U.S. patent application number 11/039599 was filed with the patent office on 2005-08-04 for method of manufacture of a hydrofluoroalkane.
This patent application is currently assigned to SOLVAY S.A.. Invention is credited to Janssens, Francine, Mathieu, Veronique.
Application Number | 20050171391 11/039599 |
Document ID | / |
Family ID | 34639816 |
Filed Date | 2005-08-04 |
United States Patent
Application |
20050171391 |
Kind Code |
A1 |
Janssens, Francine ; et
al. |
August 4, 2005 |
Method of manufacture of a hydrofluoroalkane
Abstract
Method of manufacture of a hydrofluoroalkane comprising the use
of a Lewis base as stabilizer of the hydrofluoroalkane.
Inventors: |
Janssens, Francine;
(Vilvoorde, BE) ; Mathieu, Veronique; (Wavre,
BE) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ, LLP
P O BOX 2207
WILMINGTON
DE
19899
US
|
Assignee: |
SOLVAY S.A.
Brussels
BE
|
Family ID: |
34639816 |
Appl. No.: |
11/039599 |
Filed: |
January 19, 2005 |
Current U.S.
Class: |
570/118 |
Current CPC
Class: |
C07C 17/386 20130101;
C07C 17/42 20130101; C07C 19/08 20130101; C07C 19/08 20130101; C07C
17/42 20130101; C07C 17/386 20130101 |
Class at
Publication: |
570/118 |
International
Class: |
C07C 017/42 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 30, 2004 |
FR |
FR 04.00921 |
Claims
1. Method of manufacture of a hydrofluoroalkane comprising the use
of a Lewis base as stabilizer of the hydrofluoroalkane.
2. Method according to claim 1, in which the Lewis base contains at
least one heteroatom.
3. Method according to claim 2, in which the Lewis base is an
aliphatic alcohol selected from methanol, ethanol, n-propanol,
isopropanol, n-butanol, isobutanol, tert-butanol, the pentanols or
ethylene glycol.
4. Method according to claim 3, in which the Lewis base is
isopropanol.
5. Method according to claim 1, in which the Lewis base does not
form an azeotrope with the hydrofluoroalkane.
6. Method according to claim 1, in which from 1 to 10 000 mg of
Lewis base is used per kg of hydrofluoroalkane.
7. Method according to any one of claim 1, in which the
hydrofluoroalkane contains at least one Lewis acid.
8. Method according to claim 7, in which the content of Lewis acid
in the hydrofluoroalkane is from 0.1 to 500 mg/kg of
hydrofluoroalkane.
9. Method according to claim 1, in which the stabilized
hydrofluoroalkane is subjected to a temperature from 50 to
200.degree. C.
10. Method according to claim 1, in which the Lewis base is
employed during purification of the hydrofluoroalkane.
11. Method according to claim 1, comprising a stage of distillation
of a stabilized hydrofluoroalkane.
12. Method according to claim 1, in which the hydrofluoroalkane is
selected from the group consisting of 1,1-difluoroethane,
1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane,
pentafluoroethane, 1,1,1,3,3-pentafluoropropane,
1,1,1,3,3,3-hexafluoropropane, 1,1,1,2,3,3,3-heptafluoropropane,
1,1,1,3,3-pentafluorobutane and
1,1,1,2,3,4,4,5,5,5-decafluoropentane.
13. Method according to claim 12, in which the hydrofluoroalkane is
selected from the group consisting of 1,1,1,3,3-pentafluoropropane
and 1,1,1,3,3-pentafluorobutane.
14. Stabilized hydrofluoroalkane containing from 1 to 500 mg/kg of
a Lewis base.
15. Stabilized hydrofluoroalkane according to claim 14, wherein
said Lewis base contains isopropanol or ethylene glycol.
16. Stabilized hydrofluoroalkane according to claim 14, selected
from 1,1,1,3,3-pentafluoropropane and
1,1,1,3,3-pentafluorobutane.
17. Stabilized hydrofluoroalkane according claim 14, comprising at
least one Lewis acid.
18. Stabilized hydrofluoroalkane according to claim 17, in which
the content of Lewis acid in the hydrofluoroalkane is from 0.1 to
500 mg/kg of hydrofluoroalkane.
19. Method according to claim 1, in which the Lewis base is an
alcohol, amine or phosphorus-containing compound.
20. Method according to claim 6, in which the Lewis acid is an iron
compound.
21. Stabilized hydrofluoroalkane according to claim 17, in which
the Lewis acid is an iron compound.
Description
[0001] The present invention relates to a method of manufacture of
a hydrofluoroalkane and a stabilized hydrofluoroalkane.
[0002] Hydrofluoroalkanes can be used, for example, as a blowing
agent for polyurethane foams or as a constituent of solvent
compositions.
