CS197311B2 - Method of catalysis of amino compounds chemical conversion - Google Patents

Description

The present invention relates to the chemical conversion of amino compounds of the formula R 4 -NH 2 to the corresponding N-alkyl derivatives, N-cycloalkyl derivatives, N-aralkyl derivatives and / or N-aryl derivatives of aliphatic, cycloaliphatic, araliphatic and / or aromatic amino compounds by reductive alkylation with R 5 or R 1 -CHO in the presence of a supported catalyst containing platinum and optionally rihenium, wherein R 1, R 2, R 3 and R 4 are each independently alkyl, cycloalkyl, aryl, or aralkyl of up to 10 carbon atoms, and the alkyl group may optionally be substituted with alkoxy C 1 -C 4 and the aryl group may be substituted with a thiosubstitute, or R 2 and R 3 together form a cycloalkyl group of up to 10 carbon atoms.

N-substituted amino compounds are used as an admixture in anti-corrosion compositions. They are also valuable starting materials or intermediates in the synthesis of many pharmacologically active substances and herbicidally active substances.

In the description and definition of the invention, the terms "aliphatic", "cycloaliphatic", "araliphatic", "aromatic", "alkyl", "cycloalkyl", "aralkyl" and "aryl" mean compounds or groups in which the hydrocarbon structures may optionally carry additional functional groups, such as halogen, thio, alkoxy, etc.

Numerous methods are known in the art for the preparation of N-substituted amino compounds.

According to one group of known methods, the N-substituent is formed by reacting the corresponding amine compound with a hydrocarbon corresponding to the desired substituent and containing a reactive group, primarily a halogen atom or a hydroxyl group [Houben-Weyl: Methoden der organischen Chemie, XI / 1 'Pages 24 and 108 (1957)],

In reaction with hydrocarbon halides, the amino compound reacts with alkyl halides, cycloalkyl halides, aralkyl halides or aryl halides. In this reaction, hydrogen halide is cleaved to form an acid addition salt with the N-substituted amino compound. Therefore, the end product must be released from the salt, which is an additional process that involves the formation of large amounts of by-products. Taking into account the necessary separation and cleaning processes, the process is very labor intensive and cannot be automated. It is therefore usually used only for preparative and laboratory purposes.

In the preparation of N-substituted amino compounds from primary amines and hydroxyl group hydrocarbons, the final product is obtained in the form of the free base, but catalysis of the reaction causes problems. If the reaction is carried out homogeneously in a catalytic manner in the presence of acids, corrosion resistant devices are required and the acid used as catalyst must be removed from the final product by a special procedure. In a heterogeneous catalytic process, the reaction may be accelerated by dehydration catalysts (aluminum, silicon, titanium, thorium, chromium, etc.) or ihydration-dehydration catalysts (noble metals, nickel, copper (II) chromite, etc.). time, generally 5 to 10 hours, and catalyst activity decreases rapidly.

More preferred and more modern than these methods is N-alkylation of olefins [Stroh: Angew. Chem. 69, 124 (1957). A disadvantage of this process is that alkali metals are needed as catalysts and can be poorly recovered, and here the reaction time is several hours.

The most widespread method for producing N-substituted amino compounds is reductive alkylation with oxo compounds. Catalytically activated hydrogen is used as the reducing agent, and the reaction is preferably carried out at elevated pressure. Nickel, cobalt, copper (II) chromate and noble metals are primarily used as catalysts. When using nickel, cobalt and copper (II) chromite as the catalyst, the reaction proceeds relatively slowly and takes several hours (anh. 37, 567/19501, Ind. Eng. Chem. I (3), 179/19621). It is further disadvantageous that the selectivity of these catalysts is insufficient; the entire excess of oxo compound used as reactant is hydrogenated to alcohol. This side reaction requires additional purification procedures and results in an extremely high consumption of hydrogen and oxo compound, making the process uneconomical. The side reactions are also disadvantageous in terms of the heat of reaction of the main reaction.

