Abstract:
A process for catalytic hydrogenation of adiponitrile to hexamethylenediamine at elevated temperature and elevated pressure in the presence of catalysts based on elemental iron as catalytically active component and ammonia as solvent comprises a) hydrogenating adiponitrile at from 70 to 220° C. and from 100 to 400 bar in the presence of catalysts based on elemental iron as catalytically active component and ammonia as solvent to obtain a mixture comprising adiponitrile, 6-aminocapronitrile, hexamethylenediamine and high boilers until the sum total of the 6-aminocapronitrile concentration and the adiponitrile concentration is within the range from 1 to 50% by weight, based on the ammonia-free hydrogenation mixture, b) removing ammonia from the hydrogenation effluent, c) removing hexamethylenediamine from the remaining mixture, d) separating 6-aminocapronitrile and adiponitrile from high boilers individually or together, and e) returning 6-aminocapronitrile, adiponitrile or mixtures thereof into step a).
Abstract:
In a process for preparing alcohols by gas phase hydrogenation of carboxylic acids or esters thereof at elevated temperature and elevated pressure in the presence of catalysts consisting of or comprising, as hydrogenating components, oxides of main group VI and/or subgroup IV, the hydrogenation is carried outa) at from 250.degree. C. to 400.degree. C. and from 5 bar to 100 bar in the presence ofb) primary or secondary alcohols, the molar hydrogen/alcohol ratio being at most 800.
Abstract:
Process for preparing primary amines which have at least one functional group of the formula (—CH2—NH2) and at least one further primary amino group by alcohol amination of starting materials having at least one functional group of the formula (—CH2—OH) and at least one further functional group (—X), where (—X) is selected from among hydroxyl groups and primary amino groups, by means of ammonia with elimination of water, wherein the reaction is carried out homogeneously catalyzed in the presence of at least one complex catalyst comprising at least one element selected from groups 8, 9 and 10 of the Periodic Table and also at least one donor ligand.
Abstract:
Preparing a primary amine by alcohol amination of alcohol with ammonia and elimination of water includes reacting, in a homogeneously catalyzed reaction, a mixture of alcohol, ammonia, nonpolar solvent, and catalyst, in a liquid phase, to obtain a product mixture. The process then includes phase separating the product mixture into a polar product phase and a nonpolar product phase, and separating off the nonpolar product phase. At least some of the nonpolar phase returns to the homogenously catalyzed reaction. The process further includes separating off amination product from the polar product phase. At least some of the catalyst is in the nonpolar phase, and the catalyst accumulates in the nonpolar phase.
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:
A method for the production of C1-C10-alkyl 2-keto-L-gulonates by esterification of 2-keto-L-gulonic acid anhydrate with an anhydrous C1-C10-alkyl alcohol in the presence of an acidic homogeneous catalyst in a reactor cascade comprising at least two reactors, one of these reactors being a tubular reactor, without the water forming in the esterification being removed from the reaction space.
Abstract:
A process for the coproduction of 6-aminocapronitrile and hexamethylenediamine starting from adiponitrile by a) hydrogenating adiponitrile in the presence of a catalyst comprising an element of the eighth transition group as catalytically active component, to obtain a mixture comprising 6-aminocapronitrile, hexamethylenediamine, adiponitrile and high boilers, b) distillatively removing hexamethylenediamine from the mixture comprising 6-aminocapronitrile, hexamethylenediamine, adiponitrile and high boilers, and either cl) distillatively removing 6-aminocapronitrile, and then d1) distillatively removing adiponitrile, or c2) simultaneously distillatively removing 6-aminocapronitrile and adiponitrile into separate fractions is characterized by base of column temperatures below 185° C. in steps d1) or c2).
Abstract:
A cyclic lactam and a cyclic amine are coproduced by reacting an aliphatic alpha, omega-diamine with water in the gas phase in the presence of a heterogeneous catalyst.
Abstract:
A material useful as catalyst for the hydrogenation of alpha, Omega-dinitriles comprises a) iron or a compound based on iron or mixtures thereof, (b) from 0.001 to 0.3% by weight based on (a) of a promoter based on 2, 3, 4 or 5 elements selected from the group consisting of aluminum, silicon, zirconium, titanium and vanadium, (c) from 0 to 0.3% by weight based on (a) of a compound based on an alkali and/or alkaline earth metal, and also (d) from 0.001 to 1% by weight based on (a) of manganese.
Abstract:
A process for preparing aliphatic alpha,omega-amino nitrites by partial hydrogenation of aliphatic alpha,omega-dinitriles in the presence of a catalyst, wherein the catalyst used for the partial hydrogenation comprises (a) iron or a compound based on iron or mixtures thereof and (b) from 0.01 to 5% by weight, based on (a), of a promoter based on 2,3,4 or 5 elements selected from the group consisting of aluminum, silicon, zirconium, titanium and vanadium and (c) from 0 to 5% by weight, based on (a), of a compound based on an alkali metal or alkaline earth metal.