FR2768727A1 - SYNTHESIS OF 1,1,1,3,3-PENTAFLUOROPROPANE - Google Patents

Abstract

The invention relates to the manufacture of 1, 1, 1, 3, 3-pentafluoropropane by reaction of hydrogen fluoride with in particular 1, 1, 1, 3, 3-pentachloropropane in the liquid phase and in the presence of a catalyst. The use of a titanium-based catalyst avoids the corrosion problems generated by antimony-based catalysts.

Description

-1 -

DESCRIPTION

  The present invention relates to the field of fluorinated hydrocarbons and to

  more particularly for object the manufacture of 1,1,1,3,3pentafluoropropane.

  Due to the depletion of the ozone layer, a limitation of the

  production of fully halogenated chlorofluorocarbons (CFCs) has been scheduled

  implemented in 1986 (Montreal Protocol) and an update (Copen-

  hague in 1992) stopped the principle of the total abandonment of these products at the end of 1995. o0 Researches to find substitutes for these compounds focused initially on products containing hydrogen atoms (HCFC), then on products that no longer contain chlorine: hydrofluorocarbons. Among these, one

  growing interest in C3 compounds seems to be emerging.

  1,1,1,3,3-Pentafluoropropane, known under the designation F245fa, is harmless to the ozone layer. It therefore belongs to the category of potential substitutes for CFCs and its use has been mentioned in various patent applications, in particular as blowing agent for foam (JP 5239251), as propellant and cleaning solvent for the electronic industry (DD 298419) and

  finally as heat transfer fluid (JP 2272086).

  1,1,1,3,3-pentafluoropropane can be prepared in different ways, in particular: - by catalytic hydrogenation of 1,1,3,3,3pentafluoro-1 -propene

  (Knunyants et ai., Izvest. Akad. Nauk. S.S.S.R., Otdel. Khim. Nauk. 1960, 1412-

  1418; C.A. 55: 349c and Kinet. Katal. 1967, 8 (6), 1290-1299; C.A. 69: 3510 On), - by hydrogenolysis of 1,2,2-trichloro-1,1,3,3,3- pentafluoropropane (patent

US 2942036),

  - by reaction of tetrahydrofuran with cobalt trifluoride (Burdon and

  al., J. Chem. Soc. C, 1969, 13, 1739-1746).

  Since these methods cannot be used industrially, it has recently been proposed in patent applications EP 703 205 and WO 9601797 to manufacture the

  1,1,1,3,3-pentafluoropropane by reaction of hydrogen fluoride with 1,1,1,3,3-

  pentachloropropane or a partially fluorinated derivative of 1,1,1,3,3pentachloropro-

  pane, in liquid phase and in the presence of a catalyst. 1,1,1,3,3pentachloropro-

  pane, used as a starting material, can be easily prepared in a single step by reacting carbon tetrachloride with vinyl chloride, two widely available industrial products. By "partially fluorinated derivative of

  1,1,1,3,3-pentachloropropane "is understood here to mean the intermediate reaction compounds

  res such as 3-chloro-1,1,1,3-tetrafluoropropane (F244), 3,3dichloro-1,1,1 -

- 2-

  trifluoropropane (F243), 1-chloro-3,3,3-trifluoropropene (F1233zd), 1,1,3,3-

  tetrachloro-1-fluoro propane (F241), 1,3,3-trichloro-1,1-difluoropropane (F242), 1,3,3-trichloro-3-fluoro-propene (F 1231 zd), 1, 3dichloro-3,3-difluoro-propene

  (F1232zd) and 1,3,3,3-tetrafluoro-propene (F1234ze).

  Although these two publications generally mention that the catalyst

  can be chosen from metallic derivatives, in particular those of the metals found

  pertaining to the main groups Illa, IVa and Va and to the subgroups IVb, Vb and Vlb, they

  recommend the preferential use of antimony derivatives and more particularly

  antimony pentahalides which lead to a significant transformation

  0o aunt of 1,1,1,3,3-pentachloropropane and a high selectivity in 1,1,1,3,3-

  pentafluoropropane. All of the examples in these two publications were produced using

  as catalyst an antimony pentahalide (SbCI5 or SbF5). Unhappy-

  ment, the use of these catalysts is accompanied by corrosion phenomena

  important, which makes industrial exploitation of such a process difficult.

  On the other hand, international application WO 97/08117 describes a process for the preparation, in two stages, of a fluorinated aliphatic compound, starting from an olefin

  chlorinated, which uses a chlorofluorinated olefin as an intermediate.

  Thus, Example 1 of this patent describes the preparation of F245fa, from 1,1,3,3-tetrachloro-1-propene, also known as F 1230za, with compulsory passage through 1-chloro-3,3, 3-trifluoropropene as an intermediate. This document teaches that only the conversion step of the chlorofluorinated olefinic intermediate must be catalyzed. The catalyst envisaged for this stage is a fluoride of Sb, Sn, Ti and very particularly a mixture of Sb (V) and Ti (IV). This process is

  however difficult to implement industrially.

