Heaxafluorobutadiene production process

FIELD: industrial organic synthesis.

SUBSTANCE: invention relates to perfluoroolefins production technology, notably to heaxafluorobutadiene CF2=CF-CF=CF2. Process comprises reaction of 1,2,3,4-tetrachlorohexafluorobutane with zinc in aqueous medium at 30 to 90°C. Reaction is carried out by metering 1,2,3,4-tetrachlorohexafluorobutane into reaction vessel containing zinc and water, while simultaneously desired product formed is recovered. Advantageously, process is conducted in presence of promoter selected from acids such as sulfuric acid and hydrochloric acid, soluble weak base salts such as zinc and ammonium halides, interphase transfer catalysts such as quaternary ammonium salts, quaternary phosphonium salts, tetrakis(dialkylamino)phosphonium salts, and N,N',N"-hexaalkyl-substituted guanidinium salts, or mixtures of indicated substances.

EFFECT: increased purity of heaxafluorobutadiene and simplified technology.

4 cl, 7 ex

 

The invention relates to the field of chemical technologies for perfluoroolefins, namely getattributename CF2=CF-CF=CF2. The specified connection is used as a monomer in various polymerization processes, as well as other areas of technology. One of the main conditions of practical application of hexafluorbutadiene is getting this connection a high degree of purity.

The level of technology.

A method of obtaining hexafluorbutadiene reaction dehalogenase 1,4-dibromo - or 1,4-diaperforums.com ethylmagnesium in tetrahydrofuran to yield 96% (Gianangelo Bargigia, Vito Tortelli, Claudio Tonelli, Silvana Modena; US Patent 5,082,981).

Signs that are common to known and claimed methods are in use in the reaction of dehalogenase fluorinated perhalogenated.

The reason getting in the known method the required technical result is used as starting compounds remote dibromo - or diaperforums.com. In addition, the need to apply for the reaction of dehalogenase magyarkanizsa compounds and organic solvents significantly limit the technological capabilities of a known method.

A method of obtaining hexafluorbutadiene reaction of 1,2-dibromotetrafluoroethane with zinc dimethylformamide in the presence of catalysts to yield 47% (Hirokazu Aoyama, Kume Takuji, JP 2001114710).

Signs that are common to known and inventive method, are used as starting compounds of fluorinated perhalogenated and zinc.

The reason getting in the known method the required technical result is the low yield of the target product, and the need to use organic solvents and their subsequent regeneration.

The closest analogue (prototype) is a method of obtaining hexafluorbutadiene reaction dehalogenase 1,2,3,4-tetrachlorohexafluorobutane zinc in the environment of absolute ethanol with a yield of 93.5% (R.P. Ruh, R. A. Davis, K.A. Allswde, GB 798407).

Signs that are common to known and inventive method, are used as starting compounds 1,2,3,4-tetrachlorohexafluorobutane and zinc.

The reason getting in the known method the required technical result is needed, use as solvents absolute ethanol or other anhydrous alcohols and their subsequent regeneration. In addition, to obtain pure hexafluorbutadiene necessary cleaning products from the interaction of the solvent with the reagents and the resulting connections.

The essence of the invention.

The problem to address with the invention, is to simplify the technology for clean hexafluorbutadiene by overcoming the disadvantages of the known methods.

The technical result of solving the above problem, is to conduct the reaction dehalogenase 1,2,3,4-tetrachlorohexafluorobutane zinc in aqueous medium at elevated temperature, which eliminates the need for regeneration of an organic solvent and purification of the resulting hexafluorbutadiene from impurities of the solvent and by-products generated.

The technical result is also achieved by the fact that the reaction dehalogenase is carried out by dosing 1,2,3,4-tetrachlorohexafluorobutane into the reaction vessel containing zinc and water. Eye-catching target product is taken simultaneously with the dosage. So get hexafluorbutadiene purity above 98% without the use of additional rectification.

The technical result is also achieved by the fact that the reaction dehalogenase carried out at a temperature from 30 to 90°C, better 45-60°C.

