HU207708B - Process for producing n,n-dialkyl derivatives of aniline and toluidines - Google Patents

Abstract

N,N-di:alkyl-derivs. of aniline and toluidines of formula (I), where R1 : 1-6C alkyl gps. and R2 : H atom or Me gp. - are prepd. from anilines or toluidines and alcohols of formula R1OH (1) in the presence of hydrogen and catalyst. The catalyst contg. 87.5 - 95 mole% Cu-(11)-oxide and 5-12.5 mole% Cr(III)-oxide is pretrated. Reaction steps are needed for the introduction of a Me gp. and single step for alkyl gps. of longer chain length. - (Dwg.0/0)

Description

The present invention relates to aniline and toluidines, which are hydrogen and catalysts for the preparation of the Ν, dial-dialkyl derivatives of aniline and toluidines of the formula I in which R ^{1 is C} 1-6 straight or branched alkyl and R ^{2 is} hydrogen or methyl. in the presence of (II) with alcohols of the formula: - wherein ^R1 is as defined above -, by reaction of.

The amines of formula (I) are widely used intermediates in the dye and dye industry, the pesticide industry and the plastics industry.

A known method for the preparation of N, N-dialkyl derivatives of aniline and toluidines is the reaction of the primary amine with an alkyl halide or dialkyl sulfate. Thus, N, N-diethyl-meta-toluidine is obtained in almost 93% yield by methylation of N-N-diethyl-metatoluidine with ethyl chloride. Czechoslovak patent. The reaction is carried out in the presence of 30% aqueous sodium hydroxide and iodine in a nitrogen atmosphere at 180 ° C for 6 hours. Diethyl sulfate is used for N-ethylation of toluidines according to U.S. Patent No. 539,031. Soviet Patent Specification. The “Rev. Roum. Chim 1988, 33 (3), 289. " The lem, diet-diethylation of meta-toluidine can be carried out with diethyl sulfate in xylene solvent in the presence of sodium bicarbonate at a temperature of 135-145 ° C. Ν, Ν-Dimethylation of para-toluiclin in aqueous solution in the presence of sodium hydroxide and sodium bicarbonate at 150-200 ° C was performed with dimethyl sulfate according to the procedure described in "Meat Hsuek Tang Pao, 1979, (2), 122." copyright notice. Ν, Ν-Dimethyl-para-toluidine is formed in 81% yield. The use of both alkyl halides and dialkyl sulfates produces acidic, corrosive by-products and the alkylating agent is highly toxic. The processes are usually carried out in batch mode, the product being purified in several steps. In addition to the tertiary amine, there is always a secondary amine in the reaction mixture. This is a problem for the methyl derivatives because they cannot be separated by fractional distillation due to the proximate boiling points of the secondary and tertiary amines.

A very widely used alkylating agent is an alcohol having the same number and structure of alkyl atoms to be introduced. Alkylation is generally carried out in the presence of an acidic catalyst in the temperature range of 170-400 ° C. Most of the processes use a mineral acid, in particular sulfuric acid or phosphoric acid, as catalyst. A2 335 906; 348738; 2658728; and U.S. Patent Nos. 2754285; U.S. Patent Nos. 4,198,125 to 5,193 to 5,193, discloses the use of phosphoric acid. The conversion is never complete, with the primary and secondary amines always present alongside the tertiary amine and the alkylated derivative of the aromatic ring in the reaction mixture.

The use of phosphorus oxychloride as catalyst is disclosed in U.S. Patent No. 2918023. German patent specification. The yield of Ν, Ν-dimethylaniline is low, only 17%.

Zeolites mixed with alumina may be used as acidic catalysts, in addition, alumina may be pure or mixed with silica.

When pure aluminum silicates are used, the processes are characterized by high yields (400 ° C) and low yields (40%). This is reported by Costa, Ν. E. et al., An. Quim., Ser. A, 1981, 77 (3), 428-32], Polymerization of aromatic amines as a side reaction is significant. The use of an alumina-silica mixture catalyst is disclosed in U.S. Patent No. 7,381,331. Japanese Patent Specification. The process is batchwise and produces 280, Ν-dimethylaniline (98.1%) in 3 hours at 280 ° C. Japanese Patent No. 7,890,227 also discloses the use of a mixed alumina-silica catalyst for the N-ethylation of metatoluidine. The N, N-diethyl derivative is 9% present in the reactor product during ethylation at 270 ° C.

