CS254747B1 - Process for the production of hexafluoroalkanols - Google Patents

Abstract

The purpose of the solution is the production of hexafluoroalkanols from hexafluoropropene. These compounds serve as special solvents, are used in the preparation of polymeric substances for fabric treatments and for applications in microelectronics and optoelectronics. The mentioned hexafluoroalkanols are produced by the photochemically initiated reaction of hexafluoropropene with aliphatic alcohols with a number of carbon atoms of 2 to 5 at a pressure of 0.1 to 0.5 MPa and at temperatures of -40 to 120 °C. During the reaction, hexafluoropropene is introduced into a photochemical reactor.

Description

The invention relates to a process for the preparation of hexafluoroalkanols of the general formula

CF - CHF-CH ,, - CR ¹ R ² 3

OH

Wherein R is hydrogen or alkyl of 1 to 5, R is alkyl of 1 to 3, by reacting hexafluoropropene with aliphatic alcohols of 2 to 5 with initiation by ultraviolet radiation.

Fluorinated alkanols are prepared by a number of synthetic procedures and methods. Substitution, reduction and addition reactions are used to convert precursors of the resulting alkanols. Among the substitution reactions, chloromethyl, bromomethyl and especially iodomethyl were converted to hydroxymethyl. Reductions include several methods. By catalytic reduction of fluorinated ketones, secondary alcohols are obtained, catalytic reduction of perfluorocarboxylic acids gives corresponding primary fluorinated alkanols. Reduction of functional acid derivatives to be carried out! with various complex hydrides, also provide the corresponding fluoroalkanols, while the functional derivatives of the dicarboxylic acids yielded the corresponding fluorinated diols.

Addition reactions include several types. These include the addition of fluorinated or non-fluorinated organometallic reagents to the non-fluorinated or fluorinated aldehydes, leading in particular to the formation of secondary fluorinated alcohols. Furthermore, it is the addition of formaldehydes to fluorinated alkenes in hydrogen fluoride or alkali metal fluorides catalysis. Finally, it is the addition of alcohols to the fluorinated alkenes to form primary, secondary and tertiary fluorinated alkanols.

The preparation of hexafluoroalkanols by addition of simpler aliphatic alcohols to hexafluoropropene is reported in the literature. The additions are caused by the thermal decomposition of the radical reaction initiators and thus it is necessary to work at elevated temperature and higher pressure. The additions are also initiated by ultraviolet radiation under the influence of an external ultraviolet radiation source and the starting hexafluoropropene is sealed under pressure. However, the quartz reaction vessels allow to operate only in a limited volume and their operation is associated with a considerable risk.

The disadvantages of the prior art are eliminated by the process for the preparation of hexafluoroalkanols of the general formula

CF, -CHF-CH.-CR ¹ R ^{2 3 2} I

OH

Wherein R is hydrogen or alkyl of 1 to 5, R is alkyl of 1 to 3, by reaction with aliphatic alcohols of 1 to 5 with initiation by ultraviolet radiation. The process according to the invention consists in carrying out the reaction in a photochemical reactor at a pressure of 0.1 to 0.5 MPa at temperatures of -40 to 120 ° C. In the reaction, the hexafluoropropene is fed to the reactor, the outlet of the reactor may be connected to the atmosphere via, for example, a hydraulic closure. The reaction time depends on the volume of the reactor and the amount of starting alcohol present in the reactor, pressure, radiation source intensity and reaction temperature. The source of ultraviolet radiation in the quartz shell is either completely immersed in the liquid phase or only partially, or with a small amount of alcohol, the source can be placed above the liquid phase inside the reactor. Additive ultraviolet radiation is emitted, for example, by a mercury or xenon lamp.

The process of the invention has a number of advantages. The reaction can be carried out in a considerable volume and the course of the reaction, respectively. its speed is relatively easy to control. Other rate control options are provided by reaction temperature and relatively small pressure changes. The process according to the invention is further described in several exemplary embodiments.

Example 1

Hexafluoropropene was fed at a rate sufficient to react to a 400 ml submersible photochemical reactor containing 278 g of ethanol at a temperature of 10 ° C and 0.14 MPa. The radiation source was a 250 W ultraviolet lamp. A total of 17 g of hexafluoropropene was added over 17 h. The reaction mixture was then rectified,

117 DEG-120 DEG C. 79.5 g of 3,3,4,5,5,5-hexafluoro-2-pentanol of min. 98%

Example 2

350 g of 2-propanol were charged to a 500 ml submerged photochemical reactor and hexafluoropropene was introduced into the reactor at an external cooling rate of -20 ° C at a rate sufficient to react. The source of ultraviolet radiation was a 400 W lamp, a total of 103 g of hexafluoropropene was added. The reaction mixture was then subjected to rectification and from 125 to 127.5 ° C, 146 g of 3,3,4,5,5,5-hexafluoro-2-methyl-2-pentanol of min. 99% wt.

Example3

Hexafluoropropene was fed for 12 hours at 70 [deg.] C. under a pressure of 0.26 MPa in a 400 ml submersible photochemical reactor containing 250 g of 1-butanol. Unreacted hexafluoropropene was collected downstream of the reactor in a dry ice trap. The reaction mixture was then rectified and 86 g of 1,1,1,2,3,3-hexafluoro-4-heptanol having a purity of ca. 95% wt.

The hexafluoroalkanols prepared according to the invention have a number of uses. They are used, for example, in the preparation of polymeric substances for fabric treatment and for applications in microelectronics and optoelectronics.

Claims (1)

A process for the preparation of hexafluoroalkanols of the general formula CF ₃ -CHF-CH ₂ -CR ¹ R ² , OH Wherein R is hydrogen or alkyl of 1 to 5, R is alkyl of 1 to 3, by reacting hexafluorpropene with aliphatic alcohols of 2 to 5 with initiation by ultraviolet radiation, characterized in that hexafluorpropene to a photochemical reactor at a pressure of 0.1 to 0.5 MPa at temperatures of -40 to 120 ° C.