RU2602240C1 - Reagent for introduction of perfluoro-tert-butyl group, method for production thereof and method for producing perfluoro-tert-butyl-substituted compounds - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to use of 1,1-dichlorohexafluoroisobutylene as a reagent for introduction of perfluoro-tert-butyl group in a method of producing compounds, containing perfluoro-tert-butyl group, involving preparation of perfluoro-tert-butyl anion in a solution, and reacting obtained perfluoro-tert-butyl anion with different electrophilic reagents, is characterised by that perfluoro-tert-butyl anion is obtained by reacting 1,1-dichlorohexafluoroisobutylene with fluorine caesium in polar aprotic solvent, such as dimethyl formamide or acetonitrile. Invention also relates to a two-step method of producing 1,1-dichlorohexafluoroisobutylene from 1,1,1-trichloro-3,3,3-trifluoro-2-(trifluoromethyl)propanol, first step of which consists in producing an ester of 1,1,1-trichloro-3,3,3-trifluoro-2-(trifluoromethyl)propanol and acid, such as acetic, trifluoroacetic or methanesulphonic, by reacting with anhydride or with acyl chloride of corresponding acid in presence of a base, and second reaction of obtained ester with metal, such as zinc, in a polar boiling solvent, such as sulfolane, with subsequent extraction of produced 1,1-dichlorohexafluoroisobutylene by distillation of reaction mixture.

EFFECT: using less toxic alternative reagent.

5 cl, 1 tbl, 18 ex

Description

The invention relates to the chemistry of organofluorine compounds, in particular to reagents for introducing perfluorinated substituents, methods for producing compounds containing perfluorinated substituents, in particular compounds containing a perfluoro-tert-butyl group, as well as to methods for producing fluorochloro-olefins, namely 1,1-dichlorohexafluoroisobutylene .

Compounds containing perfluorinated substituents are increasingly used in all areas of modern technology, in particular in the production of monomers for polymers with special properties: enhanced chemical and thermal stability and a number of other special properties that make them indispensable for creating unique materials for modern technology, including for obtaining photoresists used in semiconductor devices (EP A1 20030924, EP 1319981 A2 20030618); perfluoro-tert-butyl iodide is used as a working medium for photoionization lasers (RU 2439762 (C1), 2012).

In the 50-70 years of the last century, in significant quantities, perfluoroisobutylene was obtained as a by-product of the industrial process for producing tetrafluoroethylene by pyrolysis of chladone-22. The availability of perfluoroisobutylene stimulated the study of its chemical properties. In particular, it was shown that, when interacting with the F-anion, it forms a perfluoro-tert-butyl anion, upon the action of which various electrophilic reagents are obtained compounds containing a perfluoro-tert-butyl group. Thus, perfluoroisobutylene served as a source of perfluoro-tert-butyl anion for introducing a perfluoro-tert-butyl group into various classes of organic compounds (Dyatkin B.L., Delyagina N.I., Sterlin S.R., Uspekhi khimii, vol. 45 , 1976, p. 1205-1221).

Scheme 1

Since perfluorizobutylene is highly toxic and has a low boiling point (6-7 ° C), working with it required the use of specialized equipment and increased safety measures. In addition, due to changes in the technological process for the industrial production of tetrafluoroethylene, aimed at eliminating the formation of highly toxic substances, perfluoroisobutylene has ceased to be available, and thus the work on introducing the perfluoro-tert-butyl group has practically ceased.

The aim of the present invention is to develop a method of introducing a perfluoro-tert-butyl group without the use of perfluoroisobutylene using an alternative reagent, low toxicity, easy to use and affordable.

The present invention provides a reagent for introducing a perfluoro-tert-butyl group - 1,1-dichlorohexafluoroisobutylene - and a method for introducing a perfluoro-tert-butyl group into molecules of various organic compounds using this reagent, as well as a method for producing this reagent.

1,1-Dichlorohexafluoroisobutylene is a 1,1-dichloro-substituted analog of perfluoroisobutylene. It is known that 1,1-dichlorohexafluoroisobutylene is 250 times less toxic than perfluoroisobutylene [S.M. Timperley J. Fluor. Chem., 1999, 94, 37-41], in addition, it is a liquid with a boiling point of 68-70 ° C, and not a gas like perfluoroisobutylene.

