U.S. patent application number 11/007919 was filed with the patent office on 2006-06-15 for direct one-step synthesis of cf3-i.
This patent application is currently assigned to HONEYWELL INTERNATIONAL INC.. Invention is credited to Sudip Mukhopadhyay, Hsueh Sung Tung.
Application Number | 20060129006 11/007919 |
Document ID | / |
Family ID | 36224871 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060129006 |
Kind Code |
A1 |
Mukhopadhyay; Sudip ; et
al. |
June 15, 2006 |
DIRECT ONE-STEP SYNTHESIS OF CF3-I
Abstract
The present invention provides a process for the preparation of
trifluoromethyl iodide. The process includes the step of:
contacting in a reactor a compound represented by the formula:
CF.sub.3--W and a compound represented by the formula: Z-I wherein
W is selected from CF.sub.3, hydrogen and bromine; Z is selected
from hydrogen, iodine and chlorine. The step of contacting is
carried out, optionally in the presence of a catalyst and further
optionally in the presence of air, at a temperature, pressure and
for a length of time sufficient to produce the trifluoromethyl
iodide.
Inventors: |
Mukhopadhyay; Sudip;
(Buffalo, NY) ; Tung; Hsueh Sung; (Getzville,
NY) |
Correspondence
Address: |
Colleen D. Szuch, Esq.;HONEYWELL INTERNATIONAL INC.
Patent Services Department
101 Columbia Road
Morristown
NJ
07962
US
|
Assignee: |
HONEYWELL INTERNATIONAL
INC.
|
Family ID: |
36224871 |
Appl. No.: |
11/007919 |
Filed: |
December 9, 2004 |
Current U.S.
Class: |
570/174 |
Current CPC
Class: |
C07C 17/204 20130101;
C07C 17/093 20130101; C07C 17/158 20130101; C07C 17/093 20130101;
C07C 19/16 20130101; C07C 19/16 20130101; C07C 19/16 20130101; C07C
17/204 20130101; C07C 17/158 20130101 |
Class at
Publication: |
570/174 |
International
Class: |
C07C 19/07 20060101
C07C019/07 |
Claims
1. A process for the preparation of trifluoromethyl iodide,
comprising the step of: contacting in a reactor a compound
represented by the formula: CF.sub.3--W and a compound represented
by the formula: Z-I wherein W is selected from the group consisting
of CF.sub.3, hydrogen and bromine; Z is selected from the group
consisting of hydrogen, and chlorine; and wherein said step of
contacting is carried out, optionally in the presence of a catalyst
and further optionally in the presence of air, at a temperature,
pressure and for a length of time sufficient to produce said
trifluoromethyl iodide.
2-3. (canceled)
4. The process of claim 1, wherein W is bromine and Z is
hydrogen.
5. The process of claim 1, wherein W is bromine and Z is
chlorine.
6. The process of claim 1, wherein W is hydrogen and Z is
hydrogen.
7. The process of claim 1, wherein W is hydrogen and Z is
chlorine.
8. A process for the preparation of trifluoromethyl iodide,
comprising the step of: contacting in a reactor a compound
represented by the formula: CF.sub.3--W and a compound represented
by the formula: Z-I wherein W is CF.sub.3 and Z is iodine; and
wherein said step of contacting is carried out, optionally in the
presence of a catalyst and further optionally in the presence of
air, at a temperature, pressure and for a length of time sufficient
to produce said trifluoromethyl iodide.
9. The process of claim 1, wherein W is CF.sub.3 and Z is
hydrogen.
10. The process of claim 1, wherein said step of contacting is
carried out at a temperature from about 20.degree. C. to about
650.degree. C.
11. The process of claim 1, wherein said step of contacting is
carried out at a pressure from about 1 atm to about 100 atm.
12. The process of claim 1, wherein said step of contacting is
carried out for a length of time from about 0.01 sec to about 300
hours.
