HU207033B - Process for producing chlorine anilines from chloronitrobenzene by heterogenous hydrogenation under pressure - Google Patents

Abstract

3,4-di:chloro-anilines are prepd. from o-, m-, p-, -chloro-nitro-benzenes and 3,4-di:chloro-nitro-benzene by hydrogenation at 50-150 deg. C and 3-15 MPa pressure using fixed bed catalyst. - Hydrogenation is carried out on 60-80% porous gamma-Al2O3 of a specific surface: 120-160 m2/g; average dia. is 0.8-1.2 mm; average length 3-5 mm and 5-6 N/m breaking strength. The catalyst opt. treated by HCl and tetra-butyl-ammonium-hydroxide contains 0.2-5.0 wt.% Pli

Description

The present invention relates to a process for the preparation of chloroanilines from chloronitrobenzenes in the presence of a catalyst under pressure.

Chloroanilines are very important parent compounds. They are used in large quantities by the organic chemical industry as intermediates for the production of biologically active derivatives. The reduction of halogen-containing aromatic nitro compounds to aromatic amines is a difficult task to avoid simultaneous or subsequent hydrogenolysis. Hydrogenolysis results in halogen cleavage, which causes loss, contamination and can cause severe corrosion. The reduction can only be carried out in a suitable solvent, with a highly selective catalyst and under optimum reaction conditions.

The authors of the publications and patent literature found in the literature recommend a wide variety of laboratory solutions, but little is known about continuous operation on an industrial scale. Based on the types of catalysts used for the reduction, the literature can be divided into the following groups:

- containing nickel,

- copper chromium oxide ("copper chromium"),

- precious metal bearing,

- reports on the use of sulphidated transition metal and precious metal catalysts.

It is not advisable to reduce halogen-containing aromatic nitro compounds with nickel active component catalysts since the selectivity is inadequate and the reaction mixture always contains hydrochloric acid, which poses a risk to the reactor structural material and, on the other hand, deactivates the catalyst continuously. Generally, nickel-containing catalysts can achieve satisfactory reaction rates only at very high pressures.

N.P. Sokolova, A.A. Balangyin, N.P.Maximova and Z.M. Lags. Nauk. SzzzzR ser. Him., 11, 1885-1891 (1966)], Raney nickel catalysts and supported nickel catalysts were also studied in continuous operation. On a catalyst containing 501% nickel, 64% conversion with 0.8% hydrochloric acid formation was achieved.

Copper chromium oxide catalysts are also not recommended for the reduction of halogen-containing aromatic nitro compounds, since very strong conditions are required for the reduction. No. 2791613. U.S. Pat. Hydrogenation was carried out at 150 ° C and 3.5-12.0 MPa, yielding 64-96% with formation of 1-5% aniline.

Hydrogenation may also be carried out on supported noble metal catalysts. P. N. Ovosinyikov, 1.1. Báty, G. A. Chistyakova [Katal. Reaction desired. Heb. Faze Tr. Conf 2. Alma-Ata, Kaz. (1966)] investigated the reduction of chloronitrobenzenes on, among others, catalysts containing palladium, platinum, ruthenium, radium, osmium and rhenium. A catalyst containing 21% palladium on carbon was used for the hydrogenation of p-chloronitrobenzene. At this time, very significant (30-40%) chlorine cleavage, ring saturation and amino group cleavage were also observed. Catalysts containing 21% ruthenium or radium behaved similarly to palladium catalysts. The catalyst containing 21% osmium is sufficiently selective, but the palladium catalyst has significantly less activity. Rhenium-containing catalysts are highly selective. Platinum catalysts are the best in terms of selectivity. A catalyst containing 1-2% platinum has thirty times less activity than a similar palladium catalyst. According to Rylander (Catalytic Hydrogenation over Platinum Metals, Academic Press, New York-London 181 (1967)), palladium cleaves halogen much better than platinum or radium. Decreasing the platinum content of the catalyst significantly increases the selectivity and at the same time slightly decreases the hydrogenation activity.

Platinum is recommended for the reduction of 3,4-dichloro-nitrobenzene by 1% and platinum for the reduction of πι and p-chloro-nitrobenzene by 0.5%. The former authors [Him. Prom., 44, 3, 215-216 (1968)] has also been prepared in continuous operation with para-chloroaniline.

