CA2004831A1 - Process for the preparation of 1,1-dichloro-1-fluoroethane - Google Patents
Process for the preparation of 1,1-dichloro-1-fluoroethaneInfo
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- CA2004831A1 CA2004831A1 CA002004831A CA2004831A CA2004831A1 CA 2004831 A1 CA2004831 A1 CA 2004831A1 CA 002004831 A CA002004831 A CA 002004831A CA 2004831 A CA2004831 A CA 2004831A CA 2004831 A1 CA2004831 A1 CA 2004831A1
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- hydrogen fluoride
- vinylidene chloride
- catalyst
- anhydrous hydrogen
- reaction
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C19/00—Acyclic saturated compounds containing halogen atoms
- C07C19/08—Acyclic saturated compounds containing halogen atoms containing fluorine
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/07—Preparation of halogenated hydrocarbons by addition of hydrogen halides
- C07C17/087—Preparation of halogenated hydrocarbons by addition of hydrogen halides to unsaturated halogenated hydrocarbons
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/07—Preparation of halogenated hydrocarbons by addition of hydrogen halides
- C07C17/08—Preparation of halogenated hydrocarbons by addition of hydrogen halides to unsaturated hydrocarbons
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- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
PROCESS FOR THE PREPARATION OF
1,1-DICHLORO-1-FLUOROETHANE
ABSTRACT OF THE DISCLOSURE
The present invention provides a process for the preparation of 1,1-dichloro-1-fluoroethane (known in the art as HCFC-141b). The procass comprises the step of: reacting anhydrous hydrogen fluoride and vinylidene chloride by using excess anhydrous hydrogen fluoride in the presence of a catalytic amount of a catalyst of the formula RmAClnFp wherein A is titanium, zirconium, or hafnium: R is an alkyl, alkenyl, or aryl group; m is 0 to 2: n is 0 to 4; and p is 0 to 4 with the proviso that at least one of n and p is not zero and m+n+p satisfies the valence of A, for a time and at a temperature sufficient to form 1,1-dichloro-1-fluoroethane.
The 1,1-dichloro-1-fluoroethane produced by the present process is useful as a blowing agent for the production of rigid urethane thermoinsulation foam.
1,1-DICHLORO-1-FLUOROETHANE
ABSTRACT OF THE DISCLOSURE
The present invention provides a process for the preparation of 1,1-dichloro-1-fluoroethane (known in the art as HCFC-141b). The procass comprises the step of: reacting anhydrous hydrogen fluoride and vinylidene chloride by using excess anhydrous hydrogen fluoride in the presence of a catalytic amount of a catalyst of the formula RmAClnFp wherein A is titanium, zirconium, or hafnium: R is an alkyl, alkenyl, or aryl group; m is 0 to 2: n is 0 to 4; and p is 0 to 4 with the proviso that at least one of n and p is not zero and m+n+p satisfies the valence of A, for a time and at a temperature sufficient to form 1,1-dichloro-1-fluoroethane.
The 1,1-dichloro-1-fluoroethane produced by the present process is useful as a blowing agent for the production of rigid urethane thermoinsulation foam.
Description
8~1.
PROCESS FOR THE PREPARATION OF
1,1-DICHLORO-1-FLUOROETHANE
BACKGROUND OF THE INVENTION
The present invention relates to a p~ocess for the preparation of l,l-dichloro-l-fluoroethane, and more particularly, to a process for the preparation of l,1-dichloro-1-fluoroethane wherein a titanium, hafnium, or zirconium based catalyst is used.
Trichlorofluoromethane (known in the art as CFC-11) is currently available in commercial quanti~ies and is used as a blowing agent for rigid urethane thermo-insulation foam. Currently, l,l-dichloro-l-fluoro-ethane (known in the art as HCFC-141b) is considered to be a replacement for CFC-ll because HCFC-141b does not deplete ozone in the stratosphere to the same extent as CFC-ll. See K.T. Dishart et al., POLYURETHANES WORLD
20 CONGRESS 1987, 59 (1987) and G. Mouton et al., POLYURETHANES WORLD CONGRESS 1987, 67 ~1987). Because the demand for HCFC-141b will increase dramatically in the future, commercially viable processes for the preparation of HCFC-141b in high yield are needed.
HCFC-141b may be produced by reacting vinylidene chloride with anhydrous hydrogen fluoride. The reaction is expressed by the following equation:
CH2=CC12 + HF --~ CH3CFC12 The reaction proceeds slowly at room temperature but speeds up at temperatures above 40C. At 60C, this non-catalytic reaction gives the highest selectivity for HCFC-141b.
~0a~`~83~l.
As examples of the non-ca~alyzed reaction, A.L.
Henne et al., J. Am. Chem.Soc. 65, 1271 (1943) report tha~ after three hours at 65C with four moles of hydrogen fluoride. vinylidene chloride gave only 50%
HCFC-141b, 15~ tar, 10% recovered vinylidene chloride, 5% l,l,l-trichloroethane and traces of l-chloro-l,l-difluoroethane tknown in the art as HCFC-142b). U.S.
Patent 3,833,676 teaches the reaction of 1,1,1-trichloroethane with hydrogen fluoride in the absence of catalyst at 110C for 15 minutes to yield 58.2%
l,l-dichloro-l-fluoroethane: 41.7~ l-chloro-l,l-difluoroethane; 0.10~ l,l,l-trichloroethane; and 0.03%
l,l,l-trifluoroethane. A much longer batch cycle time of greater than six hours is required in order ~o convert 99.9~ or more of the vinylidene chloride. A
high conversion is desirable because it is difficult to separate the starting vinylidene chloride from the product HCFC-141b. Increasing the temperature in an attempt to increase HCFC-141b yield just increases the formation of a side product, HCFC-142b and thus, reduces the selectivity for HCFC-141b.
Because long batch cycle times as required in the foregoing non-catalytic reaction in order to increase the yield of HCFC-141b are commercially impractical, attempts were made in the prior art to catalyze the foregoing reaction.
U.S. Patent 4,258,225 teaches the reaction of vinylidene chloride and anhy~rous hydrogen fluoride in the presence of tantalum pentafluoride. The reaction was conducted at 25C for three hours. The yield of HCFC-141b was about 36% while the remaining product was a dark oil. The low HCFC-141b yield makes this process commercially impractical also.
~0~ 3:1.
A.E. Feiring, J _of F'luorine Chem. 1 7 (1~79) reports on the addition of hydrogen fluoride to tetra-and trichloroethene and related compounds in the presence of tantalum pentafluoride, niobium penta-fluoride, titanium tetrachloride, or molybdenumpentachloride. The article concluded that tantalum penta~luoride appeared to be the most active of the materials tested. The article reported that the reaction of 0.4 mole vinylidene chloride and 0.5 mole anhydrous hydrogen fluoride in the presence of 0.01 mole tantalum pentafluoride at 25C for three hours yielded only 40~ HCFC-141b; the remaining product was tar. This process is commercially unattractive because the removal o~ tar trom the product is expensive and again, a low HCFC-141b yield is undesirable.
U.S. Patent 2,005,708 teaches the preparation of chlorofluoroethanes, but no~ l,l-dichloro-l-fluoro-ethane, by the reaction of chlorinated ethanes or ethenes with hydrogen f luoride in the presence of an antimony halide at temperatures above 95C and under pressure.
