FR2695123A1 - Process for the preparation of fluorinated ethane compounds - Google Patents

Abstract

The present invention relates to a process for preparing a fluorinated organic ethane compound. According to the invention, the process comprises reacting an ethylene compound or a halogenated ethylenic compound with uranium hexafluoride at an elevated temperature, the molar ratio of the ethylene compound or of the halogenated ethylenic compound to the hexafluoride of uranium being in the range between 1: 1 and 1.2: 1. This process finds application in the manufacture of fluorinated organic ethane compounds which can more particularly be substitutes for CFCs.

Description

The present invention relates to a process for preparing compounds

  halogenated organic compounds; and particularly to a process for preparing fluorinated ethane compounds as substitutes for

  CFCs (chlorofluorocarbons) known to be destructive to the ozone layer.

  A number of catalytic processes are known for the manufacture of fluorinated ethanolic compounds. In the Proposal for Replacement of the Freons Destroying the Earth's Ozone Layer with Ozone-Safe Substitutes (Proceedings of All-Union Conference on Refrigeration and Ozone-Safe Freons, Leningrad, Ozone-Safe, 1989), there is provided a catalytic hydrofluorination method for the preparation of fluorinated ethano compounds, which uses antimony pentachloride as a liquid phase catalyst. The process is carried out at a temperature in the range from 130 to 160 C and in a pressure range of 6 to 8 kg / cm 2 G Gas phase hydrofluorination is

  work at a temperature in the range of 150 to 350 C on a catalyst.

  Previous processes for making a chlorofluorocarbon are generally based on the concept of replacing chlorine atoms with

fluorine atoms.

  For example, U.S. Patent No. 3,235,608 (1966) discloses a process for fluorinating chlorinated or fluorochlorinated C1-12 hydrocarbons using uranium hexafluoride. Fluoridation is conducted using an inorganic fluoride catalyst such as sodium fluoride, potassium, calcium etc in a fluidized bed at a temperature in the range of 70 to 600 C However, this process is not economical since it requires the

  fluoride catalyst and an excess amount of uranium hexafluoride.

  In addition, US Pat. No. 3,382,049 describes a method for fluorinating trichlorethylene using uranium hexafluoride. The main purpose of fluoridation in this method is to obtain uranium tetrafluoride, and therefore detailed information. In addition, it is observed that any excess amount of uranium hexafluoride in the reactor can destroy the HCFC-122a compound.

produced in CFC-113 compound.

  The present inventors have sought to solve the above-mentioned problems; and, as a result, have succeeded in developing a process for preparing a fluorinated ethanolic compound, which may be less hazardous to the ozone layer, by lowering the excess amount of ethylenic compounds as starting materials to uranium hexafluoride as a catalyst during the

  reaction between said two compounds.

  It is therefore an object of the present invention to provide a method

  improved for the preparation of a fluorinated ethanolic compound.

  According to one aspect of the invention there is provided a process for preparing a fluorinated ethanolic compound which comprises reacting an ethylene compound or a halogenated ethylenic compound with uranium hexafluoride at an elevated temperature in which the molar ratio of the ethylene compound or the halogenated ethylenic compound to uranium hexafluoride is in the meantime

between 1: 1 and 1.2: 1.

  In the process of the present invention, a fluorinated organic compound is obtained by the fluorination of an unsaturated ethylenic compound with uranium hexafluoride as shown in the following reaction scheme (1):

C = C + UF 6 CF CF + UF 4 (1)

  The halogenated ethylenic compound used in the process of the present invention may include trichlorethylene (C 2 HCl), vinylidene chloride (C 2 H 2 C 12), vinyl chloride (C 2 H 3 C 1), vinylidene fluoride

(C 2 H 2 F 2) and the like.

  The uranium hexafluoride can be diluted with an inert diluent gas to have a concentration of 20-100% by volume for the fluorination reaction, particularly to obtain a stable organic compound. The inert diluent can include nitrogen, neon, argon and analogs As a diluent, the product from the reaction system, fluorides-containing-

  organic substances can be used by recycling.

  The choice of the limited molar ratios for the ethylene or halogenated ethylenic compound and uranium hexafluoride to be fed is based on the fact that if the aluminum hexafluoride is fed in a larger quantity than the upper limit of the range, the final product will be subject to degradation or decomposition due to its interaction with excess uranium hexafluoride; and, if the uranium hexafluoride is fed in an amount lower than the lower limit, it leads to overconsumption of ethylene or halogenated ethylenic compound and to

  overall degradation of the final product.

  The ethylene or halogenated ethylenic compound is preferably fed into the reactor in dispersed form, thereby improving the efficiency of the reaction and thus providing the desirable fluorination process in the flame. In accordance with the reaction of the ethylene or compound Halogenated ethylenic with ammonium hexafluoride is carried out by vaporization of each compound in the reaction system and mixing and contacting

with each other.

  The fluorination reaction is carried out at a high temperature in the range between 80 and 400 ° C., preferably between 100 ° C. and 350 ° C. and at a pressure slightly below atmospheric pressure, preferably

-20 kg / m 2 (-20 mm H 20).

  The fluorinated organic compounds obtained according to the present invention

  have fluorides at positions 1 and 2 of their chains.

  Qualitative and quantitative analyzes of the compounds thus obtained can be carried out by gas chromatography, by IR spectrometry and by

  by NMR method (using H and F 19) to determine their composition.

  The following examples illustrate the present invention more

  specifically, without limiting the scope of the invention.