Proposed by the present invention a method for producing compounds containing a perfluoro-tert-butyl group, is as follows.

1,1-Dichlorohexafluoroisobutylene (1) is reacted with cesium fluoride in a polar aprotic solvent, preferably dimethylformamide (DMF), or acetonitrile in a molar ratio of 1,1-dichlorohexafluoroisobutylene: cesium fluoride 1: 3-3.5, and perfluoride is formed tert-butyl anion. The perfluoro-tert-butyl anion formed from 1,1-dichlorohexafluoroisobutylene and CsF in acetonitrile or dimethylformamide is stable for at least a day and interacts with a wide variety of electrophiles similarly to the perfluoro-tert-butyl anion obtained from perfluoroisobutylene and fluoride compounds containing a perfluoro-tert-butyl group. Under the action of various electrophilic reagents, such as alkyl halides, allyl halides, benzyl halides, propargyl halides, heterocyclic compounds, halogens, sulfur and sulfur-containing compounds, nitrogen-containing compounds, carbonyl compounds, compounds containing a perfluoro-tert-butyl group are obtained.

The undoubted practical value of the proposed method is the significantly lower toxicity of 1,1-dichlorohexafluoroisobutylene (1) compared to perfluoroisobutylene and a higher boiling point (TPK (1) = 68-70 ° C), which allows working with it under standard conditions for organic synthesis including scaling up the process for industry.

The present invention also provides a method for synthesizing the starting 1,1-dichlorohexafluoroisobutylene (1) from 1,1,1-trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-ol (2).

A known method for producing 1,1-dichlorohexafluoroisobutylene with a 30% yield by heating a solution of triphenylphosphine in bromotrichloromethane with an excess of hexafluoroacetone in a sealed ampoule (Bartlett, PD; Wheland, RC, Journal of the American Chemical Society, 1972, vol. 94, p. 2145-2146 )

A known method for producing 1,1-dichlorohexafluoroisobutylene by heating 1,1,1-trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-ol (2) with dibromotrimethylphosphorane in 30% yield (REA Dear, E. E. Gilbert, JJ Murray Tetrahedron, 1971, 27, 3345-3355).

A known method of producing 1,1-dichlorohexafluoroisobutylene by dechlorohydroxylation of 1,1,1-trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-ol (2) by heating it with PCl ₅ with a yield of 42% at a conversion of 40 % (REA Dear, E.E. Gilbert, JJ Murray Tetrahedron, 1971, 27, 3345-3355), thus, the total yield without conversion is only 16%, which makes it unsuitable for industrial use.

1,1,1-Trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-ol (2) is an available intermediate for the synthesis of various organofluorine compounds. A method for its synthesis from hexafluoroacetone and trichloroacetic acid with a preparative yield of 75% was developed earlier (Zeyfman Yu.V., Izvestia AN Seriya Khimiya, 1992, v. 41, 464-467).

The present invention provides a two-step process for the preparation of 1,1-dichlorohexafluoroisobutylene from 1,1,1-trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propanol with a total yield of more than 50%, suitable for industrial use.

The first stage of the proposed method consists in obtaining an ester of 1,1,1-trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-ol and an acid such as acetic, trifluoroacetic or methanesulfonic, by reacting it with anhydride or an acid chloride of the corresponding acid in the presence of a base, and the second by reacting the resulting ester with a metal such as zinc in a polar high boiling solvent such as sulfolane, followed by isolation of the resulting 1,1-dichlorohexafluoroisobutylene from the reaction mixture by distillation.

It could be assumed that 1,1,1-trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-ol (2) could be dechlorohydroxylated to olefin with zinc in an alcohol or acetic acid medium, however, in the reaction (2) with zinc dust in acetic acid, the reduction of the trichloromethyl group is observed and a mixture of the corresponding tertiary alcohols containing CHCl ₂ , CH ₂ Cl and CH ₃ groups is formed. To avoid the restoration of the trichloromethyl group, to facilitate the departure of the hydroxyl group, it was acylated, converting to ester.