13-22. (canceled)
23. The process of claim 1, wherein the process is a batch
process.
24. The process of claim 1, wherein the process is a continuous
process.
25. The process of claim 1, wherein the reactor further comprises a
diluent selected from the group consisting of a gas, a solvent and
a mixture thereof.
26. The process of claim 25, wherein said gas is selected from the
group consisting of: nitrogen, helium, argon and a mixture
thereof.
27. The process of claim 25, wherein said solvent is a liquid
fluorocarbon.
28. The process of claim 1, further comprising the step of: passing
the trifluoromethyl iodide through a scrubber containing an aqueous
alkali solution.
29. The process of claim 1, further comprising the step of: passing
the trifluoromethyl iodide through a scrubber containing a drying
agent.
30. The process of claim 1, further comprising the step of: cooling
at a temperature below the boiling temperature of the
trifluoromethyl iodide to condense.
31. The process of claim 1, further comprising the step of:
isolating the trifluoromethyl iodide from the reaction mixture in
substantially pure form.
32. The process of claim 1, wherein at least 10 wt % of the
reactants are converted to trifluoromethyl iodide.
33. The process of claim 1, wherein at least 80 wt % of the
reactants are converted to trifluoromethyl iodide.
34. The process of claim 1, wherein at least 95 wt % of the
reactants are converted to trifluoromethyl iodide.
35. A process for the preparation of trifluoromethyl iodide,
comprising the step of: contacting in a reactor a compound
represented by the formula: CF.sub.3--W and a compound represented
by the formula: Z-I wherein W is hydrogen; Z is iodine; and wherein
said step of contacting is carried out in the absence of a catalyst
and absence of air, at a temperature, pressure and for a length of
time sufficient to produce said trifluoromethyl iodide.
36. A process for the preparation of trifluoromethyl iodide,
comprising the step of: contacting in a reactor a compound
represented by the formula: CF.sub.3--W and a compound represented
by the formula: Z-I wherein W is hydrogen; Z is iodine; and wherein
said step of contacting is carried out in the presence of one or
more catalysts selected from the group consisting of iodide,
nitrate, oxide, bromide, carbonate, chloride, acetate,
acetylacetonate salts of Cu (II), Hg (II), Pt (II), Pd (II), Co
(III), Mn (III), Rh (III), Ni (II), V (IV), TI (III), and Ge (III),
and at a temperature, pressure and for a length of time sufficient
to produce said trifluoromethyl iodide.
37. A process for the preparation of trifluoromethyl Iodide,
comprising the step of: contacting in a reactor a compound
represented by the formula: CF.sub.3--W and a compound represented
by the formula: Z-I wherein W is bromine; Z is iodine; and wherein
said step of contacting is carried out in the absence of a catalyst
and in the presence or absence of air, at a temperature, pressure
and for a length of time sufficient to produce said trifluoromethyl
iodide.
38. A process for the preparation of trifluoromethyl iodide,
comprising the step of: contacting in a reactor a compound
represented by the formula: CF.sub.3--W and a compound represented
by the formula: Z-I wherein W is bromine; Z is iodine; and wherein
said step of contacting is carried out in the presence of one or
more catalysts selected from the group consisting of iodide,
nitrate, oxide, bromide, carbonate, chloride, acetate,
acetylacetonate salts of Cu (II), Hg (II), Pt (II), Pd (II), Co
(III), Mn (III), Rh (II), Ni (II), V (IV), TI (III), and Ge (III),
and at a temperature, pressure and for a length of time sufficient
to produce said trifluoromethyl iodide.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to a process for the
preparation of trifluoromethyl iodide. More particularly, the
present invention relates to a process for the preparation of
trifluoromethyl iodide from CF.sub.3--W and Z-I wherein W is
CF.sub.3, hydrogen or bromine and Z is hydrogen, iodine or
chlorine.
