Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1998-06-06
2000-03-14
Kunz, Gary L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568303, 568308, 568309, 568320, 502102, 502103, C07C 4500, C07C 4900, C07C 4587, C07C 4976, B01J 3100
Patent
active
060375019
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for the preparation of fluorenes, a process for the preparation of fluorenones from inexpensive and easily available diphenylmethanes using the process, and a catalyst for use in such processes. Fluorenones are useful as intermediates for organic synthesis and raw materials for resins. Particularly, bisphenol derivatives are useful as raw materials for heat-resistant epoxy resins, polycarbonates or polyesters.
BACKGROUND ART
Fluorenones are compounds of high utility as intermediates for organic synthesis or raw materials for resins. Known examples of the preparation process of fluorenones include oxidation of fluorenes and liquid phase oxidation of benzophenone using palladium acetate as an oxidizing reagent.
As the process for the oxidation of fluorenes, liquid phase reaction is disclosed in German Offenlegungsschrift DE-1,262,268 and 1,940,051, while vapor phase reaction is disclosed in JP-A-60-233028 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
The raw material fluorenes are however mainly obtained by separation from tar. From the viewpoints of the separation cost and problem of limited resources, use of the tar is not economically advantageous.
Concerning a process for obtaining fluorenes by synthesis, catalytic cyclodehydrogenation of an alkylbiphenyl compound is described in U.S. Pat. No. 3,325,551. According to its description, 9,9-dimethylfluorene is prepared from 2-isopropylbiphenyl as shown specifically by the following reaction formula: ##STR1##
The above process is however economically disadvantageous because the raw material biphenyl compound should be separated from a tar fraction similar to the case of fluorenes or a coupling reaction of benzene at high temperature is required where obtaining by synthesis. In addition, the raw material alkylbiphenyl compound requires introduction of an alkyl group into a specific position of a benzene ring, so that such a compound is not an easily available compound.
On the other hand, processes for the synthesis of a fluorenone from benzophenone are disclosed in J. Org. Chem. Vol. 40, No. 9, 1365-1367(1975); J. Chem. Soc. Perkin Trans Vol.I. 11, 1236-(1976); and the like.
The above processes are however accompanied with the industrial problems such as necessity of a large amount of palladium, low productivity per expensive palladium, long reaction time and insufficient yield, because the reaction effected in these processes is a reagent reaction in which palladium acetate is added to benzophenone in at least an equivalent amount, and is also a liquid phase reaction.
Accordingly, in view of the above circumstances, an object of the present invention is to provide an industrially advantageous process for the preparation of fluorenes at a low cost and in a high yield.
DISCLOSURE OF THE INVENTION
The present inventors have made an investigation to solve the above-described problems. As a result, it has been found that by a catalytic dehydrogenation reaction in an industrially desirable vapor phase, fluorenes can be obtained in a high yield from a diphenylmethane-base aromatic compound which is easily available inexpensively.
The present invention therefore provides a process for the preparation of fluorenes represented by the following formula (II): ##STR2## wherein R.sub.1 and R.sub.2 each represent a hydrogen atom, a methyl group or an ethyl group, or R.sub.1 and R.sub.2 together represent .dbd.O, and R and R' each represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, which comprises subjecting an aromatic compound represented by the following formula (I): ##STR3## wherein R.sub.1, R.sub.2, R and R' are the same as defined in (II) above to a vapor-phase intramolecular cyclodehydrogenation reaction.
Described specifically, it has been found that according to the above process of the present invention, two aromatic rings in the formula (I) form a ring by the intramolecular dehydrogenatio
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P. Hanson et al.: "Sandmeyer reactions" J. Chem. Soc. Perkin Trans. 2, (1994) vol. 4, pp. 691-696 XP002086436 see p. 691, Scheme 1.
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Iida Toshiya
Maeda Isamu
Saito Noboru
Kunz Gary L.
Nippon Shokubai Co. , Ltd.
White Everett
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