JP2008246400A - Dehydrogenation reaction of alcohol and catalyst therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid catalyst for the dehydrogenation reaction using an industrially inexpensive carrier but requiring no oxidizing agent and easily separated from a product, its manufacturing method and a manufacturing method of a saturated carbonyl compound by the dehydrogenation reaction of a saturated secondary alcohol compound using the catalyst. <P>SOLUTION: The solid catalyst for alcohol dehydrogenation reaction contains carrier comprising hydrotalcite represented by the general formula: [Mg<SB>8-z</SB>Al<SB>z</SB>(OH)<SB>16</SB>]<SP>z+</SP>[X<SP>n-</SP><SB>z/n</SB>]*mH<SB>2</SB>O and rhodium supported on the hydrotalcite carrier and is manufactured by adding hydrotalcite represented by the general formula to a solution of a rhodium compound and stirring the obtained mixture to subject the same to solid-liquid separation and drying treatment before reducing the dried mixture. The saturated carbonyl compound is manufactured by dehydrogenating the saturated secondary alcohol compound under a condition using no oxidizing agent in the presence of the solid catalyst for alcohol dehydrogenation reaction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an alcohol dehydrogenation catalyst, a method for producing the same, and an alcohol dehydrogenation reaction using the catalyst.

Synthesis of carbonyl compounds by oxidative dehydrogenation of alcohol is one of the most important functional group transformations in organic synthesis to obtain intermediates such as fragrances and pharmaceutical agricultural chemicals. Conventionally, stoichiometric oxidation reagents using heavy metal salts such as chromium and manganese have been used, but these methods have become a serious problem from the environmental viewpoint, such as by-production of a large amount of highly toxic waste after the reaction. Yes. On the other hand, in recent years, from the viewpoint of environmentally friendly green chemistry, attention has been focused on the development of a catalytic method using an oxidizing agent such as molecular oxygen or a hydrogen acceptor. The following alcohol oxidation reaction catalyst systems have been reported so far (Patent Documents 1 and 2, Non-Patent Document 1).
However, these are examples using a homogeneous catalyst, which is accompanied by a problem that it is difficult to separate the catalyst and the product.

  On the other hand, a heterogeneous solid catalyst for the oxidation reaction of alcohol in which the catalyst and the product are easily separated is also known. For example, a solid catalyst in which palladium is supported using alumina or the like as a carrier, a method using a hydrotalcite-based oxidation catalyst, and a method using a hydroxyapatite-based oxidation catalyst are known (Patent Documents 3 to 6). However, in these solid catalysts, the separation of the catalyst and the product can be easily performed by filtration, but there is a problem that an oxidizing agent such as oxygen or a hydrogen acceptor is required.

  Recently, a catalyst that does not use an oxidant or a hydrogen acceptor has also been reported (Non-Patent Documents 2 to 6). However, these are mostly examples of homogeneous catalysts, and there are examples of heterogeneous Ru catalysts, but the problem is that catalyst preparation is complicated in many stages and requires special compounds (ligands). There is a point.

  Therefore, it has been desired to develop a catalyst that uses a solid catalyst that can be easily separated from a product and that can be used industrially at low cost as a catalyst for alcohol dehydrogenation reaction that does not require an oxidant.

JP-A-57-108035 JP-A-3-93742 JP 2000-70723 A JP2000-086245 JP 2002-274852 JP2002-275116 R. H. Meijer et al., J. Mol. Catal. A: Chemical, 2004, 218, 29 J. Ho Choi, N. Kim, Y. J. Shin, J. H. Park and J. Park, Tetrahedron Lett., 2004, 45, 4607 H. Junge and M. Beller, Tetrahedron Lett., 2005, 46, 1031 J. Zhang, G. Leitus, Y. Ben-David and D. Milstein, J. Am. Chem. Soc., 2005, 127, 10840 J. van Buijtenen, J. Meuldijk et al., Organometallics, 2006, 25, 873 K. Fujita, N. Tanino and R. Yamaguchi, Org. Lett., 2007, 9 (1), 109

  An object of the present invention is to provide a solid catalyst for dehydrogenation reaction of an alcohol which does not require an oxidant and which uses a carrier that can be easily separated from a product and can be used industrially at low cost. And Another object of the present invention is to provide a method for producing a saturated carbonyl compound by dehydrogenation of a saturated secondary alcohol compound using the alcohol dehydrogenation solid catalyst.

