| JPS63253034 | PROCESS USING PHOSPHORUS COMPLEX |
| JP2023080371 | METHOD FOR PRODUCING ORGANIC FLUORINE COMPOUNDS |
| JP6306121 | Phosphine ligand for catalytic reaction |
HSUEHSUNG TUNG (US)
MUKHOPADHAY SUDIP (US)
HSUEHSUNG TUNG (US)
BRANDT, EMELÉUS, HASZELDINE: "Organometallic and Organometalloidal fluorine compounds. Part III. Trifluoromethyl derivatives of sulfur" J. CHEM. SOC., 1952, pages 2198-2252, XP009066178
| 1. | A process for the production of CF3I, the process comprising reacting a source of iodine selected from the group consisting of hydrogen iodide, iodine and iodine monochloride with a reactant selected from the group consisting of those of the formula: CF3R where R is selected from the group consisting SH, SSCF3, Sphenyl, and SSi(CH3)3 in the presence of a metal salt catalyst. |
| 2. | A process according to claim 1 wherein the reaction is conducted as a vapor phase reaction. |
| 3. | A process according to claim 1 wherein the reaction is conducted as a liquid phase reaction. |
| 4. | A process according to claim 1 wherein the reaction is conducted at a temperature of from about 50° to about 600° C. |
| 5. | A process according to claim 1 wherein the metal salt catalyst is selected from salts of Cu, Hg, Pt, Pd, Co, Mn, Rh, Ni, V, Tl, Ba, Cs, ca, K and Ge and mixtures thereof. |
| 6. | A process according to claim 5 wherein the metal salt is on a support material. |
| 7. | A process according to claim 6 wherein the support material is selected from the group consisting of a basic oxide, BaCO3, CSNO3, Ba(NO3) 2, activated carbon, basic alumina, and Zrθ2. |
| 8. | The process of claim 7 wherein the catalyst isPd/activated carbon. |
| 9. | The process according to claim 8 wherein the reaction is conducted in the presence of a source of oxygen. |
| 10. | A process according to claim 1 wherein the reaction is conducted in the presence of a source of oxygen and iodine is employed as a reactant. |
Field of the Invention
[0001] This invention relates to a direct one-step method for the synthesis of trifluoromethyl iodide, CF3I, by reaction of iodine with various perfluoromethyl compounds.
Background to the Invention
[0002] Mechanical refrigeration systems, and related heat transfer devices such as heat pumps and air conditioners, using refrigerant liquids are well known in the art for industrial, commercial and domestic uses. Chlorofluorocarbons (CFCs) were developed in the 1930s as refrigerants for such systems. However, since the 1980s the effect of CFCs on the stratospheric ozone layer has become the focus of much attention. In 1987 a number of governments signed the Montreal Protocol to protect the global environment setting forth a timetable for phasing out the CFC products. CFCs were replaced with more environmentally acceptable materials that contain hydrogen or hydrochlorofluorocarbons (HCFCs). Subsequent amendments to the Montreal protocol accelerated the phase-out of these CFCs and also scheduled the phase-out of HCFCs. Additionally, it is expected that the European Union member states will shortly recommend banning the use of materials that have a Global Warming Potential (GWP) of 50 or more. Thus, there is a requirement for a non-flammable, non-toxic alternative to replace these CFCs and HCFCs. In response to such demand industry has developed a number of hydrofluorocarbons (HFCs), which
have a zero or near zero ozone depletion potential.
[0003] CF3I is a non-toxic, non-flammable, low global warming potential molecule with almost zero ozone depletion potential. Also the life cycle of the CF3I in the atmosphere is only a couple of days. Thus, there is incentive to synthesize this molecule in a low-cost route for using it as a refrigerant with or without the presence of a known or existing refrigerants. The CF3I is also useful a foam blowing agent and can be used to replace more environmentally damaging foam blowing agent previously employed in the production of polymeric foams.
[0004] Prior to this invention the methods known for the production of CF3I have involved or required one or more of expensive and/or not readily available reactants, multi-steps processes, processes with low selectivity for CF3I, processes with low yields, and processes limited to lab scale production quantities. The following are exemplary of such prior art processes.
[0005] In the article "Study on a novel catalytic reaction and its mechanism for CF3I synthesis", Nagasaki, Noritaka et al., Catalysis
Today (2004), 88(3-4), 121-126, a vapor phase production process has synthesized CF3I by the reaction between CHF3 with I2 in the presence of a catalyst including alkali metal salts, which are supported on an activated carbon carrier. A consideration of the reaction mechanism suggests that the reaction proceeds via CF2 carbenes formed on the catalyst surface as intermediates, followed by carbene disproportionation to CF3 radicals, followed by reaction with b to give CF3I.
