Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Reexamination Certificate
1998-11-30
2001-11-13
Siegel, Alan (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
Reexamination Certificate
active
06316682
ABSTRACT:
APPLICABLE INDUSTRIAL FIELDS
The present invention relates to a method of producing 1,1,1,3,3-pentafluoropropane, which is an alternative compound to CFC's and HCFC's and is important in industry as a blowing agent, a refrigerant, a detergent, and a propellant that does not destroy the ozone in the ozone layer.
PRIOR ART
As to the method of producing 1,1,1,3,3-pentafluoropropane (hereinafter referred to as HFC-245fa), the following methods are known: a method of obtaining HFC-245fa (WO 95/04022) in which 1,1,1,3,3,3-hexachloropropane, obtained by the addition of carbon tetrachloride and vinylidene chloride, is fluorinated to produce 1,1,1,3,3-pentafluoro-3-chloropropane. Next, the obtained 1,1,1,3,3-pentafluoro-3-chloropropane is reduced with hydrogen to produce HFC-245fa. Also a method of obtaining HFC-245fa (EP 0611744) by hydrogen reduction of 1,1,1,3,3-pentafluoro-2,3-dichloropropane or 1,1,1,3,3-pentafluoro-2,2,3-trichloropropane.
Both of these methods, however, require 2 processes: a fluorination process to obtain a precursor by fluorinating chlorides and a reduction process to reduce the obtained compound with hydrogen. Consequently, they have the disadvantage of being industrially inferior in terms of economic efficiency and the like because of the length of time taken by these processes.
Furthermore, because the hydrogen fluoride (hereinafter referred to as HF) yielded in the fluorination process forms a minimum azeotropic composition of about 1:1 mole with HFC-245fa, if any HF exists in the reaction system, unreacted HF will form an azeotrope with the HFC-245fa, which must then be removed from the system.
The HF is separated from HFC-245fa by a commonly known method and is recovered or discarded. That is, although HF is separated by a liquid separation operation, the inventors of the present invention has made it clear that the liquid separation of the azeotrope cannot be performed when the quantity of HF is large.
Moreover, in the case of washing with water, because the HF contained in an azeotrope is discarded as it is, there is a large loss of HF in this process. Besides, although it is possible to extract HF, when the quantity of HF is large, the economic efficiency of the method is reduced, resulting in high costs for the recovery of HF.
There is another known method of producing HFC-245fa, used to obtain HFC-245fa (WO 96/01797). In this method, 1,1,1,3,3-pentachloropropane is obtained by a reaction from the addition of carbon tetrachloride and vinyl chloride, and is then fluorinated with HF in the presence of a fluorination catalyst to produce HFC-245fa.
In this method, however, because the HFC-245fa produced forms an azeotropic composition with the unreacted HF, it is difficult to separate HFC-245fa, and the cost of purifying it is prohibitive, as mentioned above. Consequently, this method cannot be called an economically profitable method.
OBJECT OF THE INVENTION
The object of the present invention is to provide an economical method of producing HFC-245fa with superior selectivity, which is an alternative compound to CFC's and HCFC's and is important in industry as a blowing agent, a refrigerant, a detergent, and a propellant that does not destroy ozone in the ozone layer.
CONSTITUTION OF THE INVENTION
After carefully studying the methods of producing HFC-245fa in order to solve the above-mentioned problems, the inventors of the present invention found that HFC-245fa in particular, can be easily formed by reacting readily available 1,1,1,3,3-pentachloropropane with a fluorinated antimony chloride under conditions that exclude hydrogen fluoride; and further that HFC-245fa can be obtained with high selectivity by maintaining the amount of fluorine in the fluorinated antimony chloride, and by adequately controlling the reaction conditions.
As a result, the inventors found a method of economically producing HFC-245fa in high yields using only a fluorination process of a chloride as the raw material (that is, without the need for a hydrogen reduction process), resulting in the completion of the present invention.
