METHOD FOR THE PREPARATION OF FLUORATED ORGANIC COMPOUNDS

Description

BACKGROUND OF INVENTION (1) Field of Invention:

[0001] This invention relates to novel methods for preparing fluorinated organic compounds, and more particularly to methods of producing fluorinated olefins.(2) Description of Related Art:

[0002] Hydrofluorocarbons (HFCs), in particular hydrofluoroalkenes such tetrafluoropropenes (including 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf) and 1,3,3,3-tetrafluoro-1-propene (HFO-1234ze) have been disclosed to be effective refrigerants, fire extinguishants, heat transfer media, propellants, foaming agents, blowing agents, gaseous dielectrics, sterilant carriers, polymerization media, particulate removal fluids, carrier fluids, buffing abrasive agents, displacement drying agents and power cycle working fluids. Unlike chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), both of which potentially damage the Earth's ozone layer, HFCs do not contain chlorine and thus pose no threat to the ozone layer.

[0003] Several methods of preparing hydrofluoroalkenes are known. For example, U.S. Pat. No. 4,900,874 (Ihara et al) describes a method of making fluorine containing olefins by contacting hydrogen gas with fluorinated alcohols. Although this appears to be a relatively high-yield process, for commercial scale production the handling of hydrogen gas at high temperature raises difficult safety related questions. Also, the cost of producing hydrogen gas, such as building an on-site hydrogen plant, can be in many situations prohibitive.

[0004] U.S. Pat. No. 2,931,840 (Marquis) describes a method of making fluorine containing olefins by pyrolysis of methyl chloride and tetrafluoroethylene or chlorodifluoromethane. This process is a relatively low yield process and a very large percentage of the organic starting material is converted in this process to unwanted and / or unimportant byproducts..

[0005] The preparation of HFO-1234yf from trifluoroacetylacetone and sulfur tetrafluoride has been described. See Banks, et al., Journal of Fluorine Chemistry, Vol. 82, Iss. 2, p. 171-174 (1997). Also, U.S. Pat. No. 5,162,594 (Krespan) discloses a process wherein tetrafluoroethylene is reacted with another fluorinated ethylene in the liquid phase to produce a polyfluoroolefin product.

[0006] Henne Albert L et al., "Fluorinated Derivatives of Propane and Propylene. VI", Journal of the American Chemical Society, American Chemical Society, vol. 68, 1946-01-01, pages 496-497, discloses synthesis of fluorinated derivatives of propane and propylene.

[0007] Paleta Oldrich et al., "Synthesis of Perfluoroallylchloride and Some Chlorofluoropropenes", Bulletin de la Societe Chimique de France, Society Francaise de Chimie, no. 6, 1986-01-01, pages 920-924 discloses the preparation of fluorinated propenes containing chlorine atoms using several general procedures.

[0008] Marian O Burgin et al., "Unimolecular Reaction Kinetics of CF2ClCF2CH3 and CF2ClCF2CD3: Experimental Evidence for a Novel 1,2-FCl Rearrangement Pathway", The Journal of Physical Chemistry A, vol. 105, 2001-01-01, pages 1615-1621 discloses the reaction of CF 2 ClCF 2 CH 3 and CF 2 ClCF 2 CD 3 via elimination of HF (DF) and also by a 1,2-FCl rearrangement.SUMMARY

[0009] Applicants have discovered a method for producing fluorinated organic compounds, including hydrofluoropropenes, which comprises converting at least one compound of Formula (IAA):         CH 2 =CClCF 3      (IAA) to the compound         CF 3 CF 2 CH 3 and subsequently converting the CF 3 CF 2 CH 3 (245cb) to a compound of Formula (II) (CF 3 CF=CH 2 (1234yf)).

[0010] As used herein and throughout, unless specifically indicated otherwise, the term "converting" includes directly converting (for example, in a single reaction or under essentially one set of reaction conditions, an example of which is described hereinafter) and indirectly converting (for example, through two or more reactions or using more than a single set of reaction conditions).DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS FLUORINATION OF THE COMPOUND OF FORMULA IAA

[0011] The compound of Formula (IAA), is subjected to fluorination reaction(s) to produce CF 3 CF 2 CH 3 (245cb). Preferably this gas phase reaction is at least partially catalyzed.DEHYDROHALOGENATION OF CF 3 CF 2 CH 3 (245cb)