[0003] 2. Description of the Prior Art
[0004] An article by Dhooge et al. in Proceedings of the 4th
Conference on Aerospace Materials, Processes, and Environmental
Technology, page 259-268 (2000), describes vapor phase production
process for, the preparation of CF.sub.3I by the reaction between
CHF.sub.3 with I.sub.2 in the presence of a catalyst including
alkali metal salts supported on an activated carbon carrier. The
reaction mechanism appears to proceeds via CF.sub.2 carbenes formed
on the catalyst surface as intermediates, followed by carbene
disproportionation to CF.sub.3 radicals, followed by reaction with
I.sub.2 to give CF.sub.3I (see Nagasaki, Noritaka et al., Catalysis
Today (2004), 88(3-4), 121-126).
[0005] JP 52068110 (1977) describes the preparation of CF.sub.3I by
vapor-phase reaction of Freon 23 with iodine in the presence of
alkali or alkaline earth metal salts.
[0006] DE 1805457 (1970) describes the preparation of CF.sub.3I and
C.sub.2F.sub.5I from the reaction of corresponding bromides and KI
without solvent.
[0007] Naumann et al., J. Fluorine Chem., 67(1), 91-3(1994)
describes the preparation of CF.sub.3I from CF.sub.3Br by a
multi-step reaction, which employs elemental Zn.
[0008] European Patent Application EP 266,281 A1 (1988) describes
the preparation of CF.sub.3I from CF.sub.3Br by contact with a
metal or an alkali metal dithionite and SO.sub.2 followed by
treatment with iodine in a carboxylic or sulfonic acid.
[0009] Lee, K.-H. et al., Hwahak Konghak, 39(2), 144-149 (2001)
describes the preparation of CF.sub.3I by iodination of
CF.sub.3CO.sub.2H with iodine using a flow reactor over various
salt-impregnated catalysts.
[0010] Su, D. et al., J. Chem. Soc., Chem. Commun. (11),
807-8(1992) describes the preparation of CF.sub.3I by treatment of
XCF2CO2Me (X=Cl or Br) with iodine in the presence of potassium
fluoride and copper (I) iodide.
[0011] Chiriac, M. et al., Inst. Tehnol. Izot. Mol., 33(11),
1018-20 (1982) describes the preparation of CF.sub.3I from
Ag-trifluoroacetate.
[0012] However, in view of the high cost of the raw materials
required and the formation of solid by-products that are difficult
to dispose of because of their adverse impact on the environment,
none of these methods provide a practical and economical process
which could be adapted to large scale process for the preparation
of CF.sub.3I.
[0013] Furthermore, there is no report in the literature of any
catalytic vapor-phase process for making CF.sub.3I in high yield.
Therefore, a high yield, catalytic vapor-phase process, which
avoids the formation of solid by-products and the adverse impact of
such solid by-products on the environment would be welcome by the
Chemical Industry.
[0014] The above described problems can be avoided by the use of a
process for the preparation of trifluoromethyl iodide from
CF.sub.3--W and Z-I wherein W is CF.sub.3, hydrogen or bromine and
Z is hydrogen, iodine or chlorine according to the present
invention.
SUMMARY OF THE INVENTION
[0015] In broad concept, the present invention provides a process
for the preparation of trifluoromethyl iodide. The process includes
the step of:
[0016] contacting in a reactor a compound represented by the
formula: CF.sub.3--W
[0017] and a compound represented by the formula: Z-I
[0018] wherein W is selected from CF.sub.3, hydrogen and bromine; Z
is selected from hydrogen, iodine and chlorine. The step of
contacting is carried out, optionally in the presence of a catalyst
and further optionally in the presence of air, at a temperature,
pressure and for a length of time sufficient to produce the
trifluoromethyl iodide.
[0019] The present invention has the advantage of providing high
yields and high purity trifluoromethyl iodide while avoiding the
formation of solid by-products and their adverse impact on the
environment.