U.S. Patent 2,452,975 teaches the preparation of chlorofluoroethanes, but not l.l-dichloro-l-fluoro-ethane, by the reaction of chloroethanes with hydrogen fluoride in the presence of stannic chloride.
U.S. Patent 4,147,733 teaches the preparation of fluorocarbons, but not l,l-dichloro-l-fluoroethane, by the reaction of chlorinated hydrocarbons with hydrofluoric acid in the presence of an aluminum, chromium or nickel fluoride catalyst at 275 to 425C.
4~3~1.
U.S. Patent 2.49s,407 teaches that ~ichloro-ethylene and anhydrous hydrogen fluoride were reacted in the presence of stannic chloride for 1.75 hours to produce l,~-dichloro-l-fluoroethane with a 32.7~
conversion and a 43% yield based on dichloroethylene.
Again, a low HCFC-141b yield is commercially unappealing.
U.S. Patent 4,766,258 teaches that the reaction of vinylidene chloride and anhydrous hydrogen fluoride in the presence of a stannic halide catalyst and water for one hour produced HCFC-141b in a 29~ yield. The reference also states that when a halide, other than a stannic halide, such as titanium tetrachloride is used to produce a hydrocarbon fluoride by reacting a hydrogen-containing hydrocarbon halide and anhydrous hydrogen fluoride, by-products such as higher boiling substances, oligomers and black precipitates form in even greater amounts than when the reaction is performed with stannic halide as the catalyst. Again, a low HCFC-141b yield is undesirable.
Thus, a need exists in the art for a process for the preparation of l,l-dichloro-l-fluoroethane wherein the reaction time is shorter than that of known processes and l,l-dichloro-l-fluoroethane is produced in a higher yield than in known processes.
S~ARY OF THE I NVENTI ON
The present invention responds to the foregoing need in the art by providing a process for the preparation of l,l-dichloro-l-fluoroethane. The process comprises the step of: reacting anhydrous hydrogen fluoride and vinylidene chloride by using excess anhydrous hydrogen fluoride relative to the 831.
vinylidene chloride in the presence of a catalytic amount of a catalyst of the formula:
RmAclnFp wherein A is titanium, zirconium, or hafnium: R is an alkyl, alkenyl, or aryl group; m is 0 to 2: n is O to 4; and p is 0 to 4 with the proviso that at least one of n an~ p is not zero and mln~p satisfies the valence of A, for a time and at a temperature sufficient to form l,l-dichloro-l-fluoroethane. The term "excess anhydrous hydrogen fluoride~' as used herein means that the molar ratio of anhydrous hydrogen fluoride to vinylidene chloride is greater than 1:1. In other words, a deficiency of vinylidene chloride is used.
Regarding the non-catalyzed reaction of vinylidene chloride and anhydrous hydrogen fluoride as discussed in the aforementioned Henne article and U.S.
Patent 3,833,676, the present process is more advantageous because it reduces reaction time by more than 75~ to obtain 99.9% conversion of vinylidene chloride, Compared with the processes of the aforemeneioned U.S. Patent 4,253,225 and Feiring article which use tantalum pentafluoride to catalyze the reaction of vinylidene chloride and anhydrous hydrogen fluoride, the present process produces l,l-dichloro-l-fluoroethane in a higher yield in a shorter reaction time. Compared with the process of the previously discussed U.S. Patent 2,495,407 which uses stannic chloride to catalyze the reaction of dichloroethylene and anhydrous hydrogen fluoride, the present process produces l,l-dichloro-l-fluoroethane in a higher yield in a shorter reaction time.
~0~831 Although the above-mentioned U.S. Patent 4,766,258 mentions the use o~ titanium tetrachloride in the fluorination of hydrogen-containing hydrocarbon halides, the reference does not teach the present reaction. Further, because U.S. Patent 4,766,258 indicates yields of less than 2g% when titanium tetrachloride is used to fluorinate hydrogen-containing hydrocarbon halides, the reference would not lead a person of ordinary skill in the art to the present process.
Although the above-mentioned Feiring article teaches the use of titanium tetrachloride in the fluorination of tetrachloroethylene, the reference does not teach the present reaction. The purpose of the paper was to test the usefulness of catalysts including tentalum pentafluoride, niobium pentafluoride, titanium tetrachloride and molybdenum pentachloride in the fluorination of tetra-, tri- and dichloroethene. The paper concluded that tantalum pentafluoride appears to be the most active catalyst and reported that the reaction of 0.4 mole vinylidene chloride and 0.5 mole anhydrous hydrogen fluoride in the presence of tantalum pentafluoride at 25C for three hours yielded only 4Q%
HCFC-141b. Based on these teachings, the reference would not lead a person of ordinary skill in the art to the present process.
As such, the present invention provides a process for the preparation of l,l-dichloro-l-fluoro-ethane wherein the reaction time is shorter than that of known processes and 1,1-dichloro-1-fluoroethane is produced in a higher yield than in known processes.
Other advantages of the present invention will become apparent from the following description and appended claims.
DETAILED DESCRIPTI~N OF THE PREFERRE~ E 30DIMENTS
Commercially available anhydrouS hydrogen f luoride and vinylidene chloride may be used in the present invention. The addition of anhydrous hydrogen fluoride to the carbon-carbon double bond of the vinylidene chloride is a stoichiometric reaction in which one mole of anhydrous hydrogen fluoride is required for each mole of vinylidene chloride used.
Generally, the anhydrous hydrogen fluoride and vinylidene chloride are reacted with an excess of anhydrous hydrogen fluoride relative to the vinylidene chloride. It has been found that because the undesirable tars or high boilers are mainly formed by coupling or polymerization reactions among vinylidene chloride molecules, the amount of tars or high boilers formed during the reaction can be minimized by minimizing the amount of starting ~inylidene chloride used. As such, the use of excess vinylidene chloride is disadvantageous. Preferably, the anhydrous hydrogen fluoride and vinylidene chloride are reacted in a molar ratio of about 1.5:1 to about 5:1. The use of anhydrous hydrogen fluoride in an amount greater than the molar ratio of 5:l causes other fluorinated alkanes to form. More preferably, the anhydrous hydrogen fluoride and vinylidene chloride are reacted in a molar ratio of about 1.5:1 to about 4:1 and most preferably abou~ 1.5:1 to about 3:1.
The catalyst used is of the formula:
RmAclnFp whersin A is titanium, zirconium, or hafnium: R is an alkyl, alkenyl, or aryl group; m is O to 2; n is O to 4: and p is O to 4 with the proviso that at least ons ~.0~
of n and p is not zero and m+n+p satisfies the valence of A. For R, examples of useful alkyl groups include methyl, ethyl, isopropyl, butyl, pentyl, hexyl, heptyl and octyl. For R, examples of useful aryl groups include phenyl and naphthyl. The aryl group may also be substituted so as to include groups such as benzyl, tolyl and halogenated phenyls. For R, examples of useful alkenyl groups include cyclopentadienyl and pentamethylcyclopentadienyl.
When A is zirconium, preferred catalysts include zirconium tetrachloride, zirconium tetrafluoride, zirconium tetrabromide and zirconocene dichloride.
