Chemistry of hydrocarbon compounds – Aromatic compound synthesis – By condensation of entire molecules or entire hydrocarbyl...
Reexamination Certificate
2001-02-02
2003-01-07
Dang, Thuan D. (Department: 1764)
Chemistry of hydrocarbon compounds
Aromatic compound synthesis
By condensation of entire molecules or entire hydrocarbyl...
C585S446000
Reexamination Certificate
active
06504070
ABSTRACT:
This invention claims priority to Japanese Patent Application 2000-32673, filed Feb. 3, 2000.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of preparing an alkyl-substituted aromatic hydrocarbon, which comprises alkylating an aromatic hydrocarbon with an olefin in the presence of a catalyst comprising an iridium compound having at least one iridium atom and at least one &bgr;-diketonato ligand to produce the alkyl-substituted aromatic hydrocarbon.
2. Description of the Related Art
A method of preparing an alkylbenzene by using benzene and a straight-chain &agr;-olefin has been known for a long time. However, since the alkylation is conducted at the &bgr;-position of the olefin in the Friedel-Crafts alkylation reaction using a Br&phgr;nsted acid or a Lewis acid as the prior art, the main product is an alkylbenzene wherein the &bgr;-position is substituted with benzene. Depending on the reaction conditions, plural kinds of branched alkylbenzenes are further produced by the alkylation reaction between the branched olefin and the inner olefin produced by isomerization of the olefin, which occurs simultaneously. To produce a n-alkybenzene wherein the &agr;-position is substituted with benzene, a combination of Friedel-Crafts acylation and a Clemmensen reduction must be employed. For example, n-propylbenzene must be obtained by acylating benzene with propanoyl chloride to form 1-phenyl-1-propanone and reducing said 1-phenyl-1-propanone, as shown in scheme (3) (see “BURGOYNE Organic Chemistry”, written by E. E. BURGOYNE, translated by Toshio GOTO and Minoru ISOBE, (first edition and second impression), Mar. 1, 1984, published by Tokyo Kagaku Dojin, pages 98, 99, 141 and 142). A study of alkylation using the shape selectivity of zeolite has recently been reported (see, for example, Appl. Catal. A 184 (1999) 231-238, “Alkylation of benzene with dodecene. The activity and selectivity of zeolite type catalysts as a function of the porous structure”, written by Y. Cao et al.). Even if n-alkylbenzene can be produced, it is difficult to selectively produce n-alkylbenzene by using these techniques.
As used herein, the term “selectively prepare” or “selectively produce” means that a desired aromatic hydrocarbon substituted with a desired alkyl and/or at a desired position is prepared or produced in a relatively higher proportion than that of the other substituted or non-substituted aromatic hydrocarbon or other products. Although its specific proportion varies depending on the compound to be substituted or substitution position (see Table 1), the relationship between the raw material and product can be clearly grasped by testing based on the matters disclosed in the present specification, particularly results of Examples and Table 1. Similarly, the term “high selectivity” means that a target alkyl-substituted aromatic hydrocarbon is produced in a higher proportion than that of the other reaction products (which are typically undesired products). Similarly, the term “mainly includes” means that the amount of the product is significantly larger than that of the other products.
The present invention makes it possible to efficiently prepare an aromatic hydrocarbon substituted with a predetermined alkyl at a predetermined position, which has never before been easily obtained by a conventional method, comparatively easily by using a specific catalyst.
The aromatic hydrocarbon obtained by the reaction can be optionally separated by a conventional method such as distillation to give a final product.
When 2,6-diethylnaphthalene is prepared by using naphthalene and ethylene, 1-alkylnaphthalene is selectively produced by the Friedel-Crafts alkylation reaction using a Br&phgr;nsted acid or a Lewis acid as the prior art because of high orientation to the &agr;-position of naphthalene. Furthermore, it is difficult to selectively produce 2,6-diethylnaphthalene because of the low position selectivity of the second alkylation and the occurrence of isomerization. An improvement in selectivity of 2,6-dipropylnaphthalene due to the shape selectivity of zeolite has recently been reported (U.S. Pat. No. 5,026,942), where high selectivity has been realized by using propylene as an olefin. If 2,6-naphthalenedicarboxylic acid is prepared from 2,6-dialkylnaphthalene, the smaller the number of the carbon atoms in the naphthalene side chain, the better.
