Abstract: Process for preparing metal alkoxides by means of transalcoholization, wherein a lower metal alkoxide is fed via a side feed into a reactive distillation column comprising a rectifying section situated above the feed and a stripping section situated below the feed; a higher alcohol is fed into the stripping section, the bottom and/or a bottoms circuit of the column; a solution of a higher metal alkoxide in the higher alcohol is taken off at the bottom of the column and/or from the bottoms circuit; and a vapor comprising lower alcohol is taken off at the top of the column, the vapor is at least partially condensed and a substream of the condensate is recycled to the top of the column as reflux. The process enables the preparation of metal alkoxides with a reduced energy requirement.

Abstract: The present invention relates to an integrated process for simultaneously preparing at least two mixtures comprising alkali metal methoxide and methanol in at least two parallel reactive distillation columns, wherein one rectification column is used for providing a methanol stream which is then used as methanol source for the reactive distillation columns, and wherein the top streams of said reactive distillation columns are used as methanol source for said rectification column.

Abstract: A method for controlling a reactive distillation column for effecting a transalcoholisation reaction, comprising feeding a metal methoxide into the reactive distillation column via a side feed; feeding a reactant alcohol into a lower part of the reactive distillation column; withdrawing methanol from the top of the reactive distillation column; and withdrawing a solution of a product metal alkoxide in the reactant alcohol from the bottom of the reactive distillation column; wherein the method comprises a process control scheme selected from: Scheme A: establishing a signal S1 which is responsive to a temperature in the rectifying section disposed above the feed of the metal methoxide; and manipulating in response to the signal S1 the feed amount of the reactant alcohol; Scheme B: establishing a signal S1 which is responsive to a temperature in the rectifying section disposed above the feed of the metal methoxide; and manipulating in response to the signal S1 the heat supplied to the bottom of the reactive dis

Abstract: A process for preparing metal alkoxides by transalcoholisation, comprising: feeding a lower metal alkoxide and a higher alcohol into a reactive distillation column; removing a solution of a higher metal alkoxide in the higher alcohol from the bottom of the column or from a recycle stream taken from the bottom of the column; and removing a gaseous lower alcohol from the top of the column, at least partially condensing the gaseous lower alcohol, and recirculating a part of the condensate to the top of the column; wherein an auxiliary alcohol is provided in the reactive distillation column, the boiling point of the auxiliary alcohol being between the boiling point of the lower alcohol and the boiling point of the higher alcohol at the pressure prevailing in the reactive distillation column. The process allows for high conversion of a lower metal alkoxide to a higher metal alkoxide while limiting the formation of solid deposits in the column, while having low energy requirements.

Abstract: A catalytic process for preparing an ?,?-ethylenically unsaturated carboxylic acid salt, comprising a) contacting an alkene and carbon dioxide with a carboxylation catalyst, an organic solvent, and an alkoxide having a secondary or tertiary carbon atom directly bound to an [O?] group, to obtain a crude reaction product comprising the ?,?-ethylenically unsaturated carboxylic acid salt and an alcohol by-product which is the conjugate acid of the alkoxide, b) allowing the ?,?-ethylenically unsaturated carboxylic acid salt to precipitate out from the crude reaction product; and c) subjecting at least part of the crude reaction product to a mechanical separation step while maintaining the alcohol by-product in liquid form to obtain a solid phase comprising the ?,?-ethylenically unsaturated carboxylic acid salt and a liquid phase comprising the carboxylation catalyst, the organic solvent and the alcohol by-product.

Abstract: Process for preparing metal alkoxides by means of transalcoholization, wherein a lower metal alkoxide is fed via a side feed into a reactive distillation column comprising a rectifying section situated above the feed and a stripping section situated below the feed; a higher alcohol is fed into the stripping section, the bottom and/or a bottoms circuit of the column; a solution of a higher metal alkoxide in the higher alcohol is taken off at the bottom of the column and/or from the bottoms circuit; and a vapor comprising lower alcohol is taken off at the top of the column, the vapor is at least partially condensed and a substream of the condensate is recycled to the top of the column as reflux. The process enables the preparation of metal alkoxides with a reduced energy requirement.

Abstract: A process for the preparation of a saturated aliphatic carboxylic acid with 3 to 5 carbon atoms by oxidation of the corresponding aldehyde with oxygen in which (a) the corresponding aldehyde is converted with oxygen at a temperature of 40 to 150° C. and an oxygen partial pressure of 0.001 to 1 MPa to obtain a mixture containing the saturated aliphatic carboxylic acid and ?2 mol-% of the corresponding aldehyde with respect to the saturated aliphatic carboxylic acid, (b) the mixture obtained in step (a) is thermally treated in the liquid phase at a temperature of 80 to 250° C. and a pressure of 0.1 to 2 MPa abs for 0.25 to 100 hours, and (c) the mixture obtained in step (b) is distilled in a distillation apparatus to obtain a distillate containing ?90 wt.-% of the saturated aliphatic carboxylic acid and having an active oxygen content of 0 to 25 wt.-ppm based on the distillate.

