DE1237084B - Process for the preparation of 1, 2-dichloro-1, 1, 2, 3, 3, 3, -hexafluoropropane - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

Number:
File number:
Registration date:
Display day:

C07c

German class: 12 ο -2/01

A39869IVb / 12o
April 3, 1962
March 23, 1967

It is already known (see J. Amer. Former Soc, 68 [1946], p. 496), 1,2-dichlorohexafluoropropane Reaction of chlorofluoropropane and an antimony chlorofluoride as a fluorinating agent in the liquid phase at relatively high temperature and high Create pressure in a sealed pressure vessel. Such a process is obviously inefficient. Such fluorinations can also be carried out with powerful fluorinating agents such as cobalt (III) fluoride, be performed. Here, however, the refluorination of the fluorinating agent is a separate operation with elemental fluorine required, its use of course a disadvantage represents.

The present invention relates to a process for the preparation of 1,2-dichloro-1,1,2,3,3,3-hexafluoropropene, this at relatively low temperatures and essentially under normal pressure can be carried out continuously. The new process also avoids the disadvantages which occur in processes with pressure vessels or when using elemental fluorine.

According to the invention, a process for the preparation of 1,2-dichloro-1,1,2,3,3,3-hexafluoropropane is provided proposed from a chlorofluoropropane in the presence of antimony chlorofluoride, which thereby is characterized in that 1,1,2-trichloro-1,2,3,3,3-pentafluoropropane with anhydrous hydrogen fluoride, at normal pressure and at a temperature of 90 to 130 ° C, in the presence of a solid catalyst, consisting of granular, with the compound

(x at least = 2, but less than 5) impregnated activated carbon, the activated carbon content of the catalyst being at least 25 percent by weight and the antimony content being 10 to 35 percent by weight.

Thus, according to a typical embodiment of the process, gaseous!, L ^ -Trichlor-l ^ jS ^^ - pentafluoropropane and gaseous anhydrous hydrogen fluoride are continuously measured, mixed and placed in a tubular reaction vessel, which is preferably entirely with the said solid catalyst made of activated carbon and antimony fluorochloride is filled and made of an inert material such as nickel, monel or innconel (protected name) and is inserted in a suitable, tubular, electric furnace with automatic heating means in order to maintain the temperature desired for the reaction. The process according to the invention for the production of
1,2-dichloro-l, l ₅ 2,3,3,3-hexafluoropropane

Applicant:

Allied Chemical Corporation,
New York, NY (V. St. A.)

Representative:

Dr. rer. nat. J.-D. Mr. v. Uexküll, patent attorney, Hamburg 52, Königgrätzstr. 8th

Named as inventor:

Richard Francis Sweeney, Dover;

Cyril Woolf, Morristown, N.J. (V. St. A.)

Claimed priority:

V. St. v. America April 5, 1961 (100 808) -

The reaction takes place according to the following formula: CF ₃ CFCICfCI ₂ + HF -> CF ₃ CFCICF ₂ Cl + HCl

The separation of the product obtained can be carried out using the methods customary in the relevant technology Proceedings happen. For example, the products leaving the reaction zone can be passed through sprinkler towers passed to remove hydrogen fluoride and hydrogen chloride; that the towers Leaving material can be dried, and then put in a collecting container by appropriate Cooling, e.g. B. with dry ice-acetone, condensed will. The condensate obtained can then be used to obtain the desired product as well as for Separation of the unreacted products, which can be reused in the cycle, in be fractionally distilled using a suitable device.

The catalyst can be made by impregnating activated carbon with pentavalent antimony fluorochloride getting produced. The activated carbon used consists of commercially available granular Material. Suitable materials consist of different types of activated carbon with a particle size corresponding to a screen size of 8 to 14 Tyler standard or 8 to 14 meshes per 2.5 cm, such as "Columbia 6 G", "Columbia SW" and "Darco" (ge

709 520/434

3 4

protected names). The grain size of the provided that χ at least equal to 2, but less than-5

However, activated carbon is not used and is preferably at least 3, but less than 5.

particularly critical. Usually the reaction is carried out in The theoretically required molar ratio of

elongated reaction tubes carried out, with hydrogen fluoride to organic starting material

the activated carbon, preferably an average 5, is approximately 1: 1. Less than the theoretical

One twentieth grain diameter and an amount of hydrogen fluoride can be used.

A quarter or better, an eighth to a tenth, however, does not offer any advantage and is therefore not to be used

of the vessel diameter. prefer. Preferably using a molecular

The pentavalent antimony fluorochloride can work on excess of hydrogen fluoride, which in the

Various ways are incorporated into the activated carbon in the range from 1: 1 to 5: 1 and preferably from 2: 1 to

den, for example, the grains of carbon can be about 4: 1.

