摘要:
A process for preparing a hydrogen peroxide solution having a hydrogen peroxide content of not less than 2.5% by weight, which comprises continuously reacting hydrogen and oxygen in an aqueous, alcoholic or aqueous/alcoholic reaction medium in the presence of a catalyst containing palladium.
摘要:
Alkenes are prepared by partial hydrogenation of alkynes in the liquid phase at from 20 to 250° C. and hydrogen partial pressures of from 0.3 to 200 bar over fixed-bed supported palladium catalysts which are obtainable by heating the support material in the air, cooling, applying a palladium compound and, if required, additionally other metal ions for doping purposes, molding and processing to give monolithic catalyst elements, by a process in which A) alkynes of 10 to 30 carbon atoms are used as starting compounds, B) the palladium compound and, if required, the other metal ions are applied to the support material by impregnation of the heated and cooled support material with a solution containing palladium salts and, if required, other metal ions and subsequent drying, and C) from 10 to 2000 ppm of carbon monoxide (CO) are added to the hydrogenation gas or a corresponding amount of CO is allowed to form in the liquid phase by slight decomposition of a compound which is added to the reaction mixture and eliminates CO under the reaction conditions. The process is particularly advantageous if the partial hydrogenation is carried out in a tube reactor by the trickle-bed or liquid phase procedure with product recycling at cross-sectional loadings of from 20 to 500 m3/m2*h. The process is particularly suitable for the preparation of 3,7,11,15-tetramethyl-1-hexadecen-3-ol (isophytol), 3,7,11-trimethyl-l-dodecen-3-ol (tetrahydronerolidol), 3,7,11-trimethyl-1,4-dodecadien-3-ol, 3,7,11-trimethyl-1,6-dodecadien-3-ol (dihydronerolidol), 3,7-dimethyloct-1,6-dien-3-ol or 3,7-dimethyloct-1-en-3-ol from the corresponding alkynes.
摘要:
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 pressure prior to the hydrogenation, recycling the inert solvent to the absorption stage, and hydrogenating the diester in the liquid phase over a fixed-bed catalyst.
摘要:
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. in the absence or presence of said prenol to form citral product.
摘要:
Organic iodine compounds are separated from carbonylation products of methanol, methyl acetate and dimethyl ether and from mixtures of such carbonylation products by a process wherein the iodine compounds are removed by liquid phase extraction with a non-aromatic hydrocarbon.
摘要:
Anhydrous or substantially anhydrous formic acid is obtained by hydrolysis of methyl formate, in a process wherein(a) methyl formate is hydrolyzed,(b) the methanol and excess methyl formate are distilled from the hydrolysis mixture obtained,(c) the bottom product of distillation (b), consisting of formic acid and water, is extracted, in a liquid-liquid extraction, with an extractant which in the main takes up the formic acid,(d) the resulting extract phase, consisting of formic acid, the extractant and a part of the water, is subjected to distillation,(e) the top product obtained from this distillation and consisting of all or part of the water introduced into the distillation, and part of the formic acid, is recycled, as vapor, into the lower part of the distillation column of stage (b),(f) the bottom product of distillation stage (d), consisting of the extractant, with or without part of the water, and the greater part of the formic acid, is separated by distillation into anhydrous or substantially anhydrous formic acid and the extractant, and(g) the extractant leaving stage (f) is recycled to the process.
摘要:
In the acid-catalyzed esterification of mercaptoalkyl alcohols by means of carboxylic acids to form mercaptoalkly carboxylates, formation of undesirable, usually sparingly soluble by-products usually occurs. The process of the invention in the absence of acid catalysts avoids the formation of such by-products. Particularly when the esterification of the invention is carried out as reactive distillation using reactive column and residence vessel, good degrees of conversion can also be obtained without acid catalyst and at the same time the formation of the by-products can be largely avoided.
摘要:
Apparatus and processes for continuous distillative separation of a mixture comprising one or more alkanolamine(s), wherein the separation is performed in one or more dividing wall column(s) and the alkanolamine or the alkanolamines is/are withdrawn as a side draw stream or side draw streams (side fraction(s)).
摘要:
A process is described for continuously hydrogenating unsaturated compounds, in which particles of a first hydrogenation catalyst are suspended in a liquid phase in which an unsaturated compound is dissolved, the liquid phase, in the presence of a hydrogenous gas at a first partial hydrogen pressure and at a first temperature, is conducted through a packed bubble column reactor in cocurrent counter to the direction of gravity, the effluent from the bubble column reactor is sent to a gas-liquid separation, the liquid phase is sent to a crossfiltration to obtain a retentate and a filtrate, the retentate is recycled into the bubble column reactor and the filtrate, in the presence of a hydrogenous gas at a second partial hydrogen pressure and at a second temperature, is passed over a bed of a second hydrogenation catalyst, wherein the second partial hydrogen pressure is at least 10 bar higher than the first partial hydrogen pressure.
摘要:
Process for obtaining formic acid by thermal separation of a stream comprising formic acid and a tertiary amine (I), in which a liquid stream comprising formic acid and a tertiary amine (I) in a molar ratio of from 0.5 to 5 is produced by combining tertiary amine (I) and a formic acid source, from 10 to 100% by weight of the secondary components present therein are separated off and formic acid is removed by distillation in a distillation apparatus at a bottom temperature of from 100 to 300° C. and a pressure of from 30 to 3000 hPa abs from the liquid stream obtained, the bottom discharge from the distillation apparatus being separated into two liquid phases and the upper liquid phase being recycled to the formic acid source and the lower liquid phase being recycled for separating off the secondary components and/or to the distillation apparatus.