[0012] The compound CF 3 CF 2 CH 3 (245cb) is dehydrofluorinated to CF 3 CF=CH 2 (1234yf).EXAMPLES

[0013] Additional features of the present invention are provided in the following examples.Example 1 (Reference Example) Selective catalyzed-transformation of CCl 2 =CClCH 2 Cl to CF 3 CCl=CH 2 (HFO-1233xf) in gas-phase

[0014] A (56 cm) 22-inch long and 1.27 cm 1 / 2-inch diameter Monel pipe gas-phase reactor is charged with about 120 cc of a catalyst or a mixture of two catalysts. In case of a mixture, Cr 2 O 3 catalyst is kept at the bottom zone of the reactor at a constant temperature of about 270°C-500°C and the other catalyst, such as FeCl 3 / C, is kept at the middle and the top zone of the reactor at a constant temperature of about 120°C - 220°C. The reactor is mounted inside a heater with three zones (top, middle, and bottom). The reactor temperature is read by custom-made-5-point thermocouples kept inside at the middle of the reactor. The bottom of the reactor is connected to a preheater, which is kept at 300°C by electrical heating. The liquid-HF is fed from a cylinder into the pre-heater through a needle valve, liquid mass-flow meter, and a research control valve at a constant flow of about 1 to about 1000 grams pre hour (g / h). The HF cylinder is kept at a constant pressure of 412 kPa (45 psig) by applying anhydrous N 2 gas pressure into the cylinder head space. About 10 to about 1000 g / h of CCl 2 =CClCH 2 Cl is fed as a liquid through a dip tube from a cylinder under about 412 kPa (45 psig) of N 2 pressure. The organic flows from the dip tube to the preheater (kept at about 250°C) through a needle valve, liquid mass-flow meter, and a research control valve at a constant flow of 1-1000 g / h. The organic is also fed as a gas while heating the cylinder containing organic at about 220°C. The gas coming out of the cylinder is passed through a needle valve and a mass flow controller into the preheater. The organic line from the cylinder to the pre-heater is kept at about 200°C by wrapping with constant temperature heat trace and electrical heating elements. All feed cylinders are mounted on scales to monitor their weight by difference. The catalysts are dried at the reaction temperature over a period of about 8 hours and then pretreated with about 50 g / h of HF under atmospheric pressure over a period of about 6 hours and then under 446 kPa (50 psig) HF pressure over another period of about 6 hours before contacting with organic feed containing CCl 2 =CClCH 2 Cl. The reactions are run at a constant reactor pressure of about 101 to about 1136 kPa (about 0 to about 150 psig) by controlling the flow of reactor exit gases by another research control valve. The gases exiting reactor are analyzed by on-line GC and GC / MS connected through a hotbox valve arrangement to prevent condensation. The conversion of CCl 2 =CClCH 2 Cl is about 70 to about 100% and the selectivity to 1233xf is about 80% to about 95%, respectively. The product is collected by flowing the reactor exit gases through a scrubber solution comprising about 20 wt% to about 60 wt% KOH in water and then trapping the exit gases from the scrubber into a cylinder kept in dry ice or liquid N 2 . The product, 1233xf is then substantially isolated by distillation. The results are tabulated in Table 1. Table 1: Transformation of CCl 2 =CClCH 2 Cl to CF 3 CCl=CH 2 (CCl 2 =CClCH 2 Cl + 3HF → CF 3 CCl=CH 2 + 3HCl) # Catalyst T, O< C HF flow, g / h CCl 2 =CClCH 2 Cl flow, g / h % Conv of CCl 2 =CClCH 2 Cl % Sel to 1233xf 1 10% v / v Cr 2 O 3 -90% v / v FeCl 3 / C350 / 150501279812 20% v / v Cr 2 O 3 -80% v / v FeCl 3 / C350 / 150501283863 30% v / v Cr 2 O 3 -70% v / v FeCl 3 / C350 / 150501289964 30% v / v Cr 2 O 3 -70% v / v FeCl 3 / C350 / 150701279935 30% v / v Cr 2 O 3 -70% v / v FeCl 3 / C345 / 170502585906 Cr 2 O 3 350502090937 FeCl 3 / C150502074398 SbCl 5 / C15050208152Reaction conditions: Catalyst used (total) 120 cc; pressure, 122 kPa (1.5 psig); Examples 2A and 2B Liquid-phase catalytic fluorination of CF 3 CCl=CH 2 (1233xf) with HF to CF 3 CFClCH 3 (244bb) Example 2A