[0006] It has been claimed in JP 52068110 that CF 3 I is prepared in high yield by vapor-phase reaction of Freon 23 with iodine in the
presence of alkali or alkaline earth metal salts. Thus, 200 mL/min Freon 23 is introduced to iodine, the resulting gaseous mixture of Freon 23 and iodine (iodine/Freon = 2.2 molar) is passed over 800 ml_ active carbon containing 7.5% KF for 10 h at 500 0 C to give 57.8% CF 3 I.
[0007] In DE 1805457 CF 3 I and C 2 F 5 I have been prepared from the corresponding bromides and Kl without solvents. Thus, 0.3 mole CF 3 Br are passed through a layer of 3 mole Kl of 6-8 micron particle size at 500 0 C to give 15% CF 3 I, 0.3% C 2 F 6 , and 85% CF 3 Br, which is then recycled
[0008] CF 3 Br have also been used as a starting material to synthesize CF 3 I in a multi-step reaction protocol in "Preparation and properties of ZnBr(CF3) 2L - a convenient route for the preparation of CF 3 I", Naumann, Dieter; et al, Journal of Fluorine Chemistry (1994), 67(1), 91-3. ZnBr(CF 3 ) 2L (L = DMF, MeCN) is prepared by the reactions of CF 3 Br with elemental Zn in better than 60% yield. The reaction of ZnBr(CF3) 2 DMF with Iodine monochloride in DMF solution yields pure CF 3 I in better than 70% yield.
[0009] In a similar approach, disclosed in EP 266821 and US
Patent 4,794,200, CF 3 I is prepared from CF 3 Br by contact with a metal or an alkali metal dithionite and SO 2 in solution followed by filtration and treatment with iodine in a carboxylic or sulfonic acid. Thus, Zn, NaOH, and SO 2 in DMF in a Parr app. were pressurized with 3.7 bar CF3Br and the mixture, stirred 2 h whereupon the product was heated at 12O 0 C over 9 h with iodine in HOAc during which CF 3 I (32%) was generated and recovered.
[0010] A direct synthesis of CF 3 I by direct iodination of CF 3 CO 2 H
with iodine has been claimed using a flow reactor over various salt- impregnated catalysts, such as copper iodide on activated carbon, in "Synthesis of CF3I by direct iodination of CF3COOH on solid catalyst", Lee, Kyong-Hwan et al, Hwahak Konghak (2001), 39(2), 144-149. In this experiment, the effects of support types, salt types and salt contents for the manufactured catalysts and also those of reaction conditions such as reaction temperature, contact time and feeding mole ratio of reactant are tested. It has been reported that a longer contact time led to the higher yield of CF3I. The optimized reaction conditions were above 1 of I2/CF3COOH mole ratio and about 400 0 C of reaction temp. Active- carbon as a support shows better performance than alumina. For the salt impregnated on support, the best results of both salt content and salt type are 7.5 wt. percentages and CuI type, respectively. In the reaction conditions in this article, the catalyst was readily deactivated.
[0011] In "A simple, novel method for the preparation of trifluoromethyl iodide and diiododifluoromethane", Su 1 Debao et al.,
Journal of the Chemical Society, Chemical Communications (1992),
(11), 807-8, CF 3 I has been synthesized in 70-80% yields by treatment of XCF2CO2Me (X = Cl or Br) with iodine in the presence of potassium fluoride and copper (I) iodide. If Kl is used instead of KF under similar conditions, CF2I2 is obtained in 50-60% yields with traces of MeI present.
Reaction of BrCF 2 CO2K with Kl and I2 in the presence of CuI gave CF 2 I 2 in 50-60% yield without traces of MeI.
[0012] In a different approach, in "Synthesis and purification of iodotrifluoromethane, bromotrifluoromethane, trifluoromethane-d1 for laser isotope separation". Chiriac, Maria et al., Revistade Chimie (Bucharest, Romania) (1982), 33(11), 1018-20, CF 3 I of 99.9% purity have been prepared with yield >80% from Ag-trifluoroacetate.
[0013] There is, therefore, a need for an alternative, fairly simple and inexpensive process, and preferably a one-step process, for the production of CF3I that does not require expensive and/or not readily available reactants, and in which the process can be commercially adapted.
