Method of producing 1,1,2,2,3-pentafluoropropane

Details Method of producing 1,1,2,2,3-pentafluoropropane Method of producing 1,1,2,2,3-pentafluoropropane

1995-06-27

1997-05-13

Evans, Joseph E.

Organic compounds -- part of the class 532-570 series

Organic compounds

Halogen containing

570166, C07C 1720, C07C 1908

Patent

active

056294611

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/JP/01888 Dec. 24, 1993.


INDUSTRIAL FIELDS WHERE THE INVENTION CAN BE UTILIZED

This invention relates to a method of producing 1,1,2,2,3-pentafluoropropane.


PRIOR ART

1,1,2,2,3-pentafluoropropane (indicated as R-245ca hereafter) is utilized for blowing or cleaning solvent or a heat medium as a substitute for CFC and HCFC. It is especially useful as a urethane blowing agent.
As a method of preparing R-245ca, a process using a chemical reaction by the following formula by Walter et al. is known (J.A.C.S., 77, 4899 (1955)). ##STR1##
However, this reaction is not suitable for industrial use due to low yield, complicated operation, treatment for KCl after the reaction, generated by use of KF, and high cost.
On the other hand, according to a method described in U.S. Pat. No. 2,980,740, R-245ca is synthesized by reacting 2,2,3,3-tetrafluoropropanol with SF.sub.4.
But this method is not suitable for industrial use either, because low yield around 65% is obtained, SF.sub.4 is intensely poisonous as strong as phosgene, and the operation is complicated.
As mentioned above, a reaction example for R-245ca suitable for industrial manufacturing is not found at present.


OBJECT OF THE INVENTION

An object of this invention is to provide a manufacturing method suitable for industrial use which enables to produce R-245ca at high selectivity, high yield, good operationability and low cost.


CONSTRUCTION OF THE INVENTION

As a result of repeated eager study by the inventors to aim at an industrial production method for R-245ca by fluorinationg 1-chloro-2,2,3,3tetrafluoropropane (indicated as R-244ca hereafter), they found that R-245ca can be high-selectively produced by reacting R-244ca with hydrogen fluoride in the presence of an appropriate catalyst, having completed this invention.
Catalysts used in the reaction of this invention are fluorinated catalysts, for example, there can be used metal fluorides and/or metal oxyfluorides produced by fluorinating metal oxid, with HF separated from solution of metal salt by use of alkali or the like.
In this case, hydrochloride and nitrate can be used as the metal salt. And, ammonia, carbamide, and metal hydroxide can be used as the alkali.
Besides, for a method of obtaining chromium oxide, a method of obtaining it by reducing CrO.sub.3 can be adopted, and for a method of obtaining the chromium oxyfluoride, a method of treating CrF.sub.3 (nH.sub.2 O) with oxygen etc. under heating can be adopted.
For the metals used, one kind of or a mixture of two or more kinds of metals selected from alminium, chromium, manganese, nickel and cobalt can be used.
Those metal fluorides can be supplied by themselves, as well as carried on suitable carriers. For the carriers, active carbon, fluorinated alminium and so on can be used.
A reaction temperature can be adequately chosen from the range of 250.degree. to 450.degree. C., but too lower temperature is not practical due to slow reaction. The reaction temperature is desirable to be from 300.degree. to 400.degree. C.
The excess ratio of HF to R-244ca can be selected adequately from the range of 1 to 100 according to the objective conversion rate, the rate of the product, the contact times and the reaction temperature. That is, HF to R-244ca may be from 1:1 to 100:1. However, although the reaction can be carried out even if the excess ratio of HF is over 100, the productivity decreases not to be practical.
The yield of the target product can be raised by refluorinating the raw material returned to a reactor after separating necessary components from the reaction product.
R-244ca used in this invention can be obtained by reacting CF.sub.2 HCF.sub.2 CH.sub.2 OH (2,2,3,3-tetrafluoropropane-1-ol) with thionyl chloride.


POSSIBILITY OF UTILIZING THE INVENTION IN INDUSTRY

The production method of this invention is suitable for the industrial use, because the economical HF is used, R-244ca can be continuously fluorinated by gaseous phase reaction, and the selectivity and yield of the product can be improved.


EMBODIM

REFERENCES:
patent: 3258500 (1966-06-01), Swamer et al.
patent: 4147733 (1979-04-01), Fiske et al.
patent: 5264639 (1993-11-01), Morikawa et al.

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