AU613514B2 - Process for the preparation of partly fluorinated ethanes - Google Patents

Description

I-c 11 i COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952.69 COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: oo Priority: 6 I a Related Art Name of Applicant: HOECHST AKTIENGESELLSCHAFT Address of Applicant: t 4 t I Actual Inventor: Address for Service: 50 Bruningstrasse, D-6230 Frankfurt/Main 80, Federal Republic of Germany HANS ROBERT CREMER, HARALD NOICHL -RMXO 60 :a-...'atermark Patent Trademark Attorneys 50 QUEEN STREET, MELBOURNE, AUSTRALIA, 3000.

Complete Specification for the invention entitled: PROCESS FOR THE PREPARATION OF PARTLY FLUORINATED ETHANES The following statement is a full description of this invention, including the best method of performing it known to :us us 1.

14 Table 5 continued Molar ratio of R113a:R133a: 0.5 1 3.7 2 1 i r HOECHST AKTIENGESELLSCHAFT HOE 88/F 237 Dr.MA/je Description Process for the preparation of partly fluorinated ethanes The invention relates to a process for the preparation of partly fluorinated ethanes of the general formula

CF

3 -CFHC1_2in which x 0, 1 or 2.

t Partly fluorinated ethanes of the general formula

CF-CFH

1 Cl2-. have desirable properties (chemically inert, 10 difficult to ignite, non-toxic and not aggressive towards 4 9, material) of the perhalogenated fluorochlorohydrocarbons.

The perhalogenated fluorochlorohydrocarbons are held responsible for the breakdown of the upper ozone layer which protects the earth's surface from intensive UV radiation. Partly fluorinated ethanes of the general S T formula CF 3

-CFHIC

2 (x 0, 1 or 2) are either chlorinefree or already for the most part degraded in the lower layers of the atmosphere and are therefore only a low potential hazard for the upper ozone layer.

There is therefore a considerable interest in partly fluorinated ethanes as a substitute, which does not destroy the upper ozone layer, instead of perhalogenated fluorochlorohydrocarbons.

u Partly fluorinated ethanes are prepared in accordance with US-A-2,748,177 by reaction of CC1 4 CC1 3 -CClF 2 CClFz-

CF

3 or CC12FCClF 2 with anhydrous hydrogen fluoride on an aluminum fluoride catalyst at temperatures of 175 to 450"C. The disadvantage of this process is, in addition to the difficult handling of hydrogen fluoride, the formation of structural isomer mixtures of partly fluorinated ethanes, which in some cases can be separated only under expensive distillation conditions. In addition, a i 2 considerable amount of fluorochloroethanes which cannot be utilized economically are obtained in this procedure.

There was the object of providing a process for the preparation of partly fluorinated ethanes of the general formula

CF

3 CFHzC12-.

in which x 0, 1 or 2, which allows controlled prepara- .goo..l tion, with a high selectivity, of these compounds, which can be isolated as the pure product without great expen- 0 0 oo 10 diture on distillation.

0 0 0 O 0 0 0000 0 00 0 The invention relates to a process for the preparation of 0000 ooo0 partly fluorinated ethanes of the general formula CFCFH.C1 2 z- 0000 o0 o0 in which x 0, 1 or 2, which comprises reacting, as the o 0 15 reactant, partly fluorinated ethane of the general formula 0 00 S0 0a 0 00

C

2

F

3 H.C13-.

o oo °o o in which x 0, 1 or 2 0 0 0° o and, as the fluorinating agent, partly fluorinated 0 13 ethanes of the general formula

CF

3 ,_Clx-CH3-yCly in which x 0, 1 or 2 and y 0, 1, 2 or 3 with one another in gaseous form in the presence of a chromium catalyst at temperatures of 150 to 600 0 C, the reactant and the fluorinating agent having the same chemical structural formula being excluded. In reactions in which the reactant and fluorinating agent are identical, when this compound is passed in gaseous form over the chromium catalyst a dismutation reaction occurs, in 3 which only very low conversion into a large number of compounds takes place, as is described in the following Comparison Example 1.