The application of palladium to Foye and Stoye is described in [J. Am. Pharm. Assoc., 48, 4, 201-203 (1959)] for the dehalogenation of p-chloroaniline to aniline hydrochloride in 90% yield on palladium on carbon.

Various additives have been attempted in the literature to increase the selectivity of the precious metal catalysts and to reduce the reaction time. The additives are added to the catalyst or catalyst mixture.

According to a Soviet patent (168302, 1965), a catalyst containing 5% palladium and 0.04% copper was found to have good selectivity. According to another Soviet patent (No. 235,039, 1967), rhenium-promoted palladium catalyst (5% palladium and 11% rhenium, on a support) was used for the preparation of the halogen-containing aniline derivatives.

According to a United States patent (3051753, 1962), 5% by weight of rhodium-containing alumina catalyst and 11% by weight of calcium hydroxide was used in a yield of 87.7% in 5.1 hours. 3,4-dichloroaniline. Without additive, under the same reaction conditions, 3,4-dichloroaniline was formed after 16 hours in 89.2% yield. Magnesium oxide or magnesium hydroxide is also suggested as an additive in an English patent (No. 859251, 1961) in an amount of 0.1-11% by weight of the starting material. Even in this case, the halogen was not completely bound.

The use of the sodium sulfite additive is reported in a Japanese patent (No. 59,333, 1975). The amount of additive was 0.0080.08% by weight of the starting material, and the selectivity improved from 99.0% to 99.9% in the most favorable case.

Morpholine, piperidine and their N-alkyl derivatives have been reported in several reports

HU 207 033 Β catalysts contain palladium or platinum. The amount of additives, based on the feedstock, respectively was: 0.01-1.0 mol / mol and 0.1-1.0 mol / mol, 0.75-3 vol%, 0.1-1.0 vol % [964166 1352677 (1964); French Patent Specification (1964), 3291832; United States Patent No. 1966; Japanese Patent Specification (1973).

The use of trialkyl phosphites as additives can be found, for example, in British Patent Specification No. 1138,567 (1966). The amount of additive used was 0.050.5% by weight of the nitro compound and the chlorine cleavage was less than 2 mol%. The carbon content of the catalyst was 1-51%. J. R. Kosak [Catal. Org. Synth. 7, 107-117 (1980)] examined the hydrogenation of chloronitrobenzenes on palladium and platinum catalysts in the presence of 0.05 to 0.1% by weight of phosphoric acid, hypophosphoric acid and phenylphosphinic acid inhibitors. The chlorine cleavage rate was 0.021.21%.

Hydrogenation can also be accomplished with catalysts containing transition metal and noble metal sulfides. These catalysts are extremely selective hydrogenation catalysts, but the reaction times required to achieve virtually 100% conversion are quite long and the reaction takes place under vigorous reaction conditions. [P. N. Ovchinichov, 1.1. Báty, G. A. Chistyakova: Katal. Reaction. Heb. Faze Tr. Conf. Alma-Ata, Kaz. SzSzR. 145-149 (1966)].

A disadvantage of the processes described so far is that the appropriate conversion and selectivity, i.e., a significant chlorine cleavage, or only by special catalyst preparation operations, e.g. sulphidation - they can be provided or additives are added to the solution or catalysts to prevent chlorine decomposition. In the case of sulfidation, the reaction is very slow and the main disadvantage of the use of additives is that it is very difficult to purify the product from the additives. It is particularly difficult to use additives containing phosphoric acid or phosphoric acid esters because their presence in the product significantly increases the toxicity to warm-blooded animals. Their use was therefore not widespread.

We wanted to develop a process for the preparation of chloroanilines (ortho-, meth-, para-, and 3,4-dichloroanilines) in the preparation of chloronitrobenzenes (ortho-, meth-, para-chloro, 3,4-dichloro-nitro-). benzene) in solution in the presence of a catalyst which provides sufficient selectivity without the use of an additive. According to the invention, a noble metal (palladium, platinum, radium), preferably platinum, is applied as a catalyst.