The use of ZSM-5 zeolite is reported by Chen, P. Y. et al. (Stud, Surf. Sci. Catal. 1986, 28, 739-46). During the N-methylation of aniline, C-methylanilines were also present in the reactor product.

When copper is applied to aluminum silicate and used as a catalyst in the N-methylation of aniline, monomethylaniline is formed primarily, e.g. European Patent Specification.

Sulphates of various metals (nickel, cobalt, iron, aluminum and manganese) are also used as catalysts for N-methylation. Thus, Ν, Ν-dimethylaniline is formed with nickel sulfate catalyst at 320 ° C in 98% yield. according to Japanese Patent Specification.

High yield (90%) of N, N-dimethyl-para-toluidine is formed in the presence of a homogeneous catalyst of ruthenium chloride tributyl phosphite at 180 ° C. Became. 1988, (3), 449-52.

Another large group of catalysts are metal oxide mixed catalysts. No. 61,238,768. The Japanese Patent Application utilizes a mixture of iron-Germanic itime chromium oxide. At 320 ° C, 82% by weight of N-monomethylaniline produces 10% by weight of N, N-dimethylaniline. Copper (II) chromium (III) oxide catalyst is disclosed in U.S. Pat. The method described in Japanese Patent Specification No. 6,198,198. They are derived from N-methylaniline starting material and are N-methylated in a continuous mode at atmospheric pressure at 270 ° C in the presence of hydrogen with a 1: 1.5 molar ratio of N-methylaniline to methanol. The desired Ν, Ν-dimethylaniline is formed in 90% yield. Although not mentioned in this specification, separation of the unmodified N-methylaniline and the target product can cause considerable difficulties for known reasons.

In the preparation of the methyl derivatives, distillation separation difficulties occur due to the near boiling point of the secondary and tertiary amines. For these compounds, the product mixture requires further processing. The recovery of tertiary amines in high purity is usually accomplished by chemical methods which utilize different reactivity of amines of different orders. As a result, the processes are complex and require the generation of significant amounts of by-products.

It is generally known to produce ál, Ν-dimethylaniline by adding the appropriate amount of acetic anhydride to the reaction product. so after the aniline and

20 N-methylaniline is acetylated, Ν, Ν-dimethylaniline can be distilled from the mixture. Another method for the removal of primary and secondary amines is the method of Giumanini, A.G. et al., Boll. Chim. Farm. 1987, 126 (3), 129-32]. According to this, the product mixture is treated with a sufficient amount of formaldehyde sodium borohydride-sulfuric acid mixture to convert the remaining primary and secondary amines to a tertiary amine. These processes require additional and complex chemical operations and sometimes require expensive reagents that are difficult to handle and expensive.

It is an object of the present invention to provide an efficient process for the preparation of Ν, dial-dialkyl derivatives of anilines and toluidines which, when methylated, directly produces Ν, Ν-dimethyl derivatives in the reactor of sufficient purity and concentration. There is no need for complicated post-treatment of the product mixture, as the target product can be recovered by simple fractional distillation and no large amount of by-product is polluted. By introducing alkyl groups longer than the methyl group, the process can significantly shift the ratio of secondary tertiary amines to tertiary amine formation in the product mixture to yield the desired tertiary amine in good yield and purity after distillation of the product mixture. Since the addition of alkyl groups longer than methyl does not present any difficulty in separating the secondary and tertiary amines, the secondary amine isolated from the reaction mixture can be traced back to the beginning of the process. The advantage of the process in this case is the high tertiary amine yield and consequently the low recirculation flow rate. The process can be carried out in a conventionally constructed continuous operation apparatus.

In our experiments we have found that when the N-alkylation of aniline and toluidines is carried out with the appropriate alcohol in the presence of a hydrogen or hydrogen-inert gas mixture using copper (II) -chromium (III) oxide catalysts of appropriate composition and activation pretreatment as well as methylation carried out in two or more successive steps, the methylation is carried out with a selectivity of 99.8% or greater for the formation of the tertiary amine; In the case of N, N-dialkyl derivatives having a longer chain, the yield of tertiary amines is reduced by 80-95%, depending on the length of the chain, by increasing the length of the chain by using the process in one step. The desired tertiary amine can be separated from other components of the reactor product, such as the secondary amine, by simple distillation steps, in high purity, and the secondary amine can be traced back to the beginning of the process.