[0003] Patent application EP-A-0564036 generally envisages the
stabilization of hydrofluoroalkanes with, preferably, amylene and
describes stabilization during distillation of
1,1-dichloro-1-fluoroethan- e (HCFC-141b) against its
dehydrochlorination with this compound.
[0004] During manufacture of hydrofluoroalkanes, notably by
(hydro)fluorination of a chlorinated precursor, the formation of
olefinic impurities is often observed, which formation is
associated at least partially with dehydrofluorination of the
hydrofluoroalkane, for example during purification operations such
as distillation.
[0005] It was desirable to possess a means of reducing the
dehydrofluorination of hydrofluoroalkanes during their
manufacture.
[0006] Accordingly, the invention relates to a method of
manufacture of a hydrofluoroalkane comprising the use of a Lewis
base as stabilizer of the hydrofluoroalkane.
[0007] Generally, in the course of the method of manufacture of the
hydrofluoroalkane, Lewis base is added to the hydrofluoroalkane, so
as to form a stabilized hydrofluoroalkane. In the sense of the
invention, "method of manufacture" relates in particular to stages
of purification of a hydrofluoroalkane, said hydrofluoroalkane
resulting for example from a stage of synthesis by
hydrofluorination of a suitable precursor for example saturated or
unsaturated, chlorinated or chlorofluorinated precursors.
[0008] The Lewis base often contains at least one heteroatom and is
preferably selected from alcohols, amines, amides, nitriles and
phosphorus-containing compounds.
[0009] An aliphatic alcohol, in particular unsubstituted, selected
from methanol, ethanol, n-propanol, isopropanol, n-butanol,
isobutanol, tert-butanol and the pentanols is more particularly
preferred. N-propanol and/or isopropanol, in particular isopropanol
is quite particularly preferred.
[0010] In a particular embodiment, the alcohol is a polyol,
preferably a diol. Ethylene glycol is preferred as diol.
[0011] As amines that can be used as Lewis base, mention may be
made of the aliphatic amines or the aromatic amines. Among the
aliphatic amines, the primary amines, the secondary amines and the
tertiary amines are to be mentioned in particular. In general, the
alkanolamines, the alkylamines, such as for example ethanolamine,
n-butylamine, tert-butylamine, n-propylamine, isopropylamine,
benzylamine, hexamethylene diamine, diethylamine, triethylamine or
aromatic amines such as pyridine or aniline are used as amine.
[0012] Among the nitriles that can be used as Lewis base, mention
may be made of notably aliphatic nitriles, notably acetonitrile,
propionitrile, or adiponitrile and aromatic nitriles, notably
benzonitrile or tolunitrile. Among the nitriles, propionitrile and
adiponitrile are preferred.
[0013] Among the amides that can be used as Lewis base, mention may
be made of the linear amides such as N,N-dimethylacetamide and
N,N-dimethylformamide and cyclic amides such as
N-methylpyrrolidone. Mention may also be made of
hexamethylphosphoramide.
[0014] Among the phosphorus-containing compounds that can be used
as Lewis base, mention may be made of notably trialkylphosphine
oxides and trialkyl phosphates.
[0015] Among the trialkylphosphine oxides that can be used, mention
may be notably made of the compounds of formula (R1R2R3)PO, in
which R1, R2 and R3 represent identical or different C3-C10 alkyl
groups, preferably linear. The following are used in particular:
tri(n-butyl)phosphine oxide, tri(n-hexyl)phosphine oxide,
tri(n-octyl)phosphine oxide, n-octyldi(n-hexyl)-phosphine oxide and
n-hexyldi(n-octyl)phosphine oxide and mixtures thereof.
[0016] Among the trialkyl phosphates, mention may notably be made
of the compounds of formula (RO).sub.3PO, in which R represents a
C3-C10 alkyl group, preferably linear. Tributyl phosphate is used
in particular.
[0017] Preferably, the Lewis base does not form an azeotrope with
the hydrofluoroalkane. This makes it possible to improve the
overall economics of the method since the Lewis base can be
separated easily and reused without formation of undesirable
azeotropic fractions of hydrofluoroalkane containing substantial
amounts of Lewis base.
[0018] In the method according to the invention, generally from 1
to 10 000 mg, preferably from 50 to 1000 mg of Lewis base is used
per kg of hydrofluoroalkane.
[0019] In the method according to the invention, the
hydrofluoroalkane generally contains at least one Lewis acid, in
particular iron compounds, more particularly ferric chloride. In
this case the content of Lewis acid in the hydrofluoroalkane is
generally from 0.1 to 500 and more often from 1 to 100 mg/kg of
hydrofluoroalkane.
[0020] In the method according to the invention, the stabilized
hydrofluoroalkane is generally subjected to a temperature from 50
to 200.degree. C., for example during a purification treatment.
[0021] In the method according to the invention, the Lewis base is
preferably employed during purification of the hydrofluoroalkane,
in particular during a distillation stage.
