HU202477B - Process for joint production of cyclohexylamine and dicyclohexyl-amine by hydrogenating aniline - Google Patents

Abstract

Cyclo-hexyl-amine and Di-cyclo-hexyl-amine is prepd simultaneously by catalytic hydrogenation of aniline. Prepn at 160-280 deg.C, 70-130 MPa, 0.05-0.8 cu dm/ cu dm Xhr aniline related space-velocity and at a 200-1500 cu.m/cu.m gas/liquid ratio Hydrogen gas, or hydrogen gas contg. gas mixt is used in the presence of a supported catalyst contg 20-70% Ni and onem or several promoters. Essentially 0.015-15% amine or general formula R. R1 R2N is present. R = hydrogen atom or 1-3C alkyl gp. and R1 add R2 = 1-3C alkyl gps. - R3 = substd. phenyl-alkyl gp, substd cyclo-alkyl-alkyl gp, a substd, five member heterocyclic gp joined via an alkylene gp, a bi-cyclo-alkyl-alkyl gps. Substd and possibly unsatd piperidine gps are formed by gps R4,R5 and a N. atom, salts and N-oxides of the prod. are fungicides harmless to plants.

Description

The present invention relates to a process for the co-production of cyclohexylamine with dicyclohexylamine by hydrogenation of the aniline, varying the ratio of the products.

Both cyclohexylamine and dicyclohexylamine are important chemical raw materials. Cyclohexylamine is mainly used in the pharmaceutical industry as a starting material for the preparation of various drugs, while dicyclohexylamine is mainly used in the manufacture of corrosion inhibitors and rubber auxiliaries.

Cyclohexylamine and dicyclohexylamine are commercially produced primarily from the catalytic hydrogenation of aniline. Precious metals and skeletal catalysts can also be used as catalysts, but the use of the former is hindered by their cost and the use of the latter by their flammability. Therefore, in practice, supported nickel or cobalt catalysts are used for hydrogenation. In the catalytic hydrogenation of aniline, the ratio of cyclohexylamine to dicyclohexylamine in the product varies depending on the nature of the catalyst used. The use of a cobalt catalyst favors the formation of cyclohexylamine, but relatively vigorous conditions are required to achieve proper conversion. By using nickel supported catalysts, conversion can be achieved even under milder conditions; however, during the hydrogenation, dicyclohexylamine is formed as a major product with relatively small amounts of cyclohexylamine.

The hydrogenation of an aniline supported in the presence of a nickel catalyst is described in U.S. Pat. 218,989 and 226,299. Czechoslovakia, No. 3,240,286; Federal Republic of Germany and U.S. Patent No. 7028,368. Japanese Patent Specification. A common feature of the disclosed patents is the exclusive production of either cyclohexylamine or dicyclohexylamine, which they attempt to achieve by appropriate choice of reaction parameters and modification of the catalyst used. In the case of cyclohexylamine production, the supported nickel catalyst is modified with sodium ions (British Patent No. 964,542). A common disadvantage of such solutions is that once a catalyst charge has been adapted to produce one product (e.g. cyclohexylamine), the other product (e.g. dicyclohexylamine) can no longer be manufactured.

Since both cyclohexylamine and dicyclohexylamine are valuable chemical raw materials, the market demand and price of which can vary, it would be advisable to hydrogenate the aniline to form cyclohexylamine and dicyclohexylamine side by side in the reaction. however, the ratio of the product can be varied within wide limits to suit the particular requirements without the need to modify the particular catalyst charge and consequently to change the catalyst charge according to each desired product composition.

Our experiments have shown that when aniline (R *) 2 NH is an amine of the formula R ¹ 2

Hydrogenated in the presence of a C 1 -C 3 alkyl group on a supported nickel catalyst, the amount and quality of the added amine can be varied within a wide range of amounts of cyclohexylamine and dicyclohexylamine. Without the addition of an amine, the hydrogenation of the aniline results in a product mixture of 75-85% by weight of dicyclohexylamine and 15-25% by weight of cyclohexylamine, depending on the nature of the catalyst used and the reaction conditions. Addition of the amine (R ') 2 NH to the cyclohexylamine changes the composition of the product mixture; For example, when aniline is fed with 10% diethylamine, the weight ratio of cyclohexylamine to dicyclohexylamine in the product mixture increases under otherwise unchanged reaction conditions from 17:83 to 45:55. Amines of the formula (R ') 2 NH exert their effects reversibly, that is, when the addition of the amine is stopped, the composition of the product mixture returns to its initial value (measured in the absence of the amine). A further advantage is that the amines of the formula (R *) 2 NH do not impair the conversion of the aniline but at the same time reduce the proportion of by-products (cyclohexane and benzene) formed by deamination.

The invention thus relates to a process for the production of cyclohexylamine and dicyclohexylamine together at an aniline temperature of 160280 ° C, a pressure of 7.0-13.0 MPa, a space velocity of 0.05-0.8 dm ³ / dm ³ x an hour and 200- With a gas to liquid ratio of 1500 m ³ / m ³ , by reduction with a hydrogen gas or hydrogen gas mixture in the presence of a supported nickel catalyst containing 20 to 70% nickel and optionally one or more promoters. According to the invention, the reaction is carried out in the presence of 1 to 15% by weight of an amine of the formula (R *) 2 NH, wherein R ^{1 is C} 1-3 alkyl, relative to the aniline.

