RU2309935C1 - Method for combined preparing chloroform and alkylene carbonates - Google Patents

Abstract

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for synthesis of chloroform and alkylene carbonates of the general formula:

, wherein R means H, -CH₃. Method involves interaction of vicinal glycol with hexachloroacetone at elevated temperature in the presence of metal hydrosilicate of II-d or III-d group of the periodic system of elements followed by isolation of end products by the known methods. Calcium hydrosilicate, magnesium hydrosilicate, aluminum hydrosilicate, barium hydrosilicate or their mixtures are used preferably taken in the different mass ratios. Catalyst is used preferably in the amount 0.5-2% but preferably in the amount 0.8-1.2% of reagents mass. Invention provides increasing yield of chloroform and alkylene carbonate, enhancing their quality and expanding the raw base of substances used in catalytic process.

EFFECT: improved method of synthesis.

3 cl, 3 ex

Description

, где R=Н, СН₃.The invention relates to a technology for producing organic compounds, and in particular to a method for the joint production of chloroform and alkylene carbonates of the general formula

where R = H, CH ₃ .

Chloroform is a solvent widely used in industry and feedstock in the production of fluorochlorocarbons (freons) and other chemical products.

Alkylene carbonates - products of large-capacity organic synthesis used as solvents, extractants, especially in the petrochemical industry; additives to motor fuels to reduce smoke formation; in electrolyte compositions of lithium batteries and accumulators, etc.

On an industrial scale, chloroform is obtained by chlorinating methane (or methyl chloride) or from chloral [Industrial organochlorine products. Handbook / Ed. L.A. Oshina. - M .: Chemistry, 1978, S. 26-35]. The disadvantages of the first of these methods include high process temperatures - above 300 ° C, as well as the receipt of significant quantities of environmentally hazardous carbon tetrachloride, the production and use of which is prohibited under the Montreal Protocol. The second method is technically outdated and has low technical and economic indicators.

It is also possible to obtain chloroform by a haloform reaction of sodium hypochlorite with methyl ketones, while an acid is formed as a by-product, which is not always in demand. In addition, the process is characterized by a low yield of the target chloroform.

It is also known to obtain chloroform from acetone, ethanol or methyl acetate by treatment with bleach [F.F. Muganlinsky, Yu.A. Treger, M.M. Lyushin. Chemistry and technology of organohalogen compounds. - M .: Chemistry, 1991, p.68], for example, by the reaction:

2CH ₃ COCH ₃ + 6CaOCl ₂ → 2CHCl ₃ + Ca (CH ₃ COO) ₂ + 2Ca (OH) ₂ + 3CaCl ₂ .

The method has long been used on an industrial scale, but due to low technical and economic indicators, it has now lost its competitiveness compared to modern methods for producing chloroform.

A known method of producing chloroform by the interaction of hexachloroacetone with an alkali solution at a pH of not more than 10 and a temperature of not more than 50 ° C [Japanese patent No. 19927, 1968] by the reaction:

CCl ₃ COCCl ₃ + NaOH → CHCl ₃ + CCl ₃ COONa.

In this method, along with the target product - chloroform - sodium trichloroacetate is formed, on the formation of which alkali is consumed. Previously, sodium trichloroacetate was used as a herbicide. Currently, a new generation of herbicides is used, more environmentally friendly and effective.

A known method of producing chloroform [RF patent No. 2206558, 2003], according to which hexachloroacetone is hydrolyzed with water in the presence of a catalyst - ethanolamines - at a temperature of 95-150 ° C with simultaneous distillation of the resulting chloroform:

The main disadvantage of this method is that in the synthesis process the catalyst is gradually deactivated due to side reactions of the formation of amine trichloroacetate, amine formate, amine hydrochloride. The regeneration of the spent aqueous catalyst solution is a rather lengthy and energy-intensive process. First, the spent catalyst solution is boiled at a temperature above 100 ° C for 3-5 hours to decompose the amine trichloroacetate. Next, the solution is cooled to 20-30 ° C and 40-45% alkali is fed into it to a pH of 8-9 to decompose the amine hydrochloride and amine formate. Precipitated crystals of sodium chloride are filtered off.

