JPS5940372B2 - Alcohol oxidation method using peroxides - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing carbonyl compounds, ie aldehydes or ketones, by oxidizing alcohols.

When the alcohol is -class, an aldehyde is obtained, and when it is secondary, a ketone is obtained. The process of producing aldehydes or ketones by oxidizing alcohol is industrially important, and various methods have already been devised and are known.

The most common methods known so far are sodium dichromate, chromic anhydride and its derivatives (e.g. Collins reagent: J, Collins), W, W, Hess,
and F, J, Frank, Tetrahedron.
Lett, 3363 (1968): Pyridinium chlorochromate; E, J, Coreyand J, W.

Suggs, Tetrahedron Lett,
2647 (1975), E. J., Coreyand D.
L, Boger) Tetrahedron Lett,,
2461 (1978), :+Pyridinium dichromate (C5H5NH)2Cr207 ■ E, J, Coreya
ndG, Schmidt) TetrahedronLe
tt, 399 (1974), etc.), but when used industrially, pollution problems will occur if the chromium compound is not properly treated after the reaction, so extra expense is required. shall be.

When the alcohol is allyl alcohol, activated manganese dioxide (MnO2) is most often used, but it is not economical because usually 20 to 30 times the equivalent of MnO2 is used. In the case of special alcohols, it is known to dehydrogenate them in the gas phase at high temperatures using copper-monochrome catalysts, but this method is only used when the alcohol is volatile and stable at the reaction temperature. It has the disadvantage that it is possible.
Mofuat's oxidation using DMSO is not suitable as an industrial oxidation method except in special cases because DMSO is expensive and acetic anhydride is similarly expensive. The present inventor has intensively investigated industrially useful methods that overcome these conventional alcohol oxidation methods, and has found that an industrially inexpensive organic hydroperoxide represented by the general formula ROOH is an organic hydroperoxide of the general formula ArSeSeAr'. The present invention was completed by discovering that alcohols can be oxidized in extremely high yields to give aldehydes or ketones in the presence of selenium compounds.

In the organic hydroperoxide of the general formula ROOH of the present invention, R represents an alkyl or aralkyl group.

Examples of alkyl groups include methyl, ethyl, propyl,
Butyl, sec-butyl, -butyl, cyclobutyl,
Cyclopentyl, 1-methylcyclopentyl, cyclohexyl, 1-methyl-cyclohexyl, 2-methylcyclohexyl, cyclooctyl, 1-methylcyclohexyl, cyclododecyl, 1-methylcyclododecyl, 1.
Examples include 1.-dimethylpentyl and 1.1-dimethyloctyl, but are not limited thereto.
Examples of aralkyl groups include cumyl, 1,1-dimethyl-
Examples include, but are not limited to, 1-naphthylmethyl. In ordinary practice, from the viewpoint of economy and product isolation, if t-butyl hydroperoxide is used, sufficiently good results can be obtained. The organic selenium compound used as a catalyst has the general formula ArSeSeAr'.

Here, VCAr and Ar' are the same or different aromatic groups. Ar,. Specific examples of Ar' include phenyl,
Examples include, but are not limited to, substituted phenyl, naphthyl, substituted naphthyl, and the like. Here, as a specific example of the substituted phenyl, a substituted phenyl group of the general formula can be mentioned.

R1, R2, R3, R4, R5 may be the same or different (however, it is better not to be all H), hydrogen, methyl, ethyl, propyl, butyl, t-butyl, butyl, isobutyl, methoxy, ethoxy, phenoxy,
Hails dimethylamino, diethylamino, chlorine, bromine, fluorine, iodine, etc. As a specific example of substituted naphthyl,
It is the same as R1 to R5 in the definition of the general formula substituted phenyl group.

In either case, the substituents include fluorine, chlorine,
If bromine or iodine is contained, the total number is 2 or less for substituted phenyl, and 3 or less for substituted naphthyl.
The following is desirable. In general, there is a tendency that the oxidation rate of alcohol is faster when more electron-donating groups are substituted as substituents.
Sufficiently good results can be obtained using 6-trimethylphenyl diselenide. The organic selenium compound used as a catalyst is used in a so-called catalytic amount, and is usually used in a range of 0.00001 to 0.99 molar equivalent relative to the alcohol, preferably 0.01 to 0.5 molar equivalent. .

