DE1175225B - Process for the preparation of a mixture of vinyl fluoride and 1,1-difluoroethane - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: C 07 c

Number: File number: Registration date: Display day:

German class: 12 ο - 19 / Θ2

1175 225
U7985IVb / 12o
May 2, 1961
August 6, 1964

The process according to the invention for the preparation of a mixture of vinyl fluoride and 1,1-difluoroethane by reacting a chlorinated hydrocarbon with hydrogen fluoride at elevated temperatures in the presence of a chromium oxide catalyst is characterized in that 1,2-dichloroethane or vinyl chloride or mixtures thereof with hydrogen fluoride in the presence of chromium oxide at 200 to 500 ⁰ C converts. The reaction proceeds according to the following equation:

CH "C1CH, C1

and or

CH ₂ = CHCl - "- Cr ₂ O ₃

JCH ₂ = CHF IcH ₃ CHF ₂

The process can be carried out batchwise or continuously. In a preferred embodiment, the vaporous reaction mixture is passed over the chromium oxide catalyst contained in a tubular reaction vessel made of stainless steel or nickel. The exiting gaseous product is treated in a water scrubber and a drying device and then the resulting mixture is condensed. The components of the mixture are easily separated by distillation. The process temperature may vary between 200 and 500 ⁰ C, with the preferred temperature range between 300 and 400 ⁰ C. The higher the temperature in the range between 300 and 400 ^° C., the higher the yield of vinyl fluoride. For a given conversion e.g. B. leads to an increase in the reaction ^{temperature by 50 0} C to more than a doubling of the ratio of vinyl fluoride to 1,1-difluoroethane.

The process can be carried out at atmospheric pressure or pressures above or below atmospheric will. The use of superatmospheric pressures increases the yield of 1,1-difluoroethane and facilitates the recovery of the vinyl chloride and that by-product Hydrogen chloride. Pressures of 20 atm are advantageous. applied.

The residence time of the feed in the reaction vessel depends on the reaction temperature and the one desired Ratio of the compounds contained in the mixture. The residence time varies from one Seconds at higher temperatures to several minutes at lower temperatures. At a A typical reaction is the residence time of the steam in the reaction vessel between 1 and 10 seconds Reaction temperatures from 200 to 500 ° C. Particularly preferred is a residence time between 2 and Process for the preparation of a mixture of vinyl fluoride and 1,1-difluoroethane

Applicant:

Union Carbide Corporation, New York, N.Y.

(V. St. A.)

Representative:

Dr. W. Schalk, Dipl.-Ing. P. Wirth,

Dipl.-Ing. G. E. M. Dannenberg

and Dr. V. Schmied, Kowarzik, patent attorneys,

Frankfurt / M., Große Eschenheimer Str. 39

Named as inventor:

Joseph Peter Henry,

Charles Edward Rectenwald,

Jared Wilson Clark, Charleston W. Va. (V. StA.)

Claimed priority:

V. St. v. America June 19, 1960

(35148)

Seconds at a temperature between 300 and 400 ⁰ C. At shorter residence times achieved with vinyl chloride as the starting material a greater yield than with 1,2-dichloroethane.

The molar ratio of hydrogen fluoride to chlorohydrocarbon in the feed can be between 2 and 20 moles, preferably 3 and 10 moles, of hydrogen fluoride per mole of chlorohydrocarbon lie. An equivalent conversion of vinyl chloride can be done with about half that for dichloroethane required amount of hydrogen fluoride can be achieved.

The fluorination of dichloroethane under the conditions according to the invention gives a mixture which consists of vinyl fluoride, vinyl chloride and 1,1-difluoroethane. By changing the reaction conditions and the composition of the feed may result in the manufacture of a component in the product mix be favored.