  Titanium-based compounds such as titanium tetrachloride have already been

  used as fluorination catalysts in the liquid phase for the fluorination reaction

  tion of acetylene to 1,1-difluoroethane (US Patent 2,830,100), that of trichloro

  1,1,2,2-trichloro-1-fluoroethane thylene (US patent 4,383,128) or the synthesis of 1-

  chloro-2-fluoroethane from vinyl chloride (patent FR 1,534,403). A.E.

  Feiring (J. of Fluorine Chemistry 13 (1979) 7-18) studied the addition of HF on the tetra-

  chloroethylene catalyzed by TiCI4. This titanium compound has also been used

  as catalyst for the fluorination reaction of vinylidene chloride at 1,1-

  dichloro-1-fluoroethane (patent EP 378 942), that of trifluoroethylene in 1,1,1,2-

  tetrafluoroethane (patent EP 574,077) or that of 1,1,1,3,3,3hexachloropropane to 1-chloro-1,1,3,3,3-pentafluoropropane (patent application WO 95/04022). Certain synergistic effects have also been demonstrated between TiCI4 and SbCI3 (patent

  US 5,202,509), with a nitrated solvent or a sulfone for the synthesis of 1,1-

  -3- dichloro-1-fluoroethane from vinylidene chloride (patent application WO 94/13607) or recently with SbCl5 for the fluorination of trichlorethylene in

  F134a (J. Chem. Soc. Chem. Communications 1994 (7) 867).

  From a review of the literature, it appears that TiCI4 is most often used to catalyze the addition of HF to a double bond and rarely for the Cl-F exchange.

on a saturated substrate.

  It has now surprisingly been found that TiCI4 and more generally

  titanium-based compounds are good catalysts for the fluorination reaction of 1,1,1,3,3-pentachloropropane, 1,1,3,3tetrachloro-1-propene

  io (F1230za) or 1,3,3,3-tetrachloro-1-propene (F1l230zd) in 1, 1,1,3,3-

  pentafluoropropane. They exhibit good activity without the disadvantages generated by antimony catalysts with regard to corrosion. In addition, unlike antimony, titanium catalysts are not deactivated by reduction and practically do not lead to the underproduction of heavy C6 compounds, which cannot be recycled to give the final product.

desired (F 245fa).

  The invention therefore relates to a process for manufacturing 1,1,1,3,3-

  pentafluoropropane (F245fa) by reaction, in the liquid phase, of hydrogen fluoride with a compound A chosen from 1,1,1,3,3pentachloropropane (F240fa), a partially fluorinated derivative of F240fa, 1,1,3, 3-tetrachloro-1-propene (F1230za) or 1,3,3,3-tetrachloro-1propene (F1230zd), characterized in that one uses as

  catalyst a titanium-based compound.

  F1230zd and za can be prepared by dehydrochlorination of F240fa at a temperature between 20 and 100 C, in the presence, as catalyst, of a Lewis acid such as AIF3, AICI3, FeCl3, TiCl4. The partially fluorinated derivatives of 1,1,1,3,3-penta-chloropropane can be prepared by reacting the

  240fa with HF in the presence of a fluorination catalyst, for example based on sb.

  As titanium-based compounds, titanium halides such as chlorides, fluorides or chlorofluorides are preferably used, but oxides or oxyhalides can also be used. Titanium tetrachloride has

  particularly interesting.

  The implementation of the method according to the invention can be carried out so

  known per se, discontinuously, semi-discontinuously or continuously.

  In batch mode, the reaction is carried out in a stirred autoclave into which the reactants are introduced beforehand before the start of the reaction; the pressure in the autoclave is then the autogenous pressure and therefore varies with the progress of the reaction. When the process is implemented according to a semi-discontinuous process, the apparatus used consists of an autoclave surmounted by a simple condenser or surmounted by a retrogradation column and a reflux condenser, and fitted with a pressure regulating valve. As before, all of the reagents are introduced beforehand into the autoclave, but the products of the reaction with low boiling point (in particular F245fa) are continuously extracted during the reaction. When the process according to the invention is carried out in continuous mode, the same apparatus is used as in semi-discontinuous mode and the reagents are introduced

  continuously, preferably in a medium constituted by a solution of cataly-

sister in HF.

  The amount of catalyst to be used can vary within wide limits.

  your. It is generally between 0.0005 and 0.1 mole, preferably between 0.001 and 0.05 mole, per mole of HF. In all cases, we prefer to work with a

  amount of catalyst lower than its solubility limit in HF.

  Since the catalyst according to the invention does not generate corrosion, the quantity

  t of hydrogen fluoride to be used in discontinuous or semi-continuous mode is generally between 0.5 and 50 moles per mole of F240fa and, preferably between 2 and 20 moles. In the case of continuous mode, we prefer to operate by injecting the

  reagents in a medium consisting of HF.

