RU2051897C1 - Process for preparing alkyldimethylamines - Google Patents

Abstract

FIELD: organic chemistry. SUBSTANCE: the product: alkyl- dimethylamine of the formula: (C₁₂-C₂₀)Alk(CH₃)₂N. Reagent 1: (C₁₂-C₂₀)-alk OH. Reagent 2: HCl. Reaction conditions: at 140-190 C in the presence of (C₁₂-C₂₀)Alk(CH₃)₂N or a mixture thereof in an amount of 6 to 22 wt % based on the starting alcohol for (C₁₂-C₁₄) alcohols and in an amount of 8 to 13 wt % for (C₁₅-C₂₀) alcohols followed by amination of the resulting product with an aqueous dimethyl solution under elevated temperature and excessive pressure. EFFECT: more efficient preparation process. 1 tbl

Description

The invention relates to methods for producing asymmetric tertiary amines, in particular alkyl dimethyl amines of the general formula RN (CH ₃ ) ₂ , where R is alkyl C ₁₂ -C ₂₀ .

 Tertiary amines, with high reactivity, can interact with many compounds, forming a wide range of products. Quaternary ammonium compounds (HOURs) are of the greatest importance among them.

 Known methods for producing tertiary amines by the interaction of fatty alcohol, aldehyde and / or ketone with a number of carbon atoms up to 25 with ammonia, primary or secondary amine at elevated temperature and moderate pressure in the presence as a catalyst of metals of groups VI and VIII or their oxides, including Ni, Cr, Co, oxides of chromium, titanium, molybdenum, tungsten and mixtures thereof [1-4] The disadvantage of these methods is the need to isolate the catalyst from the product and regenerate it, which complicates the technology for producing a tertiary amine and requires additional funds during the implementation of the process.

Known methods for producing tertiary amines based on the hydrochlorination of primary fatty alcohols followed by amination with dimethylamine (5,6). According to method (5), hydrochlorination of alcohols with C ₆ -C ₂₀ alkyl radicals is carried out in the presence of amines, for example, pyridine, quinoline, aniline, taken in an amount of 50-150% by weight of alcohol, in two stages:
at 1st step with hydrochloric acid in an excess of alcohol, a temperature ^of 110-140 C, until a conversion of 50-90% alcohol
at the 2nd stage with gaseous hydrogen chloride with an excess of the latter, to a temperature of 200 ^C and a pressure of 1-3 atm. The separation of products between the stages is carried out by lowering the pressure. The hydrochlorination product after the 2nd stage contains practically no osmol and can be subjected to amination without prior distillation. However, this method of obtaining tertiary amines from primary fatty alcohols is complicated in hardware design, since it is a three-stage process.

Closest to the claimed method is a two-stage method (6), based on the reaction with hydrogen chloride of primary fatty alcohols with the purification of chloralkanes and their subsequent amination with dimethylamine:
ROH + HCl - >> RCl + H ₂ O (1)
RCl + 2NH (CH ₃ ) ₂ - >>
- >> RN (CH ₃ ) ₂ + NH (CH ₃ ) ₂ HCl (2)
In this method, as the primary fatty alcohols used alcohols with an alkyl radical of C ₁₂ -C ₁₄ and hydrochlorination with hydrogen chloride is carried out at 130-152 ^C in the presence of zinc chloride as catalyst. The resulting chloroalkanes are washed with water to purify dissolved zinc chloride. Zinc chloride remaining in hydrochlorinators is used 6-8 times, then dissolved in water, osmol is separated from it and returned to the process. To compensate for the loss of catalyst, fresh zinc chloride is periodically introduced into the hydrochlorinator.

Amination purified chloroalkanes carried aqueous dimethylamine, taken in excess, at 140-160 ^{° C} and a pressure of 16 atm in an autoclave with forced circulation of the reaction mixture. The result is a tertiary amino raw material with a basic substance content of 86-88 wt.

Technological parameters of the process for producing tertiary amines with C ₁₅ -C ₂₀ alkyl radicals by the indicated method have not been identified in the literature. There is only an indication of the possibility of the synthesis of tertiary amines with C ₄ -C ₂₂ radicals by amination of chloralkanes with dialkylamines (7).

The disadvantage of this method (6) is the need for purification of chloralkanes from the catalyst (ZnCl ₂ ) and separation of the catalyst from osmol.

The aim of the invention is to simplify and reduce the cost of the method of producing alkyldimethylamines with alkyl radicals C ₁₂ -C ₂₀ .

