Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-11-26
2002-09-24
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S882000, C568S451000
Reexamination Certificate
active
06455743
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a production process which comprises subjecting an aldehyde having from 2 to 5 carbon atoms and a polycondensate of the aldehyde to a mixing hydrogenation reaction to produce alcohols corresponding to each of these aldehydes at the same time. (As described herein, the term “corresponding to” means a particular aldehyde, when hydrogenated, necessarily results in a particular alcohol. For example, n-butyraldehyde, when hydrogenated, necessarily results in n-butanol.) More particularly, the present invention relates to a production process which comprises subjecting the two aldehydes as starting materials to a mixing hydrogenation reaction whereby the production of an ester compound and/or an ether compound as by-products is inhibited, making it possible to efficiently produce alcohols corresponding to each of the aldehydes at the same time.
2. Discussion of the Background
A process which comprises allowing an aldehyde to undergo a hydrogenation reaction (hereinafter occasionally referred to as “hydrogenation”) has long been put in practical use on an industrial basis. For example, a process which comprises allowing n-butylaldehyde produced by the hydroformylation reaction of a propylene to undergo hydrogenation to produce n-butyl alcohol and a process which comprises allowing 2-ethyl-2-hexenal produced by the aldol condensation reaction of n-butyl aldehyde to undergo hydrogenation to produce 2-ethylhexanol have been widely known.
Such an industrial hydrogenation reaction of an aldehyde is carried out in either a liquid phase or a gas phase. In either reaction system, various side reactions occur to produce a large amount of by-products, lessening the reaction selectivity. One of the undesirable by-products of the hydrogenation reaction in the gas phase is an ester compound. For example, the reaction solution obtained by the gas phase hydrogenation reaction of n-butyl aldehyde contains butyl acetate as a by-product. Further, the reaction solution obtained by the gas phase hydrogenation reaction of 2-ethyl-2-hexenal contains the 2-ethylhexyl ester of 2-ethylhexanoic acid (2-ethylhexanoic acid-2-ethylhexyl) as a by-product. Known mechanisms of production of ester compound include a mechanism where a hemiacetal is produced from an aldehyde and an alcohol, and the hemiacetal then undergoes a dehydrogenation reaction to produce an ester compound, and a mechanism where two aldehyde molecules undergo a Tischenko reaction to produce an ester compound.
In order to inhibit the production of such an ester compound as a by-product, some approaches have heretofore been disclosed such as (I) a method involving the use of, as a hydrogenation catalyst, a reducing copper oxide-zinc oxide catalyst comprising a selectivity accelerator incorporated therein (an in Japanese Patent No. 2,655,034), (II) a method involving the hydrogenation reaction in the presence of a supported catalyst comprising nickel, aluminum oxide and zirconium dioxide incorporated therein (as in JP-B-6-4551 (The term “JP-B” as used herein means an “examined Japanese patent application”)), (III) a method involving the hydrogenation reaction in the presence of a catalyst comprising copper, zinc oxide and aluminum oxide incorporated therein (as in JP-B-8-29249) and (IV) a method involving the hydrocracking of an ester produced as a by-product to effective components which are then recovered (as in JP-A-58-43930 (The term “JP-A” as used herein means an “unexamined published Japanese patent application”)).
However, the foregoing methods (I) to (III) are disadvantageous in that they require the use of a catalyst having a certain special specification that adds to the production cost. Further, the foregoing method (IV) is disadvantageous in that a reactor for the decomposition of the ester is needed in addition to the reactor for the hydrogenation of aldehyde, adding to the construction cost. Accordingly, none of these methods are industrially effective.
Further, JP-A-6-1733 discloses a production process which comprises the hydrogenation reaction of an aldehyde having 5 or less carbon atoms to produce an alcohol, wherein 1-octa-2,7-dienol, which is an unsaturated alcohol having 8 carbon atoms, is present in the reaction system.
However, the above-discussed references do not describe or suggest the production process of the present invention which comprises mixing two aldehydes, i.e., an aldehyde having from 2 to 5 carbon atoms and a polycondensate of the aldehyde, and then subjecting the mixture to a hydrogenation reaction to produce two alcohols corresponding to the two aldehydes, respectively, at the same time on an industrial basis.
Further, the production process of the present invention has not even been practiced.
The term “mixing two aldehydes, i.e., an aldehyde having from 2 to 5 carbon atoms and a polycondensate of the aldehyde, and then subjecting the mixture to a hydrogenation reaction to produce two alcohols corresponding to the two aldehydes, respectively, at the same time on an industrial basis” as used herein is meant to indicate that an aldehyde having from 2 to 5 carbon atoms and a polycondensate of the aldehyde are mixed at a specified ratio, and then subjected to a hydrogenation reaction, but does not mean that a solution having such a composition as having unreacted raw aldehydes, e.g., 91.0% of 2-ethyl-2-hexenal and 1.6% of n-butyraldehyde as disclosed in JP-B-8-29249 is supplied at the step for condensation of aldehyde to undergo the hydrogenation reaction.
One of the reasons why the production process of the present invention for obtaining two alcohols by mixing and hydrogenating two different aldehydes has never been practiced is that when such a hydrogenation reaction is allowed to occur in the presence of two or more aldehydes, by-products which cannot be normally produced when these aldehydes are individually subjected to a hydrogenation reaction are produced, requiring much labor to remove in the purification system.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a process for the production of alcohols which comprises inhibiting the production of an ester and/or ether as a by-product during the production of two alcohols to produce two desired alcohols at the same time to advantage on an industrial basis.
The inventors made extensive studies of the foregoing problems. As a result, it was found that when an aldehyde having from 2 to 5 carbon atoms and a polycondensate of the aldehyde are simultaneously supplied into the reaction system at a specified mixing ratio where they are then mixed and subjected to a hydrogenation reaction, the production of an ester compound as an undesirable by-product can be unexpectedly inhibited, the amount of an ether compound to be similarly produced can be considerably reduced and the percent production of alcohol can be enhanced, making it possible to simultaneously produce two alcohols to advantage on an industrial basis. The present invention has thus been worked out.
Two series of hydrogenation reaction systems have heretofore been required to hydrogenate two aldehydes and hence produce corresponding alcohols. The use of the process of the present invention makes it possible to unify the two series of hydrogenation reaction systems to one series. As a result, the reduction of the number of series of reaction system makes it possible to facilitate the industrial practice of this process.
The essence of the present invention is a process for the production of alcohols which comprises supplying an aldehyde having from 2 to 5 carbon atoms and a polycondensate of the aldehyde into the same reaction system at a weight ratio of from 95:5 to 5:95 where they are then mixed and subjected to a hydrogenation reaction in the presence of a catalyst to produce alcohols corresponding to the aldehydes (the aldehyde and the polycondensate thereof) at the same time.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be further described hereinafter.
As
Adachi Atsuhiro
Emoto Hiroki
Fujita Yuichi
Ueda Akio
Mitsubishi Chemical Corporation
Padmanabhan Sreeni
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