Abstract: A process is described for preparing tetrahydrogeranylacetone in which pseudoionone, geranylacetone and/or dihydrogeranylacetone in a liquid phase, in which particles of a catalyst which is capable of preferentially hydrogenating carbon-carbon double bonds over carbon-oxygen double bonds are suspended, is conducted through a device which inhibits the transport of the catalyst particles in the presence of a hydrogen-containing gas.

Abstract: A dividing-wall column having a dividing wall which is essentially disposed along the long direction of the column is proposed, which divides the column interior into a feed part, a take off part, an upper shared column part and a lower shared column part, with feed in whole or in part in the vaporous state of a mixture to be separated between the upper region of the feed part and the lower region of the feed part and/or side stream take off in whole or in part in the vaporous state between the upper region of the take off part and the lower region of the take off part, where if feed is in whole or in part in the vaporous state the cross-sectional area of the upper region of the feed part is increased by plane-parallel displacement of the dividing wall toward the upper region of the take off part, and/or if the side stream take off is in whole or in part in the vaporous state, the cross-sectional area of the lower region of the take off part is increased by displacement of the dividing wall toward the lower r

Abstract: A process is described for preparing tetrahydrogeranylacetone in which pseudoionone, geranylacetone and/or dihydrogeranylacetone in a liquid phase, in which particles of a catalyst which is capable of preferentially hydrogenating carbon-carbon double bonds over carbon-oxygen double bonds are suspended, is conducted through a device which inhibits the transport of the catalyst particles in the presence of a hydrogen-containing gas.

Abstract: A dividing-wall column having a dividing wall which is essentially disposed along the long direction of the column is proposed, which divides the column interior into a feed part, a take off part, an upper shared column part and a lower shared column part, with feed in whole or in part in the vaporous state of a mixture to be separated between the upper region of the feed part and the lower region of the feed part and/or side stream take off in whole or in part in the vaporous state between the upper region of the take off part and the lower region of the take off part, where if feed is in whole or in part in the vaporous state the cross-sectional area of the upper region of the feed part is increased by plane-parallel displacement of the dividing wall toward the upper region of the take off part, and/or if the side stream take off is in whole or in part in the vaporous state, the cross-sectional area of the lower region of the take off part is increased by displacement of the dividing wall toward the lower r

Abstract: A dividing-wall column having a dividing wall which is essentially disposed along the long direction of the column is proposed, which divides the column interior into a feed part, a take off part, an upper shared column part and a lower shared column part, with feed in whole or in part in the vaporous state of a mixture to be separated between the upper region of the feed part and the lower region of the feed part and/or side stream take off in whole or in part in the vaporous state between the upper region of the take off part and the lower region of the take off part, where if feed is in whole or in part in the vaporous state the cross-sectional area of the upper region of the feed part is increased by plane-parallel displacement of the dividing wall toward the upper region of the take off part, and/or if the side stream take off is in whole or in part in the vaporous state, the cross-sectional area of the lower region of the take off part is increased by displacement of the dividing wall toward the lower r

Abstract: A dividing-wall column having a dividing wall which is essentially disposed along the long direction of the column is proposed, which divides the column interior into a feed part, a take off part, an upper shared column part and a lower shared column part, with feed in whole or in part in the vaporous state of a mixture to be separated between the upper region of the feed part and the lower region of the feed part and/or side stream take off in whole or in part in the vaporous state between the upper region of the take off part and the lower region of the take off part, where if feed is in whole or in part in the vaporous state the cross-sectional area of the upper region of the feed part is increased by plane-parallel displacement of the dividing wall toward the upper region of the take off part, and/or if the side stream take off is in whole or in part in the vaporous state, the cross-sectional area of the lower region of the take off part is increased by displacement of the dividing wall toward the lower r

Abstract: A process is proposed for preparing C5 acetate for Vitamin A synthesis by hydroformylation of 3,4-diacetoxybut-1-ene (3,4-DABE), according to which a 3,4-DABE is used which is obtained by acetoxylation of 1,3-butadiene with acetic acid and air in the presence of a catalyst and removing by distillation the 3,4-DABE formed in this case as by-product.

