Chemistry of hydrocarbon compounds – Aromatic compound synthesis – By condensation of entire molecules or entire hydrocarbyl...
Reexamination Certificate
1999-06-25
2002-06-11
Dang, Thuan D. (Department: 1764)
Chemistry of hydrocarbon compounds
Aromatic compound synthesis
By condensation of entire molecules or entire hydrocarbyl...
C585S438000, C585S436000, C585S452000
Reexamination Certificate
active
06403852
ABSTRACT:
application is the national phase under 35 U.S.C. §371 of prior PCT International Application No. PCT/JP97/04802 which has an International filing date of Dec. 24, 1997 which designated the United States of America.
TECHNICAL FIELD
The present invention relates to a process for producing alkenyl-substituted aromatic hydrocarbons, in which an alkyl-substituted aromatic hydrocarbon having a hydrogen atom at the &agr;-position of a side chain thereof is reacted with a conjugated diene using a catalyst, thereby causing alkenylation at the &agr;-position.
BACKGROUND ART
Alkenyl-substituted aromatic hydrocarbons are useful as intermediate materials of fine chemicals such as agricultural chemicals, drugs, and chemical products, and also useful as the intermediate materials for the production of naphthalene derivatives. It is well known that they can be obtained by reacting an alkyl-substituted aromatic hydrocarbon having a hydrogen atom at the &agr;-position of a side chain thereof with a conjugated diene in the presence of a basic catalyst.
For example, the following are such known processes:
a process using an alloy of sodium metal and potassium metal as the catalyst (see JP-B 50-17975 and JP-B 51-8930);
a process using a catalyst in which sodium metal is carried on a support obtained from aluminum hydroxide and potassium hydroxide (see JP-A 6-293673);
a process using a catalyst composed of an aromatic compound that forms a charge-transfer complex with sodium metal and an alkaline earth metal salt (see JP-B 8-59523); and
a process in which a catalyst carrying an alkali metal on a support is filled in a reaction tube and production is achieved by flow-through reaction in a fixed-bed system (see U.S. Pat. No. 4,990,717).
The above catalysts and processes, however, have drawbacks that the rate of conversion of an alkyl-substituted aromatic hydrocarbon must be kept lower by reducing the amount of conjugated diene to be charged, relative to that of alkyl-substituted aromatic hydrocarbon, because of their low catalyst activity and insufficient selectivity.
The present inventors have extensively studied various alkenylation catalysts for the purpose of developing an excellent process for producing an alkenyl-substituted aromatic hydrocarbon by alkenylation at the &agr;-position of a side chain of an alkyl-substituted aromatic hydrocarbon. As a result, they have found that a catalyst obtained by the action of an alkali metal compound and an alkali metal or an alkali metal hydride on a metal oxide selected from alumina or hydrotalcite by heating in a specific temperature range can exhibit remarkably high activity on alkenylation and provide a desired alkenyl-substituted aromatic hydrocarbon with high efficiency, even if the catalyst is used in a small amount.
The present inventors also have extensively studied various alkenylation catalysts and their additives for the purpose of developing a further excellent producing process. As a result, they have found that when the reaction is carried out in the presence of an alkylaminopyridine using an alkali metal or an alloy thereof, or a catalyst carrying any of them on an inorganic compound support, or a solid base catalyst obtained by the action of an alkali metal compound and an alkali metal or an alkali metal hydride on a metal oxide selected from alumina, alkaline earth metal oxides, hydrotalcite, silica-alumina, or zeolite by heating in a temperature range of 70° C. to 700° C., higher selectivity in alkenylation can be attained with the catalyst activity being retained, and a desired alkenyl-substituted aromatic hydrocarbon can be produced with high efficiency, even if the catalyst is used in a small amount. After further various studies, they have completed the present invention.