When A is hafnium, preferred catalysts include hafnium tetrachloride, hafnium tetrafluoride and hafnocene dichloride. When A is titanium, preferred catalysts include titanium trichloride, titanium tetrachloride, titanium trifluoride, titanium tetrafluoride, titanium tetrabromide and titanocene dichloride. The most preferred catalyst is titanium tetrachloride.
Commercially available zirconium tetrachloride.
zirconocene dichloride, hafnium tetrachloride, hafnocene dichloride, titanium tetrachloride, titanium tetrabromide and titanocene dichloride may be used in practicing the present invention.
A catalytic amount of catalyst is used.
Generally, the amount of catalyst used is about 0.01 to about 50 percent mole of catalyst per mole of vinylidene chloride used. Preferably, the amount of catalyst used is about 0.1 to about 10 percent, more preferably about 0.2 to about S percent and most preferably about 0.3 to about 2 percent.
31.
The reaction is preferably conducted at a temperature of about 30 to about 100C. At reaction temperatures below this limit, the reaction becomes too slow to be useful. At reaction temperatures above this limit, the product yield is reduced by the formation of by-products. More preferably, the reaction is conducted at a temperature of about 50 to about 65C:
in this range, the highest selectivity for l,l-dichloro-l-fluoroethane exists.
Operation o~ the reaction at atmospheric pressure is convenient. Operation at a pressure of about 10 to about 130 psig (69 to 897 KPa) is preferred. Means may be provided ~or venting of the excess pressure caused by hydrogen chloride formed in the reaction and offers an advantage in minimizing formation of side products.
A useful reaction vessel is constructed from materials which are resistant to the action of anhydrous hydrogen fluoride. Examples include metallic materials and polymeric materials. For reactions at temperatures above the boiling point of vinylidene chloride which is abou~ 30C, a closed reaction vessel is used to minimize the loss of vinylidene chloride and anhydrous hydrogen fluoride.
Gene~ally, vinylidene chloride, anhydrous hydrogen fluoride and catalyst are introduced in any order into the reaction vessel as long as an excess of anhydrous hydrogen fluoride relative to the vinylidene chloride is used. The contents of the vessel are raised to the appropriate reaction temperature and are agitated by sha~ing or stirring for a time sufficient for the anhydrous hydrogen fluoride and vinylidene chloride to react. The reaction progress may be ~`0~
monitored by withdrawing samples periodically.
Preferably, the reaction time is less than about 2 hours. More preferably, the reaction time is about 0.1 to about 1.5 hours.
Preferably, a catalytic amount of the catalyst is dissolved in the anhydrous hydrogen fluoride and this mixture is heated to about 50 to about 65C before the addition of vinylidene chloride thereto. Anhydrous hydrogen fluoride has a vapor pressure of about ~0 psig at 60C and a boiling point of 19.5C; at atmospheric pressure, titanium tetrachloride has a boiling point of 136.4C. When a catalytic amount of titanium tetrachloride was mixed with anhydrous hydrogen fluoride at 60C. the mixture had a vapor pressure of around 65-70 psig. This pressure increase suggested that anhydrous hydrogen fluoride reacted with titanium tetrachloride to produce a low boiling compound such as HCl. It is believed that several titanium species also formed. The following equation summarizes the probable reaction.
4TiC14 + lOHF --~ lOHCl + TiC13F + TiC12F2 + TiC1~3 + TiF4 As such, it is believed that titanium tetrachloride can be completely fluorinated to titanium tetrafluoride or partially fluorinated to compounds such as TiC13F, TiC12F2 and TiClF3. The mixture of titanium tetrachloride and anhydrous hydrogen fluoride could contain any combination of these four fluorinated titanium species. It is believed that the reaction between vinylidene chloride and anhydrous hydrogen fluoride can be catalyzed by any of the five titanium species or any combination thereof. As such, the catalyst of the formula RmAclnFp 83~L
wherein A, R, m, n and p are as pre~iously defined covers TiC13F, TiC12F2 and TiClF3.
The l,1-dichloro-1-fluoroethane product may be isolated by any of a variety of known techniques. The contents of the reaction vessel may be discharged onto ice and the organic layer collected, washed with water and dried with a drying agent. The product may be analyzed by standard techniques including gas-liquid chromatography, NMR spectroscopy and mass spectrometry.
The present process may be conducted in batch or continuous fashion.
The 1,1-dichloro-1-fluoroethane produced by the present process is particularly useful as a blowing agent for the production of rigid urethane thermoinsulation foam. See for example U.S. Patents 4,652,589; 4,686,240;
4,699,932: 4,701,474: 4,717,518: and 4,727.094.
The present invention is more fully illustrated by the following non-limiting Examples.
For each Example and Comparative, the molar ratio of anhydrous hydrogen fluoride to vinylidene chloride was about 1.9:1. Each run was agitated at 2400 RPM.
In Table 1 below, "Cat." stands for catalyst. "VC"
stands for vinylidene chloride. 142b is known in the art and is l-chloro-l,l-difluoroethane. 140a i8 also known in the art and is l,l,l-trichloroethane. "HB's" stands for High Boilers. In the column for "Total HB's", the number shown in parenthesis indicates the number of high boilers observed.
Co~parative_l 200 grams anhydrous hydrogen fluoride were charged to a l liter autoclave at room temperature. The autoclave 5 was heated to the reaction temperature, 60OC, with agitation. Five hundreds grams of vinylidene chloride were then pumped into the autoclave at a constant rate.
The progress of the reaction was monitored by withdrawing the organic layer periodically by using a dip leg installed in the reactor. The sample was quenched with an ice/water slush immediately. The organic layer was then isolated, dried and analyzed on a gas chromatograph. The reaction was considered to be completed when 99.9%
vinylidene chloride was converted.
After the reaction was completed, the reactor was cooled quickly to the ambient temperature and the organic layer was recovered and washed with ice/water slush. The washed crude product was then isolated, dried and analyzed. The results are listed under "Cl" in Table l below.
VC % HOL
25 FEED FRAC.
TEHP. RATE (Cat./ PaES. TIHE PRODUCT ANALYSIS(%) EX CAT. (C) (~/min? VC) (PSi~ (hr.? 142b 141b VC 140a TOTAL HB's Cl NONE 60 2.16 - 80-120 6.1 1.3 93 0.10 4.2 1.2 (3) C2 BF3 60 8.64 0.78 100-120 1.5 0.9 91 0.03 2.9 4.8 (5) C3 BF3 49 8.08 1.23 75-80 2.0 0.3 87 0.15 2.7 10.2 (5) 30 C4 TaF5 60 8.64 0.76 100-120 1.25 0.9 94 0.00 2.3 2.2 (4) C5 TaF5 60 9.09 0.38 100-120 1.5 0.6 94 0.03 2.4 3.2 (4) C6 SnC1460 8.96 0.81 110-150 1.5 4.4 84 1.60 9.9 0.4 (1) 1 TiC14 60 10.20 0.83 120-130 1.25 0.4 96 0.10 1.6 1.6 (2) 2 TiC14 60 9.43 0.90 124-126 1.25 0.4 96 0.09 1.9 0.8 (3) 35 3 TiC14 50 8.77 0.97 87-95 1.50 0.4 97 0.20 1.4 1.1 (3) 4 TiC14 6010.870.92 102-113 1.25 0.7 97 0.10 1.0 1.3 (3) 33~
The mecric uni~s for the pressure are in Table 2 below.
