Chemistry of hydrocarbon compounds – Aromatic compound synthesis – Having alkenyl moiety – e.g. – styrene – etc.
Reexamination Certificate
2001-03-29
2002-10-08
Dang, Thuan D. (Department: 1764)
Chemistry of hydrocarbon compounds
Aromatic compound synthesis
Having alkenyl moiety, e.g., styrene, etc.
C585S435000, C585S436000, C585S437000, C585S457000
Reexamination Certificate
active
06462246
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to a method of directly synthesizing an alkenyl-substituted aromatic hydrocarbon from an aromatic hydrocarbon and an olefin in one step.
More specifically, the present invention relates to a method of preparing styrene by alkenylating benzene with ethylene.
2. Description of the Related Art
Styrene has hitherto been prepared by a two-step process, that is, alkylation of benzene due to ethylene and dehydrogenation of ethylbenzene obtained therefrom.
As a one-step synthesis process of synthesizing styrene directly from ethylene and benzene, a liquid phase reaction using palladium acetate has been reported by FUJIWARA (J. Am. Chem. Soc. O, 1969, 1910, 7166). In this process, the use of copper acetate or silver acetate as a redox agent makes it possible to conduct a catalytic partial oxidation reaction due to oxygen, but the reaction rate and the selectivity of styrene are low.
Although an improvement in stability of the catalyst was made by adding carboxylic acid amide (Examined Patent Publication (Kokoku) No. 51-14496), vinyl acetate, as a by-product, formed from acetic acid used as an essential solvent and ethylene cannot be inhibited and the selectivity of styrene is not sufficient. A one-step process of synthesizing styrene using a transition metal of the Group VIII (e.g. iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, etc.) is disclosed in U.S. Pat. No. 3,848,010. However, in the one-step process of synthesizing styrene, the presence of carboxylic acid such as acetic acid is indispensable and a carboxylic acid ester such as vinyl acetate, as a by-product, can not be avoided by the prior art. Therefore, it is still difficult to selectively produce only styrene.
A method of selectively preparing styrene using rhodium in the absence of carboxylic acid has been suggested by one of the present inventors (U.S. patent Ser. No. 09/277,327). However, according to any of the one-step techniques of synthesizing styrene described above, a redox agent such as copper-containing compound is indispensable to reoxidize the transition metal of the Group VIII reduced by the reaction in order to enable the transition metal of the Group VIII to serve as the catalyst. The redox agent, which is reduced by oxidizing the transition metal of the Group VIII during the reaction, itself can be reoxidized by air or oxygen. That is, according to the prior art, the coexistence of the transition metal of the Group VIII, which serves as the catalyst, redox agent and oxygen (air) was an essential condition in order to catalytically carry out this reaction.
Although the method of conducting the reaction between an aromatic hydrocarbon and styrene using palladium acetate and using only oxygen as an oxidizing agent has been known (U.S. Pat. No. 3,775,511), a principal product is acetophenone and the selectivity of stilbene as an alkenylated product is low.
As used herein, the term “selectively prepare” or “selectively produce” means that a desired aromatic hydrocarbon is prepared or produced in a relatively higher proportion than that of the other products. Similarly, the term “high selectivity” means that a target alkenyl-substituted aromatic hydrocarbon is produced in a higher proportion than that of the other reaction products (undesirable products). Similarly, the term “mainly include” 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 a predetermined alkenyl-substituted aromatic hydrocarbon, which has never before been selectively obtained by a conventional method, efficiently by using a specific catalyst and adding &bgr;-diketone. This method may preferably be carried out also in the absence of a redox agent.
The aromatic hydrocarbon obtained by the reaction can be optionally separated by a conventional method such as distillation to give a final product.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a novel method of synthesizing an alkenyl-substituted aromatic hydrocarbon by alkenylation of an aromatic hydrocarbon due to an olefin at a high selectivity. Particularly, the present invention relates to a method of preparing an alkenyl-substituted aromatic hydrocarbon, which comprises using a rhodium complex as a catalyst and adding &bgr;-diketone in the case where an aromatic hydrocarbon is alkenylated with an olefin in the presence of oxygen without necessarily requiring a redox agent such as copper-containing compound or silver-containing compound. An example of a useful reaction includes a reaction of preparing styrene by alkenylating benzene with ethylene. Styrene is a compound which is useful as a raw material of polystyrene.
The present inventors have intensively studied methods of preparing an alkenyl-substituted aromatic hydrocarbon in the presence of oxygen. As a result, they have found a method of selectively alkenylating an aromatic hydrocarbon by using a rhodium complex as a catalyst and adding &bgr;-diketone.
This invention relates to a method of preparing an alkenyl-substituted aromatic hydrocarbon, which comprises alkenylating an aromatic hydrocarbon with an olefin using &bgr;-diketone together with a rhodium complex catalyst in the presence of oxygen and in the absence of a redox agent.
This invention relates to the method of preparing an alkenyl-substituted aromatic hydrocarbon, 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 a heteroatom or 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 invention also relates to the method of preparing an alkenyl-substituted aromatic hydrocarbon, wherein said &bgr;-diketone is &bgr;-diketone represented by the following scheme (1).
(provided that R
1
to R
3
respectively represent an arbitrary substituent and may be the same).
This invention also relates to the method of preparing an alkenyl-substituted aromatic hydrocarbon, wherein said &bgr;-diketone is 2,4-pentanedione(acetylacetone) or 2,2,6,6-tetramethyl-3,5-heptanedione.
This invention further relates to the method of preparing an alkenyl-substituted aromatic hydrocarbon, wherein said rhodium complex is a complex in the formal oxidation state of Rh (I).
This invention further relates to the method of preparing an alkenyl-substituted aromatic hydrocarbon, wherein said rhodium complex is a complex having at least one rhodium atom and at least one &bgr;-diketonato ligand.
This invention specifically relates to the method of preparing an alkenyl-substituted aromatic hydrocarbon, wherein said rhodium complex is any one selected from dicarbonylacetylacetonatorhodium (I), acetylacetonatobis(ethylene)rhodium (I), chloro(1,5-cyclooctadiene)rhodium (I) dimer, chlorotris(triphenylphosphine)rhodium (I), and norbornadiene[1,4-bis(diphenylphosphino)butane]rhodium (I) tetrafluoroborate.
This invention more specifically relates to the method of preparing an alkenyl-substituted aromatic hydrocarbon, wherein said olefin is ethylene and said aromatic hydrocarbon is benzene.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
The formal oxidation state of Rh (I) used in the present invention means that a starting substance of a catalyst is rhodium (I). Similarly, the formal oxidation state of Rh (III) means that a starting substance of a catalyst is rhodium (III).
The aromatic hydrocarbon used in the present invention is a cyclic compound wherein a &pgr; electron orbital is delocalized, and any monocyclic and polycyclic compound can be used. Specifically, it is an aromatic hydrocarbon having 6 to 20 carbon atoms, and preferably 6 to 12 carbon atoms. At least one atom of the aromatic ring is hydrogen which
Matsumoto Takaya
Nishikawa Shinji
Yoshida Hajime
Dang Thuan D.
Foley & Lardner
Nippon Mitsubishi Oil Corporation
LandOfFree
Method of preparing alkenyl-substituted aromatic hydrocarbon does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of preparing alkenyl-substituted aromatic hydrocarbon, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of preparing alkenyl-substituted aromatic hydrocarbon will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2999506