Method of purifying perfluoroarenes

FIELD: chemistry.

SUBSTANCE: halogen used is bromine or iodine, and sulphuric anhydride is used in form of its solution in sulphuric acid with concentration of 5-60%. The chemical treatment process is carried out at temperature of 20-80°C, preferably at 50-70°C, with weight ratio of the sulphuric anhydride to halogen equal to 1-10:1, preferably 1.5-3:1.

EFFECT: obtaining highly pure product.

3 cl, 4 ex

 

The invention relates to the field of purification of perfluorinated organic compounds, particularly to cleaning performancenow to 99.95% and higher are used as reagents in organic synthesis and special solvents in industry and intelligence.

The level of technology

Known purification method performancenow received by dehalogenating of chlorodiphenylmethane method of preparative chromatography ["Synthesis of organofluorine compounds", edited by Elecronica, M.: Chemistry, 1973, p.90],

Signs that are common to known and claimed methods are used as feedstock product raw after synthesis.

The reason getting in the known method the required technical result is that this method allows cleaning only small quantities of substances, in addition, preparative chromatography differs considerable effort and high cost.

The closest analogue (prototype) is a method of cleaning performancenow ["Synthesis of organofluorine compounds", edited by Elecronica, M.: Chemistry, 1973, str-135], in which cleaning is performed by rectification method (fractional acceleration) product raw on the Packed column with an efficiency of 18 to 20 theoretical plates.

Signs, the two the stories shared by well-known and inventive method, consist in the use of rectification.

The reason getting in the known method the required technical result is that this method allows you to clean perforare far from boiling impurities, but it is not very effective at removing hydrogen polyfluoroarenes with close boiling points. Purity performancenow obtained in this way is not more than a 99.0-99.7 per cent.

The invention

The problem to which the invention is directed, is to increase the degree of purification performancenow. For use performancenow in modern practice requires their high purity, in particular the complete absence of impurities containing aromatic protons. Conventional treatment methods do not allow to achieve the desired result. The proposed method allows to obtain perforare free from undesirable impurities, with a basic substance content of more than 99.95 per cent.

The technical result causing the problem lies in the fact that the primary chemical treatment of the hydrogen-containing impurities in the source perforating translated to the heavy bromine - and iodine-containing products separated in the second stage rectification.

Achieved technical result that for purification from hydrogen-containing azeotrope impurities SN is Chala chemical processing is carried out product raw mixture of sulfur dioxide and free halogen, followed by purification by distillation.

Achieved technical result is also the fact that it is proposed to use the processing of raw mixture of sulfur dioxide and free halogen, in particular bromine or iodine, or mixtures thereof.

Achieved technical result that for the purification of used sulfuric anhydride in the form of its solution in sulphuric acid with a concentration of from 5 to 60%, better than 20%.

Achieved technical result is also the fact that the primary treatment process is conducted at temperatures from 20°C to the boiling point, it is better 50-70°C.

New (relatively prototype) characteristics of the claimed method are in the process of cleaning performancenow in two stages: chemical treatment consisting in processing raw mixture of sulfur dioxide and free halogen, and the secondary cleaning - rectification of the mixture.

Information confirming the possibility of carrying out the invention

Performancesee products after synthesis usually contain impurities, where the fluorine atoms are partially replaced by other halogen atoms and hydrogen. If the first products have a higher boiling point and can be easily separated by distillation, the hydrogen-containing impurities boil very close and cannot be completely removed by distillation. Thus, the boiling point of hexaferrite is 80-82°C, Penta is Tarantola 85°C, 1,2,3,5-tetrafluorobenzene 83°C; pentafluorophenol 145°C, 2,3,5,6-tetrafluorophenol 140°C. At the same time, practice is very important for high purity, for example when using hexaferrite in NMR spectroscopy of hydrogen containing impurities is not valid.

The present invention solves the problem of obtaining a product of the desired purity by supplementing rectification chemical treatment of the raw product with a mixture of sulfuric anhydride with a free halogen. Thus there is a complete substitution of the aromatic protons on the halogen.

The resulting halogenierten have a very high boiling point and can be easily separated from the desired products, followed by distillation.

Chemical cleaning is performed by mixing the original perforata raw with a mixture of free halogen-free sulfur dioxide to remove hydrogen containing impurities. Then the product is sent to distillation for separation of the target compounds. Pre-raw is separated from the acid layer and, if necessary, neutralize. The neutralization process is not mandatory and is required if the equipment is used for rectification, is not resistant to the used reagents.

For processing as halogen prefer to use bromine or iodine, chlorine gas and unsuitable for work. The number of halogen SEL is extended depending on the concentration of impurities, it is usually take 5-10% by weight purified perforata, the weight ratio of sulfuric anhydride and halogen 1-10:1, better than the 1.5-3:1. The use of large quantities of reagents not economically feasible, and small amounts greatly slow down the cleanup process.

Sulphuric anhydride is usually used in the form of a solution in sulfuric acid (oleum), suitable for cleaning solutions with a concentration of 5-60%, better than 20%, as the most available and cheap. The use of pure sulfuric anhydride valid, but is impractical due to its high cost, hazards in the work and a low boiling point.