PRES.
F (KPa) Cl 552-828 3 60~-656 Major by-products of the reaction include 20 HCFC-142b, HCC-140a, HCl and hiqh boilers. The High boilers consisted of fluorinated 4-carbon and 6-carbon compounds, ~ome polymeric materials and the stabilizer used in the 6tarting vinylidene chloride. The crude product compositions were determined by analyzing the recovered liquid phase product. HCFC-142b has a boiling point much lower than room temperature and thus, the actual selectivity for HCFC-142b is slightly higher than that indicated in Table 1. HCC-140a wa generated from the reaction between vinylidene chloride and hydrogen chloride. Hydrogen chloride and HCFC-142b were formed from the reaction between HCFC-141b and HF. High boilers were mainly produced from coupling reactions and polymerization among vinylidene chloride molecules.
3~.
-- lg --The results indicate that ~he long reaction time of 6.1 hours has to be used ~or a non-catalyzed reaction.
S ComDaratives 2 and 3 In the same autoclave as in Comparative 1. two separate runs were conducted under similar conditions.
Boron trifluoride was charged to the reactor after 200 grams of anhydrous hydrogen fluoride were charged. The mixture was then heated to 60 and 49C respectively prior to the vinylidene chloride feed (500 g). The reactions were monitored in the same way as in Comparative 1. The crude product was also recovered and analyzed the same way. The results are listed under "C2" and "C3" in ~able 1 above.
Boron trifluoride seemed to promote coupli~g reactions and produced more high boilers (or tars). As a result. it produced a lower selectivity for HCFC-141b than the non-catalytic reaction of Comparative 1.
ComParatives 4 and S
Using the same apparatus as in Comparative 1.
the same reaction conditions as in Comparative 2 were used for these two runs, except tantalum pentafluoride was used as catalyst. The results are listed under "C4" and "C5" in Table 1 above.
These results are surprising in view of the results reported by the aforementioned Feiring reference. The article reported that the reaction of 0.4 mole vinylidene chloride and 0.5 mole anhydrous hydrogen fluoride in the presence of tantalum pentafluoride at 25C for three hours yielded only 40%
~00~31 HCFC-141b. It is believed that the better yield results ~rom dissolving tantalum pentafluoride in the anhydrous hydrogen fluoride and heating this mixture to the reaction temperature before adding a deficiency of vinylidene chloride thereto.
Tantalum pentafluoride improved the selectivity and reduced reaction time. but still produced slightly more tars.
ComDarative 6 Tin tetrachloride was studied in this run. The number of moles of catalyst used was about the same as lS in Comparative 2. The other reaction conditions were also quite similar. The crude product was also recovered in the same way. A third phase heavier than the organic phase was also observed ~hich suggested that tin tetrachloride was not very soluble in either the anhydrous hydrogen fluoride or the organic phase.
The results of crude organic product analysis are listed under "C6" in Table 1 above.
Tin tetrachloride reduced the amounts or high boilers. bu~ did not catalyze the reaction as well as the other catalysts. Tin tetrachloride promoted the formation of HCFC-142b and HCC-140a. resulting in lower selectivity for HCFC-141b.
The catalytic activity of titanium tetrachloride was also studied in the same 1 liter autoclave. The reaction conditions were similar to those used for Co~paratives 4 and 5, except titanium tetrachloride was used as catalyst instead of tantalum pentafluoride.
3 ~831.
The desired amounts of fresh titanium tetrachloride were used ~or these three runs re.spectively. For Examples 1 and 2, 60C was employed and 50C was used for Example 3. The results of these three experiments are listed under 1, 2 and 3 in Table 1 above.
When tantalum pentafluoride was used, the yield of 141b was 94%. In the present process, the yield of 141b was 96-97%. As such, titanium tetrachloride is more selective and produces less ta~s. This yield increase represents a major economic advantage to a commercial user of the present process who will be producing substantial quantities of 141b. Savings of over one million dollars per year are expected.
Titanium tetrachloride is also commercially available and less expensive than tantalum pentafluoride.
The reaction conditions for this run were almost identical to those of Example 3, except that titanium tetrachloride and about 90 geams anhydrous hydrogen fluoride were recycled from Example 3. 105 grams of fresh anhydrous hydrogen fluoride were also added for the reaction by assuming that 95% catalyst was retained in the anhydrous hydrogen fluoride phase. The results of this run are listed under 4 in Table 1 above. The recycled titanium tetrachloride showed the same catalytic activity as the fresh catalyst used in Examples 1 and 2.
As illustrated by Examples 1 through 4, titanium tetrachloride gave the highest selectivity for l,l-dichloro-l-fluoroethane and did not produce more high boilers than the non-catalytic reaction.
Exam~les 5-15 Using the same apparatus and reaction procedures as in Comparative 2, the catalysts o~ Table 3 below are run using the following conditions: temperature =
60OC: vinylidene chloride feed rate = ~0 g/m; catalyst/
vinylidene chloride ~ mole reaction = 0.8-1: pressure =
80-120 psig (552-828 KPa): and time - 1.5 hours.
EX. CAT.
S ZrCl4 6 ZrF4 15 7 Zrcl2(c5H5)2 8 HfC14 ~ HfF4 HfC12(C5H5)2 11 TiC13 2012 TiC14 13 TiF3 14 TiF4 lS TiC12(C5H5) Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.
PROCESS FOR THE PREPARATION OF
1,1-DICHLORO-1-FLUOROETHANE
BACKGROUND OF THE INVENTION
The present invention relates to a p~ocess for the preparation of l,l-dichloro-l-fluoroethane, and more particularly, to a process for the preparation of l,1-dichloro-1-fluoroethane wherein a titanium, hafnium, or zirconium based catalyst is used.
Trichlorofluoromethane (known in the art as CFC-11) is currently available in commercial quanti~ies and is used as a blowing agent for rigid urethane thermo-insulation foam. Currently, l,l-dichloro-l-fluoro-ethane (known in the art as HCFC-141b) is considered to be a replacement for CFC-ll because HCFC-141b does not deplete ozone in the stratosphere to the same extent as CFC-ll. See K.T. Dishart et al., POLYURETHANES WORLD
20 CONGRESS 1987, 59 (1987) and G. Mouton et al., POLYURETHANES WORLD CONGRESS 1987, 67 ~1987). Because the demand for HCFC-141b will increase dramatically in the future, commercially viable processes for the preparation of HCFC-141b in high yield are needed.
HCFC-141b may be produced by reacting vinylidene chloride with anhydrous hydrogen fluoride. The reaction is expressed by the following equation:
CH2=CC12 + HF --~ CH3CFC12 The reaction proceeds slowly at room temperature but speeds up at temperatures above 40C. At 60C, this non-catalytic reaction gives the highest selectivity for HCFC-141b.
~0a~`~83~l.
As examples of the non-ca~alyzed reaction, A.L.
Henne et al., J. Am. Chem.Soc. 65, 1271 (1943) report tha~ after three hours at 65C with four moles of hydrogen fluoride. vinylidene chloride gave only 50%
HCFC-141b, 15~ tar, 10% recovered vinylidene chloride, 5% l,l,l-trichloroethane and traces of l-chloro-l,l-difluoroethane tknown in the art as HCFC-142b). U.S.