[0015] About 327 grams of HF, about 50 grams 1233xf, and about 75 grams SbCl 5 were charged into a 1-L autoclave. The reaction mixture was stirred at a temperature of about 80°C for about 3 hours under about 4376 kPa (620 psig) of pressure. After the reaction, the reactor was cooled to about 0°C and about 300 ml water was then added slowly into the autoclave over a period of about 45 min. After complete addition of water under stirring, the reactor was cooled to room temperature and then the overhead gases were transferred to another collecting cylinder. The yield of CF 3 CFClCH 3 was about 90% at a 1233xf conversion level of about 98%. The other major by-products were CF 3 CF 2 CH 3 (2%), and an unidentified isomer of a C4 compound of the general formula, C 4 H 3 Cl 3 F 4 (8%).Example 2B

[0016] About 327 grams HF, about 50 grams 1233xf, and about 75 grams SbCl 5 were charged into a 1-L autoclave. The reaction mixture was stirred at 80°C for about 3 hours under about 4411 kPa (625 psig) of pressure. After the reaction, the reactor was cooled to about 45°C and then the overhead gas mixture was passed through a well dried KF, NaF, or Al 2 O 3 (350 g) packed column kept at about 80°C to strip off HF from the gas stream. The gases coming out of the column are collected in a cylinder kept in dry ice (-70 O< C) bath. The yield of CF 3 CFClCH 3 was 87% at a 1233xf conversion level of 93%. The other major by-products were CF 3 CF 2 CH 3 (1%), and an unidentified isomer of a C4 compound of the general formula, C 4 H 3 Cl 3 F 4 (7%). The product, CF 3 CFClCH 3 was isolated by distillation with 98% purity.Example 3 (Reference Example) Selective catalyzed-transformation of CCl 3 CCl=CH 2 to CF 3 CCl=CH 2 (HFO-1233xf) in gas-phase

[0017] A 56 cm (22-inch) long and 1.27 cm (1 / 2-inch) diameter Monel pipe gas phase reactor was charged with 120 cc of a catalyst or a mixture of two catalysts. In case of a mixture, Cr 2 O 3 catalyst is kept at the bottom zone of the reactor at a substantially constant temperature of from about 270°C to about 500°C and the other catalyst, such as FeCl 3 / C is kept at the middle and the top zone of the reactor at a substantially constant temperature of from about 120°C to about 220°C. The reactor was mounted inside a heater with three zones (top, middle, and bottom). The reactor temperature was read by custom-made-5-point thermocouples kept inside at the middle of the reactor. The bottom of the reactor was connected to a pre-heater, which was kept at about 300°C by electrical heating. The liquid-HF was fed from a cylinder into the pre-heater through a needle valve, liquid mass-flow meter, and a research control valve at a substantially constant flow of from about 1 to about 1000 g / h. The HF cylinder was kept at a substantially constant pressure of about 412 kPa (45 psig) by applying anhydrous N 2 gas pressure into the cylinder head space. A feed rate of from about 10 g / h to about 1000 g / h of CCl 3 CCl=CH 2 was fed as a liquid through a dip tube from a cylinder under about (412 kPa (45 psig) of N 2 pressure. The organic was flown from the dip tube to the pre-heater (kept at about 250°C) through needle valve, liquid mass-flow meter, and a research control valve at a substantially constant flow of from about 1 to about 1000 g / h. The organic is also fed as a gas while heating the cylinder containing organic at about 220°C. The gas effluent from the cylinder is passed through a needle valve and a mass flow controller into the pre-heater. The organic line from the cylinder to the pre-heater was kept at about 200°C by wrapping with constant temperature heat trace and electrical heating elements. All feed cylinders were mounted on scales to monitor their weight by difference. The catalysts were dried at the reaction temperature over a period of about 8 hours and then pretreated with about 50 g / h of HF under atmospheric pressure over a 6 hour period and then under about 446 kPa (50 psig) HF pressure over a 6 hour period before contacting with organic feed, CCl 3 CCl=CH 2 . The reactions were run at a substantially constant reactor gauge pressure ranging from about 101 to about 791 kPa (about 0 to about 150 psig) by controlling the flow of reactor exit gases by another research control valve. Those gases exiting reactor were analyzed by on-line GC and GC / MS connected through a hotbox valve arrangements to prevent condensation. The conversion of CCl 3 CCl=CH 2 was in a range of from about 90% to about 100% and the selectivity to CF 3 CCl=CH 2 (1233xf) was about 79%. The effluent contained in addition HFO-1243zf in an amount of about 7.7%, 1232-isomer in an amount of about 1.3%, and 1223 in an amount of about 0.8%, and an unidentified byproduct. The product was collected by flowing the reactor exit gases through a 20-60 wt% aq. KOH scrubber solution and then trapping the exit gases from the scrubber into a cylinder kept in dry ice or liquid N 2 . The product, 1233xf was then substantially isolated by distillation. Using only Cr 2 O 3 catalyst, a selectivity of about 68% to 1233xf at a conversion level of about 79% was achieved.Examples 4A - 4D Direct Liquid-phase catalytic fluorination of CCl 3 CCl=CH 2 with HF to CF 3 CFClCH 3 (244-isomer) Example 4A