Scheme 3

Sulfolane turned out to be the best solvent for the elimination of compounds (3) with zinc to synthesize olefin (1), and 1,1,1-Trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propane- 2-yl methanesulfonate (3c) with zinc. In this case, the preparative yield of 1,1-dichlorohexafluoroisobutylene (1) is 61%.

Thus, the invention provides a method for producing compounds containing a perfluoro-tert-butyl group from 1,1-dichlorohexafluoroisobutylene, low toxicity and easy to use due to the relatively high boiling point of the reagent, and a preparative method for producing the starting 1,1-dichlorohexafluoroisobutylene from available raw materials. Both methods are suitable for industrial use.

The advantages of the proposed method were demonstrated in the synthesis of previously not described (perfluoro-tert-butyl) butadiene (7), which can be used to obtain fluoropolymers (Scheme 4, 5), (examples 4, 5).

Scheme 4

Scheme 5

The technical result of the invention is a new reagent for producing perfluoro-tert-butyl substituted compounds, significantly less toxic than perfluoroisobutylene, which is, in addition, a liquid with a sufficiently high boiling point, and not a gas, and a method for using it to produce various compounds containing perfluoro- A tert-butyl group suitable for industrial use, as well as a method for producing this reagent from available raw materials, is also suitable for industrial use.

The implementation of the method is illustrated by the following examples.

(Chemical shifts of ¹⁹ F NMR in the examples are given relative to the external standard CFCl ₃ , ¹ H NMR relative to the external standard TMS)

Example 1

Obtaining 1,1-dichlorohexafluoroisobutylene (1)

1) 1,1,1-Trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-yl methanesulfonate (3c).

To a solution of 1,1,1-trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-ol (2) (427.5 g, 1.498 mol) in acetonitrile (1000 ml) with stirring and temperature 5 ÷ 10 ° C, triethylamine (167 g, 1.65 mol) is added and methanesulfonyl chloride (189 g, 1.65 mol) is added dropwise. The mixture is stirred for 3-4 hours at a temperature of 20 ÷ 25 ° C and left overnight. Then the mixture is poured into a double volume of water, the lower layer is separated, washed twice with a double volume of water, if necessary adding a little acetone to prevent thickening, add P ₂ O ₅ (10 g) and distillate in vacuum (0.1 Torr), collecting the fraction boiling at 60 ÷ 80 ° C.

508.3 g of 1,1,1-Trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-yl methanesulfonate (3c) (93%) are obtained, with an admixture of 4% (2). T.kip. 80 ° C (0.1 Torr). NMR ¹ H δ: 3.35 (s, CH ₃ ); NMR ¹⁹ F δ: -64.5 (s, CF ₃ ).

2) 1,1-Dichlorohexafluoroisobutylene (1).

To a suspension of 183 g (2.81 mol) of zinc dust in sulfolane (500 ml), activated by the addition of trimethylchlorosilane (13 ml), 1,1,1-trichloro-3.3 is added dropwise with stirring at a temperature of 130 ÷ 150 ° C , 3-trifluoro-2- (trifluoromethyl) propan-2-yl methanesulfonate (3c) (508 g, 1.40 mol), during which the resulting reaction product is distilled off from the reaction mixture.

198 g (61%) are obtained. 1,1-dichlorohexafluoroisobutylene with a purity of 98%. T.kip. 68-70 ° C. NMR ¹⁹ F δ: -61.5 (s, CF ₃ ).

Example 2

Obtaining 1,1-dichlorohexafluoroisobutylene (1)

1) 1,1,1-Trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-yl acetate (3a).

To a solution of 1,1,1-trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-ol (1) (142.7 g, 0.5 mol) in acetonitrile (500 ml) with stirring at a temperature of 5 ÷ 10 ° C, triethylamine (53.1 g, 0.525 mol) was added and acetyl chloride (41.2 g, 0.525 mol) was added dropwise. The mixture is stirred for 3 hours at a temperature of 20 ÷ 25 ° C and poured into a double volume of cold water, the lower layer is separated, washed twice with a double volume of cold water, add P ₂ O ₅ (10 g) and distilled in vacuum (10-15 Torr) collecting fraction boiling at 50 ÷ 65 ° C. The resulting distillate is re-distilled in vacuo (10-15 Torr).