It has been found that the desired partly fluorinated ethanes are obtained in a particularly high selectivity if partly fluorinated ethane of the general formula

CF

3 -CHCl 3 .z o, in which x 0, 1 or 2, is employed as the reactant, Swhich is therefore preferred.

Chromium(III) compounds, such as oxides, hydroxides, nitrates or halides, are used as the chromium catalyst tic for the process according to the invention. The chromium(III) compounds are preferably activated before being employed for transfluorination with gaseous hydrogen fluoride.

SParticularly high selectivities are achieved if the chromium catalyst is employed together with a support, such as magnesium oxide or graphite, and the supported chromium catalyst is activated by a hydrogen fluoride treatment. One possibility for the preparation of the supported chromium catalyst is described in US-A- S4,547,483.

This supported chromium catalyst consists of at least by weight of magnesium fluoride and 0.5 to 29 by weight of chromium and has an atomic ratio of magnesium:chromium 1.5 to 50. Chromium is present in this catalyst as chromium oxyfluoride.

To prepare the supported chromium catalyst just mentioned, 1 mol of a water-soluble chromium(III) salt is reacted with at least 1.5 mol of magnesium hydroxide or magnesium oxide in the presence of water, and the reaction mixture is thus converted, if appropriate by -4evaporation, into a paste containing chromium hydroxide and a magnesium salt. The paste is dried and treated with hydrogen fluoride at temperatures of 20 to 500 0 C. The paste can furthermore also contain MgO or Mg(OH) 2 depending on the excess of magnesium used.

The treatment with hydrogen fluoride is advantageously carried out at a temperature of 100 to 400°C. The catalyst is treated with at least 2 mol of hydrogen fluoride per mol of metal compound employed (chromium salt, )0 magnesium oxide). The fluorination time is 0.5 to B hours. In order to effect more rapid removal of the water i formed and to avoid undesirable temperature peaks, HF can I be diluted by an inert gas (for example N 2 or air).

ii It is also possible to prepare catalysts of virtually S 15 identical empirical composition by mixing pulverulent Shydrated chromium oxide with pulverulent magnesium i fluoride and treating the mixture with hydrogen fluoride.

A high selectivity of the process according to the invention is achieved if it is carried out at a temperature of 250 to 400 0 C, in particular 320 to 360°C. The i process according to the invention operates equally well i under reduced, normal or elevated pressure.

To achieve high conversions, an average contact time of 1 to 300 seconds, in particular 10 to 100 seconds, should be maintained during the reaction. The average contact time is calculated from the formula: Volume of the catalyst [ml Average contact time [S] Volume of starting substances fed in per second [ml/s] Particularly high selectivities are achieved if a molar ratio of reactant:fluorinating agent (1 to 15) (10 to preferably (1 to 7) (5 to is established.

It has furthermore been found that an excess of reactant has a favorable inf luence on the selectivity of the reaction.

The process according to the invention also gives good results if a mixture of partly fluorinated ethanes of the general formula

CF

3 Cl.-CH 3 -,Cly in which x 0, 1 or 2 and y 0, 1, 2 or 3, is employed as the fluorinating agent.

a C .0 Equations of possible reactions according to the invention are listed in Table 1: Table 1 Reactant Fluorinating agent End product By-product t 4 t 9 t 3 CF 3 -CCl 3 2 CF 3 -CC1 3

CF

3 -CC1 3 3 CE' 3 -CCl 3 2 CE' 3 -CC1 3 2 CF 3 -CC1 3

CE'

3 -CCl 3

CF

3 -CC1 3 2 CE' 3 -CC1 3

CE'

3 -CC1 3

CF

3 -CCl 3

CE'

3 -CC1 3 2 CF 3 -CHCl 2

CE'

3 CHCl 2

CF

3

-CH

2 C1+ 2 CE' 3 -CHC1 2

CE'

3 CHCl 2 2 CE' 3

-CH

2 Cl+

CE'

3

CH

2 Cl+

CE'

3

CH

2 C1 CClF 2

CH

2 Cl CC1 2

CH

2 C1

CE'

3 CHC1 2

CE'

3 CHC1 2 CC1E' 2 CHCl 2 CClE' 2 CHC1 2 CC1 2 F- CHC1 2

CE'

3

CH

3 CClF 2

CH

3 CC1 2 F- CH 3 CCl 2 '-CCd 3

CE'

3

CH

2

C).