It is a characteristic of the invention that the catalysts used are copper (II) -chromium (III) oxide catalysts containing 87.5-95 mol% of copper (II) oxide and 5-12.5 mol% of chromium (III) - oxides and are subjected to activation before use.

The N-methylation is carried out in one or more reaction steps, wherein in the first reaction step a temperature of 180-250 ° C, a pressure of 2-15 x ^{10 5} Pa, a molar ratio of 4-10 methanol / aromatic amine, 0.2-0.8 kg / dm ³ x maintaining a liquid load and a gas-liquid ratio of 600 to 1200 dm ³ / dm ^{3 in the} presence of hydrogen or a hydrogen-inert gas mixture containing at least 40% by volume hydrogen and removing the alcohol and water content of the product mixture prior to the second or further reaction step. The second and subsequent reaction steps at 200-260 ° C, 2-15 x ^{10 5} Pa, a molar ratio of 1.5-5 alcohol / N-methyl aromatic amine, 0.2-0.8 kg / dm ³ x hour fluid load and 600-1200 dm ³ / dm ³ gas-liquid ratio. In the case of a plurality of reaction steps, the second reaction step involves working near the lower limit of the temperature limit, the third and subsequent reaction steps near the upper limit of the temperature limit. The reaction is carried out in the presence of hydrogen or a hydrogen-inert gas mixture containing at least 40% by volume of hydrogen. For alkyl groups longer than methyl, only one reaction step is used at 180-250 ° C, 2-15 x ^{10 3} Pa, 4-10 molar alcohol / aromatic amine ratio, 0.2-0.8 kg / dm ³ x hour fluid load and 600-1200 dm ³ / dm ³ gas to liquid ratio. The introduction of the methyl group can also be carried out in one step. According to the invention, copper (II) chromium (III) oxide catalysts are used which contain 87.5-95 mol% of copper (II) oxide and 5-12.5 mol% of chromium (III) oxide. The composition of the catalysts was characterized by the ratio of oxides to each other and the presence of auxiliaries, if any, e.g. graphite used for tabletting was ignored. The catalysts were obtained in a manner known per se.

Activation of the catalyst is also an essential element of the process of the invention, which activation is also novel.

Pretreatment activation of dm ³ catalyst at atmospheric pressure;

- 1 to 2 dm ³ / h, preferably 1.2 to 1.6 dm ³ / h, with heating at 10 ° C / h to 160 ° C to 180 ° C by feeding C ₅ -C ₈ alkane, cycloalkane or any mixture thereof at temperatures up,

- after reaching the given temperature value, the addition of hydrogen was started in the amount of 20 dm ³ / h,

- this quantity was gradually increased to 200 dm ³ / h over 24 hours, taking into account the specific points in the catalyst space,

- in the temperature range 160-180 ° C,

With 200 dm ³ / h of hydrogen, we let it run for 8 hours,

- then it increased to 100 dm ³ per hour polyalkyl hydrogen addition of up to 500 dm ³ / h,

- when this volume was reached, the liquid supply was stopped,

- addition to 500? M ³ / h Hydrogen flow was operated with the equipment 16 hours the temperature range 160-180 ° C,

- then gradually set at 2 bar / h

EN 207 708 Β the desired pressure and the desired temperature at 20 ° C / h.

With activated catalyst, production periods of more than 1500 hours can be achieved.