[0020] These and other benefits of the present process will become
more evident from the detailed description of the invention that
follows.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The present invention provides a process for the preparation
of trifluoromethyl iodide from CF.sub.3--W and Z-I wherein W is
CF.sub.3, hydrogen or bromine and Z is hydrogen, iodine or
chlorine.
[0022] CF.sub.3I is a non-toxic, non-flammable, low global warming
potential compound with almost zero ozone depletion potential (See,
for example, Dhooge et al., Proceedings of the 4th Conference on
Aerospace Materials, Processes, and Environmental Technology, page
259-268 (2000)).
[0023] In addition, the life cycle of the CF.sub.3I in the
atmosphere is only about two days. Therefore, the Chemical Industry
has a substantial incentive to produce this compound by a low-cost
and environmentally acceptable route for use as a refrigerant
either alone or in combination with other known or existing
refrigerants.
[0024] Accordingly, the present invention provides a catalytic
process, which uses low cost feedstocks, such as, CHF.sub.3 and
Iodine or Hydrogen Iodide as the starting materials to produce
CF.sub.3I with high selectivity.
[0025] As mentioned herein above, the processes described in the
prior art generally are limited to lab-scale demonstration.
Furthermore, the raw materials used in these methods are not
readily available or expensive. Therefore, a substantial incentive
exists for the development of alternative commercial processes for
the manufacture of CF.sub.3I.
[0026] Accordingly, the present invention provides herein a
commercially useful catalytic process to achieve these
objectives.
PREFERRED EMBODIMENTS
[0027] In a one preferred embodiment, W is hydrogen and Z is iodine
(1a and 1b), wherein the process proceeds at least in part
according to the following equation: ##STR1##
[0028] or at least in part according to the following equation:
##STR2##
[0029] In another preferred embodiment, W is bromine and Z is
iodine (2a), wherein the process proceeds according to the
following equation: ##STR3##
[0030] In still another preferred embodiment, W is bromine and Z is
hydrogen (2b), wherein the process proceeds according to the
following equation: ##STR4##
[0031] In yet another preferred embodiment, W is bromine and Z is
chlorine (2c), wherein the process proceeds according to the
following equation: ##STR5##
[0032] In still another preferred embodiment, W is hydrogen and Z
is hydrogen (3a or 3b), wherein the process proceeds at least in
part according to the following equation: ##STR6##
[0033] or according to the following equation: ##STR7##
[0034] In yet another embodiment, W is hydrogen and Z is chlorine
(4a), wherein the process proceeds, with or without O.sub.2, at
least in part according to the following equation: ##STR8##
[0035] In still another embodiment, W is CF.sub.3 and Z is iodine
(5a), wherein the process proceeds, with or without O.sub.2, at
least in part according to the following equation:
CF.sub.3--CF.sub.3+I.sub.2.fwdarw.2CF.sub.3--I (5a)
[0036] In still a further embodiment, W is CF.sub.3 and Z is
hydrogen (5b), wherein the process proceeds, with or without
O.sub.2, at least in part according to the following equation:
CF.sub.3--CF.sub.3+2HI+1/2O.sub.2.fwdarw.2CF.sub.3--I+H.sub.2O (5b)
Process Conditions:
[0037] In the practice of the process of the present invention, the
step of contacting is preferably carried out at a temperature from
about 20.degree. C. to about 650.degree. C., at a pressure from
about 1 atm to about 100 atm, and for a length of time from about
0.01 sec to about 300 hours.
[0038] The process can be either a batch process or it can be a
continuous process.
[0039] The reactor can further comprise a diluent, such as, a gas,
a solvent or a mixture thereof. When the diluent is a gas, the
diluent can be nitrogen, helium, argon or a mixture thereof. When
the diluent is a solvent, the diluent is a solvent, which is
preferably a liquid fluorocarbon.