Patent 3,833,676 teaches the reaction of 1,1,1-trichloroethane with hydrogen fluoride in the absence of catalyst at 110C for 15 minutes to yield 58.2%
l,l-dichloro-l-fluoroethane: 41.7~ l-chloro-l,l-difluoroethane; 0.10~ l,l,l-trichloroethane; and 0.03%
l,l,l-trifluoroethane. A much longer batch cycle time of greater than six hours is required in order ~o convert 99.9~ or more of the vinylidene chloride. A
high conversion is desirable because it is difficult to separate the starting vinylidene chloride from the product HCFC-141b. Increasing the temperature in an attempt to increase HCFC-141b yield just increases the formation of a side product, HCFC-142b and thus, reduces the selectivity for HCFC-141b.
Because long batch cycle times as required in the foregoing non-catalytic reaction in order to increase the yield of HCFC-141b are commercially impractical, attempts were made in the prior art to catalyze the foregoing reaction.
U.S. Patent 4,258,225 teaches the reaction of vinylidene chloride and anhy~rous hydrogen fluoride in the presence of tantalum pentafluoride. The reaction was conducted at 25C for three hours. The yield of HCFC-141b was about 36% while the remaining product was a dark oil. The low HCFC-141b yield makes this process commercially impractical also.
~0~ 3:1.
A.E. Feiring, J _of F'luorine Chem. 1 7 (1~79) reports on the addition of hydrogen fluoride to tetra-and trichloroethene and related compounds in the presence of tantalum pentafluoride, niobium penta-fluoride, titanium tetrachloride, or molybdenumpentachloride. The article concluded that tantalum penta~luoride appeared to be the most active of the materials tested. The article reported that the reaction of 0.4 mole vinylidene chloride and 0.5 mole anhydrous hydrogen fluoride in the presence of 0.01 mole tantalum pentafluoride at 25C for three hours yielded only 40~ HCFC-141b; the remaining product was tar. This process is commercially unattractive because the removal o~ tar trom the product is expensive and again, a low HCFC-141b yield is undesirable.
U.S. Patent 2,005,708 teaches the preparation of chlorofluoroethanes, but no~ l,l-dichloro-l-fluoro-ethane, by the reaction of chlorinated ethanes or ethenes with hydrogen f luoride in the presence of an antimony halide at temperatures above 95C and under pressure.
U.S. Patent 2,452,975 teaches the preparation of chlorofluoroethanes, but not l.l-dichloro-l-fluoro-ethane, by the reaction of chloroethanes with hydrogen fluoride in the presence of stannic chloride.
U.S. Patent 4,147,733 teaches the preparation of fluorocarbons, but not l,l-dichloro-l-fluoroethane, by the reaction of chlorinated hydrocarbons with hydrofluoric acid in the presence of an aluminum, chromium or nickel fluoride catalyst at 275 to 425C.
4~3~1.
U.S. Patent 2.49s,407 teaches that ~ichloro-ethylene and anhydrous hydrogen fluoride were reacted in the presence of stannic chloride for 1.75 hours to produce l,~-dichloro-l-fluoroethane with a 32.7~
conversion and a 43% yield based on dichloroethylene.
Again, a low HCFC-141b yield is commercially unappealing.
U.S. Patent 4,766,258 teaches that the reaction of vinylidene chloride and anhydrous hydrogen fluoride in the presence of a stannic halide catalyst and water for one hour produced HCFC-141b in a 29~ yield. The reference also states that when a halide, other than a stannic halide, such as titanium tetrachloride is used to produce a hydrocarbon fluoride by reacting a hydrogen-containing hydrocarbon halide and anhydrous hydrogen fluoride, by-products such as higher boiling substances, oligomers and black precipitates form in even greater amounts than when the reaction is performed with stannic halide as the catalyst. Again, a low HCFC-141b yield is undesirable.
Thus, a need exists in the art for a process for the preparation of l,l-dichloro-l-fluoroethane wherein the reaction time is shorter than that of known processes and l,l-dichloro-l-fluoroethane is produced in a higher yield than in known processes.
S~ARY OF THE I NVENTI ON
The present invention responds to the foregoing need in the art by providing a process for the preparation of l,l-dichloro-l-fluoroethane. The process comprises the step of: reacting anhydrous hydrogen fluoride and vinylidene chloride by using excess anhydrous hydrogen fluoride relative to the 831.
vinylidene chloride in the presence of a catalytic amount of a catalyst of the formula:
RmAclnFp wherein A is titanium, zirconium, or hafnium: R is an alkyl, alkenyl, or aryl group; m is 0 to 2: n is O to 4; and p is 0 to 4 with the proviso that at least one of n an~ p is not zero and mln~p satisfies the valence of A, for a time and at a temperature sufficient to form l,l-dichloro-l-fluoroethane. The term "excess anhydrous hydrogen fluoride~' as used herein means that the molar ratio of anhydrous hydrogen fluoride to vinylidene chloride is greater than 1:1. In other words, a deficiency of vinylidene chloride is used.
Regarding the non-catalyzed reaction of vinylidene chloride and anhydrous hydrogen fluoride as discussed in the aforementioned Henne article and U.S.
Patent 3,833,676, the present process is more advantageous because it reduces reaction time by more than 75~ to obtain 99.9% conversion of vinylidene chloride, Compared with the processes of the aforemeneioned U.S. Patent 4,253,225 and Feiring article which use tantalum pentafluoride to catalyze the reaction of vinylidene chloride and anhydrous hydrogen fluoride, the present process produces l,l-dichloro-l-fluoroethane in a higher yield in a shorter reaction time. Compared with the process of the previously discussed U.S. Patent 2,495,407 which uses stannic chloride to catalyze the reaction of dichloroethylene and anhydrous hydrogen fluoride, the present process produces l,l-dichloro-l-fluoroethane in a higher yield in a shorter reaction time.
~0~831 Although the above-mentioned U.S. Patent 4,766,258 mentions the use o~ titanium tetrachloride in the fluorination of hydrogen-containing hydrocarbon halides, the reference does not teach the present reaction. Further, because U.S. Patent 4,766,258 indicates yields of less than 2g% when titanium tetrachloride is used to fluorinate hydrogen-containing hydrocarbon halides, the reference would not lead a person of ordinary skill in the art to the present process.
Although the above-mentioned Feiring article teaches the use of titanium tetrachloride in the fluorination of tetrachloroethylene, the reference does not teach the present reaction. The purpose of the paper was to test the usefulness of catalysts including tentalum pentafluoride, niobium pentafluoride, titanium tetrachloride and molybdenum pentachloride in the fluorination of tetra-, tri- and dichloroethene. The paper concluded that tantalum pentafluoride appears to be the most active catalyst and reported that the reaction of 0.4 mole vinylidene chloride and 0.5 mole anhydrous hydrogen fluoride in the presence of tantalum pentafluoride at 25C for three hours yielded only 4Q%
HCFC-141b. Based on these teachings, the reference would not lead a person of ordinary skill in the art to the present process.
