Organic compounds -- part of the class 532-570 series – Organic compounds – Halogen containing
Reexamination Certificate
1998-12-04
2001-05-22
Siegel, Alan (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Halogen containing
C570S211000
Reexamination Certificate
active
06235952
ABSTRACT:
A method for isomerizing a halogenated ethylbenzene and a method for separating halogenated ethylbenzene isomers.
TECHNICAL FIELD
The present invention relates to a method for isomerizing a halogenated ethylbenzene and a method for separating halogenated ethylbenzene isomers. In more detail, the present invention relates to a method for isomerizing a halogenated ethylbenzene by bringing the same into contact with an acidic zeolite, for obtaining a desired isomer, and a method for separating and recovering a m-halogenated ethylbenzene from a mixture of halogenated ethylbenzene isomers.
BACKGROUND ARTS
Halogenated ethylbenzenes are known as important intermediate products of agricultural chemicals, etc. Especially m-chloroethylbenzene (hereinafter chloroethylbenzene is abbreviated as CEB) or m-bromoethylbenzene (hereinafter bromoethylbenzene is abbreviated as BEB) is expected as a raw material of agricultural chemicals with specific bioactivity as an isomer different from p- and o-isomers.- CEB or BEB is mainly produced by aromatic ring chlorination or bromination reaction of ethylbenzene, but since the reaction is very strong in ortho-orientation and para-orientation, the m-isomer can be produced only in a small amount.
Therefore, CEB and BEB isomerization methods have an important technical significance. Conventionally known isomerization reactions for these compounds include a method of using aluminum chloride, etc. as a catalyst disclosed in Olah. G. A. J. Org. CHEM. 27, 3464 (1962), a method of using HF—BF
3
as a catalyst disclosed in Japanese Patent Laid-Open (Kokai) 46-11809, etc. Furthermore, Idar A. Acta Chemica Scandinavica B39,437 (1985) describes a chloroethylbenzene isomerization reaction using a mordenite-type zeolite. Furthermore, methods for isomerizing a halogenated toluene using a zeolite as a catalyst are disclosed in Japanese Patent Laid-Open (Kokai) Nos. 57-40428, 85330, 163327 and 7-309792.
However, in the isomerization reactions of halogenated ethylbenzenes, it has been difficult to efficiently isomerize using conventional catalysts such as aluminum chloride and HF—BF
3
since the disproportionation reaction accompanying the de-ethylation reaction or intermolecular migration of ethyl groups is likely to occur, unlike the isomerization reactions of halogenated toluenes. Furthermore, because of such problems as the enormous use of catalyst for isomerization, corrosion of reactor and environmental issue in the treatment of waste catalyst, the conventional methods are not efficient. The isomerization reaction using a mordenite catalyst is less in these problems, but has such a disadvantage that since the catalyst life is short, the zeolite must be regenerated after hundreds of hours. So, a method for more efficiently obtaining a desired halogenated ethylbenzene is strongly demanded.
For separation of halogenated ethylbenzene isomers, since the halogenated ethylbenzene isomers are not so different in boiling point, a precision distillation column with a very large number of stages is necessary for separating them. So, it has been difficult to efficiently separate a m-halogenated ethylbenzene at high purity.
As methods for separating the isomers of chlorotoluene structurally different from halogenated ethylbenzenes of the present invention, Japanese Patent Publication (Tokko) No. 37-5155 discloses an adsorption separation method using a zeolite X as the adsorbent, and Japanese Patent Laid-Open (Kokai) Nos. 57-31627, 35528 and 91933 disclose adsorption separation methods using a K ion exchanged zeolite Y as the adsorbent. These methods can separate the m-isomer from the p-isomer by adsorption, but cannot separate the m-isomer from the o-isomer, and m-chlorotoluene cannot be singly separated as an extract component or raffinate component. Furthermore, Japanese Patent Laid-Open (Kokai) Nos. 58-131923 and 59-176223 disclose m-chlorotoluene separation methods using an Ag and K ion exchanged zeolite Y or a Na and Cu ion exchanged zeolite Y as the adsorbent, and these methods can separate m-chlorotoluene as a raffinate component. However, as far as the inventors examined, these adsorbents could little separate m-CEB. As described so far, no method for adsorbing and separating a halogenated ethylbenzene has been known at all, and there has been no idea of attempting it at all.
DISCLOSURE OF THE INVENTION
The inventors studied intensively to solve the problem, and as a result, found that a halogenated ethylbenzene can be isomerized by bringing the same into contact with an acidic zeolite containing at least one metal selected among metals of Groups 7 to 11. Thus, the present invention has been completed.
The present invention relates to a method of isomerizing a halogenated ethylbenzene, comprising the step of bringing the halogenated ethylbenzene into contact with an acidic zeolite containing at least one metal selected among the metals of Groups 7 to 11 for isomerizing it. In the present invention, it is preferable that the isomerization method is effected in the presence of hydrogen, and that the acidic zeolite is a faujasite-type, beta-type, mordenite-type or pentasil-type zeolite. Furthermore, it is preferable that the halogen of the halogenated ethylbenzene is chlorine or bromine.
On the other hand, the inventors studied intensively on the method for efficiently separating a halogenated ethylbenzene, and found that m-isomer can be efficiently separated from a mixture of halogenated ethylbenzene isomers, particularly of CEB or BEB, by adsorption separation, using an adsorbent containing a specific zeolite and a desorbent. Thus, the present invention as a method for separating halogenated ethylbenzene isomers has been completed. The present invention relates to a method for separating halogenated ethylbenzene isomers, comprising the step of separating a m-halogenated ethylbenzene from a mixture of halogenated ethylbenzene isomers using an adsorbent containing a zeolite X containing an alkali metal and/or alkaline earth metal, or an adsorbent containing a zeolite Y containing sodium, and a desorbent.
In the present invention, the following two embodiments are preferable: a method for separating halogenated ethylbenzene isomers, comprising the step of separating a m-halogenated ethylbenzene as an extract component using an adsorbent containing a zeolite X containing alkali metal cations and not containing silver cations or containing silver cations by less than 10% of the ion exchange sites, or containing a zeolite Y containing sodium, and a method for separating halogenated ethylbenzene isomers, comprising the step of separating a m-halogenated ethylbenzene as a raffinate component using an adsorbent containing a zeolite X containing alkali metal and/or alkaline earth metal cations and containing silver cations by 10% or more of the ion exchange sites.
The present invention is especially effective when the mixture of halogenated ethylbenzene isomers is a mixture of chloroethylbenzene isomers or a mixture of bromoethylbenzene isomers.
Furthermore, in the present invention, it is preferable that the desorbent used is an alkyl substituted aromatic hydrocarbon, halogenated aromatic hydrocarbon or halogenated alkyl substituted aromatic hydrocarbon.
REFERENCES:
patent: 4774371 (1988-09-01), Miwa et al.
patent: 5466881 (1995-11-01), Pies et al.
patent: 0 278 729 A1 (1988-08-01), None
patent: 0 699 650 A1 (1996-03-01), None
patent: 5791933 (1982-08-01), None
patent: 08309197 (1996-11-01), None
patent: 09 220474 (1997-08-01), None
Minomiya Eiichi
Miyata Satoru
Miller Austin R.
Siegel Alan
Toray Industries Inc.
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