The use of platinum metals such as palladium and platinum accelerates the alkylation reaction, but the selectivity is still not sufficient. Various methods have been proposed to increase the selectivity of the reaction. One possibility is to use platinum metals that are less active but are significantly more expensive than platinum, such as ruthenium and rhodium. According to other methods, palladium and platinum activity is reduced by sulfidation. While both methods are useful for increasing the selectivity of N-alkylation, it simultaneously reduces the alkylation activity of the catalyst, thereby increasing the reaction time [Rylander: Cat. Hydr. over Platinum Metals 295 (1967)].

Hungarian patent specification 160,732 discloses a process for preparing certain N-substituted amino compounds by reductive alkylation with oxo compounds and hydrogen. In this process, platinum is used as a catalyst and compounds of the alcohol and / or ether type are added to the system to prevent side reactions. These additives do not reduce the favorable alkylating activity of the planin catalyst, but do greatly suppress the hydrogenation of the oxo compound. In this way yields of over 95% can be achieved, the selectivity being in some cases about 90%. In this process, the amine and oxo compound are reacted in a molar ratio of 1: 4. It is characteristic of the reaction time and the stability of the catalyst that, while maintaining a space velocity of 2 h @ ^-1 in a continuously operating device, the catalyst must only be changed every 500 hours.

The disadvantages of the prior art have been eliminated by the process of catalysing the chemical conversion of the amino compounds according to the invention, which is characterized in that the reductive alkylation is carried out in the presence of a halogen-activated catalyst supported on alumina as a support.

The process according to the invention greatly increases the life of the catalyst and additions are not required.

The catalyst may optionally contain rhenium as a metal component in addition to platinum. The amount of metal component is usually 0.1 to 10% by weight, preferably 0.2 to 6% by weight, based on the carrier.

As used herein, the term "alumina as carrier" refers to natural or synthetic carriers containing at least 30% by weight of alumina, calculated on the basis of their oxide composition. Naturally, pure alumina can also be used.

The catalyst used in the process of the invention preferably contains chlorine and / or fluorine as the halogen activator. The catalyst contains activator in an amount of 0.02-5% by weight, preferably 0.05-3% by weight, based on the support. The finding that a halogen activator does not reduce the alkylation activity of the catalyst but increases it substantially is extremely surprising. It is further surprising that a substantial increase in activity is very selective; in the presence of a platinum / platinum / rhenium catalyst containing a halogen activator and supported on alumina as carrier, only -5 to 10% of the oxo compounds used in excess are hydrogenated to the corresponding alcohol. Therefore, it is unnecessary to reduce in any way. the activity of the catalyst and furthermore it is unnecessary to use additives according to Hungarian patent specification 160 732. The surprising effect underlying the invention can be explained by the as yet unclear, very favorable mutual relationship.

With dumbbell between alumina, halogen and amino.

Such a large increase in catalytic activity means that the reductive rate alkylation can be carried out in the industrial practice, as yet unprecedented. at a rate of 4 to 6 h ^-1 . In addition, the molar ratio between the starting amino compound and the oxo compound used as the reactant can be greatly reduced. Already at a molar ratio of 1: (1.5 to 3.5), the reaction is almost stoichiometric. Catalyst activity changes barely within 1500 to 2000 hours of operation. Due to this remarkable stability and achievable high space velocity, several tons of N-substituted amino compounds can be produced using 1 kg of catalyst. This enables extremely economical production.

The halogen activator may be deposited on the alumina support in a manner known per se either during the production of the metal catalyst support or thereafter. When the halogen activator is applied to a support with a metal catalyst in its manufacture, hydrogen halides are expediently used as the reactant. However, the catalyst may also be formed from halogen metal complexes. The halogen activator can also be applied to the preformed metal catalyst support in a manner known per se. This can be done directly in a hydrogenation reactor or some other device. If the halogen activator is to be applied to a preformed support with a metal catalyst, the following is expediently carried out as follows:

