EP3383836A1

EP3383836A1 - Isomerization of mdach

Info

Publication number: EP3383836A1
Application number: EP16805081.3A
Authority: EP
Inventors: Andreas Weickgenannt; Sandra KRAMP; Jan-Oliver WEIDERT; Alexander Panchenko; Artur KOZICKI; Ralph Busch
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2015-12-04
Filing date: 2016-11-30
Publication date: 2018-10-10
Also published as: US20180327347A1; US10329238B2; CN108290822A; KR20180090994A; WO2017093308A1; JP2018535994A

Abstract

The invention relates to a process for the isomerization of a starter mixture, comprising 2,4-diamino-1-methyl-cyclo-hexane, in short 2,4-MDACH, 2,6-diamino-1-methylcyclohexane, in short 2,6-MDACH, or their mixtures, characterized in that the isomerization is carried out in the presence of a support catalyst with zirconium dioxide as a support and ruthenium as an active metal.

Description

Isomerization of MDACH

The present invention relates to a process for the isomerization of a starting mixture which 2,4-diamino-1-methylcyclohexane, short 2,4-MDACH, 2,6-diamino-1-methylcyclohexane, short 2,6-MDACH, or containing mixtures thereof and characterized in that the isomerization is carried out in the presence of a supported catalyst with zirconium dioxide as the carrier and ruthenium as the active metal.

2,4-diamino-1-methylcyclohexane (2,4-MDACH) and 2,6-diamino-1-methylcyclohexane (2,6-MDACH) and mixtures thereof are obtainable by hydrogenation of the corresponding diamino-toluenes. EP-A 0796839 and WO 201 1/033104 describe the hydrogenation of mixtures of 2,4- and 2,6-diamino-toluene.

In the hydrogenation of diamino-toluene diamino-methylcyclohexane be obtained with cis or trans isomerism. When using mixtures of 2,4- and 2,6-diamino-toluene results in a significant number of different cis and trans isomers. For the further conversion of the mixtures of 2,4- and 2,6-MDACH obtained in the hydrogenation to secondary products, it is often advantageous for the mixtures to have a clear stereoisomerism. If the mixtures contain predominantly or even exclusively compounds with a cis isomerism or alternatively with a trans isomerism, this makes it possible to produce end products with a correspondingly defined stereoisomerism.

The earlier European patent application with the application number 14194717.6 (PF 76507) describes a distillative process for the separation of mixtures of 2,4- and 2,6-MDACH in mixtures with predominantly cis- and trans-isomers. In a distillative separation of the mixtures of 2,4- and 2,6-MDACH mixtures of predominantly compounds are obtained in the desired stereoisomerism. Naturally, however, mixtures are also obtained in which the compounds predominate with the opposite unwanted stereoisomerism. In order to make the latter mixtures usable or at least more usable for the intended further implementation, the proportion of the desired stereoisomerism would in turn have to be increased in these mixtures.

The object of the present invention is therefore a process for increasing the proportion of compounds having the desired stereoisomerism, ie a cis isomerism or alternatively a trans isomerism, in 2,4-MDACH, 2,6-MDACH or mixtures thereof. This method should have the highest possible selectivity, the formation of by-products should be avoided.

Accordingly, the method defined above was found. To the starting mixture

The starting mixture is preferably more than 95 wt .-%, in particular more than 98 wt .-% and particularly preferably more than 99 wt .-% of 2,4-MDACH, 2,6-MDACH or mixtures thereof. In a particular embodiment, the starting mixture consists exclusively of 2,4-MDACH, 2,6-MDACH or mixtures thereof.

Preferably, the starting mixture contains both 2,4-MDACH and 2,6-MDACH. In particular, the starting mixture contains

5 to 95 wt .-% 2,4-MDACH and

From 5 to 95% by weight of 2,6-MDACH,

based on the total weight of 2,4-MDACH and 2,6-MDACH. The starting mixture particularly preferably contains

45 to 99 wt .-% 2,4-MDACH and

From 1 to 55% by weight of 2,6-MDACH,

based on the total weight of 2,4-MDACH and 2,6-MDACH. Most preferably, the starting mixture contains

70 to 95 wt .-% 2,4-MDACH and

From 5 to 30% by weight of 2,6-MDACH,

based on the total weight of 2,4-MDACH and 2,6-MDACH. The starting mixture may contain one or more cis or trans isomers of 2,4-MDACH and 2,6-MDACH. The cis / trans isomerism refers to the position of the two amino groups. For a cis isomer, both amino groups are above or below the ring plane. In one trans isomer one amino group is above and the other below the ring plane.

