DE1179947B - Process for the preparation of N-alkylated aromatic amines - Google Patents

Description

Process for the preparation of N-alkylated aromatic amines It is known that from aromatic amines and aldehydes or ketones or from aromatic Nitro compounds and aldehydes or ketones by catalytic reductive alkylation N-alkylated aromatic amines are obtained. You already have many for this reaction various catalysts described. So it is known to use nickel catalysts too use; the ketone is hydrogenated to a considerable extent to alcohol. Also can a partial nuclear hydrogenation take place. With the also known use only low yields are obtained from platinum oxide. One has also been in discontinuous Process mixed catalysts used which contain an oxidic hydrogenation catalyst, an oxidic hydration catalyst and a basic oxide as components contain. Oxides of copper, zinc, tin, Silver, molybdenum, nickel or manganese indicated as a hydrating component Oxides of chromium, silicon, aluminum, thorium and phosphorus and as basic Component magnesium, calcium, strontium and barium oxide. It is also known Use copper on carriers. When using the copper-containing catalysts Although the hydrogenation of the nucleus is largely or completely avoided, it does so to some extent the undesirable hydrogenation of the aldehyde or ketone to the corresponding one Alcohol a. Finally, the use of platinum on charcoal or on Known alumina. However, lower yields are achieved with this catalyst. In all known catalysts, there is a need, the load capacity and the To increase the service life and in the implementation of dinitro or nitroamino compounds the formation of significant amounts of intermediate products, e.g. B.

Diamines and semi-alkylated diamines.

It has now been found that in the preparation of alkylated aromatic Amines by reacting aromatic amino, nitro or nitroamino compounds with aldehydes or ketones in the presence of hydrogen and hydrogenating agents Catalysts obtain high yields even with high loads on the catalyst, if the catalyst used is silver mixed with palladium, optionally with a Addition of nickel and / or cobalt, in the form of oxides or / and metals, expediently applied to a highly heated, silica-containing carrier, used.

So you can use or have unsupported catalysts silicate carriers. Palladium is used in an amount of 1 to 30 percent by weight, purpose- moderately 3 to 15 percent by weight, based on silver, used. Palladium can be partially replaced by nickel and / or cobalt. Nickel and or or Cobalt can be used in a three to twenty-five times weight amount, based on Palladium, be contained in the catalyst. The catalyst can be through a Addition of 1 to 50 percent by weight, in particular 5 to 25 percent by weight of manganese and / or vanadium oxide, based on silver, improve its effectiveness.

If you have a carrier for the active ingredients of the catalyst used, then it is best to use a silicate one, in particular Silica. You can also use artificial or natural silicates, such as fuller's earth, Use fuller's earth, artificial aluminum, zinc or magnesium silicates.

It is essential that these carriers of their impregnation with the active Components to a temperature of at least 900 "C, expediently to 1000 to 1300 "C, so that they only have a low water absorption capacity own. Highly heated aluminum oxide can also be used as a carrier.

A suitable catalyst is provided, for. B. so that you can Carrier soaked with salt solutions of the catalytically active metals and then through Heating in a stream of air or oxygen expediently to 300 to 700 ° C., in particular to 400 to 600 "C, converts into the oxides. It is advisable to heat the support to the temperature above 900 "C before impregnation.

The silver salts used are, for. B. the carbonates, nitrates, oxalates. Palladium can be z. B. in the form of a nitric acid containing palladium nitrate solution use. Any additions of cobalt, nickel, manganese and or or Vanadium are added in the form of appropriate salts. When using supported catalysts, 2 to 25 percent by weight, in particular 3 to 15 percent by weight (calculated as oxides, based on the total catalyst) active ingredients applied.

You can also use the oxidic catalysts whole before use or partially reduce.

The catalyst is z. B. in the form of balls, pills or extrusions applied.

The catalysts according to the invention have compared to the known Copper and platinum catalysts have the advantage that with them the reductive alkylation of amino compounds with oxo compounds already so vividly at room temperature sets in that the heat of reaction is largely sufficient to the quantitative The course of the alkylation to bring about the necessary heating without the supply of external energy. In addition, the catalysts of the invention allow higher loads (i.e. Throughputs per kilogram of catalyst and hour), and they have a longer service life than the known catalysts. The supported catalysts have a very large mechanical strength. This only happens after 9 months with the new catalytic converters regeneration is required while using known copper chromium catalysts this is already the case after 3 months.

