Abstract: The invention relates to a method for the separation of ascorbic acid from a mixture containing ascorbic acid and 2-keto-L-gulonic acid in a polar, preferably aqueous solvent, by means of liquid/liquid extraction using an amide. The method preferably also comprises steps for the back-extraction of the ascorbic acid, recycling of the extraction solvent and/or the back extraction solvent and for isolation of the ascorbic acid from the back extraction solvent. The invention further relates to a method for the production of ascorbic acid from KGA and isolation of the ascorbic acid so produced.

Abstract: The present invention relates to a process for preparing polyisobutenes by polymerizing isobutene in the presence of a Lewis acid catalyst in liquid organic phase, terminating the reaction by admixing the organic phase with an aqueous terminator in a dynamic mixer which has a rotationally symmetric mixing chamber formed from one circumferential wall and two end walls, and a mixing rotor driven such that it rotates therein, the organic phase being introduced through a first inlet orifice provided in the circumferential wall and the aqueous terminator via a second inlet orifice provided in the circumferential wall, and removing a finely dispersed mixture of the organic phase and of the terminator through an outlet orifice provided in the circumferential wall and feeding it to a phase separation. The process serves to prepare high-reactivity polyisobutenes and/or polyisobutenes with narrow molecular weight distribution.

Abstract: The invention relates to an apparatus and a process for the preparation of anhydrous or substantially anhydrous formic acid. This apparatus is constructed partly or entirely of substantially zirconium-free materials. The extractant employed is a liquid of the general formula I where the radicals R1 and R2 are alkyl, cycloalkyl, aryl or aralkyl groups, or R1 and R2 jointly, together with the N atom, form a heterocyclic 5- or 6-membered ring, and only one of the radicals is an aryl group, and where R3 is hydrogen or a C1–C4-alkyl group. The apparatus has a synthesis reactor (6), a hydrolysis reactor (1), three distillation devices (2,4,5) and an extraction device (3).

Abstract: The present invention relates to a process for extracting 2-keto-L-gulonic acid (KGA) from a polar, preferably aqueous, solvent, preferably from a solvent which comprises a mixture of ascorbic acid and 2-keto-L-gulonic acid, by means of liquid/liquid extraction using an extractant which comprises a tertiary amine and a polar organic diluent. The process of the invention preferably also comprises steps for back-extraction of the KGA and recycling of the extractant. The present invention likewise relates to a process for preparing ascorbic acid from KGA and isolating the prepared ascorbic acid.

Abstract: The invention relates to a method for the separation of ascorbic acid from a mixture containing ascorbic acid and 2-keto-L-gulonic acid in a polar, preferably aqueous solvent, by means of liquid/liquid extraction using an amide. The method preferably also comprises steps for the back-extraction of the ascorbic acid, recycling of the extraction solvent and/or the back extraction solvent and for isolation of the ascorbic acid from the back extraction solvent. The invention further relates to a method for the production of ascorbic acid from KGA and isolation of the ascorbic acid so produced.

Abstract: The invention relates to a process for obtaining anhydrous or substantially anhydrous formic acid, in which firstly aqueous formic acid is prepared by hydrolysis of methyl formate and is freed from water in the subsequent work-up. The process has the special feature that steam, which is employed for the hydrolysis of methyl formate and for heating a distillation column serving for work-up, is also used as stripping steam for waste-water stripping. The stripped waste water is produced during work-up.

Abstract: The invention relates to a process for obtaining anhydrous or substantially anhydrous formic acid, in which firstly aqueous formic acid is produced by hydrolysis of methyl formate, with the methanol content in the methyl formate having been reduced in advance. The process according to the invention has the special feature that—before the hydrolysis of the methyl formate—the methanol content of the methanol-containing methyl formate is reduced in a distillation column, this distillation column simultaneously being employed for other separation functions during work-up of the formic acid.

Abstract: The invention relates to a process for obtaining anhydrous or substantially anhydrous formic acid in which, during the work-up, a compound of the general formula I where the radicals R1 and R2 are alkyl, cycloalkyl, aryl or aralkyl groups, or R1 and R2 jointly, together with the N atom, form a heterocyclic 5- or 6-membered ring, and only one of the radicals is an aryl group, and where R3 is hydrogen or a C1-C4-alkyl group, is employed simultaneously as extractant for formic acid and as antifoam for a distillation process.

Abstract: A process for the hydroformylation of olefins having from 20 to 400 carbon atoms by reaction of the olefins with synthesis gas in the presence of a cobalt carbonyl catalyst and recovery of the cobalt catalyst by extraction of the reaction product with an aqueous acidic solution in the presence of oxygen and separation of the organic and aqueous phases, wherein (a) the aqueous phase is separated from the organic phase by means of gravitational forces to the extent that the proportion of aqueous phase dispersed in the organic phase is 2% by weight or less, based on the organic phase, and (b) the organic phase obtained in step (a) is exposed to an electric field to coalesce the remaining dispersed aqueous phase, is described. In this way, the residual cobalt content of the hydroformylation product can be reduced to less than 1 ppm.

