SU791738A1 - Method of preparing trialkanolamines - Google Patents

Description

54) METHOD FOR PRODUCING TRIALCANOLAMINES

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The invention relates to an improved process for the production of trialkanolamines, which are widely used in traditional households, especially as intermediates of organic synthesis.

In the patent literature are widely described methods for producing trialkanolamines.

A known method for producing alkanolamines by oxyalkylation of ammonia in an aqueous medium with SO-IOO C. This usually produces a mixture of mono-, di- and trialkanolamines. The ratio of MONO-, di- and trialkanolamines depends mainly on the amount of alkylene oxide and ammonia taken into the reaction, and on the process temperature.

The preparation of mono and i is also described. triethanolamines by the reaction of ethylene oxide with aqueous ammonia in the presence of diethanolamine. The process is carried out at a temperature of eo-lSO C and a pressure of 20-120 atm. The resulting mixture of ethanolamines is fractionated and diethanolamine is recycled.

Get a mixture containing 74% mono - and 26% triethanolamines.

The main disadvantage of the known methods is the low yield of trialkanolamines, multistage. In addition, in all these processes carried out in an aqueous medium, glycols are formed, the boiling points of which are close to the boiling points of alkanolamines. These impurities contaminate the target products, impair their thermal stability and therefore must be separated.

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In order to prevent the formation of glycols, it is known to conduct the process of oxyalkylation in an anhydrous medium.

This method of producing triethanolamine is that

15 mono- or diethanolamine, or their anhydrous mixtures are treated with ethylene oxide at a temperature not exceeding 50 and a pressure of 0.5 atm. The process is conducted in a stainless steel reactor.

20 steel jacketed and mixing device.

A known method for producing triethanolamine is the reaction of ethyl oxide 25 in mono- and diethanolamines in the absence of water and ammonia. The reaction is carried out for less than 2 hours at 110-180 ° C.

The disadvantage of these methods is that as a raw material,

mono- and / or diethanolamine is used, which leads to a multistage process and a decrease in the yield of the target product in terms of ethylene oxide and ammonia.

The method closest to the described method is also known, which implies, for example, that ethanolamines are obtained from ethylene oxide and aqueous ammonia and the process is carried out at a temperature not higher than in an autoclave. Then, under a gradually increasing vacuum, ammonia and water are distilled off first, then mono-, di-, and triethanolamines. The disadvantage of this method is the low yield of triethanolamine and the need to fractionate the ethanolamine mixture.

The purpose of the invention is to simplify the process and increase the yield of the target product.

This goal is achieved by the fact that trialkanolamine is obtained from alkylene oxide and anhydrous ammonia and the process is carried out in the presence of a cation exchanger as a catalyst at a temperature of 20-60 ° C and a pressure of 0.510 atm, min to the stage of separation of mono-dialkanolamine.

At the same time, the activity of the catalyst does not fall during repeated use.

Example 1. A 100 ml metal ampoule of stainless steel, equipped with a monometer, was rubbed with a metering device and a metering device, cooled to minus, 8.5 g of liquid ammonia was poured, 0.8 g of freshly activated KU-2-8 cation exchanger was added , 8 units), then try shaking at a temperature of 40 ° C, propylene oxide is dosed evenly for 30 minutes in an amount of 87 g. The dosing rate is adjusted so that the pressure does not exceed 0.5 atm. The supply of propylene oxide is stopped and the shaking continue for 5 minutes. At the end of the reaction, evaporate excess propylene oxide, the catalyst is separated.

Receive 90 g of technical triisopropanolamine, which according to the results of chromatographic analysis contains 96% of the basic substance.

: Example 2. In a stainless steel autoclave with a capacity of 1 l, equipped with a mixing device. Vom, cooled to minus 40c and purged with nitrogen, is loaded with 116 g of cooled propylene oxide and 3.4 g of cation exchanger KU-2-8 and 34.0 g of liquid ammonia. The contents of the autoclave are heated to 4 ° C, stirred for 15 minutes, and the pressure rises to 10 atm. An excess of ammonia is then evaporated, which is recycled. The reaction mass is cooled and chromatographic analysis is performed, which showed that the reaction mass contains 75.6% monoisopropanolamine, 16.4% diisopropanolamine and 7.9% triisopropanolamis. Then, propylene oxide is metered into the reaction mass at such a rate that the temperature in the reactor does not exceed 50 s The pressure is 1.5 atm. The reaction mass is periodic. taken from the reactor and analyzed. The process is carried out until exhaustive oxypropylation. Then a small excess of propylene oxide is evaporated, the catalyst is separated, which is recycled to the process.

5 Get 374.8 g of technical triisopropanolamine with the content of the main substance of 98.9%.

Example 3. In a cooled autoclave load 68 g of liquid

0 ammonia in a stream of nitrogen, 7 g of cation exchanger KU-2-8, then, with stirring, propylene oxide is uniformly metered over 3 hours in an amount of 700 g. Temperature during dosing

5 support 60 C, pressure 1, 5 atm. The reaction is carried out until complete conversion of ammonia, an excess of propylene oxide at the end of the reaction is 20% of the theoretical. At the end of the reaction, the excess oxide is evaporated.

the catalyst is filtered off. 760 g of product are obtained with a triisopropanolamine content of 95.7%, diisopropanolamine - 3.2%, monoisropropanolamine - 1.1%. The product is thermostable to 200 ° C. If necessary, triisopropanolamine is distilled.

Example 4.3 cooled autoclave, purged with nitrogen, load 90 g of liquid ammonia, 9 g of cation exchanger KU-2-8. Then, with stirring, ethylene oxide is uniformly metered in the amount of 690 g at such a rate that the temperature does not exceed 30 ° C and the pressure is 0.7 atm. For more complete conversion, a 20% excess of ethylene oxide is created at the end of the reaction. Upon completion of the reaction, the reaction mass is treated in a manner similar to that described in the previous examples.

760 g of technical triethanolamine are obtained with a content of the main substance of 98.5%.

Claims (3)

Example 5. In an autoclave, cooled to minus 40, pour 45 g of liquid ammonia, 8.5 g of cation exchanger KU-2-8. To the contents of the autoclave, with stirring, isobutylene oxide is metered in the amount of 800 g for 6 hours. During the dosing, the temperature is maintained at BO-and pressure of 10 atm. At the end of the reaction, an excess of isobutylene oxide is separated in the catalyst. Get 545 g of technical triisobutanolamine with a basic substance content of 90%. S79 Thus, this method of producing trialkanolamines allows to increase the yield of the target product up to 98%, which is the fractionation stage. Claim 1. Method for producing trialkanolamines by oxyalkylation of ammonia under heating and pressure, in order to simplify the process and increase the output of the target product, anhydrous ammonia is subjected to oxyalkylation and the process is carried out in the presence of a cation exchanger as a catalyst. 2. Method POP.1, I differ by the fact that anhydrous ammonia and alkylene oxide are taken in a molar ratio of 1: 3-5. 3. The method of pop. 1, from the fact that the aad and with the fact that anhydrous amlshak is subjected to hydroxypropylation at a temperature of 20-60 0 and a pressure of 0.5-10 atm.