[0018] About 327 grams HF, about 50 grams CCl 3 CCl=CH 2 , and about 75 grams SbCl 5 were charged into a 1-L autoclave. The reaction mixture was stirred at about 80°C for about 3 hours under about (4307 kPa) 610 psig of pressure. After the reaction, the reactor was cooled to about 40°C and about 300 ml water was then added slowly into the autoclave over a period of about 45 min. After complete addition of water under stirring, the reactor was cooled to about room temperature and then the overhead gases were transferred to another collecting cylinder. The yield of CF 3 CFClCH 3 was about 89% at a CCl 3 CCl=CH 2 conversion level of about 88%. The other major byproducts were CF 3 CF 2 CH 3 (2%), and an unidentified isomer of a C4 compound of the general formula, C 4 H 3 Cl 3 F 4 (8%).Example 4B

[0019] About 327 grams HF, about 50 grams CCl 3 CCl=CH 2 , and about 75 grams SbCl 5 were charged into a 1-L autoclave. The reaction mixture was stirred at about 100°C for about 3 hours under about (4824 kPa) 685 psig of pressure. After the reaction, the reactor was cooled to about 40°C and about 300 ml water was then added slowly into the autoclave over a period of about 45 minutes. After complete addition of water under stirring, the reactor was cooled to room temperature and then the overhead gases were transferred to another collecting cylinder. The yield of CF 3 CFClCH 3 was about 78% at a CCl 3 CCl=CH 2 conversion level of about 100%. The other major byproducts were CF 3 CF 2 CH 3 (about 4%), and an unidentified isomer of a C4 compound of the general formula, C 4 H 3 Cl 3 F 4 (about 13%).Example 4C

[0020] About 327 grams HF, about 50 grams CCl 3 CCl=CH 2 , and about 75 grams SbCl5 were charged into a 1-L autoclave. The reaction mixture was stirred at about 125°C for about 6 hours under about (5790 kPa) 825 psig of pressure. After the reaction, the reactor was cooled to about 40°C and about 300 ml water was then added slowly into the autoclave over a period of about 45 min. After complete addition of water under stirring, the reactor was cooled to about room temperature and then the overhead gases were transferred to another collecting cylinder. The major products were CF 3 CF 2 CH 3 (about 53%) and CF 3 CFClCH 3 (about 25%) at a CCl 3 CCl=CH 2 conversion level of about 100%. The other major by-products were and unidentified isomer of a C4 compound of the general formula, C 4 H 3 Cl 3 F 4 (8%) and tar.Example 4D

[0021] About 327 grams HF, about 50 grams CCl 3 CCl=CH 2 , and about 75 g SbCl 5 were charged into a 1-L autoclave. The reaction mixture was stirred at about 150°C for about 6 hours under about (5790 kPa) 825 psig of pressure. After the reaction, the reactor was cooled to about 40°C and about 300 ml water was then added slowly into the autoclave over a period of about 45 minutes. After complete addition of water under stirring, the reactor was cooled to about room temperature and then the overhead gases were transferred to another collecting cylinder. The major products were CF 3 CF 2 CH 3 (about 57%) and CF 3 CFClCH 3 (about 15%) at a CCl 3 CCl=CH 2 conversion level of about 100%. The other major by-products were and unidentified isomer of a C4 compound of the general formula, C 4 H 3 Cl 3 F 4 (about 11%) and tar.Example 5 Catalytic conversion of CF 3 CF 2 CH 3 to CF 3 CF=CH 2