The following are the cis and trans isomers of 2,4-MDACH and 2,6-MDACH:

2,4-isomer 2,6-isomer 2,4-isomer 2,4-isomer ice cis trans trans

5 6 7

2,6-isomer 2,4-isomer 2,6-isomer

trans ice ice

Shown are only diastereomers. Compounds 2 and 7 are meso forms. To each of the other compounds there is still a corresponding enantiomer, so that there are a total of 12 different isomers.

As already described above, 2,4-MDACH and 2,6-MDACH are usually obtained as mixtures by hydrogenation of the corresponding diamino-toluene. From these mixtures, the compounds with the desired isomerism (ice or trans) can be separated. The residue remaining is a mixture in which the compounds with the undesired isomerism (ice or trans) predominate; such a mixture is usually the starting mixture for the process of isomerization as defined above.

In the following, the compounds with the undesired isomerism are each the total amount of all trans isomers of 2,4-MDACH and 2,6-MDACH or, alternatively, the total amount of all cis isomers 2,4-MDACH and 2,6-MDACH 2,4-MDACH and 2,6-MDACH.

In the starting mixture, the proportion of all compounds with the undesired isomerism is generally at least 51% by weight, in particular at least 55% by weight, particularly preferably at least 60% by weight and in a very particularly preferred embodiment at least 70% by weight. , In the starting mixture, the proportion of all compounds having the undesired isomer is generally not more than 100% by weight, in particular not more than 95% by weight, more preferably at least 90% by weight and in a very particularly preferred embodiment not more than 80% by weight. -%.

The above weights are based on the total amount of all trans and cis isomers of 2,4-MDACH and 2,6-MDACH.

The compounds with the undesired isomerism are preferably the total amount of all trans isomers of 2,4-MDACH and 2,6-MDACH.

The catalyst The isomerization of the starting mixture, which comprises 2,4-MDACH, 2,6-MDACH or mixtures thereof, is characterized in that the isomerization is carried out in the presence of a supported catalyst with zirconium dioxide as carrier and ruthenium as active metal. In addition to ruthenium, the supported catalyst may contain further active metals. Consider, for example, Metals of Groups IVb, Vb, Vlb, Vllb, VIIIb, Ib or IIb of the Periodic Table.

Specifically, it is nickel, palladium, platinum, cobalt, rhodium, iridium, copper, manganese or tin.

Preferred further active metals are metals of VIII. Subgroup of the Periodic Table, in particular rhodium, palladium and platinum.

The supported catalyst contains the active metals either in elemental form or in the form of compounds, e.g. B. oxides. The term metal therefore includes below elemental metals or metals, such as those present in chemical bonds, be it in ionic form or covalently bonded form. All weights of the active metals, however, refer only to the metals as such and, in the case of the metal compounds, do not include the other constituents of the compounds. When using the active metals in the form of their oxides or optionally also other compounds is generally carried out at higher temperatures, a reduction of the oxides to the metals, especially in the presence of hydrogen. This reduction can be done at the beginning of the reaction or in advance in a separate step. In a preferred embodiment, it is at least 30 wt .-%, in particular at least 50 wt .-%, more preferably at least 70 wt .-% and most preferably at 90 wt .-% of the active metals of the supported catalyst to ruthenium , In In a particular embodiment, the supported catalyst contains only ruthenium as the active metal.

The supported catalyst contains active metals, or exclusively ruthenium in the particularly preferred embodiment, preferably in a total amount of 0.01 to 20 weight percent, preferably 0.05 to 15 weight percent, particularly preferably 0.1 to 10 weight percent, based on the total weight of supported catalyst.

The preparation of the supported catalyst is known.

The carrier zirconia may e.g. in the form of extrudates, spheres or tablets, for example with diameters of 1 to 10 mm, or preferably in the form of powder. On the support, the active metals z. B. be applied in the form of metal salt solutions. The support can be brought into a desired shape before or after the application of the active metals.

The supported catalyst is preferably dried at temperatures of up to 300 ° C and then calcined at temperatures up to 700 ° C or directly calcined at up to 700 ° C. Preferably, the supported catalyst is activated with hydrogen at a temperature of, for example, 100-350 ° C prior to its use. This can be done after introducing the catalyst into the reactor, for example before or after the start of the isomerization.