After the reaction is completed, a part of the organic selenium compound used can be recovered and reused. Alcohols that are oxidized to give aldehydes or ketones according to the present invention are not particularly limited, but representative examples include the following.

Methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, octanol, 1-decanol, dodecanol, undecanol, cyclopentanol, cyclohexanol, cyclooctanol, cyclododecanol, benzyl alcohol, phenethyl alcohol, 3-phenyl -1-propanol, benzhydrol, allyl alcohol, 5-
Hexen-1-ol, cinnamyl alcohol, trasos-2-hexenol, geraniol, 1-phenyl-4-hexen-3-ol, citronellol, 1-menthol, 2-methyl-5-isopropylidene-2-hexenol, 2 -Cyclopentinol, 4-acetoxy-2-cyclopentynol, lactic acid methyl ester, lactic acid amide, 4-oxo-1-pentanol, 4-tetrahydropyranyloxy-2-cyclopentanol, 1.4
Typical examples include -dihydroxy-2-cyclobenzene, 1,7-octadien-3-ol, ethyl ω-hydroxycaproate, methyl 2-hydroxy-3-phenylpropionate, and cholesterol. Of course, it is not limited to this. As shown in these examples, alcohols may have functional groups such as olefin, carboxylic ester, ketone, aldehyde, amide, and nitro in the same molecule. However, if the olefin is present in the same molecule at a position where it is likely to be cyclized, a catalytic amount of amines is added. As the amines, secondary amines with large steric hindrance are particularly preferably used. Examples of this include cyclohexyl igpropylamine, diisopropyl ane, etc., but are not limited thereto. In normal practice, the use of cyclohexyl isofuropylamine gives satisfactory results.
The reaction of the present invention is extremely easy to carry out; it is sufficient to mix alcohol, organic hydroperoxide, and organic selenium compound as a catalyst and heat the mixture to a predetermined temperature.

The reaction may be carried out with or without the use of a solvent, but in ordinary practice, aromatic hydrocarbons such as benzene, toluene, and xylene are preferably used, but are of course not limited thereto.

Ester solvents such as ethyl acetate, ether, THF
1 Ether solvents such as dimethoxyethane, halogenated hydrocarbons such as methylene chloride, chloroform, t-
Tertiary alcohols such as butanol can also sometimes be used successfully. The reaction temperature is usually selected appropriately between -30 and 200°C, but preferably 1°C from room temperature.
It is preferable to carry out the reaction at a temperature of 50°C.

The reaction product is usually isolated by distillation, but if it has a high boiling point, it is isolated and purified by column chromatography or recrystallization.

The present invention will be specifically explained below using Examples. Example 1 I-decanol 15.87 (1
00 mmol) and bis(2,4,6-trimethylphenyl)diselenide 19,87 (50 mmol) were dissolved and refluxed.

To this, 70% t-butyl hydroperoxide 18.2
A solution of y (150 mmol) in 50 ml of benzene is added dropwise over 30 minutes. After further refluxing for 5 hours, the reaction solution was washed with saturated sodium hydrogen chloride solution and then with saturated saline solution,
After removing the solvent, distillation (B.p.95~7/10mm
), 14.47 (92%) of decanal was obtained. Example 2 (2,4,6-trimethylphenyl)diselenide (198 w, 0.5 mmol) was dissolved in 2 ml of benzene, then 70% t-dissolved in 3 ml of benzene.
141 m9 (1.1 mmol) of butyl hydroperoxide are added.

Then geraniol 154 dissolved in 5 ml of benzene
Add η (1.0 mmol) and reflux for 1 hour. After removing the solvent under reduced pressure, purification by silica gel column chromatography (hexane/ether 10:1) yielded bis(2,4,6-trimethylphenyl)diselenide 161.
η (81% recovery) and geranial 152 mg (10
0%) was obtained. The infrared, NMR, and elemental analysis values of geranial matched those of the standard product. The retention time of the GlPC analysis was also consistent with that of the standard sample. Examples 3 to 15 Example 1
Table 1 shows examples in which various alcohols were oxidized in the same manner as above.

Claims (1)

[Claims] 1 An organic hydroperoxide represented by the general formula ROOH (wherein R represents an alkyl group or an aralkyl group) is used as an oxidizing agent, and ArSeSeAr' is used as a catalyst.
(wherein Ar and Ar' are the same or different aromatic groups).