142 g of 1,1,1-Trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-yl acetate (3a) are obtained (87%). T.kip. 62-63 ° C (10 Torr). NMR ¹ H δ: 2.2 (s, CH ₃ ); NMR ¹⁹ F δ: -65 (s, CF ₃ ).

2) 1,1-Dichlorohexafluoroisobutylene (1).

To a suspension of zinc dust (49.5 g, 0.756 mol) in sulfolane (145 ml), activated by the addition of trimethylchlorosilane (3.6 ml), 1,1,1-trichloro- is added dropwise with stirring at a temperature of 140 ÷ 150 ° C. 3,3,3-trifluoro-2- (trifluoromethyl) propan-2-yl acetate (3a) (131 g, 0.4 mol), during which the resulting reaction product is distilled off from the reaction mixture with a boiling point of 73-75 ° C .

Get 78.3 g of a mixture containing by GLC 75% 1,1-dichlorohexafluoroisobutylene (1) and 4. Yield 63% vol.

Example 3

Obtaining 1,1-dichlorohexafluoroisobutylene (1)

1) 1,1,1-Trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-yl 2,2,2-trifluoroacetate (3b).

To a mixture of 1,1,1-trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-ol (2) (200 g, 0.7 mol) and trifluoroacetic anhydride (220.5 g, 1.05 mol) with stirring and a temperature of 5 ÷ 10 ° C, triethylamine (77.9 g, 0.77 mol) is slowly added dropwise. The mixture is stirred for 2-3 hours at a temperature of 20 ÷ 25 ° C. The volatile components are distilled off in vacuo (10-15 Torr) in a trap cooled with dry ice and then the product is distilled off, collecting the fraction boiling at 30-60 ° C (10-15 Torr). The resulting distillate for purification is re-distilled in vacuo (10-15 Torr).

227 g (85%) of 1,1,1-Trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-yl 2,2,2-trifluoroacetate (3b) are obtained. T.kip. 40 ° C (10 Torr). NMR ¹⁹ F δ: -77.02 (s, 3F, CF ₃ C (O)), -65.8 (s, 6F, CF ₃ ).

2) 1,1-Dichlorohexafluoroisobutylene (1).

To a suspension of zinc dust (78 g, 1.2 mol) in sulfolane (235 ml), activated by the addition of trimethylchlorosilane (4.5 ml), 1,1,1-trichloro is added dropwise with stirring at a temperature of 140 ÷ 150 ° C. 3,3,3-trifluoro-2- (trifluoromethyl) propan-2-yl 2,2,2-trifluoroacetate (3b) (227 g, 0.59 mol), during which the resulting reaction product is distilled off from the reaction mixture with a temperature boiling point 78-83 ° C.

Get 116.8 g of a mixture containing by GLC 90% (1) and 4. Yield 76%.

Example 4

(E) -1-Bromo-6,6,6-trifluoro-5,5-bis (trifluoromethyl) hex-2-ene (6a).

To a suspension of dry cesium fluoride (200 g, 1.32 mol) in dimethylformamide (400 ml), 1,1-dichlorohexafluoroisobutylene (1) (100 g, 0.43 mol) is added with stirring at a temperature of 5 ÷ 10 ° C. The mixture is stirred for 1-2 hours at a temperature of 20 ÷ 25 ° C, cooled to 5 ÷ 10 ° C and 1,4-dibromobut-2-ene (92 g, 0.43 mol) is added in portions. Then the mixture is stirred for 3-4 hours at 20 ÷ 30 ° C, poured into cold water, the lower layer is washed with 5% hydrochloric acid, P ₂ O ₅ (5 g) is added and distilled in vacuum (10-15 Torr), collecting fraction boiling at 40 ÷ 60 ° C. The product is re-distilled in vacuo (10-15 Torr). The resulting distillate is left in the refrigerator at 0 ÷ 5 ° C overnight, the precipitated crystals of the starting 1,4-dibromobut-2-ene are filtered off and the resulting filtrate is used further without further purification.