Soaking with an aqueous antimony trichloride or during the reaction a relatively antimony trifluoride solution can be impregnated, the small amount of free chlorine can then be dried together with fluorine by heating to remove the water, hydrogen and the organic starting material, whereupon the trivalent antimony in five- 15 the reaction vessel The antimony-valent antimony is converted by keeping halide catalyst in the pentavalent form to chlorine at about 50 to 100 ° C through the material. The amount of chlorine thus abandoned can flow. In another process for the production of 0.1 to 0.5 moles of chlorine, the activated carbon and hydrogen fluoride will fluctuate per mole of the abandoned position of the catalyst,
grains with a volatile, organic, non-20 As mentioned above, the process can be carried out, for example, with reactive solvents that are normal pressure. In such raffled antimony pentachloride or antimony trichloride, which contains in the gas phase and using, a fluorinated catalyst being carried out as a solvent, d .. h. at the hydrocarbon, such as. B. 1,1,2-trichloro-l ^^ - tri- process in which a gas stream successively fluoroethane, for antimony pentachloride or carbon flows through the reaction and recovery systems, material disulfide is used for antimony trichloride. the pressure corresponds practically to normal pressure. The mass can be used to remove the solvent, but technically in such systems it is dried by heating, and the three-fold excess pressure is used so that an economically valuable antimony is (if available) through a satisfactory gas flow by handling the equipment with chlorine at 100 to 150 ° C in the five-column column. Strictly speaking, the valuable form is transferred. If a higher antimony pressure is desired depending on the type of device, grain size of the fluorochloride charge of the activated carbon, catalyst, gas space not filled in the reactor, liquid antimony pentachloride can be slowly run into the overhead vessel and the desired contact time, actually a column of activated carbon, between 0 .14 and about 0.7 and 1.05 atmospheres, respectively, so that it is allowed to seep down through the column. 35 such process conditions, called excess antimony pentachloride, can be detected from normal pressure.

flow down the column by its own gravity. The contact time can go without a noticeable drop

Following the impregnation of the activated carbon, the effectiveness of the process will vary considerably!

grains and, after any necessary transformation, generally results with increasing contact time

development of the total antimony to antimony pentachloride 40 and temperature of the. Reaction vessel a greater

the impregnated charcoal can for example at 40 to reaction. Even with such a short contact time of

150 ⁰ C are gassed with hydrogen fluoride, around 1 second you get considerable conversions,

Antimony pentachloride into the pentavalent antimony but the contact times can also be 120 seconds

to convert chlorofluoride. be. The contact times are preferably in

The relative amounts of activated carbon and five- 45 range from 2 to 20 seconds. The contact time that

valuable antimony fluorochloride in the finished, fixed temperature of the reaction vessel and the ratio

Catalyst can vary considerably. That of the constituents participating in the reaction

the finished catalyst contains at least 25 weight- are interrelated to a considerable extent

Percent activated carbon. What method of getting to- gether, and the optimal conditions in relation to

Position of the catalyst is also used, the 50 depending on the device and the contact time

Procedure and the relative amounts of activated carbon working procedures can be determined by test experiments *

and antimony halide must be adjusted so that.

that the amount of stored in the activated charcoal to isolate the reaction products that

pentavalent antimony in the finished catalyst 1,2-dichloro-1,1,2,3,3,3-hexafluoropropane, not for

10 to 35 percent by weight, preferably 20 to 55 percent organic starting material,

30 percent by weight. Containing hydrogen fluoride and hydrogen chloride

To some extent, the composition of a sprinkler tower may vary around the bulk of the pentavalent antimony fluorochloride component of the final hydrogen fluoride and the hydrogen chloride from the catalyst as well. Remove the co-mingling of the gas stream. The latter can, according to the size of the treatment, 60 exit from the sprinkler through a relatively weak one composed of activated carbon and antimony pentachloride, e.g. B. 10 ° / ₀ sodium hydroxide solution gesture Henden mass adjusted with hydrogen fluoride will remove traces acid to leads. After be. The composition of the pentavalent drying by dehydrating agent such as calcium antimony fluoride chloride component chloride of the finished catalysis can, the dried gas stream by a crystallizer has the formula: 65, for example, with dry ice-acetone mixture at -78 ° C ", p, _{r] #} cooled Cold trap passed and completely condensed bbba> U _s -x ; will. The condensate in the cold trap can then be subjected to the treatment with hydrogen fluoride so that it is fractionally distilled in a suitable manner to im

essentially pure Ι, Ί
to win propane.

1,2 - dichloro -1,1,2,3,3,3 - hexafluoropropane (boiling point about -35 ⁰ C) is used as a solvent, heat transfer media, as well as dielectric as an intermediate for the production of refrigerants and perfluoropropene.