CClF 2

CH

2 Cl CClF 2

CH

2 Cl

CY

3

CH

3 CCl' 2

CH

3

CF

3

CH

3 CCl' 2

CH

3 43 CF 3

-CF'

2

CE'

3 -CE'C1 2 4 CE' 3 -CE'C1 2 43 CE' 3

-CF'

2 42 CE' 3 -CE'C1 2 42 CF 3 -CE'C1 2 4 CE' 3 -CE'C1 2 4 CE' 3 -CE'C1 2 42 CE' 3 -CEC 4 CE' 3 CEC1 2 4 CF 2 -CFC1 2 4 CF 3

-CFC'

2 42 CF 3 -CHFC1 4 CE 3 -CFCI 4 CE' 3

-CH

2 F 42 CE' 3 -CHFC1 4 CF3-CHE'C1 42 CE' 3

-CH

2 F 4 CE' 3

-CH

2 F CC1 2

=CHCI

CC1 2 =CHC1

CC.

2 =CHC1 Cc1 2 =cc1 2 CC1 2 =CC1F CC1 2 =CC1 2 CC). =CCE' CC1 2 =CC1 2 CC1 2

=CH

2 CC1 2

=CH

2

CC.CH

CC

2 =CC1 2 CC1 2 =CHCl CC1 2 =CHC1 CC1 2 =CHC1 CC1.

2

=CH

2 CC1 2

=CH

2 CC1

=H

CC12=C HCl HC1 HCl

HC.

HC1 HC1

HF

HF

HCl Cl 2

HF

HF

HF

HF

HF

HF

HE'

7 2 6 Particularly high conversions are achieved with the following fluorinating agents listed in Table 2, individually or as a mixture with one another: Table 2 Fluorinating agent Formula 1,1-Dichloro-l-fluoroethane l-Chloro-1,1-difluoroethane 1,1,1-Trifluoroethane 1-Fluoro-1,1,2-trichloroethane 1,2-Dichloro-1,1-difluoroethane 1-Chloro-2,2,2-trifluoroethane ,tc 1-Fluoro-1,1,2,2-tetrachloroethane 0 1,l-Difluoro-1,2,2-trichloroethane 1,l-Dichloro-2,2,2-trifluoroethane Fluoropentachloroethane 1,1-Difluoro-tetrachloroethane I t CC1,F-CH 3 CC1F 2

-CH

3

CF

3

-CH

3 CC1 2

F-CH

2 Cl CClF 2

-CH

2 Cl

CF

3

-CH

2 Cl CCl 2 F-CHCl 2

CCIF

2 -CHCl 2

CF

3 CHCl 2 CC12F-CCl 3

CCIF

2 -CC1 3 The advantage is that the desired partly fluorinated ethanes can easily be isolated in a pure form from the reaction product by fractional distillation because of 0 their low boiling point.

If the fluorinating agent is employed in excess, the excess fluorinating agent can be used again as the fluorinating agent together with the by-products formed, or the by-products formed are regenerated with hydrogen fluoride in a subsequent fluorination stage and employed again as fluorinating agent.

A suitable embodiment of the process according to the invention is the following: the reactant and the fluorinating agent are first vaporized and mixed in gaseous form in a mixing zone and heated to the reaction temperature.

This gas mixture is fed into the contact zone. The contact zone consists of a temperature-controlled tube in which a loose pile of catalyst is located. The reaction products are condensed and the organic phase is subjected to fractional distillation.

7 The nomenclature of the fluorohydrocarbons is according to the method customary in the art, which is explained in "Rbmpps Chemie-Lexikon (Rbmpps Chemical Dictionary)", Frankh'sche Verlangshandlung, Stuttgart, (1973), volume 2, page 1172.

The invention is illustrated in more detail with the aid of the following examples.

The individual fractions were analyzed by gas chromatography and additionally identified with the 1 F and 'H-NMR method. The percentages stated are percentages by weight.