[0040] The process can further include one or more of the following
steps:
[0041] (1) passing the trifluoromethyl iodide through a scrubber
containing an aqueous alkali solution;
[0042] (2) passing the trifluoromethyl iodide through a scrubber
containing a drying agent;
[0043] (3) cooling at a temperature below the boiling temperature
of the trifluoromethyl iodide to condense; and
[0044] (4) isolating the trifluoromethyl iodide from the reaction
mixture in substantially pure form.
[0045] In operation, preferably at least 10 wt % of the reactants
are converted to trifluoromethyl iodide. More preferably, at least
80 wt % of the reactants are converted to trifluoromethyl iodide,
and most preferably, at least 95 wt % of the reactants are
converted to trifluoromethyl iodide.
[0046] The following non-limiting examples are illustrative of the
various embodiments of the present invention. It is within the
ability of a person of ordinary skill in the art to select other
variable from among the many known in the art without departing
from the scope of the present invention. Accordingly, these
examples shall serve to further illustrate the present invention,
not to limit them.
[0047] Unless otherwise indicated, all parts and percentages are on
a weight basis.
EXAMPLE 1
One-Step Synthesis of CF.sub.3I from CHF.sub.3
[0048] CF.sub.3I is synthesized in a cost-effective way by reacting
CHF.sub.3 with I.sub.2 and O.sub.2 (or Air) in the presence of a
catalyst including one or more iodide, nitrate, oxide, bromide,
carbonate, chloride, acetate, acetylacetonate salts of Cu (II), Hg
(II), Pt (II), Pd (II), Co (III), Mn (III), Rh (III), Ni (II), V
(IV), TI (III), and Ge (III) at 50-600.degree. C. in a vapor or
liquid-phase process.
[0049] The catalyst salts can be used directly (100 wt %) or a
portion (2-60 wt %) on an active support such as activated carbon,
alumina, SiO.sub.2, or ZrO.sub.2.
[0050] A mixture of salts supported on an active carbon, alumina,
glass, SiO2, SBA-15 support can also be used to obtain higher
selectivity to CF.sub.3I formation.
[0051] Thus, 20 SCCM (Standard Cubic Centimeter Per Minute) of
CHF.sub.3 is passed through a 50 cc 2 wt % Cu-5 wt % Pd-3 wt % Pt/C
catalyst bed placed in a 1/2-inch Monel reactor in the presence of
20 SCCM of air or O.sub.2 and 20 SCCM of Iodine at 550.degree. C.
to yield 40-95 mol % of CF.sub.3I. The product mixture is analyzed
by GC and GCMS.
[0052] Stoichiometric amount of O.sub.2 is necessary for a
thermodynamically favorable pathway (Eq 1) as written below because
without the presence of O.sub.2 the reaction is not favorable (Eq
2): 2CHF.sub.3+I.sub.2+1/2O.sub.2.fwdarw.2CF.sub.3I+H.sub.2O,
.DELTA.G=-158 kJ/mol (Eq 1) CHF.sub.3+I.sub.2.fwdarw.CF.sub.3I+HI,
.DELTA.G=+73.06 kJ/mol (Eq 2)
[0053] The reaction of CHF.sub.3, 12 and O.sub.2 can also go in a
different pathway as written below:
3CHF.sub.3+I.sub.2+O.sub.2.fwdarw.2CF.sub.3I+CO.sub.2+3HF,
.DELTA.G=-397 kJ/mol (Eq 3)
[0054] Eq 1 and 3 are both possible on the same active catalyst
site, thus, the overall rate of CF.sub.3I production will be the
sum total of the rate of Eq 1 and Eq 3.
[0055] CHF.sub.3, which is a common byproduct from fluorocarbon
industries, can also be synthesized easily by vapor phase reaction
of HF with CHCl.sub.3 in the presence of a chromium oxide based
catalyst at 200-450.degree. C. Thus, the overall process is highly
cost effective.
