of cyclic ketones which conform to formula I in which n denotes an integer from 1 to 10, and which may be substituted, at elevated temperature in the presence of catalysts in the vapor phase, wherein the reaction is carried out in the absence of oxygen or in the presence of less than 0.5 mol of oxygen per mol of compound I at temperatures ranging from 250° to 600° C. and using catalysts having a surface area (BET) of more than 0.5 m2/g.

Abstract: In a process for preparing 1,4-butanediol, tetrahydrofuran and &ggr;-butyrolactone by oxidation of butane to give a product stream comprising maleic anhydride, absorption of maleic anhydride from the product stream using a high-boiling alcohol to give a liquid absorption product comprising monoesters and diesters of maleic acid and also high-boiling alcohol, after-esterification of the liquid absorption product and subsequent hydrogenation of the after-esterified product in the liquid phase, the high-boiling alcohol is a polyhydric alcohol having a boiling point at atmospheric pressure of above 233° C. and the after-esterified product has an acid number of less than 30 mg KOH/g and a water content of less than 1% by weight.

Abstract: A process for the preparation of 1,6-hexanediol and 6-hydroxycaproic acid or esters thereof by catalytic hydrogenation of adipic acid, adipic acid monoesters or adipic acid diesters or streams of starting material which contain adipic acid or esters thereof as essential constituents, in which the bottom product obtained in the distillation of the hydrogenation product, following removal of the hexanediol and hydroxycaproic acid or esters thereof, and essentially comprises oligomeric esters of 6-hydroxycaproic acid, is recycled to the hydrogenation, and the resulting mixture of starting material and recycle stream is reacted at from 100 to 300°C., at from 10 to 300 bar in the liquid phase and at a molar ratio of carboxyl groups to be hydrogenated to hydrogen in the reactor of from 1:5 to 1:100 on hydrogenation catalysts is described.

Abstract: A process is provided for stabilizing and/or lowering the color number of alkenyl compounds containing a divalent or trivalent heteroatom in the &agr;-position to the double bond, wherein an oxidizing agent is added to the alkenyl compounds.

Abstract: A method of storing and transporting N-vinyl-&egr;-caprolactam is provided wherein the N-vinyl-&egr;-caprolactam is kept in the liquid phase.

Abstract: A process for producing 1,6-hexanediol by hydrogenation of adipic esters and/or 6-hydroxycaproic esters in the gas phase at elevated temperature and elevated pressure in the presence of chromium-free catalysts comprises hydrogenating a) over a catalyst comprising copper, manganese and aluminum as essential constituents or over Raney copper, b) at a temperature of from 150 to 230° C. and a pressure of from 10 to 70 bar, c) at a molar ratio of hydrogen to ester to be hydrogenated within the range from 150:1 to 300:1, and d) at a catalyst space velocity of from 0.01 to 0.3 kg of C6 ester per liter of catalyst per hour.

Abstract: 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.

Abstract: A process for purifying alkenyl compounds having a divalent or trivalent heteroatom in the &agr;-position relative to the double bond by distillation comprises carrying out at least two distillations in which the purified alkenyl compounds are obtained from the gas phase by condensation, where the time between the first distillation after the synthesis of the alkenyl compounds and at least one further distillation is at least one day and the purified alkenyl compounds have an APHA color number of <30.

Abstract: A process for purifying alkenyl compounds having a divalent or trivalent heteroatom in the &agr;-position relative to the double bond by distillation comprises carrying out at least two distillations in which the purified alkenyl compounds are obtained from the gas phase by condensation, where the time between the first distillation after the synthesis of the alkenyl compounds and at least one further distillation is at least one day and the purified alkenyl compounds have an APHA color number of <30.

Abstract: A process for preparing 1,4-butanediol and, if desired, &ggr;-butyrolactone and THF by oxidizing butane or benzene to form a product stream including maleic anhydride, absorbing maleic anhydride from the product stream with a high-boiling inert solvent in an absorption stage to give a liquid absorption product, esterifying the liquid absorption product with a C1-C5 esterifying alcohol in an esterification stage to form an esterification product comprising the corresponding diester and high-boiling inert solvent, then hydrogenating the esterification product to give a hydrogenation product which comprises the products of value, 1,4-butanediol and, if desired, &ggr;-butyrolactone and tetrahydrofuran and the esterifying alcohol and which is separated by distillation into the products of value and the esterifying alcohol, and recycling the esterifying alcohol to the esterification zone, which comprises separating the esterification product into the diester and the inert solvent by distillation under reduced press

Abstract: A dialdehyde, trialdehyde or tetraldehyde or at least two thereof as aldehyde are hydrogenated by bringing into contact at least: the aldehyde; a catalyst comprising at least one metal selected from the group consisting of nickel, cobalt and copper in chemically bound and/or elemental form; hydrogen; at a gas pressure in the range from 5 to 350 bar and a temperature in the range from 40 to 300° C.