As such, the present invention provides a process for the preparation of l,l-dichloro-l-fluoro-ethane wherein the reaction time is shorter than that of known processes and 1,1-dichloro-1-fluoroethane is produced in a higher yield than in known processes.
Other advantages of the present invention will become apparent from the following description and appended claims.
DETAILED DESCRIPTI~N OF THE PREFERRE~ E 30DIMENTS
Commercially available anhydrouS hydrogen f luoride and vinylidene chloride may be used in the present invention. The addition of anhydrous hydrogen fluoride to the carbon-carbon double bond of the vinylidene chloride is a stoichiometric reaction in which one mole of anhydrous hydrogen fluoride is required for each mole of vinylidene chloride used.
Generally, the anhydrous hydrogen fluoride and vinylidene chloride are reacted with an excess of anhydrous hydrogen fluoride relative to the vinylidene chloride. It has been found that because the undesirable tars or high boilers are mainly formed by coupling or polymerization reactions among vinylidene chloride molecules, the amount of tars or high boilers formed during the reaction can be minimized by minimizing the amount of starting ~inylidene chloride used. As such, the use of excess vinylidene chloride is disadvantageous. Preferably, the anhydrous hydrogen fluoride and vinylidene chloride are reacted in a molar ratio of about 1.5:1 to about 5:1. The use of anhydrous hydrogen fluoride in an amount greater than the molar ratio of 5:l causes other fluorinated alkanes to form. More preferably, the anhydrous hydrogen fluoride and vinylidene chloride are reacted in a molar ratio of about 1.5:1 to about 4:1 and most preferably abou~ 1.5:1 to about 3:1.
The catalyst used is of the formula:
RmAclnFp whersin A is titanium, zirconium, or hafnium: R is an alkyl, alkenyl, or aryl group; m is O to 2; n is O to 4: and p is O to 4 with the proviso that at least ons ~.0~
of n and p is not zero and m+n+p satisfies the valence of A. For R, examples of useful alkyl groups include methyl, ethyl, isopropyl, butyl, pentyl, hexyl, heptyl and octyl. For R, examples of useful aryl groups include phenyl and naphthyl. The aryl group may also be substituted so as to include groups such as benzyl, tolyl and halogenated phenyls. For R, examples of useful alkenyl groups include cyclopentadienyl and pentamethylcyclopentadienyl.
When A is zirconium, preferred catalysts include zirconium tetrachloride, zirconium tetrafluoride, zirconium tetrabromide and zirconocene dichloride.
When A is hafnium, preferred catalysts include hafnium tetrachloride, hafnium tetrafluoride and hafnocene dichloride. When A is titanium, preferred catalysts include titanium trichloride, titanium tetrachloride, titanium trifluoride, titanium tetrafluoride, titanium tetrabromide and titanocene dichloride. The most preferred catalyst is titanium tetrachloride.
Commercially available zirconium tetrachloride.
zirconocene dichloride, hafnium tetrachloride, hafnocene dichloride, titanium tetrachloride, titanium tetrabromide and titanocene dichloride may be used in practicing the present invention.
A catalytic amount of catalyst is used.
Generally, the amount of catalyst used is about 0.01 to about 50 percent mole of catalyst per mole of vinylidene chloride used. Preferably, the amount of catalyst used is about 0.1 to about 10 percent, more preferably about 0.2 to about S percent and most preferably about 0.3 to about 2 percent.
31.
The reaction is preferably conducted at a temperature of about 30 to about 100C. At reaction temperatures below this limit, the reaction becomes too slow to be useful. At reaction temperatures above this limit, the product yield is reduced by the formation of by-products. More preferably, the reaction is conducted at a temperature of about 50 to about 65C:
in this range, the highest selectivity for l,l-dichloro-l-fluoroethane exists.
Operation o~ the reaction at atmospheric pressure is convenient. Operation at a pressure of about 10 to about 130 psig (69 to 897 KPa) is preferred. Means may be provided ~or venting of the excess pressure caused by hydrogen chloride formed in the reaction and offers an advantage in minimizing formation of side products.
A useful reaction vessel is constructed from materials which are resistant to the action of anhydrous hydrogen fluoride. Examples include metallic materials and polymeric materials. For reactions at temperatures above the boiling point of vinylidene chloride which is abou~ 30C, a closed reaction vessel is used to minimize the loss of vinylidene chloride and anhydrous hydrogen fluoride.
Gene~ally, vinylidene chloride, anhydrous hydrogen fluoride and catalyst are introduced in any order into the reaction vessel as long as an excess of anhydrous hydrogen fluoride relative to the vinylidene chloride is used. The contents of the vessel are raised to the appropriate reaction temperature and are agitated by sha~ing or stirring for a time sufficient for the anhydrous hydrogen fluoride and vinylidene chloride to react. The reaction progress may be ~`0~
monitored by withdrawing samples periodically.
Preferably, the reaction time is less than about 2 hours. More preferably, the reaction time is about 0.1 to about 1.5 hours.
Preferably, a catalytic amount of the catalyst is dissolved in the anhydrous hydrogen fluoride and this mixture is heated to about 50 to about 65C before the addition of vinylidene chloride thereto. Anhydrous hydrogen fluoride has a vapor pressure of about ~0 psig at 60C and a boiling point of 19.5C; at atmospheric pressure, titanium tetrachloride has a boiling point of 136.4C. When a catalytic amount of titanium tetrachloride was mixed with anhydrous hydrogen fluoride at 60C. the mixture had a vapor pressure of around 65-70 psig. This pressure increase suggested that anhydrous hydrogen fluoride reacted with titanium tetrachloride to produce a low boiling compound such as HCl. It is believed that several titanium species also formed. The following equation summarizes the probable reaction.
4TiC14 + lOHF --~ lOHCl + TiC13F + TiC12F2 + TiC1~3 + TiF4 As such, it is believed that titanium tetrachloride can be completely fluorinated to titanium tetrafluoride or partially fluorinated to compounds such as TiC13F, TiC12F2 and TiClF3. The mixture of titanium tetrachloride and anhydrous hydrogen fluoride could contain any combination of these four fluorinated titanium species. It is believed that the reaction between vinylidene chloride and anhydrous hydrogen fluoride can be catalyzed by any of the five titanium species or any combination thereof. As such, the catalyst of the formula RmAclnFp 83~L
wherein A, R, m, n and p are as pre~iously defined covers TiC13F, TiC12F2 and TiClF3.
The l,1-dichloro-1-fluoroethane product may be isolated by any of a variety of known techniques. The contents of the reaction vessel may be discharged onto ice and the organic layer collected, washed with water and dried with a drying agent. The product may be analyzed by standard techniques including gas-liquid chromatography, NMR spectroscopy and mass spectrometry.
The present process may be conducted in batch or continuous fashion.
The 1,1-dichloro-1-fluoroethane produced by the present process is particularly useful as a blowing agent for the production of rigid urethane thermoinsulation foam. See for example U.S. Patents 4,652,589; 4,686,240;
4,699,932: 4,701,474: 4,717,518: and 4,727.094.
The present invention is more fully illustrated by the following non-limiting Examples.
For each Example and Comparative, the molar ratio of anhydrous hydrogen fluoride to vinylidene chloride was about 1.9:1. Each run was agitated at 2400 RPM.