Example 1 0o 30 ml of chromium/magnesium catalyst prepared according to US-A-4,547,483 were introduced into an electrically heated glass tube 50 cm in length and 1 cm in internal diameter. 1,1,1-Trichloro-trifluoroethane (R113a) and 1chloro-2,2,2-trifluoroethane (R133a) were vaporized, mixed in a temperature-controlled tube 70 cm long and passed over the catalyst at a molar ratio of 3.5:1. The average catalyst contact time was 37 seconds. The experi- 20 ment was carried out at various temperatures for in each c case 12 hours. The results are shown in Table 3.

Table 3 Temperatures Components 80 300 320 340 360 CF3CFC12 (end product) 16.4% 24.5% 42.9% 52.9% 58.4%

CF

3

CCI

3 (reactant) 66.2% 57.8% 39.0% 26.0% 19.7% CF-CHC (fluorinating agent) 11.8% 10.3% 5.1% 3.3% 1.1% CCl2=CHC (byproduct) 4.6% 6.6% 11.8% 14.7% 16.3% other products 1.2% 3.1% 8 Table 3 (continued) Tanperatures Component 280 300 320 340 360 Conversion (based on R133a): 24.3% 35.6% 66.1% 78.8% 92.6% Conversion (based on R113a): 21.4% 31.7% 54.7% 69.0% 76.5% An increase in temperature at the catalyst leads to an increase in conversion; however, the content of other products also increases.

Example 2 l1,1,1-Trichloro-trifluoroethane (R113a) and l-chloro- 2,2,2-trifluoroethane (R133a) were passed in a molar ratio of 0.6 1 over the chromium/magnesium catalyst (as in Example 1) at 340"C in the experimental set-up of Example 1. The average catalyst residence time was 21 seconds. The experiment was carried out for 10 hours. The C' result was as follows:

CF

3 -CFCl 2 14.2

CF

3 -CC1 3 32.3

CF

3

-CH

2 Cl 45.6 CCl 2 =CHC1 4.0 j CF 3 -CHC1 2 <0.2 2 5 other products 3.7 Conversion 32.7 (based on R113a) The comparison of Examples 2 and 1 (340"C) shows that a higher content of reactant in the gas mixture leads to an increase in selectivity.

9 Example 3 ml of chromium oxyfluoride catalyst which had first been prepared from hydrated chromium oxide (Guignet's green) with HF/N 2 by the method described in the Patent US-A-4,145,368 were placed in the experimental set-up of i Example 1. 1,1,1-Trichloro-trifluoroethane (Rll3a) and Sl-chloro-2,2,2-trifluoroethane (R133a) were passed over the catalyst at 340"C. The molar ratios, the contact times and the amounts of organic components are summarized in Table 4. The experiment was carried out for 12 hours.

Table 4 Molar ratio of R113a:R133A 0.6 1 3.5 1 Average contact time: 21 37 (seconds) Components:

CF

3 -CFC12 (end product) 8.9 32.3

CF

3 -CC13 (reactant) 37.9 46.9

CF

3

-CH

2 C1 (fluorinating agent) 46.3 7.4 CCl 2 =CHCl (by-product) 2.6 9.2

CF

3

-CHC

2 1 (by-product) 1.3 1.2 other products 3.1 3.0 Conversion based on R113a: 21.7 43.1 Conversion based on R133a: 52.7 Example 3 shows the use of a different catalyst to that in Examples 1 and 2.