Abstract: The present invention relates to a continuous process for the preparation of unsaturated acetals by reacting olefinically unsaturated aliphatic compounds with allyl alcohols in a reaction column, where the reactants are only partially reacted in the reaction column, the resulting acetal is concentrated in at least two successive evaporation stages, and the recovered reactants are returned to the reaction column.

Abstract: A process is proposed for preparing C5 acetate for Vitamin A synthesis by hydroformylation of 3,4-diacetoxybut-1-ene (3,4-DABE), according to which a 3,4-DABE is used which is obtained by acetoxylation of 1,3-butadiene with acetic acid and air in the presence of a catalyst and removing by distillation the 3,4-DABE formed in this case as by-product.

Abstract: An &agr;,&bgr;-unsaturated carbonyl compound of formula (I) where R1 is saturated C1-40-hydrocarbyl or a substituted or unsubstituted aromatic radical containing moiety, and R2, R3 and R4, independently of one another, are hydrogen or a C1- to C4-alkyl group, is selectively hydrogenated in the liquid phase to a saturated carbonyl compound of formula (II) with hydrogen in the presence of a pulverulent palladium and/or rhodium catalyst and in the presence of an organic base, by conducting the hydrogenation in a packed bubble column reactor in which product is recycled and hydrogen gas is recirculated.

Abstract: The present invention relates to a continuous process for the preparation of unsaturated acetals by reacting olefinically unsaturated aliphatic compounds with allyl alcohols in a reaction column, where the reactants are only partially reacted in the reaction column, the resulting acetal is concentrated in at least two successive evaporation stages, and the recovered reactants are returned to the reaction column.

Abstract: The process for the preparation of carbonyl compounds of the formula I where R1 and R2 are a hydrocarbon radical, or R1 and R2 together are an unsubstituted or substituted alkylene group, and X is ═O or two alkoxy groups, comprises oxidizing alcohols of the formula II  where R1 to R2 and X are as defined above, with oxygen in the gaseous phase a) at temperatures of from 270 to 600° C. on silver coated catalysts which comprise an abrasion-resistant coating of metallic silver on a core of inert support material, or b) at temperatures of from 450 to 750° C. on silver crystals and/or copper crystals having a particle size of from 0.1 to 2.5 mm for a residence time of at most 0.1 second. Also claimed is an advantageous overall process for the preparation of &agr;-diketones, preferably diacetal, from the corresponding ketone, in particular methyl ethyl ketone, via the carbonyl compounds of the formula I where X is two alkoxy groups.

Abstract: The fixed-bed catalyst comprises palladium and selenium or tellurium or a mixture of selenium and tellurium on a silicon dioxide support and has a BET surface area of from 80 to 380 m2/g and a pore volume of from 0.6 to 0.95 cm3/g in the pore diameter range from 3 nm to 300 &mgr;m, with from 80 to 95% of the pore volume being in the pore diameter range from 10 to 100 nm. It is prepared by impregnating a silicon dioxide support with a solution of a palladium compound and a selenium compound or tellurium compound or a mixture of a selenium compound and a tellurium compound, drying it and reducing it in the presence of hydrogen. The catalyst is used, in particular, for isomerizing 3-buten-1-ol compounds.

Abstract: The process for the preparation of carbonyl compounds of the formula I where R1 and R2 are a hydrocarbon radical, or R1 and R2 together are an unsubstituted or substituted alkylene group, and X is=O or two alkoxy groups, comprises oxidizing alcohols of the formula II where R1 to R2 and X are as defined above, with oxygen in the gaseous phase a) at temperatures of from 270 to 600° C. on silver coated catalysts which comprise an abrasion-resistant coating of metallic silver on a core of inert support material, or b) at temperatures of from 450 to 750° C. on silver crystals and/or copper crystals having a particle size of from 0.1 to 2.5 mm for a residence time of at most 0.1 second. Also claimed is an advantageous overall process for the preparation of &agr;-diketones, preferably diacetal, from the corresponding ketone, in particular methyl ethyl ketone, via the carbonyl compounds of the formula I where X is two alkoxy groups.