The metal catalyst deposited on the support 1h of any structure and shape (crystalline, amorphous, liquid, extruded, lozenged, irregularly shaped, etc.) is removed to remove moisture, e.g. Dry for 5 hours at atmospheric pressure at 200-250 ° C in a gas stream. As the drying gas stream, for example, hydrogen, nitrogen, argon, methane or mixtures thereof can be used. Several hundred liters of drying gas are required per liter of catalyst. The heating rate is preferably 50 ^and C / h. If flammable gas is used for drying, it is removed from the apparatus after drying by flushing with inert gas. A few percent of oxygen is then admixed to the gas mixture, the temperature is raised to 450 to 480 ° C, and the pressure is raised to 0.5 to 1.0 MPa. When the stated temperature and pressure is reached, a calculated amount of a volatile organic halogen compound such as dichloroethane, trichloroethylene, carbon tetrachloride, chloroform, dichlorotetrafluoroethane, tetrafluoroethylene or the like is added to the gas stream. Under the conditions prevailing in the reactor, SO evokes halogen from these compounds and binds in the catalyst. Since no hydrogen halide is formed in the weakly oxidizing atmosphere and the total amount of halogen released is bound to the support surface, no corrosion damage occurs.

And correspondingly powdered activated catalyst may be in batch or k ⁶ continously process uses also suspended, but is conveniently used as a fixed bed. The reductive alkylation can be carried out batchwise or continuously, continuous operation being preferred. Before starting the alkylation, the apparatus is purged with an inert gas, then the inert gas is replaced with hydrogen or a hydrogen rich gas mixture. The pressure in the reductive alkylation is 1.0 MPa to 6.0 MPa, the temperature 170 to 300 ° C. The amount of feed gas depends on its hydrogen concentration, molar ratio and molar mass of the amino and oxo compound, the space velocity and the shape of the reactor. Several hundred liters of hydrogen or a hydrogen rich gas mixture are calculated per liter of the mixture. If the process is carried out batchwise, the activated, pulverized catalyst is kept in the reaction mixture by stirring or by introducing gas and after the reaction is filtered, centrifuged or removed from the product mixture by another suitable separation process. The production mixture contains, besides the water formed in the reaction, an excess of alkylating components and a few percent alcohol, the desired N-substituted amino compound or the desired N-substituted amino compound in a yield of 95 to 99%. The target compounds are isolated from the production mixture in a manner known per se.

As already mentioned, various aliphatic, cycloaliphatic, araliphatic or aromatic primary amines can be used as starting materials in the process according to the invention. These compounds may carry additional functional groups on the hydrocarbon moiety, for example oxygen, nitrogen or sulfur containing groups. The oxo compounds used as the reactant may be aliphatic, cycloaliphatic, araliphatic or aromatic ketones or aldehydes which, like the amines, may carry additional functional groups on the hydrocarbon moiety.

Various amino and / or oxo compounds can also be reacted simultaneously in the process of the invention. In this case, a mixture of the respective N-substituted amines is obtained.

Since the system according to the invention does not contain any corrosive substances, the process can also be carried out in devices made of ordinary carbon steel. The elements of continuously operating equipment are the same as those used for continuous heterogeneous catalytic hydrogenation: dosing tank, feed pump, water source, compressor, preheater, reactor, cooler, pressurized gas and liquid separator, product tank, gas circulation compressor, control apparatus. In discontinuous operation, an autoclave equipped with a stirring device is used to keep the catalyst floating, heatable, refrigerable and suitable for working under pressure, or a similar device is used. The invention is further illustrated by the following non-limiting examples.

Example 1

The mixture of cyclohexylamine and cyclohexanone in a molar ratio of 1: 2.8 at a space velocity of 5.5 h ^-1 , in a continuously operating apparatus, is hydrogenated with pure hydrogen at a pressure of 4.0 MPa at 265 ° C. The reactor is charged with a catalyst containing 3.6 vol. platinum, which is deposited on the alumina carrier. 2.8 wt. % fluorine activator. At 1850 operating hours, the catalyst showed no significant loss of activity. The product contains 97.2 wt. % dicyclohexylamine based on the amino compound. From the cyclohexanone excess, an average of 6.5 wt. Example 2 o-Toluidine and proplonaldehyde at a molar ratio of 1: 1.8 at a space velocity of 3.5 hr ¹ , in a continuously operating device, at a pressure

4.5 MPa and 215 ° C hydrogenated with ammonia synthesis gas (75% Hz and 25% N2) The reactor is charged with a catalyst containing 0.5 wt% platinum and 0.5 wt% rhenium, the carrier of which consists of 80% by weight of alumina and 20% by weight of aluminum silicate were applied to the support as described above by 0.8 wt% fluorine and 0.6 wt% chlorine as activator. After removal of the non-amine compounds, the production mixture contained 95.7% by weight of N-propyl-o-toluidine and, on average, 4.8% of the excess propionaldehyde sc hydrogenated.