In Table 1 below, "Cat." stands for catalyst. "VC"
stands for vinylidene chloride. 142b is known in the art and is l-chloro-l,l-difluoroethane. 140a i8 also known in the art and is l,l,l-trichloroethane. "HB's" stands for High Boilers. In the column for "Total HB's", the number shown in parenthesis indicates the number of high boilers observed.
Co~parative_l 200 grams anhydrous hydrogen fluoride were charged to a l liter autoclave at room temperature. The autoclave 5 was heated to the reaction temperature, 60OC, with agitation. Five hundreds grams of vinylidene chloride were then pumped into the autoclave at a constant rate.
The progress of the reaction was monitored by withdrawing the organic layer periodically by using a dip leg installed in the reactor. The sample was quenched with an ice/water slush immediately. The organic layer was then isolated, dried and analyzed on a gas chromatograph. The reaction was considered to be completed when 99.9%
vinylidene chloride was converted.
After the reaction was completed, the reactor was cooled quickly to the ambient temperature and the organic layer was recovered and washed with ice/water slush. The washed crude product was then isolated, dried and analyzed. The results are listed under "Cl" in Table l below.
VC % HOL
25 FEED FRAC.
TEHP. RATE (Cat./ PaES. TIHE PRODUCT ANALYSIS(%) EX CAT. (C) (~/min? VC) (PSi~ (hr.? 142b 141b VC 140a TOTAL HB's Cl NONE 60 2.16 - 80-120 6.1 1.3 93 0.10 4.2 1.2 (3) C2 BF3 60 8.64 0.78 100-120 1.5 0.9 91 0.03 2.9 4.8 (5) C3 BF3 49 8.08 1.23 75-80 2.0 0.3 87 0.15 2.7 10.2 (5) 30 C4 TaF5 60 8.64 0.76 100-120 1.25 0.9 94 0.00 2.3 2.2 (4) C5 TaF5 60 9.09 0.38 100-120 1.5 0.6 94 0.03 2.4 3.2 (4) C6 SnC1460 8.96 0.81 110-150 1.5 4.4 84 1.60 9.9 0.4 (1) 1 TiC14 60 10.20 0.83 120-130 1.25 0.4 96 0.10 1.6 1.6 (2) 2 TiC14 60 9.43 0.90 124-126 1.25 0.4 96 0.09 1.9 0.8 (3) 35 3 TiC14 50 8.77 0.97 87-95 1.50 0.4 97 0.20 1.4 1.1 (3) 4 TiC14 6010.870.92 102-113 1.25 0.7 97 0.10 1.0 1.3 (3) 33~
The mecric uni~s for the pressure are in Table 2 below.
PRES.
F (KPa) Cl 552-828 3 60~-656 Major by-products of the reaction include 20 HCFC-142b, HCC-140a, HCl and hiqh boilers. The High boilers consisted of fluorinated 4-carbon and 6-carbon compounds, ~ome polymeric materials and the stabilizer used in the 6tarting vinylidene chloride. The crude product compositions were determined by analyzing the recovered liquid phase product. HCFC-142b has a boiling point much lower than room temperature and thus, the actual selectivity for HCFC-142b is slightly higher than that indicated in Table 1. HCC-140a wa generated from the reaction between vinylidene chloride and hydrogen chloride. Hydrogen chloride and HCFC-142b were formed from the reaction between HCFC-141b and HF. High boilers were mainly produced from coupling reactions and polymerization among vinylidene chloride molecules.
3~.
-- lg --The results indicate that ~he long reaction time of 6.1 hours has to be used ~or a non-catalyzed reaction.
S ComDaratives 2 and 3 In the same autoclave as in Comparative 1. two separate runs were conducted under similar conditions.
Boron trifluoride was charged to the reactor after 200 grams of anhydrous hydrogen fluoride were charged. The mixture was then heated to 60 and 49C respectively prior to the vinylidene chloride feed (500 g). The reactions were monitored in the same way as in Comparative 1. The crude product was also recovered and analyzed the same way. The results are listed under "C2" and "C3" in ~able 1 above.
Boron trifluoride seemed to promote coupli~g reactions and produced more high boilers (or tars). As a result. it produced a lower selectivity for HCFC-141b than the non-catalytic reaction of Comparative 1.
ComParatives 4 and S
Using the same apparatus as in Comparative 1.
the same reaction conditions as in Comparative 2 were used for these two runs, except tantalum pentafluoride was used as catalyst. The results are listed under "C4" and "C5" in Table 1 above.
These results are surprising in view of the results reported by the aforementioned Feiring reference. The article reported that the reaction of 0.4 mole vinylidene chloride and 0.5 mole anhydrous hydrogen fluoride in the presence of tantalum pentafluoride at 25C for three hours yielded only 40%
~00~31 HCFC-141b. It is believed that the better yield results ~rom dissolving tantalum pentafluoride in the anhydrous hydrogen fluoride and heating this mixture to the reaction temperature before adding a deficiency of vinylidene chloride thereto.
Tantalum pentafluoride improved the selectivity and reduced reaction time. but still produced slightly more tars.
ComDarative 6 Tin tetrachloride was studied in this run. The number of moles of catalyst used was about the same as lS in Comparative 2. The other reaction conditions were also quite similar. The crude product was also recovered in the same way. A third phase heavier than the organic phase was also observed ~hich suggested that tin tetrachloride was not very soluble in either the anhydrous hydrogen fluoride or the organic phase.
The results of crude organic product analysis are listed under "C6" in Table 1 above.
Tin tetrachloride reduced the amounts or high boilers. bu~ did not catalyze the reaction as well as the other catalysts. Tin tetrachloride promoted the formation of HCFC-142b and HCC-140a. resulting in lower selectivity for HCFC-141b.
The catalytic activity of titanium tetrachloride was also studied in the same 1 liter autoclave. The reaction conditions were similar to those used for Co~paratives 4 and 5, except titanium tetrachloride was used as catalyst instead of tantalum pentafluoride.
3 ~831.
The desired amounts of fresh titanium tetrachloride were used ~or these three runs re.spectively. For Examples 1 and 2, 60C was employed and 50C was used for Example 3. The results of these three experiments are listed under 1, 2 and 3 in Table 1 above.
When tantalum pentafluoride was used, the yield of 141b was 94%. In the present process, the yield of 141b was 96-97%. As such, titanium tetrachloride is more selective and produces less ta~s. This yield increase represents a major economic advantage to a commercial user of the present process who will be producing substantial quantities of 141b. Savings of over one million dollars per year are expected.
Titanium tetrachloride is also commercially available and less expensive than tantalum pentafluoride.
The reaction conditions for this run were almost identical to those of Example 3, except that titanium tetrachloride and about 90 geams anhydrous hydrogen fluoride were recycled from Example 3. 105 grams of fresh anhydrous hydrogen fluoride were also added for the reaction by assuming that 95% catalyst was retained in the anhydrous hydrogen fluoride phase. The results of this run are listed under 4 in Table 1 above. The recycled titanium tetrachloride showed the same catalytic activity as the fresh catalyst used in Examples 1 and 2.
As illustrated by Examples 1 through 4, titanium tetrachloride gave the highest selectivity for l,l-dichloro-l-fluoroethane and did not produce more high boilers than the non-catalytic reaction.