Abstract: Method for preparing a ?-hydroxyketone having 4 to 8 carbon atoms by reacting formaldehyde with a branched or unbranched dialkyl ketone having 3 to 7 carbon atoms in the liquid phase in a reactor in the presence of a basic component at a temperature of 50 to 150° C. and a pressure of 0.2 to 10 MPa abs, in which (a) a trialkylamine having 1 to 4 carbon atoms per alkyl group is used as basic component and the reaction (b) is carried out in the presence of 1 to 25% by weight water, based on the liquid phase, and (c) at a molar ratio of trialkylamine to formaldehyde in the liquid phase of from 1 to 5.

Abstract: Method for preparing 1-hydroxy-2-methyl-3-pentanone (I) by reacting formaldehyde with diethyl ketone in a reactor in the presence of water and a basic component at a temperature of 50 to 150° C. and a pressure of 0.2 to 10 MPa abs, in which the basic component used is a trialkylamine from the group comprising trimethylamine, N,N-dimethylethylamine, N,N-diethylmethylamine, triethylamine, N,N-dimethyl-n-propylamine, N-ethyl-N-methyl-n-propylamine, N,N-dimethylisopropylamine, N-ethyl-N-methylisopropylamine, N,N-dimethyl-n-butylamine, N,N-dimethylisobutylamine and N,N-dimethyl-sec-butylamine, and from the reaction mixture obtained, trialkylamine as low boiler and a bottom product comprising 1-hydroxy-2-methyl-3-pentanone (I) as high boiler are separated in a distillation apparatus, wherein the distillation apparatus is operated at a top pressure of 0.2 to 1 MPa abs.

Abstract: Processes for preparing tetrahydrofuran and/or butane-1,4-diol and/or gamma-butyrolactone are provided, including a process for preparing tetrahydrofuran (THF) from succinic acid that has been obtained by conversion of biomass, by conversion of the succinic acid to succinic anhydride, and hydrogenation of the succinic anhydride, with removal of certain secondary components.

Abstract: Processes for preparing tetrahydrofuran and/or butane-1,4-diol and/or gamma-butyrolactone are provided, including a process for preparing tetrahydrofuran (THF) from succinic acid that has been obtained by conversion of biomass, by conversion of the succinic acid to succinic anhydride, and hydrogenation of the succinic anhydride, with removal of certain secondary components.

Abstract: A process which isolates tetrahydrofuran from a stream of tetrahydrofuran, alkanol and high boilers, by: (a) separating off a first stream of tetrahydrofuran and alkanol as azeotrope in a first distillation stage; (b) feeding part of the first stream into a reactor for esterifying maleic anhydride, giving a second stream of tetrahydrofuran and monoalkyl maleate; (c) separating the second stream into a third stream of monoalkyl maleate and a fourth stream of tetrahydrofuran in a second distillation stage; (d) feeding the fourth stream of tetrahydrofuran from the second distillation stage and the part of the first stream from (a) which is not fed to the reactor into a third distillation stage to obtain a product stream of tetrahydrofuran and a sixth stream of tetrahydrofuran and alkanol; (e) recirculating the sixth stream from the third distillation stage into the first distillation stage or the reactor in (b).

Abstract: A process which isolates tetrahydrofuran from a stream of tetrahydrofuran, alkanol and high boilers, by: (a) separating off a first stream of tetrahydrofuran and alkanol as azeotrope in a first distillation stage; (b) feeding part of the first stream into a reactor for esterifying maleic anhydride, giving a second stream of tetrahydrofuran and monoalkyl maleate; (c) separating the second stream into a third stream of monoalkyl maleate and a fourth stream of tetrahydrofuran in a second distillation stage; (d) feeding the fourth stream of tetrahydrofuran from the second distillation stage and the part of the first stream from (a) which is not fed to the reactor into a third distillation stage to obtain a product stream of tetrahydrofuran and a sixth stream of tetrahydrofuran and alkanol; (e) recirculating the sixth stream from the third distillation stage into the first distillation stage or the reactor in (b).

Abstract: A process for decreasing fumaric acid deposits in the preparation of maleic anhydride by heterogeneously catalyzed oxidation of a hydrocarbon with molecular oxygen, in which the maleic anhydride is absorbed from the crude product mixture in an absorbent in an absorption column and desorbed again in a desorption column, the entirety or a portion of the absorbent depleted in maleic anhydride, for controlled precipitation of fumaric acid, being cooled and/or concentrated by evaporating a portion of the absorbent to such an extent that the difference between the concentration of fumaric acid in the recycle stream at the outlet of the desorption column under the conditions existing there and the equilibrium concentration of fumaric acid according to the solubility curve after the cooling and/or evaporation of a portion of the absorbent is greater than or equal to 250 ppm by weight, and the fumaric acid precipitated as a solid is removed completely or partly from the absorbent recycling system and the fumaric acid-

Abstract: The invention relates to methods for removing gaseous contaminants and aerosols from a vapor-saturated gas stream, in which method a gas stream containing a) at least one gaseous contaminant which is soluble in a scrubbing liquid, with or without salt formation, and b) at least one aerosol with a particle size from 0.01 to 10 &mgr;m, is brought into contact, in a scrubber column, with a scrubbing liquid, the temperature of which is lower by at least 2° C. than the temperature of the gas stream, resulting in the formation of a vapor phase, the degree of saturation S of which is greater than 1, and in the removal of the gaseous and particulate contaminants from the gas stream.