[0022] Accordingly, a particular embodiment of the method according
to the invention comprises at least one stage of distillation of
the stabilized hydrofluoroalkane. Preferably the method according
to the invention comprises at least two stages of distillation of
the stabilized hydrofluoroalkane, one intended to remove "light"
impurities and the other intended to remove "heavy" impurities. In
this particular embodiment, the Lewis base is preferably added to
the hydrofluoroalkane before it is subjected to distillation. It
can also be added in a distillation column.
[0023] "Hydrofluoroalkane" is intended to denote an alkane
consisting of atoms of carbon, hydrogen and fluorine. The
hydrofluoroalkane is often selected from 1,1-difluoroethane,
1,1,1-trifluoroethane, 1,1,1,2-tetrafluoroethane,
pentafluoroethane, 1,1,1,3,3-pentafluoropropan- e,
1,1,1,3,3,3-hexafluoropropane, 1,1,1,2,3,3,3-heptafluoropropane,
1,1,1,3,3-pentafluorobutane and
1,1,1,2,3,4,4,5,5,5-decafluoropentane. Preferably, it is selected
from 1,1,1,3,3-pentafluoropropane and 1,1,1,3,3-pentafluorobutane.
1,1,1,3,3-pentafluorobutane is more particularly preferred.
[0024] The invention also relates to a stabilized hydrofluoroalkane
containing from 1 to 500 mg/kg of a Lewis base. It was found that
the stated content of Lewis base in the hydrofluoroalkane makes it
possible to minimize its potential dehydrofluorination, for example
during its use or its storage.
[0025] The examples given below are intended to illustrate the
invention though without limiting it.
EXAMPLE 1
Stabilization of 1,1,1,3,3-pentafluorobutane by isopropanol
[0026] 25 mg of FeCl.sub.3 and 125 mg of isopropanol were placed
with 25 g of 1,1,1,3,3-pentafluorobutane in a sealed penicillin
bottle. The 1,1,1,3,3-pentafluorobutane contained 153 mg olefins/kg
initially. The medium was placed in a stove regulated at 50.degree.
C. for 7 h. A sample of the liquid phase was then taken for
analysis by gas chromatography. An olefins content of 152 mg/kg was
measured, which corresponds to the amount present in the initial
sample. The same reaction medium was heated at 70.degree. C. for a
further 7 days. The olefins content measured in the liquid phase
was 141 mg/kg.
EXAMPLE 2
Stabilization of 1,1,1,3,3-pentafluorobutane by ethylene glycol
[0027] 25 mg of FeCl.sub.3 and 125 mg of ethylene glycol were
placed with 25 g of 1,1,1,3,3-pentafluorobutane in a sealed
penicillin bottle. The 1,1,1,3,3-pentafluorobutane contained 153 mg
olefins/kg initially. The medium was placed in a stove regulated at
70.degree. C. for 7 h. A sample of the liquid phase was then taken
for analysis by gas chromatography. An olefins content of 152 mg/kg
was measured, which corresponds to the amount present in the
initial sample.
EXAMPLE 3 (COMPARATIVE)
Test of Stability in the Presence of FeCl.sub.3 Only
[0028] 25 mg of FeCl.sub.3 was placed with 25 g of
1,1,1,3,3-pentafluorobu- tane in a sealed penicillin bottle. The
1,1,1,3,3-pentafluorobutane contained 153 mg olefins/kg initially.
The medium was placed in a stove regulated at 50.degree. C. for 7
h. A sample of the liquid phase was then taken for analysis by gas
chromatography. An olefins content of 250 mg/kg was measured, i.e.
an increase in the concentration of olefins of 98 mg/kg relative to
the amount present in the initial sample. The same reaction medium
was heated at 70.degree. C. for a further 7 days. The olefins
content measured in the liquid phase was 368 mg/kg.
EXAMPLE 4
Distillation of 1,1,1,3,3-pentafluorobutane with and without
isopropanol
[0029] Purification of 1,1,1,3,3-pentafluorobutane was carried out
by means of two distillation stages:
[0030] The 1,1,1,3,3-pentafluorobutane (without isopropanol)
feeding the first distillation contained between 10 and 20 mg/kg of
olefins. In the presence of ferric chlorides (at concentrations
between 20 and 300 mg/kg) at the base of the second distillation,
degradation of the 1,1,1,3,3-pentafluorobutane was observed. The
latter was characterized by re-formation of olefins, the
concentrations of which were from 40 to 60 mg/kg at discharge from
the second distillation.
[0031] 300 to 500 mg/kg of isopropanol was added to the
1,1,1,3,3-pentafluorobutane feeding the first distillation column.
No further degradation of the 1,1,1,3,3-pentafluorobutane was
observed in the second distillation and the contents of olefin at
discharge from this stage were between 10 and 20 mg/kg.
* * * * *