Process for the continuous preparation of tetracyclododecens

Details Process for the continuous preparation of tetracyclododecens Process for the continuous preparation of tetracyclododecens

2001-07-05

2002-10-15

Dang, Thuan D. (Department: 1764)

Chemistry of hydrocarbon compounds

Alicyclic compound synthesis

Polycyclic product

C585S361000

Reexamination Certificate

active

06465703

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a process for a continuous preparation of tetracyclododecenes, more particularly, the invention relates to a process for preparing highly purified tetracyclododecenes (may be abbreviated hereafter as TCD), which can be a raw material of cycloolefin (co)polymers possessing excellent characters concerning their optical property, high transparency, heat resistance, and oil absorbency, from an inexpensive raw material of crude dicyclopentadiene (DCPD) in a stable, continuous, and longstanding process.
BACKGROUND ART
Cycloolefin (co)polymers are the focus of industrial attention as polymers that possess excellent characters concerning the optical property, high transparency, heat resistance, and oil absorbency. Cycloolefins represented by TCD are a useful raw material for polymer. These cycloolefins are generally prepared using organometallic complex catalysts. A polymerization method is roughly classified into two: one is a single polymerization of cycloolefins polymerized at their olefinic site, or the copolymerization with lower alpha-olefins using Ziegler catalysts or metallocene catalysts. The other is known as the metathesis polymerization that employs the carbene-type catalysts.
With regard to the preparative method of TCD, a typical method is mixing cyclopentadiene (may be called CPD hereafter), dicyclopendtadiene (may be called DCPD hereafter), or a mixture thereof, with norbornene and ethylene, in a heated condition, yielding a reaction mixture containing tetracyclododecenes and norbornenes. This is followed by the recovery and circulation of norbornenes in the reaction mixture. A method of preparing tetracyclododecenes, accompanied with the processes of recovery and circulative re-use of generated norbornenes, is reported, for example, in Japan Open H06-9437. This patent proposes a use of DCPD having the purity higher than a specific value as a raw material, and a circulative re-use of recovered norbornenes generated in the reaction, since the industrially available crude DCPD contains a large amount of impurities. However, the raw material DCPD of high purity mentioned in the above patent is likely to bring about a high cost for the raw material naturally, therefore, rarely adopted in the industrial production.
The present inventors investigated processes that employ crude DCPD as a raw material, and found that a continuous, longstanding operation of producing TCDs involves a possibility of unstable reaction condition due to the impurities present in crude DCPD employed. This leads to inability to continue the operation in an extreme case. The present invention proposes a production method of TCDs using inexpensive crude DCPD as a raw material in a stable, continuous, and longstanding process.
DISCLOSURE OF THE INVENTION
The first item of the present invention relates to a continuous method involving the processes of 1 to 4 that are shown below, for the production of tetracyclododecenes shown by the general formula (3), characterized by inclusion of a process of removing at least a part of 2-methyl-2-norbornenes shown by the general formula (4), which may be contained in the obtained reaction mixture.
1) A process of feeding 2-norbornenes shown by the general formula (1), crude cyclopentadiene and/or dicyclopentadiene, and an olefin shown by the general formula (2) into a reaction vessel continuously for the reaction (where R1 and R2 in these formulae are identical or different functional groups, and are any of a hydrogen atom, a methyl group, or an ethyl group).
2) A process of separating 2-norbornenes from the reaction mixture by distillation.
3) A process of circulating at least a part of separated 2-norbornenes to said reaction vessel.
4) A process of separating tetracyclododecenes from the reaction mixture.
The second item of the present invention relates to a continuous production method of tetracyclododecenes shown by the general formula (3) chracterized by inclusion of the following processes of 1 to 7.
1) A process of feeding 2-norbornenes shown by the general formula (1), cyclopentadiene and/or dicyclopentadiene, and an olefin shown by the general formula (2) into a reaction vessel continuously for the reaction (where R1 and R2 in these formulae are identical or different functional groups, and are a hydrogen atom, a methyl group, or an ethyl group).
2) A process of separating an olefin shown by the general formula (2) from the reaction mixture.
3) A process of circulating at least a part of the separated olefin to the above reaction vessel in said process of 2.
4) A process of separating 2-norbornenes from the reaction mixture succeeding said process of 2.
5) A process of circulating at least a part of separated 2-norbornenes to the above reaction vessel in said process of 4.
6) A process of separating and removing 2-methyl-2-norbornenes from the reaction mixture succeeding said process of 4.
7) A process of isolating tetracyclododecenes from the reaction mixture succeeding said process of 6.
According to a method described in the present invention, it is possible to produce TCDs in a stable and longstanding process recovering the generated 2-norbornenes from the reaction mixture, and re-using them in a circulative manner. The detailed description of the invention is given hereafter.
The olefin shown by the general formula (2) in the present invention is precisely taken to mean ethylene, propylene, 1-butene, trans-2-butene, and is-2-butene.
The 2-norbornenes (may be called as alkyl-norbornenes hereafter) shown by the general formula (2) in the present invention are precisely taken to mean 2-norbornene, 5-methyl-2-norbornene (methyl-norbornene), 5-ethyl-2-norbornene (ethyl-norbornene), and 5,6-dimethyl-2-norbornene (dimethylnorbornene). The endo form and the exo form of these compounds may be included in this category if they exist.
The tetracyclododecenes shown by the general formula (3) are precisely taken to mean tetracyclododecene (1,4:5,8-dimethano-1,2,3,4,4
a,
5,8,8
a
-octahydronaphthalene), methyltetracyclododecene(2-methyl-1,4:5,8-dimethano-1,2,3, 4,4
a,
5,8,8
a
-octahydro-naphthalene),ethyltetracyclododecene((2-ethyl-1,4:5,8-dimethano-1,2,3,4,4
a,
5,8,8
a
-octahydronaphthalene),and dimethyl-tetracyclododecene(2,3-dimethyl-1,4:5,8-dimethano-1,2,3,4,4
a,
5,8,8
a
-octahydronaphthalene). The steric isomers of these compounds such as the endo-exo form, the endo-endo form, the exo-endo form, as well as the steric isomers substituted with different groups may be included.
FIG. 1
illustrates a process flow exhibiting a preferred embodiment of the present invention. In the figure, the feed line of norbornenes necessary at the initiation of the reaction is omitted, and Number 1 means a solvent vessel. It is preferred to employ a solvent having the boiling point of 50-180 degrees centigrade under the ordinary pressure in a preferred embodiment of the invention. The purpose of using solvents lies in the decrease in the concentration of each component in the reaction system leading to reduced generation of heavy-end, which is a byproduct, and especially in the prevention of solidification of the circulating 2-norbornenes when they are employed in the reaction system. It is preferred that the boiling point of the employed solvent is close to that of 2-norbornenes. In more detail, aromatic and aliphatic hydrocarbons having a carbon number of 6 to 8 are preferred.
The hydrocarbon solvent is precisely taken to mean benzene, toluene, xylene, cyclohexane, methylcyclohexane, and dimethylcyclohexane. Among them alicyclic or branched aliphatic hydrocarbons are particularly preferred because of their safety to human bodies and the environment. They include preferably, for example, iso-hexane, iso-heptane, iso-octane, cyclohexane, methylcyclohexane, dimethylcyclohexane, and ethylcyclopentane. Here the compounds like iso-hexane, iso-heptane, and iso-octane are taken to mean hexane, heptane, and octane that possess a hydrocarbon branch or branches larger than or equal to the methyl group. They may be employed regardle

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