Example 4 1,1,1-trichloro-trifluoroethane (R113a) and 1,1-difluoro- 1,2,2-trichloroethane (R122) were reacted in a molar ratio of 3.4 1 at a temperature of 340 0 C in the 10 experimental set-up of Example 1, filled with chromium/ magnesium catalyst as in Example 1. The average catalyst contact time was 42 seconds. The experiment was carried out for 12 hours. The result was as follows:

CF

3 -CFC1 2 (end product) 45.8

CF

3 -CC13 (reactant) 30.0

CF

2 Cl-CHC12 (fluorinating agent) 0.8 CC12=CCl (by-product) :12.1 CCl 2 =CClF 8.3 other products 3.8 Conversion 4 I Sbased on R122 96.5 Sbased on R113a 62.6 Example A mixture of 1,1,1-trichloro-trifluoroethane (R113a) and 1,2-dichloro-l,l-difluoroethane (R132b) in a molar ratio o of 4.1 1 was passed over the catalyst described in

C

0 Example 1 at a temperature of 340"C in the experimental set-up of Example 1. The average catalyst contact time S0 was 42 seconds. The experiment was carried out for 12 hours. The result was as follows:

CF

3 -CFC1, (end product) 38.1

CF

3 -CC13 (reactant) 44.6

CF

2 C1-CH 2 Cl (fluorinating agent) <0.1 CCl2=CHCl (by-product) 14.3 other products 2.9 Conversion based on R132b >99.9 based on R113a 48.4 Examples 4 and 5 differ from the above Examples 1 to 3 by the choice of fluorinating agent.

I

11 't Example 6 Various mixtures of CF 3

-CHC

2 1 (R123) and CF 3

-CH

2 C1 (R133a) were passed over the chromium/magnesium catalyst described in Example 1 at 360"C in the experimental set-up of Example 1.

The average catalyst contact times, molar ratios and amounts of organic components are summarized in Table 6.

The experiment was carried out for 12 hours.

Table 6 Molar ratio of R123:R133a: 0.8:1 1.8:1 2.6:1 4.4:1 o I

O

o E 'i, 0CI Average contact time (seconds) Ccaponents:

CF

3 -CFC (end product)

CF

3 CHCl (fluorinating agent) CF3-CHC 2 (reactant) CC21,=CC (by-product) 20 other products Conversion based on R123: based on R133a: 18 19 23 22 18.0% 37.6% 27.6% 11.5% 6.6% 15.4% 22.7% 52.5% 7.4% 5.9% 21.2% 9.9% 48.7% 12.7% 7.1% tt 0 0e 19.1% 5.6% 60.7% 9.7% 4.9% 26.1% 59.3% 42.3" 24.7% 32.7% 48.2% Example 7 30 ml of the chromium/magnesium catalyst described in Example 1 were introduced into the reactor described in that example. 1,1-dichloro-2,2,2-trifluoroethane (R123) and 1,1,1-trifluoroethane (R143a) in a molar ratio of 2.6 1 were metered in at 360"C.

The catalyst contact time was 29 seconds. The experiment was carried out for 12 hours. Analysis by gas chromatography gave the following composition for the organic 12 product content:

CF

3 -CHFC1 (end product) 15.0

CF

3

-CH

3 (fluorinating agent) 13.3

CF

3 -CHC1 2 (reactant) 65.5 CC1 2

=CH

2 (by-product) 4.9 other products 1.3 Conversion: based on R143a 25.8 based on R123 20.4 Example 8 9 C S1-Chloro-2,2,2-trifluoroethane (R133a) and 1,1,1-trifluoroethane (R143a) were passed in a ratio of 2.2 1 over the chromium/magnesium catalyst at 400°C in the experimental set-up from Example 1. The catalyst contact time was 29 seconds. The experiment was carried out for 12 hours. Analysis of the organic part of the crude product by gas chromatography gave the following composition:

CF

3

-CH

2 F (end product) 7.9

CF

3

-CH

3 (fluorinating agent) 23.1

CF

3

-CH

2 C1 (reactant) 60.5 other products 8.5 (CCl 2

=CH

2

CF

2 =CHC1) Conversion based on R143a 12.3 based on R133a 11.1 Examples 6 to 8 document the subject matter of the invention for other reactant/fluorinating agent reactions.

'e U 13 Comparison Example 1 Example of the dismutation.

