Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Patent
1988-02-22
1989-10-31
Lone, Werren B.
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
568814, 568830, 568846, 568862, C07C 29132, C07C 2914
Patent
active
048779091
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a new advantageous process for reducing an aldehyde or ketone into a corresponding alcohol with isopropyl alcohol in the presence of a catalyst.
2. Background Art
When an aldehyde or ketone is treated with a metal alkoxide and an alcohol, reduction occurs to form an alcohol corresponding to the aldehyde or ketone. This reaction is well known and it is usually called "Meerwein-Ponndorf reduction" (cf. A. L. Wilds, Org. React., 2, 178 (1944). Various combinations of a metal alcoholate with an alcohol have been investigated heretofore. Among them, a combination of aluminum isopropoxide with isopropyl alcohol is employed usually, since side reactions such as aldol condensation scarcely occur in the presence thereof, it is soluble not only in alcohols but also in hydrocarbons to make a homogeneous reaction possible and the reaction proceeds rapidly in the presence thereof to form a reduction product usually in a high yield. In this reaction, hydrogen atoms are directly transferred from the alcohol into the carbonyl group of the aldehyde or ketone in the presence of aluminum and aluminum isopropoxide acts as the catalyst. This combination can be employed in the reduction of several milligrams to several hundred grams of an aldehyde or ketone, since the reaction system is simple, the reactants are relatively safe and inexpensive and the reaction proceeds under mild conditions.
However, since the reaction in the conventional process is a homogeneous reaction, troublesome operations such as hydrolysis, extraction with an organic solvent, dehydration and distillation are necessitated for isolating the product after completion of the reaction. Further, since the carbonyl group is converted into the hydroxyl group, the product has an increased hydrophilic property and, therefore, a loss thereof in the extraction from the aqueous phase with an organic solvent is large. Although aluminum isopropoxide is active in the form of mainly its timer, commercially available aluminum isopropoxide or crystalline aluminum isopropoxide is in the form of its tetramer having a low reactivity. Under these circumstances, it is recommended that the catalyst is prepared immediately before use in the reduction.
In addition, the catalyst must be stored carefully, since it is gradually hydrolyzed by water in air to form the alcohol and aluminum hydroxide. After completion of the reaction, the catalyst is hydrolyzed so as to isolate the product from the reaction system. The process has a problem that the catalyst cannot, therefore, be used repeatedly and is discharged wastefully.
3. Disclosure of Invention
An object of the present invention is to provide a catalyst which is stable, highly active and insoluble in a solvent, which can be removed easily from the reaction system after completion of the reaction and which can be used repeatedly.
The present invention provides a process for reducing an aldehyde or ketone characterized in that hydrous zirconium oxide is used in place of a metal alcoholate (mostly aluminum isopropoxide) used heretofore. The inventors were interested in the fact that alcohols are adsorbed to stable hydrous zirconium oxide and, after investigations, the inventors have found that the hydroxyl group of the hydrous zirconium oxide is converted into an alkoxyl group. The present invention has been completed on the basis of this finding.
According to the reduction process of the present invention, an aldehyde or ketone is converted into a corresponding alcohol in a high yield while by-products are formed in only a small amount. Particularly, in a liquid phase reaction, a product having a sufficiently high purity can be obtained by merely filtering off the hydrous zirconium oxide and distilling off the solvent. In a gas phase reaction, the reaction can be conducted either continuously or batchwise and the product can be isolated easily in the same manner as in the liquid-phase reaction.
Hydrous zirconium oxide can be used advantageously, since it necessitates n
REFERENCES:
Mehrotra et al, Indian Journal of Chemistry, vol. 11, No. 8, (1973) pp. 814-816.
Ishii et al, Jour. of Organic Chemistry, vol. 51, No. 2 (1986) pp. 240-242.
Nondek et al., "Collection of Czechoslovak Chemical Comm"., vol. 45, No. 7, (1980) pp. 1937-1939.
Ichinose Hiroshi
Ishiguro Shigeo
Izumi Akira
Matsushita Hajime
Mizusaki Sigenobu
Japan Tobacco Inc.
Lone Werren B.
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