Exam~les 5-15 Using the same apparatus and reaction procedures as in Comparative 2, the catalysts o~ Table 3 below are run using the following conditions: temperature =
60OC: vinylidene chloride feed rate = ~0 g/m; catalyst/
vinylidene chloride ~ mole reaction = 0.8-1: pressure =
80-120 psig (552-828 KPa): and time - 1.5 hours.
EX. CAT.
S ZrCl4 6 ZrF4 15 7 Zrcl2(c5H5)2 8 HfC14 ~ HfF4 HfC12(C5H5)2 11 TiC13 2012 TiC14 13 TiF3 14 TiF4 lS TiC12(C5H5) Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.
Claims (20)
1. A process for the preparation of a hydrochlorofluorocarbon comprising the step of:
reacting anhydrous hydrogen fluoride and vinylidene chloride by using excess anhydrous hydrogen fluoride in the presence of a catalytic amount of a catalyst of the formula RmAClnFp wherein A is titanium, zirconium, or hafnium: R is an alkyl, alkenyl, or aryl group: m is 0 to 2: n is 0 to 4: and p is 0 to 4 with the proviso that at least one of n and p is not zero and m+n+p satisfies the valence of A, for a time and at a temperature sufficient to form 1,1-dichloro-1-fluoroethane.
reacting anhydrous hydrogen fluoride and vinylidene chloride by using excess anhydrous hydrogen fluoride in the presence of a catalytic amount of a catalyst of the formula RmAClnFp wherein A is titanium, zirconium, or hafnium: R is an alkyl, alkenyl, or aryl group: m is 0 to 2: n is 0 to 4: and p is 0 to 4 with the proviso that at least one of n and p is not zero and m+n+p satisfies the valence of A, for a time and at a temperature sufficient to form 1,1-dichloro-1-fluoroethane.
2. The process of claim 1 wherein said molar ratio of said anhydrous hydrogen fluoride to said vinylidene chloride is about 1.5:1 to about 5:1.
3. The process of claim 1 wherein said anhydrous hydrogen fluoride and said vinylidene chloride are reacted in a molar ratio of about 1.5:1 to about 4:1.
4. The process of claim 1 wherein said anhydrous hydrogen fluoride and said vinylidene chloride are reacted in a molar ratio of about 1.5:1 to about 3:1.
5. The process of claim 1 wherein said reaction is conducted at a temperature of about 30 to about 100°C.
6. The process of claim 1 wherein said reaction is conducted at a temperature of about 50 to about 65°C.
7. The process of claim 1 wherein said catalyst is dissolved in said anhydrous hydrogen fluoride and heated to a temperature of about 50 to about 65°C
before reaction with said vinylidene chloride.
before reaction with said vinylidene chloride.
8. The process of claim 1 wherein said catalyst is used in an amount of about 0.3 to about 2 percent mole of catalyst per mole of said vinylidene chloride.
9. The process of claim 1 wherein said A is zirconium.
10. The process of claim 1 wherein said A is hafnium.
11. The process of claim 1 wherein said A is titanium.
12. The process of claim 1 wherein said catalyst is zirconium tetrachloride.
13. The process of claim 1 wherein said catalyst is zirconocene dichloride.
14. The process of claim 1 wherein said catalyst is hafnium tetrachloride.
15. The process of claim 1 wherein said catalyst is hafnocene dichloride.
16. The process of claim 1 wherein said catalyst is titanium tetrachloride.
17. The process of claim 1 wherein said catalyst is titanocene dichloride.
18. The process of claim 1 wherein said catalyst is titanium tetrabromide.
19. A process for the preparation of a hydrochlorofluorocarbon comprising the step of:
reacting anhydrous hydrogen fluoride and vinylidene chloride in a molar ratio of about 1.5:1 to about 5:1 in the presence of a catalytic amount of titanium tetrachloride for a time and at a temperature sufficient to form 1,1-dichloro-1-fluoroethane.
reacting anhydrous hydrogen fluoride and vinylidene chloride in a molar ratio of about 1.5:1 to about 5:1 in the presence of a catalytic amount of titanium tetrachloride for a time and at a temperature sufficient to form 1,1-dichloro-1-fluoroethane.
20. The process of claim 19 wherein said titanium tetrachloride is dissolved in said anhydrous hydrogen fluoride and heated to a temperature of about 50 to about 65°C before reaction with said vinylidene chloride.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US29012788A | 1988-12-27 | 1988-12-27 | |
| US290,127 | 1988-12-27 |
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| Publication Number | Publication Date |
|---|---|
| CA2004831A1 true CA2004831A1 (en) | 1990-06-27 |
Family
ID=23114645
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002004831A Abandoned CA2004831A1 (en) | 1988-12-27 | 1989-12-07 | Process for the preparation of 1,1-dichloro-1-fluoroethane |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0378942B1 (en) |
| JP (1) | JPH02231439A (en) |
| KR (1) | KR920004455B1 (en) |
| AU (1) | AU628904B2 (en) |
| CA (1) | CA2004831A1 (en) |
| DE (1) | DE68902638T2 (en) |
| ES (1) | ES2052050T3 (en) |
| GR (1) | GR3006274T3 (en) |
| MX (1) | MX170484B (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE69005697T2 (en) * | 1989-05-25 | 1994-07-14 | Du Pont | Process for the preparation of 1,1-dichloro-1-fluoroethane. |
| CN1037097C (en) * | 1992-12-12 | 1998-01-21 | 浙江省化工研究院 | Process for preparing 1,1-dichloro-1-fluoroethane by fluoridation of liquid-phase 1,1-dichloroethene |
| EP0795530A4 (en) * | 1994-11-09 | 1998-01-21 | Nippon Zeon Co | Process for producing halogenated organic compounds |
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1989
- 1989-12-06 KR KR1019890018044A patent/KR920004455B1/en not_active IP Right Cessation
- 1989-12-07 CA CA002004831A patent/CA2004831A1/en not_active Abandoned
- 1989-12-13 MX MX018695A patent/MX170484B/en unknown
- 1989-12-19 DE DE8989403551T patent/DE68902638T2/en not_active Expired - Fee Related
- 1989-12-19 EP EP89403551A patent/EP0378942B1/en not_active Expired - Lifetime
- 1989-12-19 ES ES89403551T patent/ES2052050T3/en not_active Expired - Lifetime
- 1989-12-21 JP JP1332462A patent/JPH02231439A/en active Pending
- 1989-12-22 AU AU47208/89A patent/AU628904B2/en not_active Ceased
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1992
- 1992-11-18 GR GR920402632T patent/GR3006274T3/el unknown
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| Publication number | Publication date |
|---|---|
| DE68902638T2 (en) | 1993-03-18 |
| KR900009517A (en) | 1990-07-04 |
| AU4720889A (en) | 1990-07-05 |
| EP0378942B1 (en) | 1992-08-26 |
| MX170484B (en) | 1993-08-25 |
| DE68902638D1 (en) | 1992-10-01 |
| EP0378942A1 (en) | 1990-07-25 |
| AU628904B2 (en) | 1992-09-24 |
| JPH02231439A (en) | 1990-09-13 |
| ES2052050T3 (en) | 1994-07-01 |
| GR3006274T3 (en) | 1993-06-21 |
| KR920004455B1 (en) | 1992-06-05 |
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