The technical result is also achieved by the fact that to reduce the induction period and activate the surface of the zinc reaction is carried out in the presence of promoters. As you can use acid, soluble salts of weak bases or catalysts is Espanola transfer or a mixture of the above compounds, mainly sulfuric or hydrochloric acid, zinc chloride, ammonium chloride, Quaternary ammonium salts, Quaternary postname salts, halides, tetrakis(dialkylamino)of phosphonium, halides, N,N',N"-hexadecylamine guanidine.

New (relatively prototype) characteristics of the claimed method consists in carrying out the process in the aquatic environment when heated, which allows to significantly simplify the technology of obtaining hexafluorbutadiene and to increase the purity of the resulting product.

Information confirming the possibility of carrying out the invention.

The reaction dechlorination of polychlorinated alkanes zinc is a widely used method for the synthesis of unsaturated hydrocarbons, including fluoride. However, most methods require the use of anhydrous organic solvents such as lower alcohols, dimethylformamide, etc. In this case, the need for regeneration of the solvent and separation from zinc salts complicates the technology of the whole process of dechlorination.

The present invention avoids the above difficulties by obtaining hexafluorbutadiene reaction dechlorination of 1,2,3,4-tetrachlorohexafluorobutane zinc in the aquatic environment when heated.

The temperature of the reaction dechlorination determines the speed of the process: high rate is temperature promotes rapid during the reaction, but also leads to the formation of by-products recovery and facilitates the ablation of intermediate reaction products (in particular, dichloracetate). The low temperature allows to achieve high selectivity, however, significantly lengthens the time of the reaction and reduces the efficiency of the process. Therefore, the temperature limits of the process, you can limit the temperature from 30°and above up to temperatures of 90°C.

Usually use a temperature of 45-60°With such a mode can be considered optimal from the point of view of maintaining rapid and controlled the course of the reaction.

The amount of zinc introduced into the process of dechlorination may vary from stoichiometric (2 g-atom) of up to 5 g-atoms per 1 mol of the original 1,2,3,4-tetrachlorohexafluorobutane. More promotes rapid reaction, but it is usually sufficient to 2.1-2.5 g-atoms of metal. Unreacted zinc can be separated easily by filtration and re-launched in the synthesis. The form in which the metal is used in the synthesis, is not essential, but the use of granulated zinc or chip complicates the mixing and subsequent extraction of residual metal from the reaction vessel, so it is preferable to use zinc in the form of fine powder (zinc dust).

To reduce the induction period of the reaction and activation of zinc, it is advisable to add water promoters. As such, you can use acid, soluble salts of weak bases, usually sulfuric or hydrochloric acid, zinc halides or ammonium, or a mixture of the above compounds is contraindicated only the use of compounds reacts with zinc salts with the formation of insoluble products. As promoters can also enter a different phase transfer catalysts such as Quaternary ammonium salts, Quaternary postname salts, halides, tetrakis(dialkylamino)of phosphonium, halides, N,N',N"-hexadecylamine guanidine. It is also possible joint use as a promoter of several listed products. The choice of catalyst depends only on its availability and effectiveness.

The addition of promoters is not mandatory, but it significantly reduces the induction period dechlorination reaction.

The process of obtaining hexafluorbutadiene in accordance with the invention is carried out by dosing with stirring 1,2,3,4-tetrachlorohexafluorobutane into the reaction vessel containing zinc with water and, if necessary, an additive promoter. The resulting target product is separated from the condensable impurities and going in about logdaemon collection. This methodology allows us to easily control the course of the reaction by varying the speed of the dosing 1,2,3,4-tetrachlorohexafluorobutane; this selects this mode, so that all of the dosed substance had time to react and eye-catching hexafluorbutadiene did not contain impurities of the source or intermediate compounds. Traces of water, carry out the reaction product can be easily separated by delamination or freezing. Thus, a simple technique gives the opportunity to get hexafluorbutadiene purity more than 98% without additional rectification. Remaining after the reaction solution of zinc chloride can be easily disposed of by known methods.

Embodiments of the invention.

