Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Patent
1992-12-08
1994-11-22
Sigel, Alan
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
570177, C07C 1708
Patent
active
053671023
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the production of 1,1-dichloro-1-fluoroethane from 1,1-dichloroethylene, also called vinylidene chloride (VC.sub.2), by reaction with hydrogen fluoride in liquid medium in the absence of catalyst(s) and at elevated temperature.
1,1-dichloro-1-fluoroethane is a synthetic product carrying in its molecule, apart from chlorine, fluorine and carbon atoms, hydrogen atoms. The boiling point of this compound is 32.degree. C. under atmospheric pressure. It can be used by itself especially as a blowing agent or in a mixture with other chlorofluorinated hydrogen-containing or hydrogen-free compounds.
The known industrial processes for obtaining 1,1-dichloro-1-fluoroethane all start with 1,1,1-trichloroethane, even though it has been known for a time that this product can be obtained by hydrotiuorination of vinylidene chloride.
Thus, Journal of Am. Chem. Soc. 1943, 65, p. 1272 already describes that the reaction of 1 mol of vinylidone chloride with 4 mol of hydrogen fluoride carried out at 65.degree. C. for 3 hours makes it possible especially obtain 50% of 1,1-dichloro-1-fluoroethane, 5% of 1,1,1-trichloroethane and 15% of tars.
Furthermore, British Patent 627,773 discloses especially the reaction of 8 mol of vinylidene chloride with about 8.7 mol of hydrogen fluoride in the presence of tin chloride at temperatures between 10.degree. C. and 35.degree. C. for 1 hour 45 minutes, as a result of which 1,1-dichloro-1-fluoroethane is obtained at a conversion rate of 32.7%, calculated with respect to the vinylidene chloride used.
However, yields and purities of this kind were not high enough for justifying industrial exploitation, or even a continuation of the studies of the production of 1,1-dichloro-1-fluoroethane by hydrofluorination vinylidene chloride, and consequently this route was abandoned in favour of the one starting with 1,1,1-trichloroethane, which apparently did not have the same disadvantages.
The applicant has now found a process for producing 1,1-dichloro-1-fluoroethane by hydrofluorination of vinylidene chloride which no longer has the drawbacks of the abovementioned processes.
Accordingly, the present invention relates to a process for the production of 1,1-dichloro-1-fluoroetnane by reaction of hydrogen fluoride with vinylidene chloride, in which the reaction is carried out in a liquid medium at a temperature above 70.degree. C. and in the absence of a catalyst.
The hydrogen fluoride necessarily has to be used in the present process in anhydrous form and in a purity of greater than 95% and preferably greater than 99% by volume. It can be introduced into the reactor in gaseous or liquid form.
The vinylidene chloride used must fulfil the same specifications as those described above for hydrogen fluoride, i.e. it has to be anhydrous and pure.
The amounts of hydrogen fluoride and vinylidene chloride, respectively, which are introduced into the reactor, are without any great importance by themselves. In contrast, it is absolutely necessary that the molar ratio in which these two reactants are introduced into the reactor is between 1.5 to 3 mol of HF per 1 mol of vinylidene chloride, if the advantageous results provided by the process of the invention are to be observed.
The reaction mixture in the inside of the hydrofluorination reactor must be maintained in the liquid state for a favourable course of the process of the invention. This can be done by using any known method. A practical method which has given good results consists in operating in a reactor which is maintained under pressure.
The reaction temperature is in general between 75.degree. C. and 130.degree. C. and preferably between 80.degree. C. and 125.degree. C. Under these conditions, the pressure in the reactor is in general between 2 and 30 bar and preferably between 5 and 25 bar.
The selectivity of 1,1-dichloro-1-fluoroethane obtained in the process of the invention is very high and reaches, under operating conditions of 100.degree. C. and for an initial VC.sub.2 /HF molar ratio of 1/2, as much as
REFERENCES:
patent: 4329323 (1982-05-01), Shiozaki et al.
patent: 4948479 (1990-08-01), Brooks et al.
patent: 4968850 (1990-11-01), Franklin et al.
Journal of Am. Chem. Soc. 1943, pp. 1271-1272; A. L. Henne et al.: "The Addition Of . . . ".
Franklin James
Janssens Francine
Sigel Alan
Solvay ( Societe Anonyme)
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