RU2230057C1 - Method of preparing polyfluorinated alkoxypropionyl fluorides - Google Patents

Abstract

FIELD: organic synthesis. SUBSTANCE: polyfluorinated alkoxypropionyl fluorides having general formula 1:

(1), where Rf represents linear or branched C₁-C₉,-perfluoroalkyl or C₁-C₉-perfluoroalkoxyalkyl, or hydrogen atom, are prepared by reaction of hexafluoropropene oxide with appropriate polyfluorocarboxyl fluoride in organic medium consisting of two components, from which one is a polar aprotic solvent, in presence of catalyst. Second component, constituting 80-90 wt % of the organic medium, is perfluorinated nonpolar solvent selected from perfluorinated cyclic C₇-C₁₁-hydrocarbons or aliphatic C₆-C₉-hydrocarbons capable of extracting acid fluorides I formed in reaction. Catalyst is N,N,N',N'-tetrasubstituted diaminomethane of formula:

, where R¹-R⁴ represent linear or branched C₁-C₆-alkyl or C₁-C₆,-perfluoroalkyl, or radical -C₂H₄OH, or pairs R¹ and R² and R³ and R⁴, together with nitrogen atom to which they are attached, may form heterocyclic residue optionally containing one more heteroatom (oxygen) and substituted by one or several alkyl radicals. EFFECT: enabled selective preparation of desired products with high yields and enabled carrying out process under atmospheric pressure. 2 cl, 1 tbl, 8 ex

Description

The invention relates to organofluorine chemistry, and in particular to a method for producing polyfluoroalkoxypropionic acid fluorides of the formula

where R _f - perfluoroalkyl C ₁ -C ₉ , perfluoroalkoxyalkyl C ₁ -C ₉ linear or branched structure, possibly containing other halogen atoms, H.

These compounds are used as intermediates for the synthesis of perfluoroalkyl vinyl ethers, as well as for the preparation of emulsifiers, fluorinated surfactants, chemically and thermally stable liquids, lubricating oils, and polymers (V. A. Ponomarenko. Fluorinated hetero-chain polymers, 1973, p. 118-123) .

Known methods for producing perfluoroalkoxypropionic acid fluorides are based on the interaction of hexafluoropropylene oxide (HFP) with perfluorocarboxylic acid fluorides

The synthesis is carried out in a polar organic solvent at temperatures from -80 to 200 ° C in the presence of various catalysts, for example, alkali metal halides (US 3250808, 10.05.60; EP 265052, 27.04.88), quaternary ammonium salts (WO 97/44303, 11/27/97), tris-dimethylaminodifluorophosphorane (DE 2461445, 07/08/07), sulfonium salts (US 4081466, 03/28/78), tetraalkylurea (JP 2-4733, 09.01 90).

In the above methods, the reaction of HFP with low boiling perfluorocarboxylic acid fluorides, such as carbonyl fluoride and trifluoroacetyl fluoride, is usually carried out under a pressure of from 0.7 to 24 atm. This complicates the process and requires special equipment.

A known method for producing halogenated carboxylic acid fluorides by reacting a fluorohydride of the formula RCOF (R is CCl ₃ or a group X (CF ₂ ) _n , where X = H, Br or SO ₂ F, n = 1-6) with OGFP in the presence of a catalytic system consisting from alkali metal fluoride and two polar aprotic solvents - dinitrile of saturated aliphatic dicarboxylic acid C ₅ -C ₈ and an ether of the formula CH ₃ O (CH ₂ CH ₂ O) _z CH ₃ (z = 2-6) (US 4940814, 10.07. 90). The reaction is carried out at a temperature of from -30 to 100 ° C. The amount of catalyst is 5-45% by weight of the carboxylic acid fluoride.

The used catalytic system for the reaction of perfluorinated carboxylic acid fluorides with HFP is not effective enough, since the yields of the target products are below 50%.