[0022] A (56 cm) 22-inch (1.27 cm (1 / 2-inch) diameter) Monel tube gas phase reactor was charged with 120 cc of a catalyst. The reactor was mounted inside a heater with three zones (top, middle and bottom). The reactor temperature was read by custom made 5-point thermocouples kept at the middle inside of the reactor. The inlet of the reactor was connected to a pre-heater, which was kept at about 300°C by electrical heating. Organic material (245cb) was fed from a cylinder kept at about 65°C through a regulator, needle valve, and a gas mass-flow-meter. The organic line to the pre-heater was heat traced and kept at a substantially constant temperature in a range of from about 65°C to about 70°C by electrical heating to avoid condensation. The feed cylinder was mounted on a scale to monitor its weight by difference. The reactions were run at a substantially constant reactor pressure of from about 101 to about 1136 kPa (about 0 to about 100 psig) by controlling the flow of reactor exit gases by another research control valve. The gas mixtures exiting reactor was analyzed by on-line GC and GC / MS connected through a hotbox valve arrangements to prevent condensation. The conversion of 245cb was in the range of from about 30% to about 70% and the selectivity to 1234yf was in the range of from about 90% 5o about 100% depending on the reaction conditions. The products were collected by flowing the reactor exit gases through a 20-60-wt% of aq. KOH scrubber solution and then trapping the exit gases from the scrubber into a cylinder kept in dry ice or liquid N 2 . The products were then substantially isolated by distillation. Results are tabulated in Table 4. Table 4: Transformation of CF 3 CF 2 CH 3 to 1234yf #CatT, °CH 2 , sccmCF 3 CF 2 CH 3 (245cb) sccmConversion of 245cb, %1234yf (Sel. %)1A57506579632B57506882573C57507373614D57506884595D575206889736E55006992537F55006793338G5500697346 Reaction conditions: pressure, 119-138 kPa (2.5-5.3 psig); catalyst, 100 cc, A is NORIT RFC 3; B is Shiro-Saga activated carbon; C is Aldrich activated carbon; D is Calgon activated carbon; E is 0.5 wt% Pd / C; F is 0.5 wt% Pt / C; G is Ni-mesh; Organic cylinder temperature is about 65OC: CF3CF2CH3 (245cb) line to the preheater is maintained at about 50OC; preheater temperature is maintained at about 350°C; N2 flow is not used; pressure is maintained at about 122 kPa (3 psig).

Claims

1. A method for producing CF3CF=CH2 (1234yf), the method comprising converting CF3CClCH2 (1233xf) to CF3CF2CH3 (245cb) and subsequently converting the CF3CF2CH3 (245cb) to CF3CF=CH2 (1234yf).

2. The method of claim 1, wherein converting the CF3CF2CH3 (245cb) to CF3CF=CH2 (1234yf) comprises contacting CF3CF2CH3 (245cb) with a catalyst in a reactor, optionally wherein the catalyst is selected from activated carbon, Pd / C, Pt / C or Ni-mesh.

3. The method of claim 2, wherein the catalyst is selected from activated carbon, 0.5 wt% Pd / C, 0.5 wt% Pt / C or Ni-mesh.

4. The method of any preceding claim, wherein converting the CF3CF2CH3 (245cb) to CF3CF=CH2 (1234yf) comprises converting the CF3CF2CH3 (245cb) in a reactor at a temperature of 550°C to 575°C.

5. The method of any preceding claim, wherein converting the CF3CF2CH3 (245cb) to CF3CF=CH2 (1234yf) comprises converting the CF3CF2CH3 (245cb) in a reactor at a gauge pressure of up to 5.3 psi (37 kPa).

6. The method of claim 5, wherein converting the CF3CF2CH3 (245cb) to CF3CF=CH2 (1234yf) comprises converting the CF3CF2CH3 (245cb) in a reactor at a gauge pressure of from 2.5 to 5.3 psi (17 to 37 kPa).

7. The method of any preceding claim, wherein converting CF3CClCH2 (1233xf) to CF3CF2CH3 (245cb) comprises reacting CF3CClCH2 with HF in the presence of a catalyst, optionally in the gas phase.

8. The method of claim 7, wherein converting CF3CClCH2 (1233xf) to CF3CF2CH3 (245cb) is carried out batch wise, continuous, or a combination of these.