Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Reexamination Certificate
1993-11-26
2001-02-20
Siegel, Alan (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
Reexamination Certificate
active
06191327
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for producing 3,3-dichloro-1,1,1,2,2-pentafluoropropane (hereinafter sometimes referred to simply as R225ca) and 1,3-dichloro-1,1,2,2,3-pentafluoropropane (hereinafter sometimes referred to simply as R225cb).
BACKGROUND ART
Hydrogen-containing chlorofluoropropanes such as R225ca and R225cb are expected to be useful as blowing agents, refrigerants or cleaning agents, like conventional chlorofluorocarbons.
Heretofore, a method for synthesizing R225ca and R225cb by the addition reaction of tetrafluoroethylene (hereinafter sometimes referred to simply as 4F) with dichlorofluoromethane (hereinafter sometimes referred to simply as R21) in the presence of an aluminum chloride catalyst, as shown by the following formula.
CF
2
=CF
2
(4F)+CHCl
2
F(R21)→CF
3
CF
2
CHCl
2
(R225ca)+CClF
2
CF
2
CHClF(R225cb)
[see 1) U.S. Pat. No. 2,462,402 (Du Pont), 1949, 2) D. Coffman, et al., Journal of American Chemical Society, 71,979 (1949), 3) O. Paleta, et al., Collect. Czech. Chem. Commun., 36, 1867 (1971)]
Thereafter, an improved synthesis of R225ca and R225cb employing aluminum chloride or halogenated aluminum oxide alone, as a catalyst in the above reaction, has been proposed.
[see 4) Japanese Unexamined Patent Publication No. 118338/1991 (Daikin), 5) Japanese Unexamined Patent Publication No. 178940/1991 (Daikin), 6) EP-0-421322-A1 (Daikin)]
Methods 1), 2) and 3) employing an aluminum chloride catalyst, have a difficulty that chloroform which forms azeotrope with the desired products, will be formed in a large amount as a by-product, and dichloropentafluoropropane isomers which are hardly separable by a usual method such as distillation because their boiling points are close to those of the desired products, will be formed as by-products. Such isomers include 2,2-dichloro-1,1,1,3,3-pentafluoropropane (hereinafter sometimes referred simply as R225aa) and 2,3-dichloro-1,1,1,2,3-pentafluoropropane (hereinafter sometimes referred to simply as R225ba). Accordingly, they have a drawback that a multi-stage purification process is required in order to obtain highly pure R225ca and R225cb, and it has been desired to suppress the formation of such by-products.
Further, in the improved methods 4), 5) and 6), formation of chloroform is suppressed to some extent, but no improvement has been made with respect to the formation of R225aa and R225ba as by-products.
DISCLOSURE OF THE INVENTION
The present inventors have conducted an extensive study for a method for efficiently producing R225ca and R225cb and as a result, have found it possible to form R225ca and R225cb in good yield substantially without formation of R225aa and R225ba by using a catalyst comprising halogenated oxide containing at least one element selected from Group 4, Group 5 and Group 13 (excluding, however, halogenated aluminum oxide alone). Further, even with a halogenated aluminum oxide, it is possible to suppress formation of R225aa and R225ba effectively by converting it to a composite halogenated oxide with other elements. Further, it has been found that R225ca and R225cb can be obtained in good yield while suppressing formation of chloroform as a by-product, by adding the excess amount of 4F to R21 when 4F and R21 are reacted.
Firstly, the present invention provides a novel method for producing 3,3-dichloro-1,1,1,2,2-pentafluoropropane and 1,3-dichloro-1,1,2,2,3-pentafluoropropane, which comprises reacting tetrafluoroethylene with dichlorofluoromethane in the presence of a catalyst comprising halogenated oxide containing at least one element selected from Group 4, Group 5 and Group 13 (excluding a halogenated aluminum oxide alone).