The catalyst carrier used is a gamma alumina, a carrier commonly used in industry. The noble metal was dissolved in solution in the form of a water-soluble salt. An aqueous solution of hexachloroplatinate was used to deposit the platinum content. After application of the platinum salt, the catalyst was dried. The dried catalyst was impregnated with 1N hydrochloric acid. The catalyst was then neutralized with an aqueous solution of tetrabutylammonium hydroxide. After neutralization, the catalyst was dried again and the catalyst reduced at low temperature.

A catalyst carrier having a specific surface area of 120-160 m ² / g, an average particle diameter of 0.8-1.2 mm, a particle length of 3-5 mm, a breaking strength of 5-6 N / m and a porosity of 60-80 is suitable for the process of the present invention. %.

The process involves the use of a solvent which completely dissolves both the starting materials and the final product at a given temperature and which is capable of removing a large amount of heat released during the exothermic reaction. Particular preference is given to lower alcohols, e.g. methanol, ethanol, isopropyl alcohol. The stock solution contains chlornitrobenzenes in a concentration of 5 to 15% by weight, preferably 10% by weight. Hydrogenation to ensure complete conversion and proper selectivity at 50-130 ° C and 5-12 MPa - preferably 80-100 ° C and

8-10 MPa - done.

The reaction may also be carried out in batch mode. It is advantageous to carry out the hydrogenation in a continuous operation on a fixed bed catalyst. The supported noble metal catalysts have been shown to have a satisfactory lifetime and are thus advantageously used in continuous hydrogenation. The activity of the catalyst used by us did not change during 500 hours of operation.

The process of the present invention provides the chloroanilines with 100% conversion and 98-99.9% selectivity. Our experiments were carried out in a titanium-lined isothermal reactor with a volume of 2 dm ³ and controlled by a microprocessor control unit. Hydrogen gas from the hydrogen bottle passed through a buffer tank to the electrically heated reactor. The feedstock was pumped from the storage tank to the reactor. The hydrogen mixed stock solution passed through the reactor jacket 3 times and then entered the reactor. The product mixture leaving the reactor ended up in a thermostable separator from which the product solution was drained from the bottom to the product collection tank. After the drip trap, the gas leaving the separator was introduced into the exhaust gas line or recirculated through the circulator.

Without limiting the scope of the invention, the following embodiments are illustrated by the following examples:

Example 1

catalyst Preparation

2000 g of gamma-alumina support were placed in a furnace and annealed at 500 ° C for 4 hours. 35 g of hexachloroplatinate (H ₂ PtCl ₆ x ₆ H ₂ O) were dissolved in 400 cm ^{3 of} distilled water and the solution was added to the support in portions with stirring. The carrier used was y-Al ₂ O ₃ with a specific surface area of 125 m ² / g, an average particle diameter of 0.8 mm, an average particle length of 3.5 mm, a breaking strength of 5 N / m and a porosity of 65%. After application of the platinum salt, the catalyst was dried at 120 ° C for 18 hours. The kata3

The lyser was then impregnated with 1N aqueous hydrochloric acid and dried again as before. The catalyst was then neutralized with 5% aqueous tetrabutylammonium hydroxide and, after drying, tetrabutylammonium hydroxide treatment was repeated. One gram of sample was then heat treated and the noble metal content determined by atomic absorption analysis. The platinum content measured was 0.64%. The catalyst was then poured into a tubular reactor as described above, and after sealing the apparatus, the reactor was heated to 50 ° C under a stream of nitrogen (50 cm ³ / h) for 5 hours. After 5 hours, the reactor was heated to 100 ° C at a heating rate of 10 ° C / h. Under isothermal conditions at 100 ° C, 5 dm ^{3 of} hydrogen gas was added to the nitrogen and the catalyst was reduced for 4 hours. Then, the added amount of hydrogen gas was increased up to 5 dm ³ per hour -rel 50 dm ³ / h. The nitrogen supply was then discontinued and the catalyst was reduced at 120 ° C for 4 hours, then the hydrogen pressure was adjusted to 10 MPa and isopropyl alcohol was added by pump to the catalyst support. The catalyst thus prepared was used to prepare the chloroanilines according to the following examples.

