Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-10-02
2003-07-29
Righter, Johann (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S814000, C560S008000
Reexamination Certificate
active
06600080
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a producing method of alcohols such as cyclohexanedimethanol. More specifically, the invention relates to a producing method of cyclohexanedimethanol via xylylene diacetate, using, for example, xylene as a starting material, and of other alcohols. Cyclohexanedimethanol is an industrially very useful compound as a raw material of polyester paint or synthetic fibers, synthetic resins, and the like.
BACKGROUND OF THE INVENTION
Conventionally known producing methods of cyclohexanedimethanol, which is an industrially very useful compound as a raw material of polyester paint or synthetic fibers, synthetic resins, and the like include: {circle around (1)} a method in which a benzene ring of terephthalic dialkylester used as a starting material is hydrogenated, and then the product cyclohexane dialkylester is subjected to hydrogenolysis; {circle around (2)} a method in which a benzene ring of terephthalic acid is hydrogenated, and then the product cyclohexane dicarboxylic acid is further hydrogenated; and {circle around (3)} a method in which a benzene ring of xylylene glycol is hydrogenated to produce cyclohexanedimethanol.
Of those three producing methods, the method {circle around (1)} is most common and there has been many reports thereon. For example, U.S. Pat. No. 3,334,149 (published date: Aug. 1, 1967) discloses a method in which a benzene ring of terephthalic dialkylester is hydrogenated using palladium/alumina supporting catalysts, and then the ester site of the product cyclohexane dialkylester is subjected to hydrogenolysis using a copper chromite catalyst to obtain the target product cyclohexanedimethanol.
Further, for example, Japanese Unexamined Patent Publication No. 242/1977 (Tokukaisho 52-242; published date: Jan. 5, 1977), which represents the method {circle around (2)}, discloses a method which uses a large amount of alcohol as a solvent, wherein a benzene ring of terephthalic acid is hydrogenated using a 5% rhodium-carbon catalyst, and the product cyclohexane dicarboxylic acid is further hydrogenated using a copper chromite catalyst so as to obtain the target product cyclohexanedimethanol.
With these producing methods, the target product can be obtained with high yield. However, the methods {circle around (1)} and {circle around (2)} require exceedingly high temperature and high pressure as the reaction conditions of the hydrogenation of the benzene ring and the carbonyl group, and they require special reaction equipment. Further, stoichiometrically, these methods require 7 moles of hydrogen for 1 mole of the raw material and thus they employ a reaction which consumes a large amount of hydrogen. Further, 2 moles of alcohols and 2 moles of water are generated as a by-product respectively in the methods {circle around (1)} and {circle around (2)}, which makes the raw material unit per Kg-product larger, i.e., the cost of producing cyclohexanedimethanol is increased. Further, the copper chromite catalyst used in a later stage contains toxic chrome and there is a disposal problem. Thus, the methods {circle around (1)} and {circle around (2)} have a drawback in environmental safety. Namely, the methods {circle around (1)} and {circle around (2)} have a problem that cyclohexanedimethanol cannot be produced safely and industrially at low cost.
Meanwhile, for example, Japanese Unexamined Patent Publication No. 187432/1996 (Tokukaihei 8-187432) (published date: Jul. 23, 1996) discloses in Example 7 a method in which a benzene ring of xylylene glycol is hydrogenated under mild conditions using a Raney ruthenium catalyst as a novel hydrogenation catalyst, so as to obtain the target product cyclohexanedimethanol, i.e., method {circle around (3)}.
With this producing method, the target product can be obtained only by the hydrogenation of the benzene ring, and, stoichiometrically, it only requires 3 moles of hydrogen for 1 mole of the raw material, and compared with the methods {circle around (1)} and {circle around (2)}, the amount of hydrogen consumed can be reduced to less than half. Further, since alcohol and water are not generated as a by-product, the raw material unit per Kg-product can be reduced. Furthermore, since the method does not use a catalyst which contains a toxic substance, there is no disposal problem.
As to a producing method of alcohols other than the cyclohexanedimethanol, for example, Japanese Unexamined Patent Publication No. 7608/1998 (Tokukaihei 10-7608) (published date: Jan. 13, 1998) discloses a method in which benzyl alcohol is produced from benzyl acetate. Further, Document Bull. Chem. Soc. Jpn., 37, 585 (1964) in pages 585 to 587 discloses a producing method of cyclohexyl methanol from benzyl alcohol.
However, there has been no established method of inexpensively and industrially producing xylylene glycol which is used as the raw material in the method {circle around (3)}.
For example, Japanese Unexamined Patent Publication No. 273927/1987 (Tokukaisho 62-273927) (published date: Nov. 28, 1987) discloses a method in which p-xylene and acetic acid are allowed to react in the presence of oxygen using a catalyst containing palladium and bismuth to obtain p-xylylene diacetate, which is then used to produce p-xylylene glycol. Further, for example, Japanese Unexamined Patent Publication No. 174950/1988 (Tokukaisho 63-174950; Published date: Jul. 19, 1988) discloses a method in which p-xylene and acetic acid are allowed to react in the presence of oxygen using, as a catalyst, palladium-bismuth compound and/or palladium-lead compound to produce p-methylbenzyl acetate and p-xylylene diacetate. Further, for example, Japanese Unexamined Patent Publication No. 231466/1996 (Tokukaihei 8-231466; published date: Sep. 10, 1996) discloses a method in which p-xylene and acetic acid are allowed to react in the presence of oxygen using a palladium and gold supporting catalyst to produce p-xylylene diacetate.
However, the catalysts disclosed in Japanese Unexamined Patent Publication No. 273927/1987 and No. 174950/1988 have low catalytic activity (turnover frequency of around 15 per unit time per unit palladium in the catalyst), and thus to improve production efficiency, it requires a large amount of catalyst with respect to p-xylene as a reaction substrate, i.e., it requires a large amount of palladium as a noble metal. Further, palladium may dissolve into a reaction solution during reaction, and in this case, the catalytic activity is further reduced and it is required to separate and recover the palladium dissolved. Thus, the catalysts of the above publications may not be a catalyst suitable for a producing method in industrial applications. Further, the catalyst disclosed in Japanese Unexamined Patent Publication No. 231466/1996 also has a low catalytic activity and to improve production efficiency a large amount of catalyst is required with respect to p-xylene as a reaction substrate, and thus, as with the above example, this catalyst may not be a catalyst suitable for a producing method in industrial applications. That is, the above catalysts all have a low catalytic activity and are not suitable for a producing method in industrial applications, and thus have a problem that xylylene glycol cannot be produced efficiently and inexpensively from xylylene diacetate.
Further, Japanese Unexamined Patent Publication No. 187432/1996 does not disclose a producing method of xylylene glycol. Namely, the method {circle around (3)} may not be suitable for industrially and inexpensively producing cyclohexanedimethanol since it is difficult to industrially obtain the raw material xylylene glycol.
Further, in the method of producing xylylene glycol by hydrolyzing xylylene diacetate, the reaction is known to be carried out in the presence of an alkali or acid catalyst. However, to carry out hydrolysis in the presence of an alkali, it would require twice or more moles of alkali with respect to the xylylene diacetate, and not only it is impossible to recover the acetic acid which is generated as a by-product with the xylylene
Nagamura Yusei
Satoh Yuuichi
Tatsumi Jun
Yamamura Kunihiro
Nippon Shokubai Co. , Ltd.
Nixon & Vanderhye P.C.
Price Elvis O.
Righter Johann
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