Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1998-06-02
1999-09-14
Shippen, Michael L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
549513, C07C 2700
Patent
active
059525339
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a novel process for preparing 1,6-hexanediol from epoxybutadiene.
1,6-Hexanediol is an important intermediate in the preparation of polyesters and polyurethanes. U.S. Pat. No. 3,070,633 describes a process for preparing 1,6-hexanediol by hydrogenation of 2,5-tetrahydrofurandimethanol. It is prepared on an industrial scale by hydrogenation of adipic acid or its derivatives (Weissermel, Arpe, Industrielle Organische Chemie, 4th edition, Verlag Chemie 1994, p. 263). A disadvantage of these processes is the use of corrosive streams which require expensive materials of construction. Furthermore, the hydrogenation is only economical at high pressures, so that suitable reactors incur high capital costs. Finally, the hydrogenation of one equivalent of adipic acid requires 4 equivalents of hydrogen.
The preparation of bisepoxyhexatrienes of the formulae Ia und Ib ##STR2## is possible, according to Kuszmann et al., Carbohydrate Research, 83 (1980) 63, by reacting ditosylates or dimesylates of tetrols with superstoichiometric amounts of base. Since, however, the precursors required are complicated to prepare and the method is linked to the formation of stoichiometric amounts of salt, it is not suitable for the preparation of the bisepoxytrienes in large amounts.
It is an object of the present invention to provide a process which allows the preparation of 1,6-hexanediol at significantly lower pressures than are used in the prior art. Furthermore, the process should be able to be carried out using less hydrogen per equivalent of hexanediol. A further aspect of the object of the present invention is to find a process which makes possible the preparation of bisepoxyhexatrienes of the formulae Ia and Ib while avoiding the abovementioned disadvantages of the prior art.
We have found that this object is achieved by a process for preparing 1,6-hexanediol, which comprises elimination of ethene to give bisepoxyhexatrienes of the formulae Ia and Ib and 1,6-hexanediol.
The overall process for preparing 1,6-hexanediol from epoxybutadiene is shown in the following reaction equation: ##STR3##
Process step a)
According to the present invention, 2 equivalents of epoxybutadiene are reacted with elimination of ethene to give the bisepoxytrienes of the formulae Ia and Ib. According to U.S. Pat. No. 4,897,498, epoxybutadiene can be prepared by epoxidation of butadiene. It is preferably used in pure form, but can also contain secondary constituents such as crotonaldehyde, 2,3-dihydrofuran and 2,5-dihydrofuran. The reaction takes place in the presence of a metathesis catalyst. These are catalysts which establish an equilibrium of the type .dbd.CH.sub.2 --R.sub.2 .revreaction.R.sub.1 --CH.sub.2 .dbd.CH.sub.2 --R.sub.1 +R.sub.2 --CH.dbd.CH.sub.2 --R.sub.2, se, and are heterogeneous or homogeneous transition metal compounds, in particular those of transition metals of groups 4 and 6-10 of the Periodic Table of the Elements. Such catalysts are described, for example, in Parshall, Ittel, Homogeneous Catalysis, 2nd edition, Wiley 1992, pp. 217-236, also in Banks, Catalysis, Vol. 4, pp. 100-129 and in Grubbs, Progress in Inorg. Chem., Vol. 24, pp. 1-50.
Preferred metathesis catalysts contain ruthenium. Particularly preferred catalysts are ruthenium compounds of the general composition RuX.sub.2 (.dbd.CHR)(PR'.sub.3).sub.2, where X is a halogen such as fluoro, chloro, bromo and iodo, R is hydrogen, alkyl cycloalkyl, aryl or aralkyl and R' is alkyl, cycloalkyl, aryl or aralkyl, as are described in WO-A 93/20111. Particular preference is also given to catalysts of the composition RuX.sub.2 (Arene)/PR.sub.3, where X is a halogen such as fluorine, chlorine, bromine and iodine and R is hydrogen, alkyl, cycloalkyl, aryl or aralkyl, as are described, also in combination with a diazoalkane compound, in Noels, J. Chem. Soc., Chem. Commun. 1995, pp. 1127-1128. Examples which may be mentioned are RuCl.sub.2 (.dbd.CHPh) (PCy.sub.3).sub.2, RuCl.sub.2 (p-cumene)/PCy.sub.3 /N.sub.2 CHSiMe.sub.3 and RuCl.sub.2 (p-cumene) (PCy.sub.
REFERENCES:
patent: 2561984 (1951-07-01), Hillyer
patent: 3070633 (1962-12-01), Utne
patent: 5395992 (1995-03-01), Ricci
Industrielle Organische Chemie, 1994, 263, Weissermel.
Carbohydrate Res. vol. 82 (1980). 73-72, Kuszmann.
Fischer Rolf
Hohn Arthur
Kratz Detlef
Pinkos Rolf
Schafer Martin
BASF - Aktiengesellschaft
Shippen Michael L.
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