Process for producing 1,1,1,3,3-pentafluoropropane

Details Process for producing 1,1,1,3,3-pentafluoropropane Process for producing 1,1,1,3,3-pentafluoropropane

1998-06-25

2000-01-25

Peselev, Elli

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

Organic compounds

Halogen containing

570167, 570168, 570169, C07C 1708

Patent

active

060180846

DESCRIPTION:

BRIEF SUMMARY
INDUSTRIAL FIELDS WHERE THE INVENTION CAN BE UTILIZED

This invention relates to a method to produce 1,1,1,3,3-pentafluoropropane, which does not destroy the ozone layer and is important for industrial fields as HFC blowing agents, refregerants and propellants.


PRIOR ART

Because of these advantages, a method to produce 1,1,1,3,3-pentafluoropropane is urgently needed to be established.
The known methods of producing 1,1,1,3,3-pentafluoropropane are as follows. Carbon tetrachloride and vinylidene chloride are prepared and an addition reaction is triggered. The reaction product, 1,1,1,3,3,3-hexachloropropane, is fluorinated to produce 1,1,1,3,3-pentafluoro-3-chloropropane which is reduced with hydrogen to produce 1,1,1,3,3-pentafluoropropane (WO 95/04022).
Either 1,1,1,3,3-pentafluoro-2,3-dichloropropane or 1,1,1,3,3-pentafluoro-2,2,3-trichloropropane is reduced with hydrogen to produce 1,1,1,3,3-pentafluoropropane (EP 061174).
These well-known methods, however, present technical and cost problems because of the prolonged chemical processes including the process in which the chloride is fluorinated to produce a precursor, and the process in which the obtained compound is reduced with hydrogen.


OBJECT OF THE INVENTION

The object of this invention is to provide a new cost-efficient method to produce 1,1,1,3,3-pentafluoropropane that gives high yield and selectivity without the disadvantages that are common with conventional production techniques.


CONSTRUCTION OF THE INVENTION

In order to solve these problems, a production method for 1,1,1,3,3-pentafluoropropane was thoroughly investigated. As a result, the inventors found that when pentachloropropane is used as a starting material and this is reacted with hydrogen fluoride in the vapor phase, an important point is that an equilibrium exists between the reaction intermediates, 1,1,1-trifluoro-3-chloro-2-propene and 1,1,1,3-tetrafluoro-2-propene, and that when 1,1,1,3,3-pentachloropropane is fluorinated in the vapor phase, 1,1,1-trifluoro-3-chloro-2-propene is obtained and the by-product, hydrogen chloride, is removed and 1,1,1-trifluoro-3-chloro-2-propene is further fluorinated to produce 1,1,1,3,3-pentafluoropropane effectively. As a result of this experiment,1,1,1,3,3-pentafluoropropane is produce with high yield from 1,1,1,3,3-pentachloropropane simply through the process of fluorination. This gives a cost-effective method to produce 1,1,1,3,3-pentafluoropropane to complete this invention.
This invention provides a manufacturing method for 1,1,1,3,3-pentafluoropropane comprising the following two processes: a first process to obtain a mixture, which contains mainly 1,1,1-trifluoro-3-chloro-2-propene, by inducing the reaction between 1,1,1,3,3-pentachloropropane and hydrogen fluoride in gaseous (vapor) phase, and a second process to remove the by-product, hydrogen chloride, from the mixture obtained in the first process, containing mainly 1,1,1-trifluoro-3-chloro-2-propene, and to obtain 1,1,1,3,3-pentafluoropropane by inducing a reaction between the remaining mixture and hydrogen fluoride in gaseous (vapor) phase. According to the claimed manufacturing method, the chemical reaction is triggered in the following two stages. ##STR1##
In the first stage (first process) in which 1,1,1,3,3-pentachloropropane is fluorinated with hydrogen fluoride in the vapor phase, there exists an equilibrium between 1,1,1-trifluoro-3-chloro-2-propene and 1,1,1,3-tetrafluoro-2-propene. Because the by-product of HCl promotes a strong tendency towards 1,1,1-trifluoro-3-chloro-2-propene, the main product is 1,1,1-trifluoro-3-chloro-2-propene even if excessive amounts of hydrogen fluoride are used. Although the intermediate, 1,1,1,3-tetrafluoropropene, and the target substance, 1,1,1,3,3-pentafluoropropane, can be obtained through these reactions, their amount is slight.
However, in this invention, after removing the by-product of HCl, the reaction product which mainly contains 1,1,1-trifluoro-3-chloro-2-propene is fluorinated with hydrogen fluoride in the vapor phase in the

REFERENCES:
patent: 5710352 (1998-01-01), Tung

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