Example 2

100 ° C and 10 MPa, i-propyl alcohol solution containing 10% by weight of p-chloro-nitrobenzene is introduced into one dm ³ / dm ³ xh space velocity of the catalyst described in the previous example, while the reactor was 1000 Nm ³ / m ³ Hydrogen gas was passed at xh. The solvent was removed by distillation from a hydrogenated solution leaving the reactor. The crude product was obtained with 100% conversion with 99.8% selectivity. Conversion and selectivity remained unchanged after 500 hours of operation.

Example 3

The procedure described in Example 2 was followed except that the starting material was o-chloronitrobenzene. O-chloroaniline was formed with 100% conversion with 99.7% selectivity. Conversion and selectivity did not change after 500 hours of catalyst operation.

Example 4

The procedure described in Example 2 was followed except that the starting material was m-chloronitrobenzene. The m-chloroaniline product was formed at 100% conversion with 99.1% selectivity. Conversion and selectivity did not change after 500 hours of operation.

Example 5

The procedure described in Example 2 was followed except that 3,4-dichloro-nitrobenzene was prepared with 99.2% selectivity at 100% conversion of the starting material, 3,4-dichloroaniline. Conversion and selectivity did not change after 500 hours of catalyst operation

Example 6

The procedure described in Example 2 was followed except that an alumina supported catalyst containing 0.64% by weight of platinum was used. Hydrochloric acid and tetrabutylammonium hydroxide treatment were not used. At this time, parachloraniline was formed with 98% conversion and 92% selectivity.

Example 7

The procedure described in Example 2 was followed except that the hydrogenation was carried out at 80 ° C and 8 MPa. The p-chloroaniline product was formed at 95% conversion with 99.8% selectivity. Conversion and selectivity did not change after 500 hours of operation.

Example 8

The procedure described in Example 2 was followed except that the hydrogenation was carried out at 4 MPa. The p-chloroaniline product was formed at 95% conversion with 95% selectivity.

Example 9

The procedure described in Example 2 was followed except that the hydrogenation was carried out at 150 ° C. The p-chloroaniline product was formed with 100% conversion with 78% selectivity. The breakdown of hydrochloric acid was extremely intense. The cooler of our stainless steel reactor was damaged by corrosion.

Example 10

The procedure described in Example 2 was followed except that the carrier was y-Al ₂ O ₃ having a specific surface area of 155 m ² / g, an average particle diameter of 1.2 mm, an average particle length of 5 mm, and a breaking strength of 6. N / m and porosity was 75% and reforming gas was used instead of pure hydrogen gas, 77% by volume of hydrogen, 23% by volume of C 1 -C ₄ hydrocarbons. Again, with 100% conversion, para-chloroaniline was formed with 99.8% selectivity.

It is apparent from the examples that very good conversions can be made with our process to produce chloroanilines, which is largely due to the choice of catalyst, including the catalyst support. 30-40% improvement in selectivity compared to the previous processes because our catalyst does not break down chlorine, contrary to what is known so far.

Claims (5)

A process for the preparation of chloroanilines, i.e. ο-, m- and p-chloroaniline and 3,4-dichloroaniline, using the corresponding chloro-nitrobenzenes, i.e. ο-, m- and p-chloronitrobenzene and 3,4-dichloro-nitrobenzene - by fixed bed catalytic hydrogenation, characterized in that the hydrogenation has a specific surface area of 120-160 m ² / g, an average particle diameter of 0.8-1.2 mm, an average particle length of 3-5 mm, HU 207 033 Β 5 to 6 N / m tensile strength 60-80% porosity on γAl ₂ O ₃ in the presence of a supported catalyst containing 0.2-5.0% platinum, optionally treated with hydrochloric acid and tetrabutylammonium hydroxide at 50-150 ° C. C at 3-15 MPa. Process according to claim 1, characterized in that the hydrogenation is carried out in a solution of 5 to 15% by weight in isopropanol. Process according to claim 1 or 2, characterized in that the hydrogenation is carried out in the presence of a catalyst containing 0.3 to 0.7% by weight of platinum. 4. Process according to any one of claims 1 to 3, characterized in that the hydrogenation is carried out at 80-120 ° C 5 is performed. 5. A process according to any one of claims 1 to 5, characterized in that the hydrogenation is carried out at a pressure of 812 MPa.