The closest technical solution is a method for producing perfluoroalkoxypropionic acid fluorides of the formula

where R _f = perfluoroalkyl C ₁ -C ₈ , n = 0-4, by catalytic reaction of OGFP with perfluorocarboxylic acid fluoride of the formula R ' _f COF (R' _f is fluoro or perfluoroalkyl C ₁ -C ₇ ) in a polar aprotic solvent at a temperature of -50 to 20 ° C (GB 1550268, 08.08.79, prototype). As the catalyst used N, N, N ', N'-tetrasubstituted diaminodifluoromethane of the formula

алкил или

. Полярный апротонный растворитель, например ацетонитрил или диглим, может включать до двух объемных частей инертного неполярного растворителя, например пентана, гексана, циклогексана, или фторсодержащего алкана, в частности трифтортрихлорэтана. В конкретных примерах осуществления данного способа в качестве исходного фторангидрида используют только фторангидрид пентафторпропионовой кислоты, при взаимодействии которого с ОГФП получают смесь низкомолекулярных олигомеров, состоящую в основном из димеров, тримеров и тетрамеров ОГФП, с суммарным выходом 75-90%.where R ¹ -R ⁴ is an alkyl C ₁ -C ₄ , as well as NR ¹ R ³ or NR ² R ⁴ represent a five- or six-membered heterocycle, possibly containing –O-,

alkyl or

. A polar aprotic solvent, for example acetonitrile or diglyme, may include up to two volume parts of an inert non-polar solvent, for example pentane, hexane, cyclohexane, or a fluorine-containing alkane, in particular trifluorotrichloroethane. In specific embodiments of this method, only pentafluoropropionic acid fluoride is used as the starting fluorohydride, when reacted with OGFP, a mixture of low molecular weight oligomers is obtained, consisting mainly of dimers, trimers and tetramers of OGFP, with a total yield of 75-90%.

The disadvantage of this method is the low selectivity of the process of obtaining the target monoaddition products - perfluoroalkoxypropionic acid fluorides and their low yield, which, for example, for perfluoropropoxypropionyl fluoride is 6-12%.

The objective of the invention is to develop a universal selective synthesis method that provides a high yield of polyfluoroalkoxypropionic acid fluorides.

The problem is achieved by the interaction of hexafluoropropene oxide with polyfluorocarboxylic acid fluoride in an environment that represents two immiscible organic solvents in the presence of a catalyst —N, N, N ′, N′-tetrasubstituted diaminomethane of the formula

where R ¹ -R ⁴ - linear or branched alkyl C ₁ -C ₆ or perfluoroalkyl C ₁ -C ₆ group C ₂ H ₄ OH or R ¹ and R ² and / or R ³ and R ⁴ together with a nitrogen atom can form a heterocyclic residue, possibly containing another heteroatom - oxygen or nitrogen and substituted by one or more alkyl groups.

As the catalysts can be used bis (dimethylamino) methane, bis (diethylamino) methane, di (piperidino) methane, di (morpholino) methane, bis (dioxethyl) aminomethane.

The amount of catalyst used in the reaction is ~ 10-15 wt.% Of the amount of perfluorinated epoxide used. A decrease in the amount of catalyst leads to a decrease in the yield of the target products, and an increase in its amount above 15 wt.% Is impractical.

This method uses a two-component organic solvent that forms two layers of the liquid phase due to the immiscibility of the components.

One of the components is a polar aprotic solvent, in which the condensation of hexafluoropropene oxide with polyfluorocarboxylic acid fluorides proceeds. Aliphatic polyethers, for example, dialkyl ethers of ethylene glycol, polyethylene glycols and nitriles propionitrile, benzonitrile and acetonitrile, are used as such solvents.

Another component of the organic medium is a perfluorinated non-polar solvent, which is a perfluorinated cyclic C ₇ -C ₁₁ or aliphatic C ₆ -C ₉ hydrocarbon capable of selectively dissolving the reaction products and inert to them. It extracts the resulting fluorohydrides of polyfluoroalkoxypropionic acids and removes them directly from the reaction zone. This ensures the selectivity of the formation of monoaddition products and eliminates the formation of high molecular weight oligomeric adducts.

The most preferred perfluorinated solvents are perfluoroheptane, perfluorooctane, perfluoromethylcyclohexane, perfluoro-1,3-dimethylcyclohexane, perfluorodecalin, perfluoromethyldecalin. The content of perfluorinated solvent in the organic medium is in the range of 80-90 wt.%, Which is sufficient for the extraction of the target products.