It has been found that the selectivity for methylation with respect to the formation of N, N-dimethyl aromatic amine is 99.8% or more when the reaction is carried out in two, sometimes multiple, reaction steps. More than two reaction steps are usually required to achieve extremely high product purity with good yields. In the first step 180-250 ° C, preferably 200-230 ° C, 2-15xl0 ⁵ Pa, preferably 3 ^SxlO-5 torr, 3-10, preferably 5-7 methanol / aromatic amine mole ratio, 0.2-0 , 8 kg / dm ³ x hours · preferably 0.4-0.6 kg / dm ³ x hours liquid load and 600-1200 dm ³ / dm ³ gas to liquid ratio. The reaction is carried out with hydrogen or min. It is carried out in the presence of 40% by volume of a hydrogen-inert gas mixture. The resulting product mixture was taken to the second reaction step after methanol and dehydration. During the first reaction step, the aromatic amine is completely converted and the product mixture contains 45-85% by weight of N, N-dimethyl aromatic amine. In the second reaction step, the molar ratio of methanol to N-methyl aromatic amine is 200 to 260 ° C, preferably 220 to 250 ° C, pressure of ^{2 to 15} x ^{10 5} Pa, preferably 3 to ⁸ x ^{10 5} Pa, 1.5 to 5, preferably 2 to 3 0.2-0.8 kg / dm ³ x hours, preferably 0.4 to 0.6 kg / dm ³ x hours, with a liquid load of 600 to 1200 dm ³ / dm ³ gas to liquid ratio. The reaction is again hydrogen or min. It is carried out in the presence of a mixture of hydrogen inert gas containing 40% by volume of hydrogen. In order to achieve high product purity and particularly high yields, a third reaction step may be employed under conditions similar to the second reaction step, whereby the temperature may be chosen so that the second reaction step is carried out in the second reaction step near the lower limit.

In the process of the present invention, the selectivity of the methylation to 99.8% or more with respect to the formation of Ν, sal-dimethyl aromatic amine is considered to be practically complete. The reaction carried out in two or more steps produces 3-5% by weight of the by-product mixture (Ν, Ν-dimethylcyclohexylamine derivatives, cyclohexanone and cyclohexanol derivatives), which can be separated from the target product by simple fractional distillation, Thus, Ν, Ν-dimethyl derivatives can be obtained in high purity even without costly chemical purification steps.

For alkyl groups longer than the methyl group, a reaction step is used. Alkylation conditions include a temperature of 180-250 ° C, a pressure of 2-15 x ^{10 5} Pa, a molar ratio of 4 to 10 alcohol / aromatic amines, a liquid loading of 0.20.8 kg / dm ³ and a gas-liquid ratio of 600 to 1200 dm ³ / dm ³ . The reaction is carried out in the presence of hydrogen or a gas mixture containing at least 40% by volume hydrogen. According to the formation of the tertiary amine, the selectivity of the alkylation is reduced by 80-95%, depending on the length of the carbon chain, with the increase of the carbon chain. 5-20% by weight of the secondary amine remaining in the reaction can be recovered from the product mixture and can be recycled to the beginning of the process. In the one-step reaction, 4-8 wt.% Of the by-product mixture (cyclohexylamine, cyclohexanone and cyclohexanol derivatives) is formed, which can be separated from the target product by distillation and the desired tertiary amines are obtained in high purity.

Advantages of the process according to the invention are as follows:

Due to the excellent activity and selectivity of the catalyst, very good selectivity for tertiary amine formation and little by-product formation can be achieved. The methylation is substantially complete, with an selectivity of tertiary amine formation of 80 to 95% for the introduction of alkyl groups longer than the methyl group.

By-product of methylation of about 3-5% by weight and addition of 4-8% by weight of carbon chain longer than the methyl group can be separated from the target product by a simple distillation process, which can be obtained in high purity.

- Methyl derivatives do not require complicated post-treatment of the product mixture and do not produce waste that pollutes the environment.

The process can be carried out in a continuous mode under simple pressure in a hydrogenation plant with long production periods.

In addition to the technical advantages of the process, it is more economical than the known processes.

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

Example 1

1 dm ³ of catalyst containing 90 mole% copper (II) oxide and 10 mole% chromium (III) oxide was charged into a pressure-tight tube reactor. The catalyst charge was activated as follows. At atmospheric pressure, 0.7 dm ³ / h of n-hexane was passed through the catalyst charge and the temperature was raised to 160-180 ° C at 10-20 ° C / h. When the temperature range was reached, hydrogen was carefully introduced at 20 dm ³ / h. Increasing the amount by 20 dm ³ / h was set to 200 dm ³ / h. Under these conditions, the equipment was operated for 2 hours. Thereafter, 200 dm ³ / h was increased to 1 m ³ / h. Here, the hexane feed was stopped and the equipment was operated under these conditions for 8 hours. The pressure, temperature and gas uptake were then adjusted to the desired value and the catalyst fill was ready for N-alkylation reactions.

The methylation is carried out as follows. The reactor was charged with an activated catalyst charge at 5 x ^{10 5} Pa in a 1: 6.5 molar mixture of aniline and methanol and 95 volumes.