The effectiveness of the catalyst can be increased by adding small amounts Promoters, e.g. B. Compounds of metals from I. to III. Main group and resp. or VI. Group of the periodic table, e.g. B.

Sodium, potassium, calcium, aluminum, chromium, molybdenum, e.g. B. in a Amount of 1 to 700/0, based on palladium, can still be improved. The catalysts can by air oxidation within a few hours at temperatures of 120 to be revived to 350 "C or higher.

Aromatic ones serve as the starting material for the reductive alkylation Amines, nitro compounds or nitramines, for example aniline, p-phenylenediamine, p-aminophenol, nitrobenzene, nitrophenols, m-dinitrobenzene, p-nitroaniline.

Virtually all saturated straight-chain can be used as aldehydes or ketones and branched aliphatic and cycloaliphatic use, for example acetaldehyde, Propionaldehyde, butyraldehyde, acetone, methyl ethyl ketone, methyl butyl ketone, methyl hexyl ketone, Diethyl ketone, ethyl butyl ketone, dipropyl ketone, butyl amyl ketone, cyclopentanone, cyclohexanone.

At least the stoichiometrically required amount is used Aldehyde or ketone per mole of amino and / or nitro compound. Usually takes an excess of aldehyde or ketone, which serves as a solvent. But you can also by solvents which are inert under the reaction conditions, e.g. B. alcohols, bring about a dilution. Preferred are the aldehydes or used Alcohols corresponding to ketones are used, e.g. B. in the alkylation with methyl ethyl ketone 2-butanol.

The amount of hydrogen is chosen so that the process in liquid Phase is carried out, but on the other hand the hydrogen also to remove the Heat of reaction is used. It is expediently circulated.

In the case of discontinuous execution, about 2.5 to 10 percent by weight are required Catalyst, based on nitrogen-containing compound, used. With continuous Processes have space velocities of 1 to 2 gramol nitrogenous Proven connection per liter of catalyst and hour.

With these loads, a single pass becomes practically more quantitative Sales achieved. It is possible to load the catalyst higher, but then it remains part of the raw material unchanged.

Since the new catalysts are very active, it is not necessary to to warm up the starting materials when the reaction starts.

The process is preferably carried out in the liquid phase. One can add the catalyst to the liquid starting material in finely divided form and move through the reaction chamber. However, the catalyst is expedient in a vertical position The reaction chamber is firmly arranged and the starting material is in a thin layer from the top passed down over the catalyst, d. H. the reaction is according to the trickle process carried out. For example, there is a solution of the reactants in the used aldehyde or ketone or in an inert solvent at normal temperature together with hydrogen under a pressure of 10 to 250 atm at the top of a introduced with catalyst provided tower-like reaction vessel. In particular with the reduction of nitro groups, there is a gradual increase in temperature; the temperature is allowed to rise to about 150cd. But you can also see the reaction at an even higher temperature, e.g. B. to 170 "C, perform. The reaction pressure is between 5 and 300 at.

The reaction mixture drawn off at the lower end of the reaction chamber is made by fractional distillation of water and excess ketone or, if alcohol was added, separated from the ketone-alcohol mixture.

If you use diamino, dinitro or nitroamino compounds, so are used when using the claimed catalysts with a single pass practically quantitative yields of dialkylated diamines achieved while one when using known hydrogenation catalysts, such as nickel or cobalt, in large Amount of diamines and the corresponding alcohol received.

The advantage of the new catalytic converter is that it lasts longer and the load capacity are much higher than with the previously known catalysts and in addition there is no noticeable hydrogenation of the ketone to alcohol.

In the following examples, parts mean unless otherwise indicated, parts by weight.

Parts by weight and volume are in the same proportion as grams to liters.

Example 1 To produce the catalyst, 854 g to 1100 C heated and comminuted silica strands with an aqueous, weakly nitric acid Solution of 67.3 parts of silver nitrate, with 28.48 g of a 90 /, intrinsic nitric acid Palladium solution and an aqueous solution containing 8.54 g of vanadium as an oxalate soaked and dried. This catalyst mixture is then increased to 400 to 600cd heated, whereby the introduced salts are converted into the metal oxides and the catalyst about 2.89 g palladium oxide, 45.6 g of silver oxide and Contains 15.2 g of vanadium pentoxide.