In the proposed method for the production of alkyldimethylamines of the general formula AlkN (CH ₃ ) ₂ from primary fatty alcohols Alk OH by hydrochlorination with gaseous hydrogen chloride under heating and amination of the hydrochlorination product at elevated temperature and overpressure with an Alk-hydrocarbon radical C ₁₂ -C ₂₀ , hydrochlorination of alcohols is performed at ^about 140-190 in the presence of a tertiary amine selected from amines having an alkyl radical of C ₁₂ to C ₂₀ individually and as mixtures in an amount by weight of the loaded alcohols 6-22% for alcohols with alkyl th radical of C ₁₅ -C ₂₀ and 8-30% for alcohols with an alkyl radical of C ₁₂ -C _14, respectively, followed by amination hydrochlorination product. Amination is carried out at a temperature of 150-155 ^about C and a pressure of 16 atm.

An essential distinguishing feature of the proposed method is that the hydrochlorination of alcohols is carried out in the presence of asymmetric tertiary amines with a C ₁₂ -C ₂₀ alkyl radical in an amount of 6-22% by weight of loaded alcohols for alcohols with an C ₁₅ -C ₂₀ alkyl radical and 8-30% for alcohols with an alkyl radical of C ₁₂ -C ₁₄ , as well as the fact that the amination of the hydrochlorination product is carried out without preliminary purification of this product.

The advantage of the proposed method is that the replacement of zinc chloride with a tertiary amine at the stage of hydrochlorination of alcohols C ₁₂ -C ₂₀ eliminates the washing of chloralkanes to remove zinc chloride and separate the catalyst from osmol, which greatly simplifies the hardware design of the method and reduces the cost of technology. In addition, the replacement of deficient zinc chloride with a tertiary amine, which is the target product of the process, also provides advantages of the proposed method. The proposed method can be used to obtain individual tertiary amines and when using individual tertiary amines as catalysts for the hydrochlorination process.

The effect of the use of a tertiary amine at the stage of hydrochlorination of alcohols of the C ₁₆ -C ₂₀ fraction was unexpected, since the use of tertiary amines with alkyl radicals C ₁₂ -C ₁₄ in the hydrochlorination of alcohols of the C ₁₂ -C ₁₄ fraction proved to be less effective than when hydrochlorinating the alcohols of the C ₁₆ fraction -C ₂₀ , although based on the prior art, the latter were considered less active. Namely, in the presence of 6 wt. tertiary atoms of the C ₁₂ -C ₁₄ fraction, ceteris paribus, the content of the tertiary amine in the crude amination product was 74.6 wt.% if the alcohols of the C ₁₂ -C ₁₄ fraction were used as a feedstock. about 85.3 wt. in the case of using alcohols of the C ₁₆ -C ₂₀ fraction (see table, experiments 5 and 12), while when using zinc chloride as a catalyst, an inverse relationship takes place.

 The table shows examples of the preparation of alkyldimethylamines according to the known method (1-3) and according to the claimed (4-24) both for mixtures of fatty alcohols (4-17, 23, 24), and for individual alcohols (18, 21, 22). Examples 4-17, 23, 24 show data on the use of mixtures of alkyldimethylamines as a catalyst, and in examples 18-22, individual alkyldimethylamines.

 PRI me R. In a glass reactor, heated with an oil bath equipped with a stirrer, direct refrigerator and bubbler, load alcohols, tertiary amine (experiments 4-24) or zinc chloride (experiments 1-3). After supplying water to the refrigerator and turning on the stirrer, the temperature in the reactor is raised to the working temperature. Hydrogen chloride is fed into the reactor from a cylinder through a Tishchenko flask containing concentrated sulfuric acid.

Excess hydrogen chloride is absorbed in the column with water. Hydrogen vapors carried away with hydrogen chloride are collected in a trap from which organic substances are drained back to the reactor. The progress of the reaction is monitored by the release of water. As the rate of water evolution decreases, the temperature of the reaction mass is gradually increased to 185-190 ^о С (experiments 4-7 and 9-24) or up to 150 ^о С (experiments 1-2).

The product of the hydrochlorination of alcohols of the C ₁₂ -C ₂₀ fraction obtained in the presence of tertiary amines (experiments 4-24) is loaded into the autoclave without any forced circulation of the reaction mixture, designed for an operating pressure of 30 atm, without any preliminary treatment. An aqueous solution of dimethylamine (37.6 wt.% Basic substance) is added to the autoclave.

The autoclave is heated using an oil bath. The temperature was maintained at 150-155 ^C for 6.5 h, the pressure in the autoclave was ≈16 atm. At the end of the reaction, the product is discharged into a separatory funnel. After separation of the organic and aqueous layers, the aqueous layer is drained. The organic layer is washed many times with hot water to isolate dimethylamine salts from it, analyzed chromatographically and chemically, titrating a sample of the product 0.1 N hydrochloric acid solution in the presence of methyl red indicator.

 The hydrochlorination product (experiments 1-3), obtained in the presence of zinc chloride by a known method, is separated from the zinc chloride and osmol before amination and washed repeatedly with water, after which it is loaded into the autoclave and the amination process is carried out as described above.

 The amount of starting reagents, the fractional composition of alcohols, the amount of catalyst used (in grams and as a percentage of the mass of loaded alcohols), the amount and composition of the crude amination product are presented in the table.