Frequently, the supported catalyst is activated before introduction into the reactor and then passivated with oxygen on the surface, so that it can still be stored or is safe to handle. Only in the reactor is then the final activation, z. B. by hydrogen.

The process The isomerization can be carried out in the liquid phase or gas phase. In a liquid phase isomerization, the temperature and pressure are chosen so that the starting mixture during the isomerization is liquid.

Preferably, the isomerization is carried out in the liquid phase.

The isomerization is preferably carried out at a temperature of 20 to 300 ° C, preferably from 50 to 200 ° C, especially from 80 to 200 ° C. This temperature corresponds to the temperature of the starting mixture during the isomerization. In a particularly preferred embodiment, the temperature is a maximum of 180 ° C.

A particularly preferred Temperaurbereich is therefore 120 to 180 ° C or 140 to 180 ° C. The isomerization can be carried out at reduced pressure, atmospheric pressure or overpressure. In general, the pressure is 0 to 500 bar. In particular, he can z. B. 20 to 300 bar. A desired pressure can be adjusted by supplying appropriate amounts of hydrogen or inert gas. Hydrogen is usually used to activate the catalyst and can therefore simultaneously serve to set a corresponding pressure.

For liquid phase reactions, the pressure chosen generally has little effect on the result of the reaction.

In the isomerization, solvents may also be used, preferably those which are miscible with the starting mixture. Preferably, no solvents are used. The isomerization can be carried out continuously or discontinuously (batch process).

In the batchwise operation, the isomerization can be carried out, for example, in a stirred tank or stirred autoclave, a loop reactor, a jet loop reactor, a bubble column or a fixed bed reactor with pumped circulation. The discontinuous isomerization is preferably carried out in a stirred kettle or a stirred autoclave. In the batchwise procedure, the starting mixture and the catalyst are generally initially charged completely in the reactor. The catalyst may be in the batch process in the reactor z. B. be introduced as a fixed bed or in another form. In a preferred embodiment, the catalyst may be suspended in the starting mixture and the resulting suspension filled into the reactor. In the continuous operation, the hydrogenation is e.g. in a continuously operated stirred tank reactor, a continuously operated loop separator, a continuously operated jet loop reactor, a continuously operated bubble column or a continuously operated fixed bed reactor with pumped circulation or a stirred tank cascade. In the continuous operation, the starting mixture or its solution is continuously supplied and the resulting isomerized mixture (product mixture) removed. In the continuous procedure, the catalyst is z. B. as a fixed bed in the reactor and is renewed only when needed and / or regenerated.

The product mixture obtained can be worked up further.

The catalyst can be separated from the product mixture, for example, by a solid-liquid separation, such as filtration, sedimentation or centrifugation. The product mixture obtained contains cis and trans isomers. The proportion of previously predominant, undesired isomers is reduced and the proportion of the desired isomers is increased. An increase in the proportion of desired isomers beyond the thermodynamic equilibrium can not be achieved. The thermodynamic equilibrium of the cis to trans isomers of 2,4-MDACH and 2,6-MDACH is generally about 60:40.

The product mixture is therefore preferably separated by distillation into a cis-rich and a trans-rich fraction. In fraction with the unwanted isomerism can be recycled back into the isomerization process.

The process described above effects effective isomerization of the undesired isomers into the desired isomers. Catalytic reactions on 2,4-MDACH and 2,6-MDACH can easily give rise to monoamines such as methylcyclohexylamine (MCHA for short) by elimination of ammonia. The catalytic process described above produces very little MCHA. The process therefore has a high selectivity with respect to 2,4-MDACH, 2,6-MDACH or mixtures thereof.

Examples

Various catalysts were tested in the process of isomerization of MDACH and measured after the end of isomerization, the isomer distribution and the selectivity. The proportion of cis and trans MDACH in the MDACH starting mixture, the reaction conditions, the selectivity and the ratio of cis to trans MDACH after the end of the isomerization are given in Table 1.

The isomer ratio and the selectivity were determined by gas chromatography after assignment of the signals to the individual isomers by measuring the areas.

Cis or trans-enriched MDACH starting mixtures were initially charged in an autoclave and admixed with the stated amount of catalyst. Subsequently, the autoclave was sealed tight and flooded with hydrogen. After adjusting the temperature according to Table 1, the pressure according to Table 1 was pressed (with hydrogen) and the reaction mixture stirred for the specified time. After the reaction time, the autoclave was depressurized to room pressure and cooled to room temperature.