A mixture of gaseous hydrogen and 5% nitrogen was passed through. The catalyst bed temperature was 235 ° C, the liquid load was 0.5 kg / dm ^{3 *} x hours, and the gas-liquid volume ratio was 900 dm ³ / dm ³ . The resulting product mixture had the following distribution of aromatic amines: aniline 0%, N-methylaniline 0.2%,%, Ν-dimethylaniline 99.8%. The methanol and anhydrous portion of the product mixture contained 2.2% by weight of by-products. The methanol and water content of the product mixture was removed by distillation and the desired target product was obtained in 99.5% purity.

The catalyst activity did not decrease after 800 hours of operation.

Example 2

Two pressurized tubular reactors were charged with 1-1 dm ³ of catalyst containing 90 mole% copper (II) oxide and 10 mole% chromium (III) oxide, activated according to Example 1, except that instead of n-hexane, -hexane was used.

Methylation was performed as follows. An activated catalyst charge of the first reactor was passed through a 1: 6 molar mixture of aniline and methanol under a pressure of 5 x 10 Pa and a gas mixture of 75% by volume hydrogen and 25% by volume nitrogen. The catalyst bed had a liquid load of 0.45 kg / dm ³ x h, a gas / liquid volume ratio of 900 dm ³ / dm ³ and a temperature of 215 ° C. The resulting product mixture had the following distribution of aromatic amines: aniline: 0% by weight, N-methylaniline: 28.3% by weight, Ν, an-dimethylaniline: 71.7% by weight. The methanol and anhydrous portion of the product mixture contained 1% by weight of by-products (cyclohexanone, cyclohexanol, Ν, Ν-dimethylcyclohexylamine). The methanol and water contents of the product mixture were removed by distillation and fed to the second reactor. The second reactor is activated katalizátortöltetén 5 x ^s Torr methanol and drying the product mixture obtained in the first step, and 2-fold moles relative to the product mixture of N-methylaniline content of methanol and 75 volumes passed through% hydrogen and a gas mixture containing% nitrogen 25 vol. The catalyst bed had a liquid load of 0.45 kg / dm ³ x h, a gas / liquid volume ratio of 800 dm ³ / dm ³ and a temperature of 230 ° C. The resulting product mixture had the following distribution of aromatic amines: N-methylaniline: 0.1% by weight, Ν, Ν-dimethylaniline: 99.9% by weight. The product mixture, after methanol and dehydration, contained 4.7% by weight of by-products (cyclohexanone, cyclohexanol,,, Ν-dimethylaniline). Separated from these by distillation yields the target product in a purity of 99.5% by weight.

The catalyst activity did not decrease after 800 hours of operation.

Example 3

1 dm ^{3 of} the catalyst of the composition described in Example 1 was charged to a pressure tube reactor, and the charge was activated as described in Example 1, except that octane was used instead of n-hexane.

An activated catalyst charge of the first reactor was passed through a 1: 5 molar mixture of metatoluidine and ethanol and hydrogen at ⁵ x ^{10 5} Pa. The fluid bed catalyst loading of 0.45 kg / dm ³ Xora, gas-liquid volume ratio was 1100dm ³ / dm ^3, the temperature is 225 ° C. The resulting product mixture had the following distribution of aromatic amines: metatoluidine: 0 wt%, N-ethyl metatoluidine: 35.7 wt%, N, N-diethyl metatoluidine: 64.3 wt%. The ethanol and anhydrous portion of the product mixture contained 1.7% by weight of by-products. The by-products and N-ethyl-meta-toluidine were separated from the Ν, Ν-diethyl-meta-toluidine by distillation to give the target product in a purity of 99.2%.

The catalyst activity did not decrease after 1000 hours of operation.

Example 4

Two pressurized tubular reactors were charged with 1 to 1 dm ³ each of the catalyst composition described in Example 1 and activated in the same manner as in Example 1.