The following examples show the ability of the method of obtaining hexafluorbutadiene according to the invention, but do not exhaust it.

Example 1 (comparison with the prototype)

In a three-neck flask equipped with stirrer, dropping funnel and reflux condenser connected to the output through the bubble counter to the low-temperature trap (-78° (C)placed 100 g (1.54 mol) of powdered zinc and 100 ml absolute ethanol. To the resulting mixture at a temperature of 45°and mixing the metered dropwise the mixture to 121.6 g (0.4 mol) of 1,2,3,4-tetrachlorohexafluorobutane (the content of the basic substance b is over 99%) and 100 ml absolute ethanol with such speed, to maintain a uniform allocation hexafluorbutadiene. After dosing the reaction mass is heated to boiling for complete dechlorination reaction. The collected product from the low-temperature trap is distilled. Get 60,0 g raw, which according to gas chromatography / mass spectrometry contains 92.1 per cent of hexafluorbutadiene; 0.16% of hexabenzocoronene; 0,24% geksaftorpentan-2; 1.6% of polyfluorinated butenes (C4HF7With4H2F6); 1.1% of dichlorohexafluoropropanes and 4.8% ethylchloride. The output hexafluorbutadiene of 86.1%.

Example 2.

In a three-neck flask equipped with stirrer, dropping funnel and reflux condenser connected to the output through the bubble counter to the low-temperature trap (-78°C)place of 62.4 g (0.96 mol) of powdered zinc, 1 g triethylmethylammonium and 200 ml of water. To the resulting mixture at a temperature of 45°and mixing the metered dropwise to 121.6 g (0.4 mol) of 1,2,3,4-tetrachlorohexafluorobutane (basic substance content of more than 99%) with such speed, to maintain a uniform allocation hexafluorbutadiene. After dosing the reaction mass is heated to 60°for complete dechlorination reaction. The collected product from the low-temperature trap is separated from the frozen water and redistilled.

Get of 60.5 g of raw sugar, which according to the / mass-Spa is trometry contains 98,15% hexafluorbutadiene; 0.01% hexabenzocoronene; 0,04% geksaftorpentan-2; 1,55% polyfluorinated butenes (C4HF7With4H2F6); 0.25% dichlorohexafluoropropanes. The output hexafluorbutadiene of 92.6%.

Example 3.

In a three-neck flask equipped with stirrer, dropping funnel and reflux condenser connected to the output through the bubble counter to the low-temperature trap (-78°C)place of 62.4 g (0.96 mol) of powdered zinc and 200 ml of water. To the resulting mixture at a temperature of 60°add 12 g of 1,2,3,4-tetrachlorohexafluorobutane and stirred until completion of the induction period and the beginning of the gassing. Then dispense the remaining amount of to 121.6 g (0.4 mol) of 1,2,3,4-tetrachlorohexafluorobutane (basic substance content of more than 99%). After dosing the reaction mass is heated to boiling for complete dechlorination reaction. The collected product from the low-temperature trap is separated from the frozen water and redistilled.

Get 62.8 g of raw sugar, which according to gas chromatography / mass spectrometry contains 98,0% hexafluorbutadiene; 0.01% hexabenzocoronene; 0.02% geksaftorpentan-2; 1,35% polyfluorinated butenes (C4HF7With4H2F6); 0,62% dichlorohexafluoropropanes. The output hexafluorbutadiene 95,9%.

Example No. 4.

The process is conducted as described in example 2, using as a promoter of 2 g of bromide Tetra is IP(diethylamino)phosphonium.

Get 62,5 g raw, which according to gas chromatography / mass spectrometry contains 98,22% hexafluorbutadiene; 0,04% hexabenzocoronene; 0.05% geksaftorpentan-2; 1,22% polyfluorinated butenes (C4HF7With4H2F6); 0,45% dichlorohexafluoropropanes. The output hexafluorbutadiene 94,7%.

Example No. 5.