DISCLOSURE OF THE INVENTION
Thus, the present invention provides:
1. a process for producing an alkenyl-substituted aromatic hydrocarbon by alkenylation of an alkyl-substituted aromatic hydrocarbon having a hydrogen atom at the &agr;-position of a side chain thereof with a conjugated diene, characterized in that the process involves the use of a catalyst selected from:
(1) a solid base catalyst obtained by the action of potassium hydroxide directly on alumina by heating in a temperature range of 300° C. to 600° C. and the subsequent action of sodium metal or sodium hydride on the alumina by heating in the same temperature range;
(2) a solid base catalyst obtained by the action of an alkali metal compound on alumina by heating and the subsequent action of potassium metal or potassium hydride on the alumina in an atmosphere of an inert gas by heating, both in a temperature range of 70° C. to 500° C.; or
(3) a solid base catalyst obtained by the action of a potassium compound and sodium metal on hydrotalcite or by the action of a potassium compound and sodium hydride on hydrotalcite, both by heating in a temperature range of 100° C. to 700° C. in an atmosphere of an inert gas; and
2. a process for producing an alkenyl-substituted aromatic hydrocarbon by alkenylation of an alkyl-substituted aromatic hydrocarbon containing a hydrogen atom at the &agr;-position of a side chain thereof with a conjugated diene, characterized in that the process involves the reaction in the presence of an alkylaminopyridine of formula (1):
wherein R
1
is hydrogen or C
1
-C
6
lower alkyl, and R
2
is C
1
-C
6
lower alkyl, using as a catalyst, Na metal, K metal, or an alloy thereof, or a catalyst carrying any of them on an inorganic compound support, or a catalyst obtained by the action of an alkali metal compound and an alkali metal or an alkali metal hydride on a metal oxide selected from alumina, alkaline earth metal oxides, hydrotalcite, silica-alumina, or zeolite by heating in a temperature range of 70° C. to 700° C.
The present invention will hereinafter be explained in detail.
First, the following will describe the first embodiment of the present invention, i.e., a process for producing an alkenyl-substituted aromatic hydrocarbon by alkenylation of an alkyl-substituted aromatic hydrocarbon having a hydrogen atom at the &agr;-position of a side chain thereof with a conjugated diene, using a catalyst obtained by the action of an alkali metal compound and an alkali metal or an alkali metal hydroxide on an metal oxide selected from alumina or hydrotalcite by heating in a specific temperature range.
Examples of the alkyl-substituted aromatic hydrocarbon having a hydrogen atom at the &agr;-position of a side chain thereof, which are usually used, may include monocyclic aromatic hydrocarbons and condensed polycyclic aromatic hydrocarbons. The side chain alkyl group may be combined together to form a ring.
Specific examples of the alkyl-substituted aromatic hydrocarbon having a hydrogen atom at the &agr;-position of a side chain thereof are toluene, ethylbenzene, isopropylbenzene, n-propylbenzene, n-butylbenzene, secbutylbenzene, isobutylbenzene, xylene, cymene, diisopropylbenzene, methyl-naphthalene, tetrahydronaphthalene, and indane. Preferably used are toluene, xylene, and ethylbenzene.
Examples of the conjugated diene, which are usually used, may include those having about 4 to about 10 carbon atoms, and they may be either in straight chain form or in branched form.
Specific examples of the conjugated diene are 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Preferably used are 1,3-butadiene and 2-methyl-1,3-butadiene.
Examples of the catalyst, which can be used in the alkenylation of the present invention, may include catalysts (solid base catalysts) obtained by the action of an alkali metal compound and an alkali metal, or by the action of an alkali metal compound and an alkali metal hydride on a metal oxide selected from alumina or hydrotalcite.
The following will describe the solid base catalyst.
Examples of the solid base catalyst may include:
(1) a solid base catalyst obtained by the action of potassium hydroxide directly on alumina by heating in a temperature range of 300° C. to 600° C. in the air or under an atmosphere of an inert gas and the subseque
Suzukamo Gohfu
Yamamoto Michio
Birch & Stewart Kolasch & Birch, LLP
Dang Thuan D.
Sumitomo Chemical Co. Limited
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