CS268247B1 - Method of hexafluoroalkanoles production - Google Patents

Abstract

The production of hexafluoroalkanols is solved of formula I wherein R 1 is hydrogen or alkyl with one to three carbon atoms - CF, CHF "-CR 1 R"; k, r 2 is hydrogen or alkyl with one I up to six carbon atoms. Said alka-Η nols are produced by the reaction of hexafluoropropene with alcohols of formula II, wherein R 1 and R 6 are as defined above for ultraviolet radiation and initiators of radical reactions. . Organic are used as initiators azoles, organic peroxy compounds, benzoin and its derivatives and ketones. The preparation is done in the through-flow or a closed photoreactor at room temperature shots -30 to 70 ° c. Used ultra- H-C (OH) R R the violet radiation is from area 180 to 450 nm. Hexafluoroalkanols serve as special solvents as additives to surfactants in the preparation of substances for treatment fabrics and in the synthesis of monomers for microelectronics and optoelectronix.

Description

The present invention relates to a process for the preparation of hexafluoroalkanols by reacting hexafluoropropene with aliphatic alcohols under the simultaneous action of ultraviolet radiation and radical scavengers.

Fluorinated alkanols are prepared by a variety of synthetic procedures and methods. In the last synthetic step, substitution, addition and reduction reactions are used in the synthesis of these substances. Conversions of terminal polyfluoroalkyl iodides and polyfluoroalkyl bromides to the corresponding fluorinated alcohols have occurred among the substitution reactions. Reductions involve several methods: Catalytic reduction of fluorinated ketones yields secondary alcohols, catalytic reduction of prefluorocarboxylic acids provides the corresponding primary fluorinated aclanols. Reduction of functional carboxylic acid derivatives by various complex hydrides also provides the corresponding alkanols, whereas functional dicarboxylic fluoro acid derivatives provide the corresponding fluorinated diols. Addition reactions include several types. These include the addition of fluorinated or non-fluorinated organometallic reagents to the carbonyl group of non-fluorinated or fluorinated aldehydes, resulting in the formation of primary and secondary fluorinated alcohols. It is also the addition of formaldehyde to fluorinated alkenes in a hydrogen fluoride medium or catalyzed by alkali metal fluorides. Finally, it is the addition of alkanols to fluorinated alkenes, where primary, secondary and tertiary fluorinated alkanols are formed.

The literature also describes the preparation of fluorinated alkanols of the general formula CF ₃ CHFCF ₂ -C (OH) R ¹ R ² , where R ¹ and R ² are as defined below, by adding aliphatic alcohols to hexafluoropropene. Additions are induced by radical initiators based on organic peroxides or azo compounds. The initiators do not act on their own, but must first be decomposed to elicit an addition reaction. The decomposition is carried out thermally in a reaction vessel which also contains a reaction amount of hexafluoropropene. At the decomposition temperature, eg 80 to 150 ° C, the pressure of the reaction system is considerable and it is therefore necessary to work in pressure reactors for medium and high pressures. The literature further describes the preparation of fluorinated alkanols of the general formula CF 3 CHFCF 2 -C 6 OH 3 R by photochemically initiated addition of simple aliphatic alcohols to hexafluoropropene. This method uses only a narrow part of the ultraviolet radiation emitted, for example, by medium-pressure or high-pressure mercury lamps or xenon lamps.

The disadvantages of the previous processes are eliminated by the process for the preparation of hexafluoroalkanols of the general formula I.

CF ₃ CHF-CF ₂ -C (OH) R ¹ R ² (I) where r! is hydrogen or alkyl of one to three carbon atoms,

R ² is hydrogen or alkyl of one to six carbon atoms by reaction of hexafluoropropene with aliphatic alcohols of formula # II

HC (OH) R ¹ R ² (II).

wherein R ¹ and R ² are as defined above, initiated by organic azo compounds and (or organic peroxy compounds and / or benzoin and one by derivatives and / or ketones under the simultaneous action of ultraviolet radiation. The reaction mixture is irradiated from the outside, the reaction being carried out at temperatures of -30 DEG to 70 DEG C., the pressure not being a decisive factor, generally reaching 0.1 to 1 MPa. The amount of hexafluoropropene in the batch glass reactor, the amount of initiator, the radiation intensity, the pressure and the reaction temperature are determined.

CS 268247 Bl from 250 to greater ™ wavelength ™ lengths. Organic azo compounds, preferably azo-bis-isobutyronitrile, organic peroxy compounds, preferably dibenzoyl peroxide, di (chlorobenzoyl) peroxide, benzoin derivatives, preferably O-methylbenzoin and / or O-isopropylbenzoin and / or O-isopropylbenzoin and / or and 1-phenylbenzoin, further ketones, preferably acetone and acetophenone. In a flow-through arrangement, the radiation source is either completely immersed in the liquid phase or may be located above the liquid phase inside the reactor. When irradiated from the outside, the radiation can be suitably directed by reflective surfaces of various shapes. The ultraviolet radiation effective for the reaction is in the range of 180 to 450 nm, preferably in the range of 280 to 450 nm.