Summary of the Invention
[0014] A catalytic one-step process for the production of CF3I using relatively inexpensive reactant feedstocks has been discovered. The process comprises reacting, preferably in the presence of a source of oxygen, a source of iodine selected from iodine, hydrogen iodide or iodine monochloride (ICI) with a reactant selected from those of the formula:
CF 3 R where R is selected from the group consisting of -SH, -S-S-CF 3 , -S- phenyl, and -S-Si-(CH 3 ) 3 in the presence of a catalyst preferably consisting of a metal salt such as salts of Cu, Hg, Pt, Pd, Co, Mn, Rh, Ni, V, Tl, Ba, Cs, Ca, K and Ge and mixtures thereof.
Detailed Description of Invention
[0015] A catalytic one-step process for the production of CF 3 I comprises reacting, preferably in the presence of a source of oxygen, a source of iodine selected from iodine, hydrogen iodide or iodine monochloride with a reactant selected from those of the formula:
CF 3 R where R is selected from the group consisting of -SH, -S-S-CF 3 , -S- phenyl, and
-S-Si-(CH3)3 in the presence of a catalyst.
[0016] The process of this invention may be carried out in either catalytic vapor or liquid phase. The process is preferably conducted at a temperature of from about 50° to about 600° C. The liquid phase process is preferably conducted in a solvent. The solvent may be any suitable solvent, preferably H2SO4 or a high boiling (bp 45° to 75° C or higher) fluorocarbon solvent, such as hexafluorobenzene and the like.
[0017] The metal catalyst employed in the process may be employed alone or on a support material. The catalyst is preferably a metal salt such as salts of Cu, Hg, Pt, Pd, Co, Mn, Rh, Ni, V, Tl, Ba, Cs, Ca K and Ge and mixtures thereof. Examples of suitable support materials include basic oxides such as MgO, BaO and CaO, BaCO 3 , CSNO3, Ba (NO3) 2, activated carbon, basic alumina, and ZrO2. When the metal salt is employed on a support material the metal salt will generally be employed in an amount of from about 2 to about 60 wt%, based on the total weight of the metal salt and support combined. Examples of suitable catalyst include VO(acac)2, Pd/C, Pd(acac)2 and Co(acac)2. Preferably, a mixture of metal salts, such as Cu-Pt on a support such as activated carbon is employed to obtain higher selectivity of CF3I production.
[0018] To prevent or reduce catalyst deactivation and for iodine (I 2 ) economy it is preferred that the reaction be conducted in the presence of a source of a stoichiometric proportion of oxygen, such as air or O2.
[0019] The reaction pathway for the process of this invention is believed to be as follows, as exemplified for the reactant CF3-S-S-CF3.
CF 3 -S-S-CF 3 + I 2 + 2O 2 → 2CF 3 I + 2SO 2
[0020] The invention is illustrated by, but not limited to, the following examples.
[0021] Example 1
In a gas-phase process 20 SCCM (standard cubic centimeters) of CF 3 -S-S-CF 3 and 20 SCCM of I 2 and 20 SCCM air are passed through a 1 /2-inch (1.27 cm) reactor loaded with 50 cc of Pd/activated carbon catalyst at 350° C in the presence of air to synthesize CF 3 I. The products can be analyzed and identified by GC and GCMS.
[0022] Examples 2 to 4
In reactions as described in Example 1 , but when the reactant CF 3 -S-S-CF 3 is replaced by CF3-SH, CF 3 -S-phenyl, and CF 3 - Si(CH 3 J 3 , respectively, CF 3 I is also produced.
[0023] Examples 5 to 8
In a liquid phase process 5 gm of CF 3 -S-S-CF 3 or CF 3 SH, or CF 3 SPh, or CF 3 -Si(CHs) 3 , and 15 gm of Iodine are heated in an autoclave at 30-150 0 C for 12 hrs in the presence of an inert solvent such as 100% H 2 SO 4 solvent or a fluorocarbon solvent such as hexafluorobenzene. VO(acac) 2 is used as a catalyst. The conversion of the sulfur compounds to CF 3 I is around 80%.
[0024] The CF 3 I produced by the process of this invention is suitable for use as a refrigerant, either alone or combined with other refrigerants.
[0025] While the invention has been described herein with reference to the specific embodiments thereof, it will be appreciated that changes, modification and variations can be made without departing from the spirit and scope of the inventive concept disclosed herein. Accordingly, it is intended to embrace all such changes, modification and variations that fall with the spirit and scope of the appended claims.
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