Abstract: The invention relates to a process for the preparation of anhydrous or substantially anhydrous formic acid. The process has the special feature that a liquid of the general formula I where the radicals R1 and R2 are alkyl, cycloalkyl, aryl or aralkyl groups, or R1 and R2 jointly, together with the N atom, form a heterocyclic 5- or 6-membered ring, and only one of the radicals is an aryl group, and where R3 is hydrogen or a C1-C4-alkyl group, employed as extractant is also employed as washing liquid for the offgases produced in the process.

Abstract: The invention relates to an apparatus and a process for the preparation of anhydrous or substantially anhydrous formic acid. This apparatus is constructed partly or entirely of substantially zirconium-free materials.

Abstract: The invention relates to a process for the preparation of anhydrous or substantially anhydrous formic acid.

Abstract: The invention relates to a process for obtaining anhydrous or substantially anhydrous formic acid, in which firstly aqueous formic acid is prepared by hydrolysis of methyl formate and is freed from water in the subsequent work-up. The process has the special feature that steam, which is employed for the hydrolysis of methyl formate and for heating a distillation column serving for work-up, is also used as stripping steam for waste-water stripping. The stripped waste water is produced during work-up.

Abstract: The invention relates to a process for obtaining anhydrous or substantially anhydrous formic acid, in which firstly aqueous formic acid is produced by hydrolysis of methyl formate, with the methanol content in the methyl formate having been reduced in advance. The process according to the invention has the special feature that—before the hydrolysis of the methyl formate—the methanol content of the methanol-containing methyl formate is reduced in a distillation column, this distillation column simultaneously being employed for other separation functions during work-up of the formic acid.

Abstract: A process for the hydroformylation of olefins having from 20 to 400 carbon atoms by reaction of the olefins with synthesis gas in the presence of a cobalt carbonyl catalyst and recovery of the cobalt catalyst by extraction of the reaction product with an aqueous acidic solution in the presence of oxygen and separation of the organic and aqueous phases, wherein (a) the aqueous phase is separated from the organic phase by means of gravitational forces to the extent that the proportion of aqueous phase dispersed in the organic phase is 2% by weight or less, based on the organic phase, and (b) the organic phase obtained in step (a) is exposed to an electric field to coalesce the remaining dispersed aqueous phase, is described.

Abstract: The invention relates to a process for obtaining anhydrous or substantially anhydrous formic acid in which, during the work-up, a compound of the general formula I 1

Abstract: In a process for the hydroformylation of olefins having from 12 to 100 carbon atoms in the presence of a cobalt carbonyl catalyst at pressures of from 100 to 400 bar and at from 100 to 200° C., depressurization and recovery of the cobalt catalyst by extraction with an aqueous acid solution in the presence of atmospheric oxygen, (a) the extraction is carried out in the presence of a polymeric emulsion breaker selected from the group consisting of alkoxylated compounds containing amino, imino or OH groups, and (b) to achieve complete phase separation in the organic phase still containing small amounts of aqueous phase, the formation of relatively large droplets of the dispersed aqueous phase is effected in a coalescence stage.

Abstract: A process for isolating triphenylphosphine (TPP) from a triphenylphosphine/aluminum chloride complex dissolved in chlorobenzene by decomplexation, hydrolysis and extraction using water and subsequent separation of the liquid/liquid dispersion, which is composed of a TPP-containing chlorobenzene phase and of an containing Al and Cl compounds aqueous phase, into a TPP-containing chlorobenzene phase and into a TPP-free, aqueous phase, containing Al and Cl compounds, whereinwater is dispersed in the chlorobenzene phase in a ratio of 0.6-0.95 kg of water per kg of chlorobenzene solution in a 1st mixing apparatus in such a way that the temperature resulting from the hydrolysis is in the range from 60.degree. to 90.degree. C., the dispersion being carried out with residence times of 5-30 minutes and energy densities of 2-10 kW/m.sup.3,a second dispersion is carried out in a 2nd mixing apparatus with residence times of 5-60 minutes and energy densities of 0.05-0.5 kW/m.sup.

Abstract: Very pure maleic anhydride having a stable color is obtained by fractional distillation of crude maleic anhydride by a method in which the maleic anhydride vapor separated off from low boilers and high boilers is partially condensed so that from 0.5 to 15% by weight of the maleic anydride vapor is separated off from the vapor phase as a liquid precondensate, and the remaining very pure maleic anhydride vapor is then completely condensed.

Abstract: A process for the manufacture of 4,4'-diphenylmethane diisocyanate and a mixture of diphenylmethane diisocyanate isomers containing a controllable amount of uretdione and hydrolizable chlorine which comprises feeding crude MDI to an evaporator, condensing a head fraction in two stages in the presence of an inert gas, feeding the first stage condensate to a distillation column, producing a mixture of diphenylmethane diisocyanate isomers as an overhead, producing 4,4'-diphenylmethane diisocyanate as a side draw, and condensing each of the overhead and side draw in two stages in the presence of an inert gas.