Vinyl fluoride can according to the invention as a single product can be obtained by a mixture of dichloroethane and hydrogen fluoride in an amount between 2 and 20 moles of hydrogen fluoride per mole of ethylene dichloride at a temperature between ⁰ and 500 C in the presence of a Chromoxyd-

409 639/426

3 4

catalyst washed with water with a residence time between 2 and the ammonium chloride. then Heated wiild for 5 seconds. It is made of vinyl fluoride, the precipitate was in a shallow pan Vinyl chloride and 1,1-difluoroethane existing Ge 70 ° C dried in a vacuum oven. After partially mixed won. The vinyl chloride and the 1,1-di- siser drying the material became the paste in fluoroethane are cut into the 5 small squares at the beginning of the process, so that the water-containing used feed returned. Chromium oxide catalyst after complete drying

The suitable chromium oxide catalysts can be present in the form of cubes with an edge length of approximately 6.4 mm in various ways not claimed here. The final drying of the water will be made. The catalyst may be as a granular containing Chromoxydkatalysators carried hydrous chromium oxide are present at 480 ⁰ C, which as low-io in a nitrogen atmosphere.

impact on the reaction of ammonia with a (b) About 600 ecm (247 g) of that prepared in part (a)

aqueous chromium chloride solution is formed. 45 g of the same hydrous chromium oxide were hydrous Chromium oxide can be mixed in the form of cubes of free chromium chloride and the mixture used that come from the precipitate when it is ground in a ball mill for 16 hours. That present as a partially dried paste, produced 15 fine powder obtained was tabletted, will. The hydrous chromium oxide can also be made with (c) About 344 g (2.5 moles) of aluminum chloride

mixed with a small amount of chromium chloride and dissolved in 1.5 l of water and this solution can be tabletted with a, the chromium chloride acting as a solution of 395 g (2.5 mol) of chromium chloride in 3.671 lubricant for easier tablet production. Water mixed. The resulting solution was added, while stirring, to a mixture of chromium chloride in a flask which treated 920 g of aluminum chloride with ammonia. Water 28 ° / _o containing dilute aqueous NH _3. Furthermore, the chromium oxide can be applied to an alumina. The precipitate has been separated off and used more slowly a few times. Porous clay is washed with with water. The material was impregnated in flat chromic acid. Then, the material is given pans, cut into cubes and dried first dried at elevated temperatures and in a 25 at 6O ⁰ C, then for 2 days at 45O ⁰ C. Reduced hydrogen atmosphere. The (d) produced in this way. About 67.1 g of chromium trioxide (CrO ₃ ) were in

For the process according to the invention, the catalyst is dissolved in 102 g of water and this solution is particularly suitable. .. Stirring to 300 ecm activated alumina (y-Al ₂ O ₃ ;

After the reaction, the exiting gas with a particle size of 3.38 to 3.36 mm) is in a sub Washed with water, with a drying agent, e.g. B. 30 vacuum standing flask given. The material Silica gel, activated alumina or a mole- was made by heating the flask under reduced pressure Kularsieb, dried and the mixture condensed. Print partially dried, then in a reaction chamber Separating the mixture is this fractionated vessel made of nickel with an inner diameter distilled, optionally one or more of 2.5 cm can be added and allowed to dry completely Components are returned. 35 of the catalyst under a stream of nitrogen

It is already known, heated 1,1-difluoroethane from 200 ⁰ C. Then the orange-red catalyst corresponding dichloro ^{compound was reduced with hydrogen fluorine for 4 hours at 250 to 300 0} C to produce substance and a mercury catalyst. Similarly, a catalyst was made

However, these catalysts are uneconomical, chromium oxide is produced on λ-Α1 ₂ Ο ₃ . The »-A1 ₂ O ₃ / require a long induction period, and with the 4 ° Cr ₂ O ₃ catalyst had the advantage of a larger mechanical reaction, mercury is easily lost, so that the chemical strength.

Life of these catalysts is not very long. A mixture of 1,2-dichloroethane and fluorine

It is also known to produce 1,1-difluoroethane by means of hydrogen with a molar ratio of 1: 4 addition of hydrogen fluoride to acetylene in the vapor phase over a catalyst from Cr ₈ O ₃ . With this one. Acetylene, which is not harmless to handle at a temperature of 350 ^° C. and a contact time of 3 seconds, is passed through the addition process on y-Al ₂ O _{s (d).} The raw material used. escaping gases were freed from hydrogen fluoride

Also that from US Pat. No. 2,889,379 washed and cooled in a dry ice known processes for halogen exchange condensed in case. Passed about 20% of the product Essence of a chromium oxyfluoride catalyst can be made from vinyl fluoride and 1,1-difluoroethane, the rest was 50 due to the different starting vinyl chloride. The overall yield was over 98%. materials not with the inventive method. .