If polyalkylation is conducted using benzene and an olefin, o- and p-dialkylbenzenes are selectively produced by the Friedel-Crafts alkylation reaction using a Br&phgr;nsted acid or a Lewis acid as the prior art in accordance with o- and p-orientations, thus making it difficult to obtain a m-dialkylbenzene.
BRIEF SUMMARY OF THE INVENTION
The present invention relates to a method of preparing an alkyl-substituted aromatic hydrocarbon, which comprises alkylating an aromatic hydrocarbon with an olefin in the presence of a catalyst comprising an iridium compound having at least one iridium atom and at least one &bgr;-diketonato ligand to produce the alkyl-substituted aromatic hydrocarbon. The present invention relates to a method of preparing an alkyl-substituted aromatic hydrocarbon, which comprises using an iridium complex having a &bgr;-diketonato ligand as a catalyst in the case where an aromatic hydrocarbon is alkylated with an olefin, wherein said olefin is a substituted or non-substituted olefin having 2 to 20 carbon atoms (in which a substituent may be straight-chain or branched and also may contain one or more than one heteroatoms) and said aromatic hydrocarbon is a monocyclic or polycyclic aromatic hydrocarbon having 6 to 20 carbon atoms (said aromatic hydrocarbon may have a substituent and the substituent may contain a heteroatom or heteroatoms).
This present invention also relates to a method of preparing an alkyl-substituted aromatic hydrocarbon, in the presence of a catalyst wherein said iridium complex having a &bgr;-diketonato ligand is an iridium complex having a structure represented by the following formula (1).
(provided that R1 to R9 respectively represent an arbitrary substituent and may be the same). More specifically, the present invention relates to a method of preparing an alkyl-substituted aromatic hydrocarbon by selectively bonding a terminal carbon of an olefin with an aromatic in case the aromatic hydrocarbon is alkylated with the olefin. A particularly useful reaction is a reaction of alkylating benzene with 1-dodecene or isobutene to obtain n-dodecylbenzene or isobutylbenzene, respectively. n-dodecylbenzene is a useful compound for use as a raw material of lubricating oils and detergents, while isobutylbenzene is a useful compound for use as a raw material for ibuprofen as a drug. Alternatively, there is a reaction of alkylating naphthalene with an ethylene to obtain 2,6-diethylnaphthalene. It is possible to obtain 2,6-naphthalenedicarboxylic acid as a useful raw polymer material by oxidizing 2,6-diethylnaphthalene. These alkyl-substituted aromatic hydrocarbons are useful compounds for use as raw materials of lubricating oils, detergents, drugs, pesticides, and polymers.
DETAILED DESCRIPTION OF THE INVENTION
An object of preferred embodiment of the present invention is to provide a novel method of synthesizing an alkyl-substituted aromatic hydrocarbon by alkylation in accordance with the anti-Markovnikov rule.
The present inventors have intensively studied methods of preparing an alkyl-substituted, particularly a straight-chain alkyl-substituted, aromatic hydrocarbons. As a result, they have found a technique of bonding an olefin and especially the terminal carbon of an olefin with an aromatic and, particularly, a method of alkylating by the addition of the anti-Markovnikov rule, by using an iridium complex having a &bgr;-diketonato ligand as a catalyst. The present invention will be described in detail below.
The Markovnikov rule was originally induced from the addition of a hydrogen halide to an olefin and refers to the case where a hydrogen atom of a substrate is bonded with a carbon atom
Matsumoto Takaya
Periana Roy Anthony
Taube Douglas
Dang Thuan D.
Morrison & Foerster / LLP
Nippon Mitsubishi Oil Corporation
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