PROCESS FOR THE PREPARATION OF 1,1,1,2,3,3,3-HEPTAFLUOROPROPANE (R 227)

PROCEDE D'OBTENTION DE 1,1,1,2,3,3,3-HEPTAFLUOROPROPANE (R227)

English Abstract

The invention relates to a process for the preparation of
1,1,1,2,3,3,3-heptafluoropropane, which comprises react-
ing 2-chloroheptafluoropropane with hydrogen in a molar
ratio of from 1:1 to 1:10 in the gas phase on a pal-
ladium-, platinum-, ruthenium-, rhodium-, nickel- or
copper-containing supported catalyst at temperatures of
from 100 to 400°C and pressures of from 1 to 50 bar.

Claims

3

CLAIMS:

1. A process for the preparation of 1,1,1,2,3,3,3-
heptafluoropropane, which comprise reacting 2-
chloroheptafluoropropane with hydrogen in a molar ratio of
from 1:1 to 1:10 in the gas phase on a palladium-,
platinum-, ruthenium-, rhodium- or copper-containing
supported catalyst at temperatures of from 100 to 400°C and
pressures of from 1 to 50 bar.

2. The process as claimed in claim 1, wherein the Pd,
Pt, Ru, Rh or Cu content of the supported catalyst is from
0.2 to 5% by weight.

3. The process as claimed in claim 1 or 2, wherein a
palladium-containing supported catalyst is employed.

4. The process as claimed in any one of claims 1 to
3, wherein from 1 to 3 mol of hydrogen are employed per mole
of 2-chloroheptafluoropropane.

5. The process as claimed in any one of claims 1 to
4, wherein the pressure is from 1 to 5 bar.

6. The process as claimed in any one of claims 1 to
5, wherein the temperature is from 100 to 300°C.

Description

HOECHST ARTIENGESELLSCHAFT HOE 91/F 344 Dr.~
Description
Process for the preparation of 1,1,1,2,3,3,3-heptafluoro-
propane (R 227)
The invention relates to a process for the preparation of
1,1,1,2,3,3,3-heptafluoropropane (R 227) by hydrodechlor-
ination of 2-chloroheptafluoropropane on a catalyst.
R 227 can be employed as a propellant gas and in air-
conditioning equipment.
The preparation of R 227 from hexafluoropropene and
hydrogen fluoride with the aid of an activated charcoal
catalyst has already been disclosed (British Patent
902,590). However, the product contains unsaturated,
toxic compounds, for example unreacted hexafluoropropene.
The present invention relates to a process for the
preparation of 1,1,1,2,3,3,3-heptafluoropropane, which
comprises reacting 2-chloroheptafluoropropane with
hydrogen in a molar ratio of from lsl to 1:10 in the gas
phase on a palladium-, platinum-, ruthenium-, rhodium-,
nickel- or copper-containing supported catalyst at
temperatures of from 100 to 400°C and pressures of from
1 to 50 bar.
Examples of suitable support materials are activated
charcoal, lithium-aluminum-spinal and aluminum oxide;
activated charcoal is preferred.
The Pd, Pt, Ru, Rh, Ni or Cu content of the supported
catalyst is generally from 0.2 to 5 % by weight, based on
the total weight of the catalyst. Palladium is preferred.
The reaction temperature is preferably from 200 to 300°C;
the preferred pressure range is from 1 to 5 bar.
From 1 to 10 mol of hydrogen, preferably from 1 to 3 mol
of hydrogen, axe employed per mole of 2-chlorohepta-
fluoropropane.

~~18~~~.3
- 2 -
Since the process according to the invention is a hydro
dechlorination under hydrogenation conditions, no un
saturated compounds, in particular no toxic compounds,
are formed, in contrast to the known process of British
Patent 902,530.
The preparation of the 2-chloroheptafluoropropane employ-
ed as starting material is described in Chemical
Abstracts (C91-081033).
The gas mixture produced is washed with water, deacidi
fied and condensed. GC analysis shows the composition of
the crude gas obtained in this way.
Example
A vertical, electrically heated, tubular steel reactor
(length - 100 cm, diameter - 2 cm) was charged with
200 ml of activated charcoal doped with 0.7 % by weight
of palladium.
The catalyst was conditioned for 6 hours at 250°C while
5 I of hydrogen were passed through the catalyst per
hour. 0.4 mol/h of CF3-CC1F-CF3 and 1 mol/h of hydrogen
were then metered in at 250°C at atmospheric pressure.
The reaction gases leaving the reactor passed through a
water scrubber with subsequent drying and condensation at
-15°C.
Conversion: 89 %
Selectivity: 85 %