That is, the present invention consists of a method of producing 1,1,1,3,3-pentafluoropropane in which 1,1,1,3,3-pentafluoropropane is obtained by reacting at least one selected from the group consisting of fluorinated and chlorinated propane and chlorinated propane, expressed by a general formula of CX
3
CH
2
CHX
2
(where X in this general formula indicates either a fluorine atom or a chlorine atom; however, all of X's can never represent fluorine atoms at the same time) with a fluorinated antimony chloride.
When producing 1,1,1,3,3-pentafluoropropane (HFC-245fa) using the method of the present invention, it is especially important to carry out the reaction in the absence of HF. That is, since HFC-245fa forms a minimum azeotrope of about 1:1 mole with HF as mentioned above, if HF exists in the system, unreacted HF will form an azeotrope with the HFC-245fa that has been produced, and this will be discharged from the system together with the HFC-245fa. When the quantity of such HF is larger than those of azeotrope composition, liquid separation between HF and HFC-245fa cannot be performed.
Accordingly, in the present invention, without providing any of HF into a reactor HFC-245fa can be obtained as a product. HFC-245fa product is obtained as an organic composition, and substantially does not contain HCl or HF, through a reaction using a fluorinated antimony chloride (liquid in a reactive condition) as a source of fluorine. In this way, HFC-245fa can be efficiently obtained without operations of separation, recovery and discard of HF.
In the method of the present invention, fluorinated antimony chlorides, obtained by fluorinating antimony pentachloride or antimony trichloride can be used as fluorinating agents.
Those fluorinated antimony chlorides in which antimony is pentavalent or trivalent can be used independently or as a mixture. These fluorinated antimony chlorides can be used without any trouble if the materials of the reactor are properly selected.
It is preferable that the fluorinated antimony chlorides to be used in the reaction are fluorinated by hydrogen fluoride in order to maintain their fluorine content (because the fluorine content reduces as the reaction progresses).
Practically, the method is outlined in
FIG. 1. A
second reactor (Reactor (2)) is installed separate from a first reactor (Reactor (1)) in which the product (HFC-245fa) is to be produced.
A fluorinated antimony chloride (10), with lowered fluorine content (supplied for the reaction in Reactor (1)) is introduced into Reactor (2), and regenerated there by adding hydrogen fluoride (5). Next, the regenerated fluorinated antimony chloride (11) is returned to Reactor 1.
The regeneration of the fluorinated antimony chloride can be performed continuously, however, it is not restricted to a such way.
Moreover, it is also possible to conduct the formation reaction of HFC-245fa and the regeneration reaction of the fluorinated antimony chloride by turns in one reactor.
In the method of the present invention, no special solvent is needed but it is also possible to use a known reaction solvent if necessary. Any solvent, as long as it is inert to a fluorinating agent (a fluorinated antimony chloride), can be used as such.
In the method of the present invention, although the reaction temperature is not critical, a convenient reaction temperature range is between 50° C. and 200° C. and is preferably between 60° C. and 180° C.
Furthermore, in the method of the present invention, though the reaction pressure is not critical, a convenient reaction pressure is between atmospheric pressure and 30 kg/cm
2
G, and preferably is between atmospheric pressure and 20 kg/cm
2
G.
Though the reaction products obtained by the present invention vary according to the reaction conditions, when 1,1,1,3,3-pentachloropropane (240fa) is used as the basic raw material, besides HFC-245fa, insufficiently fluorinated products, including fluorotetrachloropropane (HCFC-241 containing isomers), d
Akinori Yamamoto
Nakada Tatsuo
Shibanuma Takashi
Armstrong Westerman Hattori McLeland & Naughton LLP
Daikin Industries Ltd.
Siegel Alan
LandOfFree
Process for preparing 1,1,1,3,3-pentafluoropropane does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for preparing 1,1,1,3,3-pentafluoropropane, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for preparing 1,1,1,3,3-pentafluoropropane will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2581179