 Since the implementation in laboratory conditions of the process according to the known method, that is, in an autoclave with forced circulation of the reaction mass, is difficult, experiment 1 gives the results of the implementation of the known method in an autoclave without forced circulation of the reaction mass, in experiment 1 "a" in an autoclave with forced circulation.

In experiments 2 and 3, the results of our experiments are presented, reproducing the known method as applied to alcohols of the C ₁₆ -C ₂₀ fraction. These experiments have shown that alcohol fraction C ₁₆ -C _20, regardless of the catalyst composition, to achieve 100% conversion of alcohols can be achieved only at a temperature of 150-190 ^o C, t. E. Higher than the known method for alcohols of fraction ₁₂ -C ₁₄ (see experiments 2, 3 and 8, 10). Based on the foregoing, it is clear that the proposed and known methods have almost the same energy intensity in relation to the alcohols of the C ₁₆ -C ₂₀ fraction. It is preferable to use a tertiary amine as a catalyst for the hydrochlorination of alcohols of the C ₁₆ -C ₂₀ fraction in an amount of 6-9 wt. and for alcohols fractions C ₁₂ -C ₁₄ 8-12 wt. With smaller amounts of catalyst, the complete conversion of alcohols is not ensured (see experiments 4, 9, 11, 12).

It should also be noted that when implementing the method in the presence of tertiary amines C ₁₂ -C ₂₀ in an amount of 6-8 wt. for alcohols AlkOH, where Alk hydrocarbon radical C ₁₅ -C ₂₀ and in an amount of 8-12 wt. for alcohols with a C ₁₂ -C ₁₄ alkyl radical, all other things being equal, not only a complete conversion of alcohols is achieved, but also a slightly higher selectivity of the process compared to the prototype. The increase in the content of the tertiary amine at the stage of hydrochlorination of alcohols to 16 wt. for alcohols C ₁₅ -C ₂₀ and up to 3, wt. for alcohols C ₁₂ -C14 contributes to an even greater increase in the selectivity of the process.

The feasibility of increasing the amount of tertiary amine in the initial mixture of more than 8 wt. for alcohols C ₁₅ -C ₂₀ and more than 12 wt. for alcohols C ₁₂ -C ₁₄ is determined by the further use of the finished product and is economically justified only if it is necessary to obtain tertiary amines with a low content of esters in the amount of impurities.

Tertiary amine fraction C ₁₂ -C ₁₄ is a transparent liquid with a boiling point of 240-280 ^{° C,} a melting point minus 13 ° ^C Density at 20 ^{° C} equal to 790 kg / m ^3, the solubility in water is 0.28 g / l . Studied the flammable properties of the product: the flash point of 110 ^{° C,} the autoignition temperature of 226 ° ^C. A tertiary amine is a class of low-toxic compounds. It irritates the skin. LD ₅₀ 2060 (1533-2587) mg / kg. The dose of a tertiary amine that is inactive in the sanitary-toxicological experiment is 0.02 mg / kg. MAC in the water of reservoirs is 0.2 mg / L.

The tertiary amine fraction C ₁₆ -C _{20 was} prepared in laboratory conditions. For this alcohols fraction C ₁₆ -C ₂₀ TU 38-107119-85 hydrochlorinated at 150-190 ^C for 14 hours in the presence of zinc chloride as catalyst. Chloroalkanes obtained was separated from the aqueous layer, washed repeatedly with water and aminated 40% aqueous solution of dimethylamine at a temperature of 150 ^C and a pressure of 16 atm. The tertiary amine was separated from the aqueous layer, washed with water and distilled under vacuum. In a similar manner, the individual tertiary amines C ₁₂ and C ₁₆ were synthesized, which were then used as catalysts for the hydrochlorination step of the proposed method. Tertiary amine fractions C ₁₆ -C ₂₀ at room temperature a mixture of liquid and solid substances with a boiling point of more than 280 ^about C.

Claims (1)

METHOD FOR PRODUCING ALKYLDIMETHYLAMINES of the general formula (C _{1 2} - C _{2 0} ) Alk (CH ₂ ) ₃ N by treatment with gaseous hydrogen chloride of alcohols of the general formula (C _{1 2} - C _{2 0} ) Alk OH at elevated temperature in the presence of a catalyst followed by amination of the obtained product an aqueous solution of dimethylamine at elevated temperature and overpressure, characterized in that the treatment with gaseous hydrogen chloride is carried out at 140-190 ^° C, and a tertiary amine of the general formula (C _{1 2} - C _{2 0} ) Alk (CH ₃ ) _{2 is} used as a catalyst N or a mixture thereof in an amount of 6 to 22 wt. .% calculated on the starting alcohol for alcohols (C _{1 2} - C _{1 4} ) AlkOH and in the amount of 8 - 30% - for alcohols (C _{1 5} - C _{2 0} ) AlkOH.

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