Yield 106 g (70%). T.kip. 50-55 ° C (10 Torr). NMR ¹ H δ: 2.8 (d, 2H, CH ₂ Br), 3.8 (d, 2H, CH ₂ C (CF ₃ ) ₃ ), 5.6-5.9 (m, 2H, CH = CH); NMR ¹⁹ F δ: -68.5 (s, C (CF ₃ ) ₃ ).

Example 5

(E) -6,6,6-Trifluoro-5,5-bis (trifluoromethyl) hexa-1,3-diene (7).

A mixture of (E) -1-bromo-6,6,6-trifluoro-5,5-bis (trifluoromethyl) hex-2-ene (6a) (100 g, 0.28 mol), potassium hydroxide (31.9 g , 0.57 mol) and sulfolane (150 ml) are heated with stirring until a strong exothermic reaction begins, as a result of which the mixture begins to boil vigorously. After completion of the spontaneous boiling of the reaction mixture, it is heated to boiling with stirring for 30 minutes and the reaction product is distilled off, collecting the fraction boiling at 80–100 ° C. After water separation, the product is distilled over solid KOH and purified by distillation.

45.7 g (60%) are obtained, 98% pure by GLC. T.kip. 97 ° C. NMR ¹ H δ: 5.6-5.8 (m, 2H, CH ₂ ), 5.9-6.0 (d, 1H, CH =), 6.6-6.7 (m, 1H, CH =), 7.0-7.2 (m, 1H, CH =); NMR ¹⁹ F δ: -67.9 (s, C (CF ₃ ) ₃ ).

Examples 6-18

For 1,1-dichlorohexafluoroisobutylene, several reactions known for perfluoroisobutylene have been carried out. The reagents used and the products obtained are shown in table 1.

General method for producing perfluoro-tert-butyl derivatives (6) from 1,1-dichlorohexafluoroisobutylene (1)

To a suspension of dry cesium fluoride (100 g, 0.66 mol) in dimethylformamide or acetonitrile (200-300 ml), 1,1-dichlorohexafluoroisobutylene (1) (50 g, 0.215 mol) is added with stirring at a temperature of 5 ÷ 10 ° C. The mixture is stirred, slowly raising the temperature to 20 ÷ 25 ° C for 2-3 hours, cooled to 5 ÷ 10 ° C and the electrophilic reagent (0.215 mol) is added in portions (see table. 1). Then the mixture is stirred for 3-48 hours at 20 ÷ 25 ° C, poured into cold water, 100 ml of methylene chloride are added, the lower layer is washed with 5% hydrochloric acid, dried, the solvent is removed by distillation and the product (6) is isolated by distillation or crystallization .

Claims (5)

1. The use of 1,1-dichlorohexafluoroisobutylene as a reagent for the introduction of a perfluoro-tert-butyl group. 2. A method of producing compounds containing a perfluoro-tert-butyl group, comprising obtaining a perfluoro-tert-butyl anion in solution and reacting the obtained perfluoro-tert-butyl anion with various electrophilic reagents, characterized in that the perfluoro-tert-butyl anion is prepared by reacting 1,1-dichlorohexafluoroisobutylene with cesium fluoride in a polar aprotic solvent such as dimethylformamide or acetonitrile. 3. The method according to p. 2, in which the molar ratio of 1,1-dichlorohexafluoroisobutylene and cesium fluoride 1: 3-3.5. 4. The method of claim 2, wherein various alkyl halides, allyl halides, benzyl halides, heterocyclic compounds, halogens, sulfur and sulfur-containing compounds, carbonyl compounds are used as electrophilic reagents. 5. A two-stage method for producing 1,1-dichlorohexafluoroisobutylene from 1,1,1-trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-ol, the first stage of which is to obtain an ester of 1.1, 1-trichloro-3,3,3-trifluoro-2- (trifluoromethyl) propan-2-ol and an acid such as acetic, trifluoroacetic or methanesulfonic, by reacting it with the anhydride or acid chloride of the corresponding acid in the presence of a base, and the second in the interaction of the obtained an ester with a metal such as zinc in a polar high boiling solvent such as sulfolane, with the subsequent selection of the obtained 1,1-dichlorohexafluoroisobutylene by distillation from the reaction mixture.