Cyclic alkylene carbonates are obtained mainly by condensation of alkene oxide and carbon dioxide [patent No. 4931571, USA, publ. 1990 / RZhKhim 1991, 21N34P). Also known are the reactions of glycols with phosgene to produce alkylene carbonates [Application of Germany No. 3838752, publ. 1990 / RZHKhim 1991, 6N139P), transesterification of dialkyl carbonates with glycols [application No. 61-130288, Japan, publ. 1986 / RJHim 1987, 22H45P]. The first method involves the use in industry of explosive alkene oxide and the use of high pressure, which makes special demands on equipment and production. Similar disadvantages characterize the production method using toxic phosgene. Difficulties in transesterification of dialkyl carbonates with glycols are associated with the fact that the process is reversible, in addition, alcohol and the resulting alkylene carbonate usually form a difficult to separate azeotropic mixture, which significantly complicates and increases the cost of the whole process. It should also be noted that the dialkyl carbonate used in the transesterification is a relatively scarce and expensive reagent.

The closest in technical essence and the achieved effect to the proposed method for the joint production of chloroform and alkylene carbonate is the method of obtaining according to US patent No. 4353831, publ. 10.10.1982, IPC С07D 317/38, С07D 317/36, NKI 549/229.

According to this method, to obtain alkylene carbonates and chloroform, a mixture of hexachloroacetone and vicinal glycols taken in an equimolar ratio is heated at a temperature of 100-250 ° C (mainly at 120-160 ° C) in the presence of small but effective amounts of bases (0.1-1 wt.%, better than 0.2-0.4 wt.%), including alcoholates, salts of strong bases and weak acids or nucleophilic organic bases:

The yield of alkylene carbonate reaches 92-96%. The yield of chloroform is about 96% of theory.

The disadvantages of this method include the following:

- a relatively high temperature of the process, 100-250 ° C (120-160 ° C), which leads to undesirable side conversions of the target alkylene carbonate in the presence of a catalyst, osmol and a decrease in product yield to 92-96%;

- the use of such an unregenerated and expensive interphase transfer catalyst as crown ether increases the production cost of products.

The aim of the proposed production method is to increase the yield of chloroform and alkylene carbonate, improve the quality of the target products and expand the raw material base of the catalytic process through the use of non-toxic, non-combustible and available catalysts.

, где R=H, СН₃, взаимодействием вицинального гликоля с гексахлорацетоном при повышенной температуре осуществляют в присутствии в качестве катализатора гидросиликата металла II или III группы периодической таблицы с выделением целевых продуктов известными методами.This is achieved by the fact that the joint production of chloroform and alkylene carbonates of the general formula

where R = H, CH ₃ , the interaction of vicinal glycol with hexachloroacetone at an elevated temperature is carried out in the presence of a metal hydrosilicate of catalyst of group II or III of the periodic table with the selection of target products by known methods.

Advantageously, according to the proposed method, a metal hydrosilicate of a group II or III of the periodic table uses a metal hydrosilicate selected from the group consisting of calcium hydrosilicate, magnesium hydrosilicate, aluminum hydrosilicate, barium hydrosilicate, or mixtures thereof in various weight ratios.

According to one of the preferred embodiments of the proposed method, the catalyst is used in an amount of 0.5-2.0%, mainly in an amount of 0.8-1.2% by weight of the reactants.

As the most affordable and effective catalysts in the proposed process, calcium, magnesium, aluminum and barium hydrosilicates or various mixtures thereof are mainly used, however, other metal hydrosilicates of group II or III of the periodic table, for example, strontium, zinc, cadmium or gallium hydrosilicate, are also possible.

According to the proposed method, these hydrosilicates of metals of group II or III of the periodic table can be used in amounts of less than 0.5% and more than 2.0% by weight of reagents. However, the use of less than 0.5 wt.% Of this catalyst increases the duration of the process and reduces the conversion of the starting reagents, and the use of the catalyst in an amount exceeding 2.0 wt.% Is technically and economically less efficient. The most optimal and preferred is the use of these metal hydrosilicates in an amount of 0.8-1.2% by weight of the reactants.