Example 1 was repeated with the change that 1,1,1-trichloro-trifluoroethane was passed over the chromium/magnesium catalyst of Example 1 at 340°C without fluorinating agent. The average catalyst contact time was 37 seconds. The experiment was carried out for 12 hours. The result was as follows:

CF

3 -CFCl 2 (end product) 1.2

CF

3 -CC1 3 (reactant) 97.5 other products 1.1 Comparison Example 2 Example 1 was repeated, but aluminum fluoride was now investigated as the catalyst. The catalyst was prepared from activated aluminum oxide (Harshaw/Filtrol, Cleveland, Ohio) in accordance with US-A-3,087,974 with CC12F-CClF 2 (R113). Various mixtures of CF 3 -CCl 3 (R113a) and CF 3

-CH

2 Cl (R133a) were then passed over the catalyst at 340"C. The average contact times, molar ratios and amounts of the organic components are noted in Table The experiment was carried out for 12 hours.

Table iMolar ratio of R113a:R133a: 0.5 1 3.7 1 Average contact time: 21 47 (seconds) Componen-s:

CF

3 -CFC1 2 (end product) 0.3 0.7

CF

3 -CC1 3 (reactant) 39.3 82.2

CF

3

-CH

2 C1 (fluorinating 53.9 14.1 agent) w,-

I

14 Table 5 continued Molar ratio of Rll3a:R133a: 0. 5 1 3. 7 1

CF

2 =CHC1 (by-product)

CF

3 -CHCl 2 (by-product) Conversion based on Rll3a: 6.1 0.4 0 2.2% 0.7% 0.5 Comparison Example 2 documents that aluminum fluoride catalysts cannot be used as the transfluorination catalyst.

a a a a t a a a. a, a a a a a, a a a a a a.

ala.

a a

I

L

Claims (10)

1. A process for the preparation of a partly fluorin- ated ethane of the formula CF 3 -CFH.Cl2-. in which x 0, 1 or 2, which comprises reacting, as the reactant, partly fluorinated ethane of the formula o ;00* C0H0Cla-4 o o C 2 F 3 a 00 o.00 in which x 0, 1 or 2 00 aoe0 and, as the fluorinating agent, a partly fluorinated 00"* ethane of the formula CF3-,Cl-CH 3 -yCly 0 in which x 0, 1 or 2 and y 0, 1, 2 or 3 with one another in gaseous form in the presence of ,a chromium catalyst at temperatures of 150 to 600"C, t the reactant and the fluorinating agent having the same chemical structural formula being excluded. a 1

2. The process as claimed in claim 1, wherein a partly fluorinated ethane of the formula CF 3 -CH.Cl 3 1 in which x 0, 1 or 2, is employed as the reactant.

3. The process as claimed in claim 1 or 2, wherein a chromium(III) compound is employed as the chromium catalyst.

4. The process as claimed in any one of the preceding claims 1 to 3, wherein the chromium catalyst is used together with a support. -T f 1A 16 The process as claimed in claim 3 or 4, wherein the chromium catalyst is activated by a hydrogen fluoride treatment.

6. The process as claimed in any one of the preceding claims 1 to 5, wherein the reaction is carried out at a temperature of 250 to 400"C.

7. The process as claimed in any one of the preceding claims 1 to 6, wherein the .reaction is carried out 0o°oo, at a temperature of 320 to 360'C. 0 6 0 8. The process as claimed in any one of the preceding claims 1 to 7, wherein an average contact time of 1 to 300 seconds is maintained during the reaction. '@0

9. The process as claimed in any one of the preceding claims 1 to 8, wherein an average contact time of to 100 seconds is maintained during the reaction. to o@ t

10. The process as claimed in any one of the preceding claims 1 to 9, wherein a molar ratio of reac- c tant:fluorinating agent (1 to 15) (10 to 1) is established.

11. The process as claimed in any one of the preceding claims 1 to 10, wherein a molar ratio of reac- tant:fluorinating agent (1 to 7) (5 to 1) is established.

12. The process as claimed in any one of the preceding claims 1 to 11, wherein a mixture of partly fluorin- ated ethanes of the formula CFa-,Cl,-CH3_yCly wherein x 0, 1 or 2 and y 0, 1, 2 or 3, is employed as the fluorinating agent. DATED this 23rd day of August 1980. HOECHST AKTIENGESELLSCHAFT WATEMARK PATENT TRADEMARK ATTORNEYS MELBOURNE. VIC. 3000.