Example 1

  In a reactor, gaseous uranium hexafluoride was fed continuously as a fluorinating agent at a rate of 2.0 kg / h (5.682 moles / h) through a spray nozzle at the same time. nitrogen gas was charged to the reactor at a rate of 318.1 Nl / hr (14.2 mol / hr) as a diluent. Trichlorethylene was introduced into the reactor through another vaporization nozzle while maintaining the molar ratio of trichlorethylene to uranium hexafluoride in the reactor at 1.08: 1.0. The fluorination process was carried out as follows:

  CHC 1 = CC 12 + UF 6> CHC 1 F CC 12 F + UF 4

  (HCFC-122 a) Fluoridation was carried out at a temperature of 200 C and

  a pressure of -20 kg / m 2 (-20 mm H 20).

  The reaction product mixture was passed through the porous nickel filter to remove uranium tetrafluoride dust and the remaining gas was condensed in a trap cooled with liquid nitrogen to obtain

the product in liquid form.

  The content of 1,2-difluoro-trichloroethane contained in the organic product was 88.7% by weight and that in 1,1-difluorotrichloroethane

did not exceed 1% by weight.

Example 2

  The procedures described in Example 1 above were repeated except that the molar ratio of trichlorethylene to uranium hexafluoride was maintained at 1.07: 1.0. The content of 1,2-difluoro-trichloroethane in the organic product was 85% by weight and that of 1,1-difluoro-trichloroethane did not exceed 1%

in weight.

  Example 3 The procedures described in Example 1 above were repeated except that the molar ratio of trichlorethylene to uranium hexafluoride was

maintained at 1.01: 1.0.

  The content of 1,2-difluoro-trichloroethane in the organic product was 81% by weight and that in 1,1-difluoro-trichloroethane did not exceed 1%

in weight.

Example 4

  In the same way as in Example 1, the fluorination process was carried out using vinylidene chloride as starting material as follows:

  CH 2 = C C 12 + UF 6 -> CH 2 F CC 12 F + UF 4

(HCFC 132 C)

  The molar ratio of vinylidene chloride to ammonium hexafluoride was maintained at 1.07: 1.0. The fluorination reaction was carried out at a temperature of 150 ° C. under a pressure of -20 kg / m 2. The content of 1,2-difluoro-dichloroethane in the organic product was 65% by weight and that in 1,1-difluorodichloroethane did not exceed 1% by weight.

Example 5

  In the same way as in Example 1, the fluorination process was carried out using vinyl chloride as starting material as follows:

  CH 2 = CHC 1 + UF 6 -> CH 2 F CHC 1 F + UF 4

  (HCFC 142a) The molar ratio of vinyl chloride to uranium hexafluoride was maintained at 1.06: 1.0. The fluorination reaction was carried out at

  temperature of 120 C and a pressure of -20 kg / m 2 (-20 mm H 20).

  The content of 1,2-difluoro-chloroethane in the organic product was 63% by weight and that of 1,1-difluoro-chloroethane did not exceed 1% by weight. Example 6 In the same way as in Example 1, the fluorination process was carried out using ethylene as starting material as follows:

  CH 2 = CH 2 + UF 6 -> CH 2 F CH 2 F + UF 4

(HFC 152)

  The molar ratio of ethylene to ammonium hexafluoride was maintained at 1.08: 1.0. The reaction was carried out at a temperature of 100 ° C.

  under a pressure of -20 kg / m 2 (-20 mm H 20) -

  The content of 1,2-difluoroethane in the organic product was 54%

  by weight and that of 1,1-difluoroethane did not exceed 1% by weight.

Example 7

  In the same way as in Example 1, the fluorination process was carried out using vinylidene fluoride as starting material as follows:

  CH 2 = CF 2 + UF 6 -> CH 2 F CF 3 + UF 4

  (HFC 134 a) The molar ratio of vinylidene fluoride to uranium hexafluoride was maintained at 1.06: 1.0. The reaction was carried out at

  350 C and under a pressure of -20 kg / m 2 (-20 mm H 20).

  The content of 1,1,1,2-tetrafluoroethane in the organic product was

  of 47% by weight and that of 1,1,2,2-tetrafluoroethane did not exceed 1%.

  As can be seen from the above examples, according to the present invention, the fluorination of unsaturated ethylenic organic compounds with ammonium hexafluoride produces organic compounds containing fluorides in the 1 and 2 positions of their chains with surprisingly high yields.

  high, that it had not been possible to obtain until then.

  The use of the present process has the additional advantage that it provides a basically waste-free process. The resulting organic fluorinated isomers have a lower polarity, and thus a higher solubility compared to fats, oils, etc. Furthermore the process makes it possible to obtain

uranium tetrafluoride.

  Although the present invention has been illustrated and described with reference to particular embodiments, it will be apparent to those skilled in the art that many changes and modifications can be made without departing from the spirit and scope. of the invention as defined in the

claims.

Claims (5)

  A process for the preparation of an ethanolic fluorinated organic compound which comprises reacting a halogenated ethylene or ethylenic compound with uranium hexafluoride at an elevated temperature wherein the molar ratio of the ethylene compound or the halogenated ethylenic compound to the ammonium hexafluoride is in the range of 1: 1 to 1.2: 1. The process according to claim 1 wherein the uranium hexafluoride   is diluted with an inert gas at a concentration of 20 to 100% by volume.   The process of claim 2 wherein the inert gas is selected from the group consisting of nitrogen, neon, argon, and the like.   fluorinated organic compounds recycled from the reaction system.   The process according to claim 1 wherein the halogenated ethylenic compound is selected from the group consisting of trichlorethylene (C 2 HCl), vinylidene chloride (C 2 H 2 C 12), vinyl chloride (C 2 H 3 C 1) and fluoride vinylidene (C 2 H 2 F 2).   The process according to claim 1 wherein the reaction of the ethylene compound or the halogenated ethylenic compound and the uranium hexafluoride is carried out by vaporizing each of the components in the reaction system in a dispersed form and mixing and contacting one with the other.