Process for the manufacture of halogenated propanes containing e

Details Process for the manufacture of halogenated propanes containing e Process for the manufacture of halogenated propanes containing e

1998-10-06

2000-05-23

Siegel, Alan

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

Organic compounds

Halogen containing

570166, 570167, 570168, C07C 1708

Patent

active

060667699

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to a process for the manufacture of halogenated propanes containing at least five fluorine substituents, and more particularly to the manufacture of halogenated propanes containing at least five end-carbon fluorine substituents (e.g., CF.sub.3 CH.sub.2 CF.sub.3) by the reaction of selected saturated compounds (e.g., CCl.sub.3 CH.sub.2 CCl.sub.3) and/or unsaturated compounds (e.g., CCl.sub.2 .dbd.CHCCl.sub.3) with hydrogen fluoride.


BACKGROUND

Compounds such as 1,1,1,3,3,3-hexafluoropropane (i.e., HFC-236fa) have found uses as refrigerants, fire extinguishants, heat transfer media, gaseous dielectrics, sterilant carries, polymerization media, particulate removal fluids, carrier fluids, buffing abrasive agents, displacement drying agents and power cycle working fluids. More particularly, HFC-236fa itself is a highly effective and environmentally acceptable fire extinguishant and refrigerant.
Canadian Patent No. 2,073,533 discloses a liquid phase process for the manufacture of HFC-236fa by contacting HCC-230fa with HF in the presence of a liquid phase catalyst (e.g., tin and antimony compounds). All of the 1,1,1,3,3,3-hexachloropropane is converted to 1-chloro-1,1,3,3,3-pentafluoropropane (i.e., HCFC-235fa) and HFC-236fa with a selectivity of greater than 45 mole % with respect to HFC-236fa. The separation of pure HFC-236fa is complicated by the presence of HCFC-235fa. Moreover, vapor processes are often preferred because operational advantages (e.g., HF corrosivity problems ware typically exacerbated in the liquid phase).
U.S. Pat. No. 5,414,165 discloses a vapor phase process for the manufacture of HFC-236fa by contacting HCC-230fa (and sufficient haloprecursors of HFC-236fa) with HF in the presence of a trivalent chromium catalyst.
CCl.sub.3 CH.sub.2 CCl.sub.3 (HCC-230fa) is a high boiling liquid (b.p. 206.degree. C. at 101.3 kPa). Efficient use of a catalytic vapor phase reactor requires that HCC-230fa be fed to the reactor as a vapor. Feeding liquid directly to a catalyst bed is well known in the art to cause deactivation of the catalyst. Evaporation of HCC-230fa in a vaporizer of standard design can cause substantial degradation to HCl, CCl.sub.3 CH.dbd.CCl.sub.2, and in particular, undesirable higher boiling materials such as chlorinated six-carbon compounds and tars. Furthermore, the fluorine-chlorine exchange reaction is typically highly exothermic. Replacing all six chlorines of HCC-230fa with fluorine to produce HFC-236fa in the catalytic reactor can cause heat management problems.


SUMMARY OF THE INVENTION

A process is provided in accordance with this invention for producing a compound of the formula CF.sub.3 CHXCF.sub.3-z Y.sub.z where X and Y are independently selected from the group consisting of H and Cl, and z is 0 or 1. The process comprises (1) contacting starting material selected from the group consisting of a compound of the formula CCl.sub.3 CHXCCl.sub.3-z Y.sub.z, a compound of the formula CCl.sub.2 .dbd.CXCCl.sub.3-z Y.sub.z, a compound of the formula CCl.sub.2 .dbd.CXCCl.sub.3-z Y.sub.z and mixtures thereof, with hydrogen fluoride at a temperature of less than 200.degree. C. to produce a fluorination product of said starting material which includes at least 90 mole percent of compounds selected from the group consisting of saturated compounds having the formula C.sub.3 HXY.sub.z Cl.sub.6-z-x F.sub.x and olefinic compounds of the formula C.sub.3 XY.sub.z Cl.sub.5-z-y F.sub.y, wherein x is an integer from 1 to 6-z and y is an integer from 1 to 5-z, said fluorination product including no more than about 40 mole percent CF.sub.3 CHXCF.sub.3-z Y.sub.z ; (2) contacting compounds selected from the group consisting of said saturated compounds and said olefinic compounds produced in (1) with hydrogen fluoride in the vapor phase at a temperature of from 200.degree. C. to about 400.degree. C. in the presence of a fluorination catalyst; and (3) reacting a sufficient amount of said saturated compounds, wherein x is an integer from 1 to 5-z and s

REFERENCES:
patent: 3381044 (1968-04-01), Wiedemann et al.
patent: 5414165 (1995-05-01), Nappa et al.
patent: 5616819 (1997-04-01), Boyce et al.

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