Abstract: The fixed-bed catalyst comprises palladium and selenium or tellurium or a mixture of selenium and tellurium on a silicon dioxide support and has a BET surface area of from 80 to 380 m2/g and a pore volume of from 0.6 to 0.95 cm3/g in the pore diameter range from 3 nm to 300 &mgr;m, with from 80 to 95% of the pore volume being in the pore diameter range from 10 to 100 nm. It is prepared by impregnating a silicon dioxide support with a solution of a palladium compound and a selenium compound or tellurium compound or a mixture of a selenium compound and a tellurium compound, drying it and reducing it in the presence of hydrogen. The catalyst is used, in particular, for isomerizing 3-buten-1-ol compounds.

Abstract: A process is described for the continuous preparation of dimethylvinylcarbinol (DMVC) by continuously reacting prenol with the aqueous solution of a protic acid in the still or in the lower part of a rectification column while distilling off the DMVC formed in the form of an azeotropic mixture with water, which comprises a) during the reaction ensuring that as far as possible no liquid two-phase mixture forms in the reaction mixture, b) distilling off the DMVC which forms at a reflux ratio of at least 2, as a result of which there is virtually no more prenol present in the distillate from the column, and c) setting the reaction volume and/or the amount of prenol added per hour and/or the concentration of protons in the reaction mixture in such a manner that the quotient, defined as residence time concentration coefficient, of the reaction volume and the volume of prenol added per hour multiplied by the concentration of protons in the reaction mixture has a value between 0.

Abstract: 3,7-Dimethyl-2,6-octadien-1-al of formula I is prepared continuously by: thermally cleaving, in the presence or absence of an acid catalyst, 3-methyl-2-buten-1-al diprenyl acetal of formula II: thereby eliminating 3-methyl-2-buten-1-ol of formula III and yielding cis/trans-prenyl 3-methylbutadienyl ether of formula IV: thermally rearranging the resultant butadienyl ether of formula IV thereby yielding 2,4,4-trimethyl-3-formyl-1,5-hexadiene of formula V: subsequently rearranging intermediate (V) thereby yielding citral product of formula I, which comprises: as the reaction proceeds, continuously distilling the reaction mixture thereby continuously removing prenol, which is formed by degradation of acetal II, and the intermediates of formula IV and V and any citral product which is formed during the reaction; and thermally rearranging said intermediates of formula IV and V at a temperature of 100-200° C.

Abstract: A process for the preparation of acetates of alcohols or phenols, in particular linalyl acetate, by causing alcohols or phenols to react with ketene in the presence of a catalyst, wherein the reaction is carried out using approximately equimolar amounts of linalool and ketene in the presence of a zinc salt of a carboxylic acid, or alternatively in the presence of a zinc compound which forms zinc acetate under the conditions of the reaction, and with vigorous mixing of the reaction mixture.Using this process, linalyl acetate and numerous other acetates interesting as perfumes or active agents can be obtained to a good degree of purity in yields of more than 90% of theory and in very good space-time yields.

Abstract: The invention relates to a process for the selective liquid-phase hydrogenation of .alpha.,.beta.-unsaturated carbonyl compounds of the formula I, ##STR1## where R.sub.1 is hydrogen or an organic radical, and R.sub.2, R.sub.3 and R.sub.4, independently of one another, are hydrogen or a C.sub.1 -- to C.sub.4 --alkyl group, to saturated carbonyl compounds of the formula II ##STR2## using hydrogen in the presence of a pulverulent palladium and/or rhodium catalyst and in the presence of an organic base. The process is carried out in a packed bubble column reactor (1, 2) with product recycling (11, 17) and circulating hydrogen gas (4, 15, 16). It is particularly suitable for the selective hydrogenation of citral to citronellal.

Abstract: A process for continuous industrial production of unsaturated aliphatic aldehydes having a boiling range from 95 to 136.degree. C. by oxidative dehydrogenation of the corresponding alcohols with an oxygen-comprising gas over a supported catalyst consisting of copper, silver and/or gold on an inert support in a tube bundle reactor, rapid cooling of the reaction gases and removal of the aldehydes from the resulting condensate with recycling of the unconverted alcohols comprisesa) vaporizing the alcohol,b) admixing the alcohol vapor with an oxygen-comprising gas,c) initially passing the resulting oxygen-comprising alcohol vapor at above the dew point of the alcohol but below the commencement temperature of the reaction through a layer of one of the abovementioned supported catalysts which is at least 0.5 cm in thickness and only thend) reacting the oxygen-comprising alcohol vapor at from 300 to 600.degree. C.