  As a result of intensive studies on hydrotalcite-based solid catalysts, the present inventors have found that when a solid catalyst having rhodium supported on a hydrotalcite support is used, a carbonyl compound is produced by dehydrogenation of an alcohol compound without using an oxidizing agent. As a result, the present invention has been completed.

That is, the present invention firstly includes a support comprising a hydrotalcite represented by the following general formula (I), and rhodium supported on the hydrotalcite support, for an alcohol dehydrogenation reaction: A solid catalyst is provided.
[Mg _8-z Al _z (OH) ₁₆ ] ^{z +} [X ^n- _{z / n} ] ・ mH ₂ O (I)
(In the formula, Z is a real number of 0 <Z ≦ 4, X ⁿ⁻ represents an anion and its charge, n is a natural number of 1 ≦ n ≦ 4, and m is a real number of 0 ≦ m ≦ 12. .)

  In the second aspect of the present invention, the hydrotalcite is added to a solution of a rhodium compound, and the resulting mixture is stirred, solid-liquid separated and dried, and then reduced under a hydrogen atmosphere. A method for producing a solid catalyst for reaction is provided.

  Thirdly, the present invention provides a method for producing a saturated carbonyl compound, characterized in that a saturated secondary alcohol compound is dehydrogenated in the presence of the solid catalyst for alcohol dehydrogenation under a condition that does not use an oxidizing agent. I will provide a.

  The catalyst of the present invention is a solid catalyst exhibiting excellent catalytic activity for alcohol dehydrogenation reaction that does not require an oxidant. Since this catalyst is a solid catalyst and the reaction product and the catalyst can be easily separated, the reaction process, apparatus, reaction management and the like can be facilitated. Furthermore, since this catalyst uses a hydrotalcite support that can be used at low cost, it is advantageous for industrial use. Further, this catalyst has a slight decrease in catalytic activity after being separated and recovered after the reaction, and can be reused repeatedly.

Hereinafter, the present invention will be described in more detail.
<Solid catalyst for dehydrogenation of alcohol>
The solid catalyst for alcohol dehydrogenation of the present invention has a hydrotalcite carrier and rhodium supported on the hydrotalcite carrier.

-Carrier-
The solid catalyst carrier for alcohol dehydrogenation reaction of the present invention is hydrotalcite and has the following general formula (I):
[Mg _8-z Al _z (OH) ₁₆ ] ^{z +} [X ^n- _{z / n} ] ・ mH ₂ O
(In the formula, Z is a real number of 0 <Z ≦ 4, X ⁿ⁻ represents an anion and its charge, n is a natural number of 1 ≦ n ≦ 4, and m is a real number of 0 ≦ m ≦ 12. )
The hydrotalcite represented by the formula is particularly preferred.

Hydrotalcite Hydrotalcite is a kind of basic layered clay compound, and has properties such as surface basicity, surface adsorption capacity, anion exchange capacity of the intermediate layer and cation exchange capacity of the basic layer. It is a material that is attracting attention. Hydrotalcite can be easily obtained industrially. The physical properties of hydrotalcite are not limited.

  In the general formula (I), Z must be a real number greater than 0 and 4 or less, preferably a real number of 0.5 to 3, more preferably a real number of 1 to 2.5.

In the general formula (I), X ⁿ⁻ represents an anion and its charge, but the type of the anion is not particularly limited. Examples of anions include halide ions such as fluoride ion, chloride ion, bromide ion or iodide ion; carbonate ion, bicarbonate ion, sulfate ion, hydrogen sulfate ion, nitrate ion, perchlorate ion, phosphate ion Oxygen acid ions such as hydrogen phosphate ion or dihydrogen phosphate ion; organic carboxylate ions such as formate ion, acetate ion or benzoic acid; complex ions such as hexacyanoferrate (III) ion or hexachloroplatinum (IV) ion Can be given. Of these, halide ions or oxyacid ions are preferred, and carbonate ions are more preferred.

  In the general formula (I), n represents the charge of the anion, and n must be a natural number of 1 to 4, and preferably a natural number of 1 to 2.

  M in the general formula (I) must be a real number of 0 to 12, preferably a real number of 0 to 8, more preferably a real number of 0 to 4.

-Catalyst preparation method (supporting rhodium on inorganic support)-
The rhodium can be supported on the hydrotalcite carrier by bringing the hydrotalcite carrier into contact with a solution containing rhodium.