Example 1 a d 3

A 1: 3.0 molar ratio of n-butylamine and ethoxyacetone is hydrogenated with pure hydrogen in a continuously operating apparatus, at a space velocity of 6 h @ ¹ , at a pressure of 3.5 MPa and 195 ° C. The reactor is charged with a catalyst containing 1.5 wt. % platinum and 0.8 wt. % of rhenium and which is supported on alumina and to which 0.6 wt. % chlorine activator. At 1600 hours of operation, the catalyst showed no significant loss of activity. The production mixture contains an average of 98.8 wt. % N-ethoxyisopropylbutylamine based on amino compounds. Of the excess ethoxyacetone, on average 3.2 wt.

He attaches

A 1: 3.5 molar ratio of p-aminothiophenol and benzaldehyde was hydrogenated in an autoclave at 50 psi at 210 ° C with ammonia synthesis gas (75% H 2 and 25% N 2). Based on the reaction mixture, 8 wt. percent catalyst, which on a carrier consisting of 70 wt. % alumina and 30 wt. % mordenite contains 1.1 wt. % platinum and 0.3 wt. % fluorine activator. After a 20 minute reaction, 95.4 wt. % p-N-benzylaminothiophenol based on the amine components. The benzaldehyde used in excess is hydrogenated to 9.5 wt. Example 5

A mixture of 2-ethyl-6-methylaniline and methyl ketone in a molar ratio of 1: 2.2 with a space velocity of 5 h ^-1 at 3.5 MPa and 220 ° C, in a continuously operating apparatus, is hydrogenated with pure hydrogen. on carrier alumina, it contains 0.6 wt. % of platinum and to which 0.6 wt. % fluorine activator. After 1600 hours of operation, the catalyst shows no significant activity losses. After removal of the non-aminated compounds, an average of 98.3 wt. % N-isobutyl-2-ethyl-6-methylaniline. From an excess of methyl ethyl ketone, an average of 5.5 wt. ° / o. Example 6 (comparative example)

A mixture of 2-ethyl-6-methylaniline and methyl ketone in a molar ratio of 1: 2.2 with different space velocities is hydrogenated under the conditions of Example 5. However, the catalyst does not contain a halogen activator. The results are shown in the table below:

10

1 301 601 901 1201 Experimental time .až to to to to hours 300 600 900 1200 1500 space velocity ^h1 2 3 4 5 2 the target product after removal of the non-cereal compounds; % 90.8 83.6 76.3 71.2 78.5 hydrogenated content of excess methyl ethyl ketone, wt. % 34.1 . 31.2 28.0 24.4 29.8

The activity of the catalyst therefore decreases substantially.

Claims (3)

SUBJECT VYNALEZU CLAIMS 1. A method for catalyzing the chemical conversion of amino compounds of the general formula R4-NH2 to the corresponding N-alkyl derivatives, N-cycloalkyl derivatives, N-aralkyl derivatives and / or N-aryl derivatives of aliphatic, cycloaliphatic, araliphatic and / or aromatic amino compounds by reductive alkylation with oxo compounds of the general formula R2-CO-R3 or R1-CHO in the presence of a supported catalyst containing platinum and optionally rhenium, wherein R1, R2, R3 and R4 each independently represent an alkyl, cycloalkyl aryl or aralkyl group having at most 10 carbon atoms, and the alkyl group may optionally be substituted with a (C 1 -C 4) alkoxy group and the aryl group may be substituted with a thiosubstitute, or R 2 and R 3 together form a cycloalkyl group of up to 10 carbon atoms, characterized in that the reductive alkylation is carried out in the presence of a halogen activated catalyst supported on alumina as carriers. 2. Process according to claim 1, characterized in that fluorine and / or chlorine is used as halogen activator. Process according to claim 1, characterized in that a catalyst containing 0.1 to 10% by weight, preferably 0.2 to 6% by weight of platinum and 0.02 to 5% by weight, preferably 0.05 to 3% by weight, is used. % by weight of the halogen activator based on the support.