The proposed process can be implemented in a batch and continuous manner at atmospheric or gauge pressure in the range of 0.05-6 bar.

Carrying out the process at atmospheric pressure allows the use of conventional technological equipment, and carrying out the process at a slight overpressure can reduce the loss of chloroform and improve its quality during isolation.

Isolation of the target products is carried out by known methods, for example, cooling, separating the catalyst by filtration, separating chloroform by distillation, isolating glycol, then alkylene carbonate by distillation under vacuum. The yield of chloroform is at least 99%, the yield of alkylene carbonate is at least 97% of theory.

Below are examples explaining the technical essence of the proposed method, but not limiting the scope of the claims defined by the formula and description.

Example 1

36 g of 1,2-propylene glycol and 1.8 g of aluminum hydrosilicate are placed in a reactor equipped with a mixing device and a condenser. With stirring and a temperature of 95-100 ° C for 1.5 hours, 126 g of hexachloroacetone are added to the mixture. At the same time, the resulting chloroform is distilled off and condensed. The reaction mixture is stirred for another 0.5-1.0 hours, raising the temperature to 120-125 ° C for more complete extraction of chloroform. The propylene carbonate remaining in the reactor is separated from the catalyst by filtration and distilled under vacuum. The catalyst is returned to the process for reuse. The amount of catalyst used is 1.1% by weight of the reactants.

The yield of chloroform is 99.3%, and propylene carbonate 97.1% of theoretical.

Example 2

18 g of ethylene glycol and 0.76 g of magnesium hydrosilicate are charged to the reactor, and 77 g of hexachloroacetone are added over 50 minutes with stirring. At the same time, the resulting chloroform is distilled off. The reaction mixture was stirred for 1 hour at a higher temperature to completely remove chloroform. The ethylene carbonate remaining in the bottom of the reactor is separated from the catalyst by filtration and distilled. The amount of catalyst used is 0.8% by weight of the reactants.

The yield of chloroform is 99.1%, and ethylene carbonate 97.6% of theoretical.

Example 3

In the reactor of example 1, 27 g of 1,2-propylene glycol and 1.45 g of calcium hydrosilicate are placed, and 94 g of hexachloroacetone are added with stirring at a temperature of 85-95 ° C. over 1 hour. At the end of the dosage of hexachloroacetone, the reaction mixture is stirred for 0.5-1 hours, and then chloroform is distilled off from the reaction mixture. The propylene carbonate remaining in the reactor is separated from the catalyst and distilled in vacuo. The amount of catalyst used is 1.2% by weight of the reactants.

The yield of chloroform is 99.7%, the yield of propylene carbonate is 97.4% of theoretical.

Similarly, ethylene or propylene carbonate and chloroform are prepared using other metal hydrosilicates of group II or III of the periodic table (or mixtures thereof), taken in an amount of 0.2 to 2.5% by weight of the reactants. Moreover, during the synthesis process, the pressure varied from atmospheric to elevated in the range of 0.05-6 ati.

Thus, the proposed method for the joint production of chloroform and alkylene carbonates allows to increase the yield of target products to 99.3% and 97.6%, respectively, and expands the raw material base of the process through the use of new effective and affordable inorganic catalysts.

Claims (3)

1. The method of co-production of chloroform and alkylene carbonates of the general formula

, where R = H, CH ₃ , by the interaction of vicinal glycol with hexachloroacetone at an elevated temperature in the presence of a catalyst, characterized in that a metal hydrosilicate of group II or III of the Periodic Table is used as a catalyst with the isolation of target products by known methods. 2. The method according to claim 1, characterized in that the metal hydrosilicate of group II or III of the Periodic table uses a metal hydrosilicate selected from the group comprising calcium hydrosilicate, magnesium hydrosilicate, aluminum hydrosilicate, barium hydrosilicate, or mixtures thereof in various mass ratios. 3. The method according to claim 1, characterized in that the catalyst is used in an amount of 0.5-2%, mainly in an amount of 0.8-1.2% by weight of the reactants.