The process of the invention has several advantages. The simultaneous use of chemical initiators and ultraviolet radiation makes it possible to significantly reduce the reaction temperature, if necessary, and to carry out photochemical decomposition of the reaction initiators even at low temperatures. The reaction rate can be easily regulated by the intensity of the radiation. The process according to the invention also allows a better use of the emitted radiation, since sources which emit exclusively in the range of 280 to 400 nm can be used.

The process according to the invention is further described in several exemplary embodiments.

Example 1

The Simax acla ampoule, which contained 105 ml of methanol, 1.2 g of dibenzoylproxide and 20.5 g of hexafluoropropene, was externally irradiated with a 200 W xenon lamp. The system was surrounded by a metal reflecting surface, the irradiation time was 8 hours at ambient temperature 22-28 ° C. The reaction mixture was then subjected to rectification to give 14.7 g of 2,2,3,4,4,4-hexafluoro-1-butanol collected between 112 and 113 ° C.

Example 2

In an immersion photochemical reactor containing 130 ml of 2-propanol and 2.2 g of azo-bis-isobutyronitrile, hexafluorepropene was introduced at 30-40 ° C for 6 hours at a rate sufficient to react 60-90% of the unreacted hexafluoropropene. sinks with dry ice. The radiation source was a medium-pressure 80 W mercury lamp and its radiation passed through Simax technical glass, which acted as a UV filter. After completion of the reaction, the reaction mixture was rectified, and 3,3,4,5,5,5-hexafluoro-2-methyl-2-pentanol was collected as a product in the range of 125 to 126 ° C in a yield of 9.6 g.

Example 3

Hexafluoropropene was introduced into the immersion photochemical photoreactor containing 120 ml of 2-butanol and 2.3 g of O-isopropylbenzoin at -30 to -20 ° C for 6 hours at a rate sufficient to react. The radiation source was an ultraviolet lamp according to Example 1. The reaction mixture was then rectified as the main product, 4,4,5,6,6,6-hexafluoro-3-methyl-3-hexanol was collected at 132-133 ° C in a yield of 18 .6 g. In the same manner, β-phenylbenzoin and O-methylbenzoin were used, the yields of said product being 14.7 and 15.3 g. Benzoin gave 12.1 g of said product under the same conditions.

Example 4

Hexafluoropropene was introduced into a submersible photochemical reactor containing 150 ml of ethanol and 4.2 g of di (chlorobenzyl) peroxide at 62 DEG C. under a pressure of 0.31 MPa for 6.5 hours. The radiation source was an ultraviolet lamp according to Example 1. The reaction mixture was rectified and 3,3,4,5,5,5-hexafluoro-2-pentanol was collected as a product in the range of 119 to 120 ° C in a yield of 23.8 g.

Example 5

The photochemical reactor of Example 2 contained a starting amount of 110 ml of 2-propanol and 15 ml of acetone. The reaction was carried out according to Example 2 at 1-8 ° C for 3 hours. After irradiation, 8 l of acetone were added and the reaction was carried out for a further 4 hours. 3,3,4,5,5,5-Hexafluoro-2-methyl-2-pentanol was isolated as a product by rectification in a yield of 21.6 g and a boiling point of 125-126 ° C.

Example 6

The photochemical reactor of Example 2 contained 125 ml of 1-pentanol and 1.6 dibenzoyl peroxide. The reaction was carried out according to Example 2 at -15 to -5 ° C. Rectification gave the main product, i.e. 1,1,1,3,3,3-hexafluoro-4-octanol with m.p. 165-168 ° C in a yield of 25.3 g.

Example 7 ·

The photochemical reactor of Example 2 contained a starting amount of 110 ml of ethanol and 5.5 g of acetophenone. The reaction was carried out according to Example 4 at a temperature of 16 to 20 ° C. Rectification of the reaction mixture gave 3,3,4,5,5,5-hexafluoro-2-pentanol in a yield of 17.6 g.

The fluorinated alkanols prepared according to the invention have a number of uses. Low-boiling alkanols serve as special solvents, are also used as chemical intermediates for the preparation of surfactants, in the synthesis of monomers for microelectronics and optoelectronics, and in the preparation of fabric conditioning agents.

Claims (1)

OBJECT OF THE INVENTION Process for the preparation of fexafluoroalkanols of the general formula I CF „CHF-CF„ -CR ¹ R ^{2 3 2} । (AND), OH where r! is hydrogen or alkyl of one to three carbon atoms, R ² is hydrogen or alkyl of one to six carbon atoms by reaction of hexafluoropropene with aliphatic alcohols of formula II HC (OH) R ¹ R ² (II), wherein R ¹ and R ² are as defined above, characterized in that the reaction is carried out simultaneously with ultraviolet radiation from the range of 180 to 450 nm and radical reaction initiators selected from the group consisting of organic azo compounds, preferably azo-bis-isoburyronitrile, and / or organic peroxy compounds, preferably dibenzoyl peroxide and di (chlorobenoyl) peroxide, and / or benzoil and its derivatives, preferably o-methylbenzoin and / or o-isopropylbenzoin and / or X * -phenylbenzoin, and / or ketones, preferably acetone and acetophenone, at temperatures of -30 to 70 ° C.