DE1670251A1 - Process for the preparation of piperazines - Google Patents

Description

Process for the production of piperazines The invention relates to a process for the production of piperazines by reaction with ethanolamines or diethanolamines or glycols with ammonia or primary amines.

It is known from French Patent Specification 1,291,969, that by reacting piperazines ethanolamines or biäthanolaminen with ammonia or amines in the presence of nickel-containing catalysts is obtained. The process has the disadvantage that it only proceeds with good yields if only a certain proportion of the nickel is present in reduced form in the catalyst. The production of such catalysts, in which only a certain proportion of the nickel is reduced, presents great difficulties on an industrial scale. In addition, the catalyst is continuously changed during the reaction, which significantly affects its activity and service life.

It has now been found that piperazines can be obtained by reacting ethanolamines or. Diethanolamines or glycols of the general formula in which R 11, R 2 and R 3 are each hydrogen atoms, alkyl, cycloalkyl or phenyl radicals, R 1 and R 2 together with the carbon atoms which they substitute can form a 5- to 12-membered, cycloaliphatic ring, X is a hydroxyl group or the rest in which R 4 represents a hydrogen atom or an alkyl radical and R 5 represents a hydrogen atom or the radical in which Ri. R 2nd and R 3 have the meaning indicated, bezeichnetg with ammonia or primary amines in the presence of hydrogen and of cobalt and / or nickel enthaltendBn hydrogenation catalysts at elevated temperature and at elevated pressure in the liquid phase advantageously than previously obtained when Hydrogenation catalysts are used which have a content of inorganic pyro or polyacids, or. their salts.

The new process has the advantage that catalysts are easy to prepare Find use that have a constant activity over a long service life.

In the preferred starting materials I, R1, R2 and R 3 each denote a hydrogen atom or an alkyl radical with 1 to 12 carbon atoms, in particular 1 to 4 carbon atoms, or a phenyl radical. R 1 and R2, together with the carbon atoms they substitute, can also form a 5- to 12-membered cycloalkane ring. X stands for a hydroxyl group or the rest R 4 denotes a hydrogen atom or an alkyl radical having 1 to 20 carbon atoms, in particular having 1 to 4 carbon atoms. In the preferred starting materials I, R 5 represents a hydrogen atom or the remainder in which Rl, R 2 and R 3 have the meaning given. Suitable starting materials are, for example, ethylene glycol, propylene glycol, ethanolamine, N-methylethanolamine, N-decylethanolamine, isopropanolamine, cyclohexanolamine- (1,2), phenylethanolamine, isobutanolamine- (192), diethanolamine, diisopropanolamine. Ethanolamine, diethanolamine, isopropanolamine, diisopropanolamine, ethylene glycol and propylene glycol are particularly preferred because they are easily accessible industrially.

Preferred primary amines have an alkyl or aralkyl radical with up to 20 carbon atoms or a cycloalkyl radical with 5 to 12 carbon atoms. Particularly preferred primary amines have an alkyl radical of 1 to 18 carbon atoms. Apart from the amino group, the residues have a hydrocarbon structure. Suitable amines are, for example, methylamine, ethylamine, butylamine, stearylamine, palmitylamine, cyclohexylamine, cyclooctylamine, cyclododecylamine, benzylamine or β-phenylethylamine.

The starting materials I and ammonia or primary amines are advantageously reacted in a molar ratio of from 1: 4 to 1:10, in particular from 1: 5 to 1: 8 . The reaction is expediently carried out at temperatures from 150 to 250.degree . Particularly good results are obtained when working at temperatures from 180 to 220 0 0 . - The reaction is advantageously carried out at pressures from 1 to 350 at, in particular from 200 to 300 at.

The reaction is carried out in the presence of hydrogenation catalysts containing cobalt and / or nickel metal. The catalysts advantageously contain 80 to 100 % by weight of cobalt and / or nickel, based on the metal content of the catalyst. In addition to cobalt and / or nickel, the catalysts can be metallegs such as copper or chromium, manganese, zinc, e.g. B. up to 20 wt.%, Based on the metal content. The catalysts can also be on supports, e.g. B. silica, silicates, aluminum phosphate, boron phosphate, aluminum oxide or activated carbon may be applied. The metal content of the catalysts is expediently 5 to 80 % by weight, based on the total catalyst.

It is an essential feature of the new process that the catalysts contain inorganic pyroacids or polyacids or their salts. In general, a content of the substances mentioned from 0.5 to 20% by weight, based on the metal content of the catalysts, is sufficient. Particularly good results are obtained with contents of 1 to 10 % by weight. Suitable additives are e.g. B. polymolybdates, poly tungstates, pyrosulfuric acid salts and in particular polyphosphoric or polyboric acids or their salts, such as sodium or calcium tetraborate. The percentages in connection with the catalysts relate to the analytically determined contents in the finished catalysts, the acids mentioned or their salts being indicated as anhydrides and the metals being indicated as such, ie irrespective of the actual binding state.

The catalysts are prepared, for example, by adding the metal components together with the acids mentioned or their salts by themselves or on a powdered support from aqueous solution, e.g. B. falls with sodium carbonate or sodium hydroxide or applies the precipitation to such a carrier, the neutral washed mass at elevated temperature, z. B. at temperatures of 60 to 180 0 C, and then the molded bodies, such as pills or strands, pressed mass, some heated to an elevated temperature, such as 300 to 800 0 C, in the muffle furnace. Instead of the acids mentioned or their salts, it is also possible to use acids or their salts which, when heated, convert into pyroacids or polyacids or their salts, e.g. B. phosphoric acid. Before use, the catalyst is reduced with hydrogen, preferably at temperatures from 200 to 300 0 0.