EXAMPLE 2
Preparation of CF.sub.3I by Oxidative Iodination of CHF.sub.3
[0056] CF.sub.3I is synthesized in a cost-effective way by reacting
CHF.sub.3 with HI and O.sub.2 (or Air) in the presence of a
catalyst including one or more iodide, nitrate, oxide, bromide,
carbonate, chloride, acetate, acetylacetonate salts of Mn (III), V
(IV), Cr (III), Mo, Co (III), TI (III), and Ge (III) at
50-600.degree. C. in a vapor phase process. The catalyst salts can
be used directly (100 wt %) or a portion (2-60 wt %) on an active
support such as activated carbon, alumina, SiO.sub.2, and
ZrO.sub.2.
[0057] A mixture of salts can be used alone (100 wt %) or it can be
supported on an active support to obtain higher selectivity to
CF.sub.31 formation.
[0058] Thus, 20 SCCM of CHF.sub.3 and 20 SCCM of HI are passed
through a 50 cc V.sub.2O.sub.5 or Pd--Pt/C catalyst bed placed in a
1-inch Monel reactor in the presence of 20 SCCM of air or O.sub.2
and at 500.degree. C. to yield 67% of CF.sub.3I. The product
mixtures are analyzed by GC and GCMS.
[0059] Stoichiometric amount of O.sub.2 is necessary for a
thermodynamically favorable pathway (Eq 5) as written below because
without the presence of O.sub.2 the reaction is not favorable (Eq
4): CHF.sub.3+HI.fwdarw.CF.sub.3I+H.sub.2, .DELTA.G=+90.26 kJ/mol
(Eq 4) CHF.sub.3+HI+1/2O.sub.2.fwdarw.CF.sub.3I+H.sub.2O,
.DELTA.G=-107.1 kJ/mol (Eq 5)
[0060] The reaction of CHF.sub.3, HI and O.sub.2 can also proceed
in a more favorable pathway (Eq 6) as written below:
3CHF.sub.3+2HI+1.5O.sub.2.fwdarw.2CF.sub.3I+CO.sub.2+3HF+H.sub.2O,
.DELTA.G=-668.5 kJ/mol (Eq 6)
[0061] CHF.sub.3, which is a common by-product from fluorocarbon
industries, can also be synthesized easily by the vapor phase
reaction of HF with CHCl.sub.3 in the presence of a chromium oxide
based catalyst at 200-450.degree. C. Thus, the overall process is
highly cost effective.
EXAMPLE 3
Catalytic One-Step Synthesis of CF.sub.3I from CHF.sub.3
[0062] CF.sub.3I is synthesized in a cost-effective manner by
reacting CHF.sub.3 with Br.sub.2 and HI in the presence of any one
or a mixture of the following iodide, nitrate, oxide, bromide,
carbonate, chloride, acetate, acetylacetonate salts, and preferably
oxide salts, of Cu, Pt, Pd, Co, Mn, Rh, Ni, V, TI, Th, Ge, and Cr,
at 10-600.degree. C. in a vapor or liquid-phase process (Eq 1).
[0063] The catalyst salts can be used directly (100 wt %) or a
portion (2-60 wt %) on an active support such as activated carbon,
alumina, SiO.sub.2, and ZrO.sub.2.
[0064] A mixture of salts supported on an active support can also
be used to obtain higher selectivity to CF.sub.3I formation.
[0065] The reaction can be written as:
CHF.sub.3+Br.sub.2+HI.fwdarw.CF.sub.3I+2HBr, .DELTA.G=-19.3 kJ/mol
(Eq 7)
[0066] CHF.sub.3, which is a common byproduct from fluorocarbon
industries, can also be synthesize easily by the vapor phase
reaction of 3 moles of HF with one mole of CHCl.sub.3 in the
presence of a chromium oxide based catalyst at 200-450.degree. C.
Thus, the overall process is highly cost effective.
[0067] Thus, 20 SCCM of CHF.sub.3, 20 SCCM of Bromine and 30 SCCM
of Iodine or HI were passed through a 50 cc Pd/C bed placed in a
1/2-inch Monel reactor to yield 70 mol % of CF.sub.3I at
500.degree. C. The reactor pressure was kept at 50 psig. The
product mixtures exiting the reactor were analyzed by an on-line GC
and GCMS couple.