Condensation of HFP with polyfluorocarboxylic acid fluorides is carried out at a temperature of from -20 to 20 ° C. At a lower temperature, the reaction rate slows down, and heating the reaction mixture above 20 ° C leads to a decrease in the yield of the target products.

Carboxylic acid fluorides that can be used in the process include: COF ₂ , CF ₃ COF, C ₂ F ₅ COF, C ₂ F ₅ OCF ₂ COF, n-C ₃ F ₇ COF, iso-C ₃ F ₇ COF, С ₃ F ₇ ОСF (СF ₃ ) СОF, C ₂ F ₅ OC ₂ F ₄ COF, C ₄ F ₉ COF, C ₇ F ₁₅ COF and others containing halogen atoms other than fluorine, Н, for example BrCF ₂ COF and НСF ₂ (CF ₂ ) ₃ COF, etc.

The molar ratio of OGFP to the starting fluorohydride is 1: 1.0-2. In this case, monoaddition products are predominantly formed and only to a small extent isomerization products of hexafluoropropenoxide. The synthesis is carried out in a reactor with a stirrer at atmospheric pressure.

Polyfluoroalkoxypropionic acid fluorides resulting from the reaction are extracted with a perfluorinated solvent. The resulting extract after the reaction is separated from the reaction mass and subjected to distillation. Target products are analyzed by GLC and identified by IR and NMR spectroscopy.

The yield of polyfluoroalkoxypropionic acid fluorides reaches 97-99%. Under the conditions of this process, OHPP oligomers are not formed, as well as the products of the addition of two or more hexafluoropropenoxide molecules to the starting fluorohydride.

Thus, the developed method allows to selectively obtain target products with high yield and conduct the process at atmospheric pressure.

The following examples illustrate the invention, but do not limit it.

Example 1. Synthesis of perfluoro-2-methoxypropionyl fluoride.

25 g of acetonitrile, 11 g of di (piperidine) methane, 210 are charged into a 500 ml glass flask equipped with a stirrer, reflux condenser cooled to minus 30 ° C, a trap cooled to minus 60 ° C, and bubblers for supplying the starting reagents. g of perfluorooctane and 125 g (0.75 mol) of hexafluoropropenoxide and 80 g (1.2 mol) of carbonyl fluoride are passed with stirring.

The reaction mass is stirred for 1-2 hours at a temperature of minus 15 - minus 18 ° C, then the temperature is raised to room temperature. The lower layer, representing the extract of the reaction products in perfluorooctane, is separated and the target product is isolated by distillation.

The result is 170 g of perfluoro-2-methoxypropionic acid fluoride

with a boiling point of 10-12 ° C and 3 g of perfluoropropionic acid fluoride. The yield of the target product is 97.3%.

Subsequent syntheses (examples 2-8) were carried out analogously to example 1. Conditions and results are presented in the table.

Claims (2)

1. The method of producing fluoride polyfluoroalkoxypropionic acids of the formula

where R _f represents perfluoroalkyl C ₁ -C ₉ , perfluoroalkoxyalkyl C ₁ -C ₉ linear or branched structure, possibly containing other halogen atoms, H, the interaction of hexafluoropropene oxide with the corresponding polyfluorocarboxylic acid fluoride in an organic medium consisting of two components, where one of the components is a polar aprotic solvent, in the presence of a catalyst, characterized in that the second component of the organic medium is a perfluorinated non-polar solvent, representing a perfluorinated cyclic C ₇ -C ₁₁ or an aliphatic C ₆ -C ₉ hydrocarbon capable of extracting the resulting fluorohydrides of the formula (1), and its amount in the organic environment is in the range of 80-90 wt.%, and N, N, N ^/ , N ^/ -tetra-substituted diaminomethane of the formula are used as a catalyst

where R ¹ - R ⁴ represent linear or branched alkyl C ₁ -C ₆ or perfluoroalkyl C ₁ -C ₆ , a group C ₂ H ₄ OH or R ¹ and R ² and R ³ and R ⁴ together with a nitrogen atom can form a heterocyclic residue possibly containing another heteroatom - oxygen and substituted by one or more alkyl groups. 2. The method according to claim 1, characterized in that the content of the catalyst is 10-15 wt.% From the source of hexafluoropropene oxide.

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