Abstract:
The present invention relates to a particularly economic overall method for producing menthol, specifically for producing optically active, essentially enantiomerically and diastereomerically pure L-menthol and racemic menthol, starting from the starting material citral which is available inexpensively on an industrial scale. The method comprises the following stepsa.1) catalytic hydrogenation of neral and/or geranial to give citronellal, b.1) cyclization of citronellal to isopulegol in the presence of an acidic catalyst, c.1) purification of isopulegol by crystallization and d.1) catalytic hydrogenation of isopulegol to give menthol.
Abstract:
This invention relates to a method of producing purified methyl isobutyl ketone (MIBK) comprising subjecting a feed stream containing MIBK and impurities to a first distillation procedure from which acetone is recovered and a bottom product containing MIBK and impurities is withdrawn. This bottom product is fed to a second distillation column, where a vapour overhead product is withdrawn, condensed and fed to an overhead liquid-liquid separator. Part of an organic phase from the overhead liquid-liquid separator is fed to the second distillation column and part is fed to a third distillation column. A vapour overhead product is withdrawn from the third column which is condensed in the same said condensor. The condensed product is fed to the same said overhead liquid-liquid separator, and purified MIBK is withdrawn from the third distillation column. This invention also relates to an apparatus used in such a method.
Abstract:
A process for purifying an acetoxylation mixture is disclosed. Allyl acetate, water, acetic acid, and from 0.1 to 10 wt. % allyl diacetate are contacted in the vapor phase with a solid acidic catalyst under conditions effective to decompose the allyl diacetate and generate an intermediate stream comprising allyl acetate, water, acetic acid, and acrolein. Acrolein is then removed from the intermediate stream, preferably by distillation, to give an allyl acetate-containing product stream. Usually, this product stream is then hydrolyzed to produce allyl alcohol. The invention includes processes in which propylene first reacts with oxygen and acetic acid in the presence of a noble metal catalyst to generate the acetoxylation mixture.
Abstract:
The present invention relates to a process for preparing at least one cyclic compound with Z cycles and 7 to 16 carbon atoms with a keto group, at least comprising the stages: (a1) oxidation of a composition (A), at least comprising one cyclic olefin with Z cycles and 7 to 16 carbon atoms and at least two C—C double bonds, by means of dinitrogen monoxide to give a composition (A1), (a2) separating off the at least one cyclic olefin with Z cycles and 7 to 16 carbon atoms with at least two C—C double bonds from the composition (A1) in order to obtain a composition (A2), and (b) distillative treatment of the composition (A2) from step (a2) in order to obtain a composition (B), comprising the at least one cyclic compound with Z cycles and 7 to 16 carbon atoms with a keto group and less than 1.0% by weight of the at least one compound with Z−1 cycles and 7 to 16 carbon atoms with at least one aldehyde group, where Z can be 1, 2, 3 or 4.
Abstract:
There are provided a process, an apparatus, and an acrolein-containing composition, for producing acrylic acid from the acrolein-containing composition at a high yield. The process for producing acrylic acid includes a refinement step of removing phenol and/or 1-hydroxyacetone from an acrolein-containing composition and an oxidation step of oxidizing acrolein in the acrolein-containing composition after the refinement step to produce acrylic acid, and the apparatus to be used in the process includes a refiner to be used in the refinement step and an oxidation reactor for oxidizing acrolein to produce acrylic acid. The acrolein-containing composition is a composition having a (mass of phenol)/(mass of acrolein) ratio of 0.020 or lower and a (mass of 1-hydroxyacetone)/(mass of acrolein) ratio of 0.020 or lower.
Abstract:
The present invention relates to a process for purifying a composition (I) comprising at least one cyclic ketone having from 7 to 16 carbon atoms, which comprises thermal treatment of the composition (I) with at least one acid and further purification by means of a process selected from the group consisting of distillation, extraction and crystallization, Furthermore, the present invention relates to a process for preparing cyclododecanone, which comprises such a purification, and the use of at least one acid for purifying a composition (I) comprising at least one cyclic ketone having from 7 to 16 carbon atoms by thermal treatment of the composition (I) with the acid.
Abstract:
The present invention relates to a process for preparing a cyclic ketone having from 7 to 16 carbon atoms, which comprises at least the steps(a) oxidation of a composition (I) comprising at least one cyclic alkene which has from 7 to 16 carbon atoms and at least one C—C double bond by means of dinitrogen monoxide to give a composition (A),(b) treatment of the composition (A) with at least one base to give a composition (B),(c) hydrogenation of the composition (B) in the presence of at least one catalyst to give a composition (C),(d) purification of the composition (C), comprising at least the steps(di) thermal treatment of the composition (C) with at least one acid or at least one catalyst comprising at least one transition metal,(dii) further purification by a method selected from the group consisting of distillation, extraction and crystallization.
Abstract:
A process for purifying an aqueous solution to obtain purified gaseous acrolein by introducing the aqueous solution into a distillation column equipped at its base with at least one boiler and at its top with at least one condenser, withdrawing a liquid mixture essentially containing water at the base of the distillation column, withdrawing a gas essentially containing acrolein and water at the top of the distillation column, cooling the gas mixture withdrawn at the top of the distillation column in the condenser, to a temperature which makes it possible to obtain, on the one hand, an aqueous condensate and, on the other hand, an acrolein-rich gas mixture, and withdrawing the acrolein-rich gas mixture.
Abstract:
The invention relates to a process for obtaining a pure aliphatic dialdehyde monoacetal by reaction of the corresponding aliphatic dialdehyde or a precursor of the corresponding aliphatic dialdehyde with one or more aliphatic mono- or polyhydric alcohols while distillatively removing water to obtain a reaction mixture which is separated distillatively, which comprises carrying out the distillative separation continuously in a dividing wall column to obtain pure aliphatic dialdehyde monoacetal as a sidestream from the dividing wall column, or in two distillation columns to obtain crude aliphatic dialdehyde monoacetal as a sidestream in the first distillation column, feed the crude aliphatic dialdehyde monoacetal to the second distillation column and obtain pure aliphatic dialdehyde monoacetal as the sidestream from the second distillation column.
Abstract:
A dry etching gas comprising a C4-6 fluorine compound which has an ether bond or carbonyl group and one or more fluorine atoms in the molecule and is constituted only of carbon, fluorine, and oxygen atoms and in which the ratio of the number of fluorine atoms to the number of carbon atoms (F/C) is 1.9 or lower (provided that the compound is neither a fluorine compound having one cyclic ether bond and one carbon-carbon double bond nor a saturated fluorine compound having one carbonyl group); a mixed dry etching gas comprising the dry etching gas and at least one gas selected from the group consisting of rare gases, O2, O3, CO, CO2, CHF3, CH2F2, CF4, C2F6, and C3F8; and a method of dry etching which comprises converting either of these dry etching gases into a plasma and processing a semiconductor material with the plasma. The dry etching gases can be safely used, are reduced in influence on the global environment, and can highly selectively dry-etch a semiconductor material at a high dry etching rate to form a satisfactory pattern shape. The dry etching method employs either of these dry etching gases.