544 parts of a 250/0 solution of p-nitroaniline in methyl ethyl ketone are every hour per part by volume of catalyst together with hydrogen under one Pressure of 55 at continuously at the top of a reaction tower at room temperature introduced. The gas velocity is set to 1000 1 H2 (calculated at normal pressure) set per liter of catalyst and hour. The reaction vessel is with the one above described catalyst filled. The reaction temperature rises in the lower part of the reaction vessel to 125 to 135 "C.

The gas-liquid mixture emerging from the reaction vessel becomes fed under the reaction pressure via a cooler to a separator in which the unused hydrogen is separated.

It is returned to the reaction vessel together with fresh hydrogen fed; the separated liquid is relaxed.

One receives from the reaction product by distillation per hour 1 part (10 / o) p-phenylenediamine and 213.8 parts (corresponding to 990 / o) N, N'-di-sec-butyl-p-phenylenediamine. The diamine fraction is returned to the reaction space, so that the overall yield can be increased to 100 ovo N, N'-di-sec-butyl-p-phenylenediamine. It will Practically no secondary butanol is formed during the reaction, so that the water of reaction separated ketone is immediately reused as a solvent for the p-nitroaniline can be. After a period of 4 months there is no decrease in effectiveness of the catalytic converter.

Example 2 In a manner analogous to Example 1, a palladium oxide, Silver oxide and V205 catalyst on silicon dioxide previously heated to 1000 ° C manufactured. I of the catalyst contains 27 g of silver oxide, 1.73 g of palladium oxide and 11.3 grams of vanadium pentoxide.

If this catalyst is used in a tower-like reaction vessel and carries 1375 parts per hour of a 9% by weight solution of p-phenylenediamine in methyl ethyl ketone sec-butanol (in a volume ratio of 1: 1) under hydrogen pressure of 200 at and represents a hydrogen velocity of 1300 1 H2 (calculated at normal pressure) per liter of catalyst and hour, is obtained at an inlet temperature of 28 "C and a reaction temperature in the lower part of the reaction vessel of about 140 "C a 1000/0 conversion. processing as in example 1 252 parts of N, N'-di-sec-butyl-p-phenylenediamine are added per hour.

The ketone added in excess is recovered quantitatively. The added secondary butanol serves as a solvent.

Example 3 To produce 11 catalyst, 854 g of silica pills, which were previously heated to 1100 "C, with an aqueous nitric acid solution that 105.7 g of nickel nitrate, Ni (NO3) 2 6 H2O, 33.1 g of silver nitrate, 14.49 g of a nitric acid Contains 90/0 palladium nitrate solution and 22.4 g of manganese nitrate, soaked and dried and heated in a stream of air to 550 ° C. Impregnation with the salt solution takes place repeatedly until the solution is completely absorbed. The content of nickel oxide is then 54.3 g, 23 g of silver oxide, 6 g of manganese oxide and 1.47 g of palladium oxide, correspondingly about 2.5% nickel, 2.5% silver, 0.15% palladium and 0.50% manganese.

Using this catalyst will be as in Example 1 every hour 480 parts of a 250/0 p-nitroaniline solution with methyl ethyl ketone together with Hydrogen under a pressure of 100 atm at ordinary temperature into the reaction tower introduced, whereby a speed of the hydrogen gas, calculated at normal pressure, of 1250 1 per liter of catalyst per hour is set.

In the lower part of the reaction vessel, the temperature rises to about 125 to 135 "C. When working up as in Example 1, 187 parts per hour are obtained N, N '- Di - sec. - Butyl - p -phenylenediamine, corresponding to 98 0 / o of theory, in addition to 20 / o diamine or monoalkylated diamines, which are reused.

Claims (1)

Claim: Process for the production of N-alkylated aromatic Amines by reacting aromatic amino, nitro or nitroamino compounds with aldehydes or ketones in the presence of hydrogen and hydrogenating agents Catalysts that can be used as a catalyst Silver mixed with palladium, optionally with an addition of nickel and or or cobalt in the form of oxides or metals, expediently on a highly heated, Silicic acid-containing carrier applied, used. Considered publications: German Patent Specifications No. 962 255, 1 077 667.