The hydrogenation of the aniline is carried out on a fixed catalyst bed in continuous operation. The temperature is preferably from 185 to 240 ° C, the pressure is preferably from 9 to 1.0 MPa, the spatial velocity for aniline is preferably from 0.15 to 0.3 dm ³ / m ³ x hour, and the gas to liquid ratio is preferably from 400 to 600 m ³ / dm ³ . The hydrogen gas may be optionally diluted with an inert gas such as nitrogen gas or hydrocarbon gas; in this case, the pressure values given refer to the partial pressure of the hydrogen gas.

The supported nickel catalyst preferably has a nickel content of 40-65% by weight. Catalysts may contain conventional supports, such as alumina and silica. Optionally, the supported nickel catalyst may contain one or more known promoters. The term 'promoter *' refers to additives that accelerate the main reaction and suppress side effects; the term "promoter" does not include catalyst additives previously used to alter the cyclohexylamine / dicyclohexylamine ratio. As a promoter, the catalyst is for example calcium,

Contains iron, magnesium and / or zinc, preferably up to 5% by weight of promoter (s). Useful promoters are described, inter alia, in the patents cited above.

Amines of the formula (R ¹ -NH) are preferably used in an amount of 1 to 51% based on the aniline. Among the amines of the general formula (R *) 2 -N, diethylamine is particularly preferred.

The invention is illustrated in detail by the following non-limiting Examples.

Example 1

In this example, for comparison purposes, a known process is described wherein the aniline is hydrogenated in the absence of an amine additive with a nickel supported catalyst.

Pure aniline was added to a 200 cm ^{2 3} reactor filled with 59% nickel alumina supported catalyst. The reactor was operated at 80 bar and 200 ° C. The raw material solution was fed at a rate of 0.05 dm ³ / h into the reactor, which corresponded to 0,25dm relation to the aniline ³ / dm ³ per hour rate. The reduction was carried out with pure hydrogen gas. Gas chromatography analysis of the product mixture revealed 75% dicyclohexylamine, 15% cyclohexylamine and 10% deamination hydrocarbon by-products (cildohexane and benzene). The weight ratio of dicyclohexylamine to cyclohexylamine in the product solution was 83:17. The crude product mixture was purified by distillation. In this way, the two products were isolated by gas chromatography with a purity greater than 99%.

Example 2

The starting material used was a mixture of 90% aniline and 10% diethylamine. The hydrogenation was carried out according to the parameters given in Example 1, except that by increasing the spatial velocity of the stock mixture, the spatial velocity with respect to aniline was set at 0.25 dm ³ / dm ³ x hour. The weight ratio of dicyclohexylamine / cyclohexylamine in the product mixture was changed to 55:45. Conversion remained above 99%; however, the proportion of deamination by-products (hydrocarbons) fell below 5%. Diethylamine mixed with the starting material, since its boiling point is significantly lower than the boiling point of the other components of the product mixture, was separated by distillation and reused. The mixture obtained after removal of diethylamine was processed as described in Example 1. Cyclohexylamine and dicyclohexylamine were obtained in a purity greater than 99%.

Example 3

The procedure described in Example 2 was followed except that 5% by weight of aniline was added. Conversion remained above 99%; the weight ratio of cyclohexylamine / dicyclohexylamine in the product mixture is 32; Changed to 68. The product mixture was worked up as described in Example 1. Cyclohexylamine and dicyclohexylamine were obtained in a purity greater than 99%.

Example 4

The procedure described in Example 2 was followed except that 1% diethylamine was added to the amine. The conversion was still above 99%; the weight ratio of cyclohexylamine / dicyclohexylamine in the product mixture was changed to 26:74. The product mixture was worked up as described in Example 2. Cyclohexylamine and dicyclohexylamine were obtained in a purity greater than 99%

Example 5

The procedure was as described in Example 2 except that the reducing agent used was a gas mixture from a catalytic gasoline reformer containing 77% hydrogen and 231% C1-C5 hydrocarbon. The pressure was adjusted to 110 bar and the temperature to 230 ° C. . The product mixture contained cyclohexylamine and dicyclohexylamine in a weight ratio of 45:55. The product mixture was worked up as described in Example 2. Cyclohexylamine and dicyclohexylamine were obtained in a purity greater than 99%

Claims (3)

PATIENT INDIVIDUAL POINTS A method for the preparation of cyclohexylamine and dicyclohexylamine together at aniline 160-280 ° C at a pressure of 7.0 to 13.0 MPa, 0.05 to 0.8 dm ³ / dm ³ x hour aniline and 2001500 m ^{With 3} / m ³ gas / liquid ratio, 20-70 wt.% Nickel and optionally one or more promoters containing nickel in the presence of a catalyst with hydrogen gas or hydrogen gas, characterized in that the reaction is 1-15% by weight of the aniline ( R *) 2 NH amine of formula - in the presence of: - wherein ^R1 is C1-C3 alkyl 2. The method of claim 1, wherein the amine of formula (R *) 2NH is used in an amount of from 1 to 5% by weight of the aniline 3. A process according to claim 1 or 2 wherein the amine of formula (R ') 2NH is diethylamine.