Abstract: A process for hydrogenating benzenepolycarboxylic acids or a derivatives thereof by bringing one or more benzenepolycarboxylic acids or derivatives thereof into contact with a hydrogen-containing gas is carried out in the presence of a catalyst containing macropores. The catalyst contains, as an active metal, at least one metal of transition group VIII of the Periodic Table alone or together with at least one metal of transition group I or VII of the Periodic Table. Except that hydrogenation of dimethyl terephthalate using a catalyst containing ruthenium as active metal, either alone or together with at least one metal of transition group I, VII or VIII of the Periodic Table, applied to a support having a mean pore diameter of at least 50 nm and a BET surface are of at most 30 m2/g, where the active metal is present in an amount of from 0.01 to 30% by weight, based on the total weight of the catalyst, and the ratio of the surface areas of the active metal and the catalyst support is less than 0.

Abstract: The invention provides an N-alkenyllactam having at least a 6-membered lactam ring, stabilized by phenothiazine and/or derivatives thereof, and a process for the stabilization of N-alkenyllactams.

Abstract: The invention relates to a process for the separation of maleic anhydride from the maleic anhydride-containing reactor offgases from the preparation of maleic anhydride by the oxidation of hydrocarbons, in which this gas stream is brought into contact with a high-boiling, inert absorbent for maleic anhydride and maleic anhydride is separated from the resultant liquid absorbate phase by vapor stripping, where the stripping agent used is an alcohol, and at least some of the maleic anhydride is reacted with the alcohol to give the ester.

Abstract: 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.

Abstract: 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.

Abstract: Hexanediol is prepared by hydrogenating dialkyl adipates or mixtures which contain a dialkyl adipate as the essential component and organic halogen compounds as impurities, by a process in which, before the hydrogenation, the dialkyl adipates or the mixtures containing dialkyl adipates are passed at from 50 to 250° C. and from 1 to 100 bar over copper catalysts which have a copper content, calculated as CuO, of from 0.5 to 80% by weight, a surface area of from 5 to 1500 m2/g, a porosity of from 0.05 to 1.5 cm3/g and a copper surface area of from 0.1 to 20 m2/g, in order to remove the organic halogen compounds.

Abstract: 2-Cyclododecyl-propanol [sic], which is in demand as musk scent, is prepared in an advantageous industrial process by reacting cyclododecene with an excess of propionic acid or of a propionic acid derivative in the presence of catalytic amounts of a free-radical initiator, and subsequently catalytically hydrogenating the 2-cyclododecylpropionic acid which is formed or the corresponding 2-cyclododecylpropionic acid derivatives.

Abstract: In a process for preparing alcohols containing cycloaliphatic groups by hydrogenation of carboxylic acids containing aromatic nuclei, or anhydrides or esters thereof, in the presence of a catalyst, the hydrogenation is carried out in one stage, and the catalyst contains at least one element from groups 8 to 10 and at least one element from group 7 of the Periodic Table of the Elements, in the form of the metal or an oxide in each case.

Abstract: A process for hydrogenating a benzenepolycarboxylic acid or a derivative thereof or a mixture of two or more thereof by bringing the benzenepolycarboxylic acid or the derivative thereof or the mixture of two or more thereof into contact with a hydrogen-containing gas is carried out in the presence of a catalyst which comprises as active metal at least one metal of transition group VIII of the Periodic Table alone or together with at least one metal of transition group I or VII of the periodic table applied to a support which contains macropores with the proviso that if dimethyl terephthalate is hydrogenated, the hydrogenation using a catalyst which comprises as active metal ruthenium either alone or together with at least one metal of transition group I, VII or VIII of the Periodic Table applied to a support, where the support has a mean pore diameter of at least 50 nm and a BET surface area of at most 30 m2/g and the amount of the active metal is from 0.