EXAMPLE 4
Catalytic One-Step Synthesis of CF.sub.3I from CHF.sub.3
[0068] CF.sub.3I can be synthesized in a cost-effective way by
reacting CHF.sub.3 with Br.sub.2 and HI in the presence of any one
or a mixture of the iodide, nitrate, oxide, bromide, carbonate,
chloride, acetate, acetylacetonate salts, and preferably oxide
salts, of Cu, Pt, Pd, Co, Mn, Rh, Ni, V, TI, Th, Ge, and Cr, at
10-600.degree. C. in a vapor or liquid-phase process (Eq 8). The
catalyst salts can be used directly (100 wt %) or a portion (2-60
wt %) on an active support such as activated carbon, alumina,
SiO.sub.2, and ZrO.sub.2. A mixture of salts supported on an active
support can also be used to obtain higher selectivity to
CF.sub.3I.
[0069] The reaction can be written as:
CHF.sub.3+Br.sub.2+HI.fwdarw.CF.sub.3I+2HBr, .DELTA.G=-19.3 kJ/mol
(Eq 8)
[0070] CHF.sub.3, which is a common byproduct from fluorocarbon
industries, can also be synthesize easily by the vapor phase
reaction of 3 moles of HF with one mole of CHCl.sub.3 in the
presence of a chromium oxide based catalyst at 200-450.degree. C.
Thus the overall process is highly cost effective.
EXAMPLE 5
Oxidative Iodination of CHF.sub.3 to CF.sub.3I
[0071] CF.sub.3I can be synthesized in a cost-effective way by
reacting CHF.sub.3 with HI and O.sub.2 (or Air) in the presence of
a catalyst including one or more iodide, nitrate, oxide, bromide,
carbonate, chloride, acetate, acetylacetonate salts of Mn(III),
V(IV), Cr(III), Mo, Co(III), TI(III), and Ge(III), at
50-600.degree. C. in a vapor phase process. The catalyst salts can
be used directly (100 wt %) or a portion (2-60 wt %) on an active
support such as activated carbon, alumina, SiO.sub.2, and
ZrO.sub.2. A mixture of salts can also be used alone (100 wt %) as
well as supported on an active support to obtain higher selectivity
to CF.sub.3I formation.
[0072] Stoichiometric amount of O.sub.2 is necessary for a
thermodynamically favorable pathway (Eq 10) as written below
because without the presence Of O.sub.2 the reaction is not
favorable (Eq 9): CHF.sub.3+HI.fwdarw.CF.sub.3I+H.sub.2,
.DELTA.G=+90.26 kJ/mol (Eq 9)
CHF.sub.3+HI+1/2O.sub.2.fwdarw.CF.sub.3I+H.sub.2O, .DELTA.G=-107.1
kJ/mol (Eq 10)
[0073] The reaction of CHF.sub.3, HI and O.sub.2 can also go in a
more favorable pathway (Eq 11) as written below:
3CHF.sub.3+2HI+1.5O.sub.2.fwdarw.2CF.sub.3I+CO.sub.2+3HF+H.sub.2O,
.DELTA.G=-668.5 kJ/mol (Eq 11)
[0074] CHF.sub.3, which a common byproduct from fluorocarbon
industries, can also be synthesize easily by the vapor phase
reaction of HF with CHCl.sub.3 in the presence of a chromium oxide
based catalyst at 200-450.degree. C. Thus the overall process is
highly cost effective.
[0075] The present invention has been described with particular
reference to the preferred embodiments. It should be understood
that variations and modifications thereof can be devised by those
skilled in the art without departing from the spirit and scope of
the present invention. Accordingly, the present invention embraces
all such alternatives, modifications and variations that fall
within the scope of the appended claims.
* * * * *