In a three-neck flask equipped with stirrer, dropping funnel and reflux condenser connected to the output through the bubble counter to the low-temperature trap (-78°C)place of 62.4 g (0.96 mol) of powdered zinc and 200 ml of water. To the resulting mixture as a promoter is added 2 ml of concentrated hydrochloric acid and then hold the process as described in example No. 3.

Get to 62.1 g of raw sugar, which according to gas chromatography / mass spectrometry contains 98,7% hexafluorbutadiene; 0.01% hexabenzocoronene; 0.02% geksaftorpentan-2; 0,82% polyfluorinated butenes (C4HF7C4H2F6); 0,42% dichlorohexafluoropropanes. The output hexafluorbutadiene 94,6%.

Example No. 6.

In a three-neck flask equipped with stirrer, dropping funnel and reflux condenser connected to the output through the bubble counter to the low-temperature trap (-78°C)place of 62.4 g (0.96 mol) of powdered zinc, 1 g triethylmethylammonium chloride and 200 ml of water. To the resulting mixture as a promoter and optionally add 2 ml of concentrate is ture of hydrochloric acid and at a temperature of 30° With intensive stirring start to dosage to 121.6 g (0.4 mol) of 1,2,3,4-tetrachlorohexafluorobutane (basic substance content of more than 99%) at a constant speed, to maintain a uniform allocation hexafluorbutadiene. After dosing the reaction mass is slowly heated to 60°for complete dechlorination reaction. The collected product from the low-temperature trap is separated from the frozen water and redistilled.

Get to 59.1 g of raw sugar, which according to gas chromatography / mass spectrometry contains 98,55% hexafluorbutadiene; 0,04% geksaftorpentan-2; 1,35% polyfluorinated butenes (C4HF7With4H2F6); 0.05% dichlorohexafluoropropanes. The output hexafluorbutadiene 89,9%.

Example No. 7.

In a three-neck flask equipped with stirrer, reflux condenser, connected to the output through the bubble counter to the low-temperature trap (-78° (C)installed on the nozzle, which returns the condensate siphon under the layer of the reaction mixture, place of 62.4 g (0.96 mol) of powdered zinc and 200 ml of water. To the resulting mixture as a promoter is added 2 ml of concentrated hydrochloric acid and heated it up to 90°C. Then, under vigorous stirring using a metering pump under a layer of liquid injected to 121.6 g (0.4 mol) of 1,2,3,4-tetrachlorohexafluorobutane (basic substance content of more than 99%). After the Osinovka the reaction mass was incubated for 15-20 minutes to complete dechlorination reaction. The collected product from the low-temperature trap is separated from the frozen water and redistilled.

Get 60,3 g raw, which according to gas chromatography / mass spectrometry contains 93,15% hexafluorbutadiene; 0.08% hexabenzocoronene, 0.06% geksaftorpentan-2; 5.25% of polyfluorinated butenes (C4HF7With4H2F6); 1,45% dichlorohexafluoropropanes. The output hexafluorbutadiene to 86.7%.

1. The method of obtaining hexafluorbutadiene reaction 1, 2, 3, 4-tetrachlorohexafluorobutane with zinc, wherein the process is carried out in aqueous medium at a temperature of 30-90°C.

2. The method of obtaining hexafluorbutadiene according to claim 1, characterized in that the reaction is carried out by dosing 1, 2, 3, 4-tetrachlorohexafluorobutane into the reaction vessel containing zinc and water, with simultaneous selection formed the target product.

3. The method of obtaining hexafluorbutadiene according to claims 1 and 2, characterized in that the process is carried out a temperature of from 45 to 60°C.

4. The method of obtaining hexafluorbutadiene according to any one of claims 1 to 3, characterized in that the process is carried out in the presence of a promoter, which is used as the acid, in particular sulfuric acid or a salt, soluble salts of weak bases, such as zinc halides or ammonium, phase transfer catalysts such as Quaternary ammonium salts, Quaternary postname salt, halogene the s tetrakis(dialkylamino)of phosphonium, or halides of N,N`,N``-hexadecylamine guanidine or a mixture of these substances.



 

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61 cl, 8 tbl, 32 ex

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