drive to be compared. Example ^

Likewise, the production of vinyl fluoride by vinyl chloride and hydrogen fluoride in a mol-

Addition of hydrogen fluoride and vinyl chloride and 55 ratio of 1: 2 were in the vapor phase at subsequent splitting off hydrogen chloride from a temperature of 350 ⁰ C and a contact time the corresponding Fluorchloräthan with alkalis 3 seconds on a Cr ₂ O ₃ -Al ₂ O ₃ -Catalyst not with the claimed process in which one passed. The gases were then compared to remove direct halogen exchange taking place. Washed excess hydrogen fluoride and con-. . ₁ 60 condensed. The distillation of the obtained products

P ^{ie ice} mixture showed a 29% conversion of vinyl

(a) 1145 ecm of water and 588 g of 28% aqueous chloride. The composition of the obtained Ammonia were mixed in with a mechanical stirrer: 72.2% vinyl chloride, 20% vinyl and dropping funnel-equipped flask and fluoride and 7.6% 1,1-difluoroethane. within 1 hour while stirring 520 g of a 37% strength 65.

Chromium chloride solution in 11% water for the contents of the flask Example 3

added dropwise. The precipitate was removed from above using a reaction vessel

standing liquid separated and for removal nickel with an inner diameter of 2.5 cm,

_{containing the C 2} O ₃ - ^ - Al ₂ O ₃ catalyst prepared according to Example 1, (d), two fluorinations were carried out. The reaction conditions and yields are given in Table 1.

At the end of each run, the catalyst was oxidized with air and then with oxygen at the reaction temperature. The time required for regeneration was about _3-2 hours.

Table 1

Reaction ^{temperature, 0} C 350 350

Contact time, seconds 3 3

Molar ratio (HF to C ₂ H ₄ Cl ₂ ) 4 10

Composition of the reaction mixture obtained

Vinyl fluoride 9.1 19.0

Difluoroethane 6.4 11.6

Vinyl chloride 84.5 68.3

Example 4

Using the reactor and catalyst of Example 3, four fluorination runs were made

carried out. The reaction conditions and yields are given in Table 2.

Example 5

Using the reaction vessel and catalyst from Example 3, three fluorination runs were made carried out. Vinyl chloride was recycled to the next batch. The reaction conditions and yields are given in Table 3. The proportion of vinyl fluoride was about 70% of the reaction products, the remainder being 1,1-difluoroethane.

Table 3

(375 ° C; 10: 1 HF / organic material; 4 seconds contact time)

15th
composition
the loading
Mole percent 20th 60.6 39.4 composition
of the product
Mole percent Difluoro vinyl 53.8 46.2 vinyl ethane chloride Vinyl chloride | Dichloroethane 50.4 49.6 fluoride 10.7 56.7 32.6 14.0 53.9 32.1 14.8 51.8 33.4

Tabel 2 D. E. F. C. 375 400 400 Reaction
temperature, ⁰ C ... 350 3 2 5 Contact time,
Seconds 3 10 10 10 Molar ratio
(HFzUC ₂ H ₄ Cl ₂ ) .. 10 composition
of the received
Reaction mixture 27.1 25.0 30.8 Vinyl fluoride ... 19.0 9.1 4.2 5.2 Difluoroethane .. 11.6 63.8 68.6 61.1 Vinyl chloride ... 68.3

35

45

Claims (3)

Patent claims: 1. A process for the preparation of a mixture of vinyl fluoride and 1,1-difluoroethane by reacting a chlorinated hydrocarbon with hydrogen fluoride at elevated temperatures in the presence of a chromium oxide catalyst, characterized in that 1,2-dichloroethane or vinyl chloride or mixtures thereof with hydrogen fluoride in the presence of chromium oxide at 200 to 500 ⁰ C converts. 2. The method according to claim 1, characterized in that one is in the reaction product recycled vinyl chloride contained in the reaction. 3. The method according to claim 1 and 2, characterized in that one is in the reaction product recycled vinyl chloride and vinyl fluoride contained in the reaction. Considered publications:
German Patent No. 859 887;
U.S. Patent Nos. 2,892,000, 2,889,379;
J. Am. Chem. Soc, 60, p. 1570 (1938). 409 639/426 7.64 ® Bundesdruckerei Berlin