Other catalysts containing cobalt and / or nickel are obtained, for example, when cobalt and / or nickel oxide or hydroxides or carbonates of the metals mentioned, optionally on a support with an aqueous solution of a pyroic or polyacid, or of their salts or of substances that pass into pyroacids or polyacids or their salts when heated, soaks and lasts for several hours, e.g. B. 2 to 5 hours, to an elevated temperature, e.g. B. 300 to 800 0 C, and reduced before use at elevated temperature, for example at 200 to 400 0 C with hydrogen.

The reaction can be carried out without a solvent. However, it is advantageous to use the reaction discharge containing piperazine and ammonia or primary amines as the solvent. Preference is given to adding 0.5 to 10 times, in particular 1 to 5 times, the amount of the reaction discharge, based on the new reaction mixture.

The process according to the invention can be carried out batchwise It is advantageous to work continuously in technology. This way of working is described here, for example: A vertical high-pressure pipe that is charged with a catalyst of the composition mentioned is from above with a mixture of the glycols mentioned, ethanol or. Diethanolamines and ammonia or primary amines in the specified ratio and recycled reaction discharge loaded. At the same time, hydrogen is added. The hydrogen becomes beneficial enriched with ammonia in a circle. Hold the during the reaction pressure and temperature conditions described. From the reaction discharge, after it has been freed from ammonia or amines, by fractional distillation Piperazine isolated.

The piperazines produced by the process of the invention are suitable for the production of emulsifiers and vulcanization accelerators and for the production of high polymers. The parts given in the following examples are parts by weight. They relate to parts of space like kilograms to liters. Example 1 A vertical high-pressure tube with a volume of 500 parts by volume is filled with a catalyst which contains 15 % by weight of cobalt oxide and 0.5 % by weight of phosphoric acid, determined as phosphorus pentoxide, on aluminum oxide. After reduction of the catalyst with hydrogen at 250 ° C., 100 parts of diethanolamine and 350 parts by volume of liquid ammonia are metered in every hour at the top of the high-pressure tube, a temperature of 200 ° C. being maintained . A pressure of 280 atm is maintained by simultaneously injecting hydrogen. Ammonia is distilled off from the reaction discharge. 115 parts per hour of a mixture are obtained which, according to gas chromatographic analysis, calculated to be anhydrous, contain 6% ethylenediamine, 3% ethanolamine, 46 % piperazine and 42 % diethanolamine. The yield of piperazine after a single pass is thus 80%. based on converted diethanolamine.

EXAMPLE 2 A vertical high-pressure pipe with a volume of 500 parts by volume is charged with a catalyst containing 19 % by weight of cobalt, 1 % by weight of chromium and 0.5% by weight of phosphoric acid on aluminum oxide. After the catalyst has been reduced with hydrogen at 250 ° C., 100 parts of ethanolamine and 350 parts by volume of liquid ammonia are metered in every hour at the top of the pressure tube , a temperature of 200 ° C. being maintained . A pressure of 280 atmospheres is maintained by simultaneously injecting hydrogen. Ammonia is distilled off from the reaction discharge. 117 parts per hour of a mixture are obtained which, according to gas chromatographic analysis, calculated anhydrous, contain 21 ethylene diamine, 17% ethanolamine, 41 piperazine and 20 5 # higher polyamines. Example 3 Under the conditions as described in Example 2, the reaction is carried out with a catalyst which contains 20% by weight of cobalt and 1 % by weight of chromium on aluminum oxide, but without the addition of phosphoric acid. 118 parts per hour are obtained of a mixture which, calculated anhydrous according to gas chromatographic analysis, contains 37% ethylenediamine, 23% ethanolamine, 17% piperazine and 21 % higher polyamines.

Example 4 A vertical high-pressure tube with a volume of 500 parts by volume is filled with a catalyst which contains 68 % by weight of nickel, 26 % by weight of copper, 3 % by weight of chromium and 3 % by weight of phosphoric acid. After reduction of the catalyst with hydrogen at 250 0 0 , 100 parts of ethylene glycol and 100 parts by volume of liquid ammonia are metered in every hour at the top of the high pressure tube, a temperature of 220 0 0 being maintained . A pressure of 280 atm is maintained by simultaneously injecting hydrogen. Ammonia is distilled off from the reaction discharge. 133 parts per hour of a mixture are obtained which, according to gas chromatographic analysis, anhydrous calculated, contains 2 % ethylenediamine, 10 % morpholine, 12% ethanolamine, 49% piperazine, 1% ethylene glycol and 13 % diglycolamine. The rest are higher polyamines.

Claims (1)

Patent claim A method for the preparation of piperazines by reacting ethanolamines or Diäthanolaminen or glycols of the general formula in which Rl, R2 and R 3 each represent hydrogen atoms, alkyl, cycloalkyl or phenyl radicals, Ri and R 2 together with the carbon atoms which they substitute can form a 5- to 12-membered, cycloaliphatic ring, X represents a hydroxyl group or the rest in which R 4 represents a hydrogen atom or an alkyl radical and R 5 represents a hydrogen atom or the radical in which R 19 R2 and R 3 have the meaning given, denoted with Am.monjak or primary amines in the presence of hydrogen and cobalt and / or nickel-containing hydrogenation catalysts at elevated temperature, Gur and at elevated pressure in the liquid phase, characterized that use is hydrogenation catalysts, which have a content of inorganic pyrophosphates or polyacids and salts thereof.