The composition of the starting mixtures and the end products were investigated by gas chromatography (GC). For this purpose, the mixture is dissolved in dioxane. This solution is injected by means of a syringe into the gas chromatograph. The gas chromatograph is equipped with a 30 m long column, which has an internal diameter of 0.25 mm and a Film thickness of 0.5 μηη has. The column itself contains as stationary phase 35 wt .-% diphenyl and 65 wt .-% dimethylpolysiloxane (column RTX35-amine from Resteck Corporation). Helium is used as the carrier gas or mobile phase. The speed of the helium is set at 40ml / min so that with a set split ratio of 40: 1, there is a constant flow of 1 mL / min He across the column. The gas chromatograph has a Flammenionisationsdetektor to determine the substances to be examined, which is operated at 280 ° C. The column in the gas chromatograph is operated at a temperature in the range of 100 to 250 ° C. In order to be able to determine the percent by weight of the peaks to be determined, a defined amount of a standard (dodecane) is added to the mixture dissolved in dioxane. The mixture thus obtained is injected into the column at an injection temperature of 100 ° C. and an inlet pressure of 1 bar. First, a heating rate of 1 ° C / min is set, which is maintained until a temperature for the column of 120 ° C is reached. Once this temperature is reached, the heating rate of the column is changed to 5 ° C / min and maintained up to the final temperature of 250 ° C. Subsequently, the column temperature is maintained at 250 ° C for 10 minutes.

Catalysts used Catalyst 1:

13% by weight of Ni, 13% by weight of Co, 20% by weight of Cu and 54% by weight of Al ₂ O ₃ (support) Catalyst 2

50 wt .-% Ni and 50 wt .-% Zr0 ₂

Catalyst 3

5% by weight of Ru and 95% by weight of ZrO ₂

Cata- lystet pressure temperature time selectivity ratio [%] [bar] [° C] [h] ice density: trans ice: trans

[%] in the starting mixture in the product mixture

1 1 100 160 12 96 75:25 66:34

2 1 100 160 12 95 75:25 65:35

3 1 100 160 12 99.7 75:25 65:35

3 1 100 160 12 99 20:80 64:36

3 1 100 160 12 99 100: 0 55:45 Example 2

Example 2

8 mL of the ruthenium-supported catalyst according to the invention (5 wt .-% Ru on ZrO-2) were in a heated with an outer jacket tube reactor (5 m height, 2 mm inner diameter) filled. After the reactor was first flooded with hydrogen, it was subsequently charged with cis-enriched MDACH. It was isomerized at varying temperature and hydrogen pressure, the catalyst loading being 1 kg of MDACH / kg of cat ^* hr, and the reactor operated in circulation, that is, part of the discharge was recycled to the reactor. The reaction effluents were analyzed by gas chromatography and the isomer distribution was determined.

Runtime temperature pressure ratio cis- selectivity

[h] [° C] [bar] trans- [%]

Starting material - - 99: 1 -

24 130 150 89: 1 1 99

72 150 150 71: 28 99

96 160 150 65:35 99

121 150 50 72:28 99

146 150 100 72:28 99

171 150 150 71: 29 99

384 150 150 71: 29 99

432 155 150 69:31 99

Claims

claims

1. A process for the isomerization of a starting mixture which comprises 2,4-diamino-1-methylcyclohexane, 2,4-MDACH for short, 2,6-diamino-1-methylcyclohexane, 2,6-MDACH for short, or mixtures thereof, characterized in that the isomerization is carried out in the presence of a supported catalyst with zirconium dioxide as support and ruthenium as active metal. 2. The method according to claim 1, characterized in that the starting mixture to more than 95 wt .-% of 2,4-MDACH,

2,6-MDACH or mixtures thereof.

3. The method according to claim 1 or 2, characterized in that the starting mixture 5 to 95 wt .-% 2,4-MDACH and 5 to 95 wt .-% 2,6-MDACH, based on the total weight of 2,4- MDACH and 2,6-MDACH.

4. The method according to any one of claims 1 to 4, characterized in that the isomerization is carried out at a temperature of 80 to 200 ° C. 5. The method according to any one of claims 1 to 5, characterized in that the isomerization is carried out continuously.