Pre-treatment is carried out at a temperature from 20°C to boiling. The low temperature slows down the cleaning process, the upper temperature limit is limited by the boiling temperature of the reaction mass is thus possible carryover of reagents, so the process is best carried out at 50-70°C.

Embodiments of the inventions

The following examples show the possibility of cleaning method performancenow according to the invention, but do not exhaust it.

Example 1

Cleaning hexaferrite bromine and 60% oleum.

In a round-bottom three-neck flask with a capacity of 6 DM3, snabzhennuyu stirrer, reflux condenser and thermometer, installed in an air bath on the heater, load 8,6 kg hexaferrite raw (with the actual content of the basic substance 99,13%; the content of pentafluorobenzoyl 0,87%), 5% weight loading hexaferrite (0.43 kg) 60% solution of sulfur trioxide in sulfuric acid (oleum) and 1.0% by weight of the product hexaferrite (0,086 kg) of dry bromine.

The resulting mass is heated when operating the mixer to a temperature of 55°C and maintained at a temperature of 55-65°C for 10-12 hours to fully develop pentafluorobenzoyl by GC analysis.

After exposure of the acid layer is separated in a separating funnel and the organic layer is neutralized sulfite-alkaline solution and washed with water. After distillation of the resulting product get 7,97 kg hexaferrite with a boiling point 80-81°C and the content of the basic substance to 99.99%, not containing pentafluorobenzoyl. The yield of 93.5%.

Example 2

Cleaning hexaferrite 20% oleum with iodine.

In a round-bottom three-neck flask with a capacity of 6 DM3, snabzhennuyu stirrer, reflux condenser and thermometer, installed in an air bath on the heating load of 7.8 kg hexaferrite raw (the content of the basic substance-99,13%; the content of pentafluorobenzoyl-0,87%), 10% weight loading hexaferrite (0,78 kg) of 20% solution of sulfur trioxide in sulfuric acid (oleum) and 1.0% by weight of the product hexaferrite (0,078 kg) iodine.

The resulting mass is heated with running is eelke to a temperature of 55°C and maintained at a temperature of 55-65°C for 10-12 hours to fully develop pentafluorobenzoyl by GC analysis.

After exposure of the acid layer is separated in a separating funnel and the organic layer is sent to a rectification. After distillation on a glass column of the obtained product is obtained of 7.48 kg hexaferrite with a boiling point 80-81°C and the content of the basic substance 99,999%, not containing pentafluorobenzoyl. Output 96,7%.

Example 3

Cleaning pentafluorophenol 60% oleum and bromine.

In enameled reactor with a high-speed stirrer load 30 kg pentafluorophenol raw content hydrogenous impurities up to 2%. Then slowly, with stirring, poured 1.5 kg of 60% oleum. After downloading the oleum was charged to the reactor, 300 g of bromine and its contents are heated to a temperature of 50-60°C.

The reaction mass is maintained at this temperature for 6-12 hours, taking samples for GC analysis. After reducing the impurity content to 0.005%, the content of the reactor is cooled to room temperature, turn off the mixer and leave the reaction mass to stand for 1 hour. The lower acid layer is drained from the reactor and sent for recycling. The upper organic layer (raw of pentafluorophenol) is drained and sent for rectification.

Rectification of pentafluorophenol raw conducted in a distillation installation, made of glass. First to a temperature of 144°With selected pridgon that as accumulation the Oia return of rectification. Conforming pentafluorophenol selected when the temperature of the top of the column 144-146°C. Receive 26,5 kg of product containing pentafluorophenol of 99.98% and a hydrogen-containing impurities is not more than 0.005%. The yield of 88.3%.

Example 4

Cleaning octafluorotoluene 60% oleum and bromine.

In a round-bottom three-neck flask with a capacity of 6 DM3, snabzhennuyu stirrer, reflux condenser and thermometer, installed in an air bath on the heater, load 7.6 kg of octafluorotoluene raw (the content of the basic substance 98,7%; impurities content of 1.27%), 10% weight on the load octafluorotoluene (0.76 kg) 60% solution of sulfur trioxide in sulfuric acid (oleum) and 1.0% by weight of the product octafluorotoluene (0,086 kg) of dry bromine.

The resulting mass is heated when operating the mixer to a temperature of 55°C and maintained at a temperature of 55 to 65°C for 10-12 hours to complete development of the hydrogen-containing impurities by GC analysis.

After exposure of the acid layer is separated in a separating funnel and the organic layer is neutralized sulfite-alkaline solution and washed with water. After distillation of the resulting product get 7,1 kg octafluorotoluene with a boiling point of 107-108°C and the content of the basic substance of 99.99% and not containing aromatic protons. The output from 94.7%.

1. Cleaning method performancenow, characterized in that Thu is to obtain a product of high purity initially carry out a chemical treatment product raw mixture of sulfur dioxide and free halogen, then the target product emit through rectification.

2. The method according to claim 1, characterized in that the halogen used in chemical processing product raw is bromine or iodine and sulphuric anhydride is used in the form of its solution in sulphuric acid with a concentration of from 5 to 60%.

3. The method according to any one of claims 1 and 2, characterized in that the said process chemical treatment is carried out at a temperature of from 20 to 80°C, better 50-70°C, and the weight ratio of sulfuric anhydride and halogen choose 1-10:1, better than the 1.5-3:1.



 

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