The following example explains the invention:

example

10

In this experiment, the catalyst was prepared in situ from activated carbon and pentavalent antimony fluorochloride in a reaction vessel which consisted of a 91 cm long nickel tube with an internal diameter of 2.5 cm and was installed in a cylindrical electric furnace. The lower end of the vessel was provided with connecting lines to introduce gaseous 1,1,2-trichloro-1,2,3,3,3-pentafluoropropane, gaseous, essentially anhydrous hydrogen fluoride and chlorine separately and in measured quantities. At the outlet, the reaction vessel was charged with 184 g of granular activated carbon with a particle size of 1.4 to 2.4 mm, available under the protected name "Columbia 6G". Approximately 704 grams of liquid antimony pentachloride was added to the top of the reaction vessel. Unabsorbed excess antimony pentachloride was drained from the bottom of the activated carbon bed. The mass of the activated carbon saturated with a total of about 522 g of antimony pentachloride was then ^{gassed for about 6 hours at about 80 to 110 °} C. with anhydrous hydrogen fluoride at a rate of about 2 mol / hour. The amount of liquid antimony pentachloride charged into the reaction vessel and the degree of absorption of the antimony halide by the activated carbon were such that the finished catalyst contained approximately 28 weight percent pentavalent antimony.

After completion of the formation of the catalyst from activated carbon and pentavalent antimony fluorochloride in the reaction vessel, the internal temperature in the reaction vessel was brought to approximately 115 ° C. and approximately during the entire fluorination of the 1,1,2-trichloro-1,2,3,3,3-pentafluoropropane held at this value. Over the course of 2 hours, approximately 283 g (1.19 moles) of II ^ trichloro-l ^^^^ - pentafluoropropane became anhydrous at a rate of approximately 0.6 moles / hour and 81.0 g (4.5 moles) became anhydrous Hydrogen fluoride was introduced into the reaction vessel at a rate of about 2.03 moles / hour and 35.0 g (0.493 moles) of chlorine at about 0.247 moles / hour. The molar ratio of hydrogen fluoride to l ^ -trichloro-l ^^^. S-pentafluoropropane in the feed was 3.4: 1. The contact time was approximately 3 seconds. The pressure in the reaction vessel and recovery unit was about 0.035 to 0.07 atmospheres, just enough above normal pressure to cause gas to flow through the system. The reaction vessel leaving the materials were performed in a conventional extraction system, in which the exiting from the reaction vessel gas stream with water, then sprayed with aqueous NaOH, dried and finally completely liquefied by condensation in a dry ice-acetone cold trap at about -78 ⁰ C. became. The total amount of organic substances condensed in the separator was approximately 218 g. Were during the distillation of the condensate approximately 88.0 g (0.398 mole) of 1,2-dichloro-1,1,2,3,3,3-hexafmorpropan, CF ₃ CFCICF ₂ Cl, with a boiling point of about -33 ⁰ C , and about g (0.514 mol)!, l ^ -Trichlor-l ^^^^ - pentafluoropropane, Cf ₃ CFCICFCI ₂ , with a boiling point of about 73 to 74 ° C. The reaction product obtained in this way contained approximately 44 mol percent of the desired l ^ -dichloro-ljl ^^^ jS-hexafluoropropane, the residue was unreacted starting material of 1,2-trichloro-1,2,3,3,3 ~ pentafluoropropane. The yield of 1,2-dichloro-1,2,3,3,3-hexafluoropropane, based on 1,1,2-trichloro-1,2,3,3,3-pentafluoropropane used, was 21%.

Claims (4)

Patent claims: 1. Process for the preparation of 1,2-dichloro-1,1,2,3,3,3 - hexafluoropropane, characterized in that l, l, 2-trichloro-l, 2,3, 3,3-pentafluoropropane with anhydrous hydrogen fluoride, at normal pressure and at a temperature of 90 to 130 ° C, in the presence a solid catalyst consisting of granular, with the compound (x at least = 2, but less than 5) impregnated activated carbon, the activated carbon content of the catalyst being at least 25 percent by weight and the antimony content being 10 to 35 percent by weight. 2. The method according to claim 1, characterized in that there is a molar ratio of hydrogen fluoride to!, l ^ -Trichlor-l ^^ jS ^ -pentafluoropropane as 2: 1 to 4: 1 applies. 3. The method according to claim 1 and 2, characterized in that the reaction is carried out in The presence of 0.1 to 0.5 moles of chlorine per mole of hydrogen fluoride executes. $ 4. The method according to claim 1 to 3, characterized in that one carries out the reaction in one tubular reaction vessel executes, with the catalyst as granules with an approximate Grain diameter corresponding to a sieve size of one eighth to one tenth of the Diameter of the reaction vessel used. 709 520/434 3.67 © Bundesdruckerei Berlin