  The temperature for implementing the process according to the invention may generally

  LEMENT be between 30 and 180 C. It is preferably chosen between 70 and

   C and, more particularly, between 100 and 140 C.

  When operating semi-discontinuously or continuously, the operating pressure is chosen so as to maintain the reaction medium in the liquid phase. She is at

  generally between 5 and 50 bars and, preferably, between 10 and 40 bars.

  The condenser temperature is adjusted according to the quantity and the

  nature of the products likely to be evacuated during the reaction. It is generally

  Slowly between -50 and 150 C and, preferably, between 0 and 100 C.

  In the following example which illustrates the invention without limiting it, the percentages

  ges indicated are molar percentages.

Example 1

  We operated according to the semi-discontinuous mode described above, in an auto-

  1 liter stirred clave made of 316L stainless steel containing a small test tube (mass: 5 g; surface: 760 mm2) made of 316L stainless steel and surmounted by a condenser supplied with industrial water at 17 C. In this autoclave we loaded 228 g of HF (11.4 moles) and 11.8 g of TiCl4 (0.062 moles). The autoclave was then heated to 110 ° C. using an oil bath circulating in a double jacket. After stabilization at -5- temperature of the reaction medium, 19 g / hour of F240fa (0.09 mol / h) were fed continuously and part of the most volatile products was degassed continuously

  via a pressure control valve maintained at 20 bar.

  After passing through a water bubbler and then through a dryer, these products were collected in a stainless steel trap cooled with liquid nitrogen.

  After 5 hours of reaction, the operation was stopped and analyzed by chromatography.

  graphs in the gas phase the trapped gases and the reaction medium. This analysis indicates that the conversion of F240fa amounts to 88% with the following selectivities: -F245fa: 11% o -F244: 36%

- F243: 35%

- F1233zd: 18%

  The percentages indicated are molar percentages.

  After separation of F245fa, unconverted F240fa and intermediaries

  sub-fluorinated F244, F243 and F1233zd can be recycled to the reactor.

  Furthermore, the weighing of the 316L stainless steel specimen maintained in the medium throughout the reaction did not show any difference in weight compared to

  its initial weight. No corrosion was therefore observed.

Example 2

  We operate according to the same operating mode, the same equipment and the

  same conditions as those described in Example 1.

  245 g of HF (12.25 moles) and 12.5 g TiCl4 (0.066 moles) are loaded into the continuously supplied autoclave. After heating the reaction medium to 110 ° C. and stabilizing the temperature, 18 g / hour of F1230za (0.1 mol / h) are fed. Part of the most volatile products is degassed continuously via a pressure control valve maintained at 20 bar. After passing through a water bubbler and then through a dryer, these products were collected in a trap.

  stainless steel cooled with liquid nitrogen.

  After 5 hours of reaction, the operation was stopped and analyzed by gas chromatography the trapped gases and the reaction medium. This analysis indicates that the conversion of F1230za amounts to 90% with the following selectivities: - F 245fa: 8%

-F244: 25%

- F 243: 25%

- F 1233zd: 39%

- heavy: 3%.

  The percentages indicated are molar percentages.

  -6- After separation of F245fa, unconverted F1230za and intermediates

  sub-fluorinated F244, F243 and F1233zd can be recycled to the reactor.

  Furthermore, the weighing of the 316L stainless steel specimen maintained in the medium throughout the reaction did not show any difference in weight compared to its initial weight. No corrosion was therefore observed. -7-

Claims (7)

REVENDICA TIONS   1. Process for the production of 1,1,1,3,3-pentafluoropropane by reaction of   hydrogen fluoride with a compound A chosen from: 1,1,1,3,3-   pentachloropropane (F240fa), a partially fluorinated derivative of F240fa, 1,1,3,3- tetrachloro-1-propene (F1230za) or 1,3,3,3-tetrachloro-1propene (F1230zd), characterized in that a compound with titanium base.   o0 2. Method according to claim 1 wherein the compound A is F240fa   or a partially fluorinated derivative of F240fa.   3. Method according to claim 1 wherein the compound A is   F1230za or 1,3,3,3-tetrachloro-1-propene (F1230zd).   4. Method according to one of claims I to 3 wherein the compound to   titanium base is a halide, an oxide or an oxyhalide of titanium, of   preferably titanium tetrachloride.   5. Method according to one of claims 1 to 4, wherein the report   HF molar / compound A is between 0.5 and 50, preferably between 2 and 20.   6. Method according to one of claims I to 5, wherein one operates at a   temperature between 30 and 180 C, preferably between 70 and 150 C, and more   especially between 100 and 140 C.   7. Method according to one of claims 1 to 6, wherein one uses   0.0005 to 0.1 mole of catalyst per mole of HF, preferably 0.001 to 0.05.