An activated catalyst charge of the first reactor was passed through a 1: 5 molar mixture of paratoluidine and methanol under a pressure of ⁸ x ^{10 5} Pa and a gas mixture of 75% by volume hydrogen and 25% by volume nitrogen. The catalyst bed had a liquid load of 0.5 kg / dm ³ x h, a gas / liquid volume ratio of 800 dm ³ / dm ³ and a temperature of 225 ° C. The resulting product mixture had the following distribution of aromatic amines: paratoluidine: 0 wt%, N-methyl para-toluidine: 30.7 wt%, N, N-dimethyl para-toluidine: 69.3 wt%. The methanol and anhydrous portion of the product mixture contained 0.8% by weight of by-products. The methanol and water contents of the product mixture were removed by distillation and fed to the second reactor. The second reactor was charged with activated gas in a gas mixture containing 75% by volume of hydrogen and 25% by volume of nitrogen in the first reaction mixture, at a pressure of ⁸ x ^{10 5} Pa, of methanol and anhydrous product obtained in the first reaction and 3 times molar ratio of N-methyl-para-toluidine. . The catalyst bed had a liquid load of 0.4 kg / dm ³ x h, a gas / liquid volume ratio of 800 dm ³ / dm ³ and a temperature of 240 ° C. The resulting product mixture had the following distribution of aromatic amines: N-methyl para-toluidine: 0.2% by weight, N, N-dimethyl para-toluidine: 99.8% by weight. The water and methanol-free portion of the product mixture contained 4.3% by-products. The by-products were removed by distillation to give the desired Ν, Ν-dimethyl para-toluidine in 99.4% purity.

The catalyst activity did not decrease after 800 hours of operation.

Example 5

1 dm ³ of catalyst of the composition described in Example 1 was charged into a pressure-tight reactor and the charge was activated as described in Example 1.

The activated catalyst charge of the first reactor is ⁶ x ^{10 5} Pa

At a pressure of 708 Β, a 1: 7 molar mixture of metatoluidine and n-hexanol and hydrogen were passed. The catalyst bed had a liquid load of 0.4 kg / dm ³ x h, a gas / liquid volume ratio of 1000 dm ³ / dm ³ and a temperature of 230 ° C. The resulting product mixture had the following distribution of aromatic amines: metatoluidine: 0 wt.%, Nn-hexyl metatoluidine: 35 wt.%, NN-di-n-hexyl metatoluidine: 65 wt.%. The n-hexanol and dehydrated portion of the product mixture contained 0.6 wt. The by-products and Nn-hexyl-meta-toluidine were removed by distillation to give the desired Ν, Ν-di-n-hexyl-meta-toluidine in 99% purity.

The catalyst activity did not decrease after 800 hours of operation,

Example 6

A pressure reactor tube reactor was charged with 1 dm ^{3 of the} catalyst composition of Example 1 and activated as described in Example 1.

The methylation was carried out in one step as follows. The activated catalyst charge was passed through a 1: 5 molar mixture of aniline and methanol under a pressure of 5 x ^{10 3} Pa and a mixture of 75 volumes of hydrogen and 25 volumes of nitrogen gas. The catalyst bed had a liquid load of 0.4 kg / dm ³ x h, a gas / liquid volume ratio of 900 dm ³ / dm ³ and a temperature of 245 ° C. The resulting product mixture had the following distribution of aromatic amines: aniline: 0.3 wt.%, N-methylaniline: 0.8 wt.%, N, N-dimethylaniline: 98.9 wt. The methanol and dehydrated product mixture contained 8.5% by weight of by-products (benzene, cyclohexanone, cyclohexanol, Ν, Ν-dimethylcyclohexylamine). After distillation of the by-products, Ν, Ν-dimethylaniline was obtained in a purity of only 98.4 wt.

From the example it can be concluded that performing the reaction in one step causes the quality of the target product to deteriorate and the yield to decrease.

Example 7

Two pressurized tubular reactors were charged with 1-1 dm ³ of a catalyst containing 70 mol% of copper (II) oxide and 30 molar chromium (III) oxide each. The two catalyst charges were activated as described in Example 1.

Methylation was performed as follows.

An activated catalyst charge of the first reactor was passed through a 1: 7 molar mixture of aniline and methanol and 75 volumes of hydrogen and 25 volumes of gas at 7 x 10 Pa. The catalyst bed had a liquid load of 0.55 kg / dm ³ x h, a gas / liquid volume ratio of 1000 dm ³ / dm ³ and a temperature of 220 ° C. The distribution of aromatic amines in the resulting product mixture was as follows: aniline: 0.7 wt.%, N-methylaniline: 55 wt.%, Ν, Ν-dimethylaniline: 44.3 wt.