Further, the present invention provides a novel method for producing 3,3-dichloro-1,1,1,2,2-pentafluoropropane and 1,3-dichloro-1,1,2,2,3-pentafluoropropane, which comprises reacting tetrafluoroethylene with dichlorofluoromethane in the presence of a catalyst comprising halogenated oxide containing at least one element selected from Group 4, Group 5 and Group 13 and at least one element selected from Group 2, Group 6, Group 12, Group 14 and Group 15.
The catalyst comprising halogenated oxide containing at least one member selected from Group 4, Group 5 and Group 13 in the present invention, can be represented by the general formula (1):
MX
p
O
q
(1)
wherein M is at least one element selected from Group 4, Group 5 and Group 13, and X is at least one element selected from F, Cl, Br and I, and 0<p<5, 0<q<2.5 and 3≦p+2q<8.
X in the above general formula (1) is preferably at least one or two elements selected from F and Cl. It is essential that component M contains an element selected from Group 4, Group 5 and Group 13. However, a case where component M is aluminum alone is excluded, since in such a case, R225aa and R225ba will be produced in a large amount as by-products.
Elements selected from Group 4, Group 5 and Group 13 may be used alone or as a mixture of two or more of them. It is considered that in halogenated oxide in which two or more elements selected from Group 4, Group 5 and Group 13 coexist, crystal lattice defects will be introduced, whereby the reaction activity will increase, and by introducing other elements with electronically different states, electronical states of the catalyst can be changed, whereby the activity of the catalyst can readily be controlled. Accordingly, in the present invention, it is preferred to use two or more elements selected from Group 4, Group 5 and Group 13, as component M. In such a case, the mixing proportions are not particularly limited, and the respective elements may be mixed in various proportions within a range from 1 wt % to 99 wt %.
For the same reason, it is possible to use, as component M, either an element or elements selected from Group 4, Group 5 and Group 13 in combination with at least one other element. Such other element is not particularly limited, but element selected from Group 2, Group 6, Group 12, Group 14 and Group 15 is preferred. Also in this case, the mixing proportions are not particularly limited, and the former and latter elements may be mixed in proportions within a range from 1 wt % to 99 wt %.
In a case where aluminum is contained as component M in the general formula (1), formation of R225aa and R225ba as by-products can be suppressed by an addition of other element. Such other element is not particularly limited, but an element selected from Group 4, Group 5 and Group 13 except for aluminum and an element selected from Group 2, Group 6, Group 12, Group 14 and Group 15, is particularly preferred. In such a case, the mixing proportions of aluminum and other element may be at any optional proportions. However, in order to suppress the formation of R225aa and R225ba effectively, it is preferred to control the mixing porportion of aluminum preferably at a level of at most 95 wt %, particularly preferably at most 70 wt %.
In the catalyst to be used in the present invention, the Group 4 element may be Ti, Zr or Hf, the Group 5 element may be V, Nb or Ta, and the Group 13 element may be B, Al, Ga, In and Tl. As the Group 4 element, each of Ti, Zr and Hf is preferred, and Ti or Zr is particularly preferred. As the Group 5 element, V, Nb or Ta is preferred, and as the Group 13 element, B or Ga is preferred.
In the catalyst to be used in the present invention, the Group 2 element may be Be, Mg, Ca, Sr, Ba or Ra, the Group 6 element may be Cr, Mo or W, the Group 12 element may be Zn, Cd or Hg, the Group 14 element may be Si, Ge, Sn or Pb, and the Group 15 element may be P, As, Sb or Bi. As the Group 2 element, Ba is preferred, as the Group 6 element, W is preferred, as the Group 12 element, Zn is preferred, as the Group 14 element, Si or Sn is preferred, and as the Group 15 element, P or Bi is preferred.
In the present invention, the method for preparing the catalyst is not particularly limited. For example, it may be a method wherein a halide of the above-mentioned element of Group 4, Group 5, Group 13, Group 2
Morikawa Shinsuke
Ohnishi Keiichi
Okamoto Hidekazu
Tanuma Toshihiro
Asahi Glass Company Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Siegel Alan
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