The methanol and anhydrous portion of the product mixture contained 2.8% by weight of by-products (cyclohexanone, cyclohexanol, Ν, Ν-dimethylcyclohexylamine). The methanol and water contents of the product mixture were removed by distillation needles and fed to the second reactor. The activated catalyst charge of the second reactor was passed through a methanol / dehydrated product mixture obtained in the first reaction step at a pressure of ⁷ x ¹⁰ Pa and a gas mixture containing methanol and 75 volumes of hydrogen and 25 volumes of nitrogen at 2.5 times the N-methylaniline content. The catalyst bed had a liquid load of 0.5 kg / dm ³ x h, a gas / liquid volume ratio of 1000 dm ³ / dm ³ and a temperature of 240 ° C. The resulting product mixture had the following distribution of aromatic amines: aniline: 0.2 wt.%, N-methylaniline: 0.8 wt.%, Ν, Ν-dimethylaniline: 99 wt. The methanol and dehydrated portion of the product mixture contained 10.5% by weight of by-products (benzene, cyclohexanone, cyclohexanol, Ν, Ν-dimethylcyclohexylamine). After separation of the by-products by distillation, Ν, Ν-dimethylaniline was obtained in a purity of 98.7%.

Comparative example

With the highest copper (II) oxide containing catalyst known in the literature, which is described in JP 7 522 542. pre-treated according to the patent specification.

Two pressurized tubular reactors were charged with 1 to 1 dm ^{3 of} catalyst each containing 61.1 molar copper (II) oxide, 31.9 molar chromium (III) oxide and 7 molar barium (II) oxide. The catalyst was not subjected to activating pretreatment. The first reactor was passed through a 1: 5.5 molar mixture of aniline and methanol and hydrogen under a pressure of ⁶ x ^{10 5} Pa. The catalyst bed had a liquid load of 0.5 kg / dm ³ x h, a gas-liquid volume ratio of 850 dm ³ / dm ³ and a temperature of 235 ° C. The resulting product mixture had the following distribution of aromatic amines: aniline: 0.5 wt.%, N-methylaniline: 52.7 wt.%, Ν, Ν-dimethylaniline: 46.8 wt. The methanol and dehydrated portion of the product mixture contained 2.2% by weight of by-products. The methanol and water contents of the product mixture were removed by distillation and fed to the second reactor. A catalyst mixture of methanol and anhydrous product obtained in the first reaction step and methanol and hydrogen in a molar ratio of 3.5 times the aniline and N-methylaniline content of the product mixture were passed through the catalyst reactor at ⁶ x ^{10 5} Pa. The fluid bed catalyst load of 0.4 kg / dm ³ Xora, the gas-liquid térl'ogatarány 800D ³ / dm ^3, the temperature was 250 ° C. The resulting product mixture had the following distribution of aromatic amines: N-methylaniline 20, 8 wt, Ν, Ν-dimethylaniline 79.2 wt. The water- and methanol-free portion of the product mixture contained 7.9% by weight of by-products. The by-products were removed by distillation to give the desired Ν, imet-dimethylaniline in a purity of only 78.6%.

From the example it can be stated that using a catalyst composition different from the composition according to the invention does not achieve the desired purity of the target product and significantly reduces the yield.

Claims (1)

Patent Claim Point Process for the Ν, Ν-dialkyl derivatives of aniline and toluidines of formula I - wherein R ¹ 1-6 Means EN 207 708 Β -C straight or branched chain alkyl, and R ² is hydrogen or methyl, - for the preparation of aniline and toluidines hydrogen and copper (II) - and chromium (HI) -containing catalyst (Π) with alcohols of the formula: - wherein R ¹ is by reacting the above, characterized in that the catalyst used is 87.5-95 mol% of copper (H) oxide and 5-12.5 mol% of chromium (HI) oxide, which is activated - C 5-8 alkane and / or cycloalkane, or a mixture thereof, by heating to 160-180 ° C, subsequently introducing hydrogen, then stopping the above hydrocarbon, introducing additional hydrogen, and finally cooling with a stream of hydrogen, reacting the activated catalyst in one or more steps 180. At -260 [deg.] C. and (2-15) x ^{10 5} Pa and aniline or toluidine and continuously supplying the appropriate alcohol and introducing hydrogen with a liquid load of 0.2-0.8 kg / dm ³ x hour and a gas-liquid ratio of 600-1200 dm ³ / dm ³ .