  Specifically, in the solid catalyst for alcohol dehydrogenation reaction of the present invention, for example, a rhodium compound is dissolved in a solvent, hydrotalcite is added to the resulting solution, and the rhodium is supported on the carrier by stirring. Thereafter, it can be obtained by solid-liquid separation / drying and reduction under a hydrogen atmosphere. This supporting reaction is typically performed at a temperature of 20 to 40 ° C. for 1 to 16 hours.

  Thus, a solid catalyst for alcohol dehydrogenation reaction in which rhodium is supported on a hydrotalcite carrier is usually obtained.

  The solvent used for the supporting reaction is not particularly limited as long as it dissolves a rhodium compound, but ethanol, methanol, water, or a mixture thereof is preferable.

  The rhodium compound is not particularly limited as long as it is soluble in the solvent used in the supporting reaction step. In addition to salts such as chloride, bromide, nitrate, sulfate, perchlorate and acetate, hexaammine rhodium chloride Bis (ethylenediamine) rhodium chloride, tris (2,4-pentanedionato) rhodium, dichlorobis (1,5-cyclooctadiene) dirhodium, dichlorobis {(2,2,1) -bicyclohepta-2,5 -Diene} dirhodium, (2,4-pentanedionato) dicarbonylrhodium, (2,4-pentanedionato) diethylenerhodium, hydridocarbonyltristriphenylphosphinerhodium, and other complexes can be used, such as chloride, bromide, Dichlorobis (1,5-cyclooctadiene) dirhodium is preferred.

  The supported amount of rhodium per 1 g of the carrier is not particularly limited, but is usually 1.0 μmol to 2 mmol, preferably 100 μmol to 2 mmol in terms of rhodium element.

-Carbonyl compound formation reaction by dehydrogenation of alcohol-
A carbonyl compound can be produced by dehydrogenating an alcohol compound in the presence of a solid catalyst for alcohol dehydrogenation reaction.

  In particular, a saturated carbonyl compound can be produced by dehydrogenating a saturated secondary alcohol compound in the presence of a solid catalyst for alcohol dehydrogenation reaction. This dehydrogenation reaction is preferably performed in a solvent. The reaction is usually carried out in an inert gas atmosphere such as argon or nitrogen. The use of an oxidant such as an oxygen-containing gas is not necessary.

  For example, in a carbonyl compound generation reaction by dehydrogenation of cyclohexanol, cyclohexanone can be obtained in a yield of 92% by using a rhodium-supported hydrotalcite catalyst.

  The saturated secondary alcohol compound may be linear (straight chain, branched) or cyclic. Specifically, in the linear form, isopropanol, 2-butanol, 2-pentanol, 3-pentanol, 2-hexanol, Secondary alkanols such as 3-hexanol, 2-heptanol, 3-heptanol, 2-octanol, 3-octanol, 4-octanol, 2-decanol, 2-dodecanol, and the like are cyclobutanol, cyclopentanol, cyclohexanol , Cycloheptanol, cyclooctanol, cyclodecanol, cyclododecanol, 2-adamantanol and other cycloalcohols. By dehydrogenating them, the corresponding saturated carbonyl compound can be produced.

  In a preferred embodiment, the saturated secondary alcohol compound may be produced in the presence of a solid catalyst for alcohol dehydrogenation without using an oxidizing agent or an oxygen atmosphere.

  The catalyst of the present invention is usually used in the range of 0.01 to 20 mol%, preferably 0.1 to 10 mol%, as rhodium with respect to the alcohol compound as a reactant.

  The alcohol dehydrogenation reaction of the present invention is carried out without solvent or preferably in the presence of a solvent. The solvent to be used is not particularly limited as long as it can dissolve the reaction product, but organic solvents such as benzene, cyclohexane, and methylcyclohexane are preferable, and a methylcyclohexane solvent is particularly preferable.

  This alcohol dehydrogenation reaction is usually performed in an atmosphere of an inert gas such as nitrogen or argon in a temperature range of room temperature to 200 ° C. for about 1 to 100 hours.

  Examples of the present invention are shown below, but the present invention is not limited to the following examples.

<Example 1>
(Preparation of rhodium-supported hydrotalcite catalyst)
Rhodium chloride hydrate (NEM Chemcat Co., Ltd.) (0.3 mmol) was dissolved in water (200 ml). To this solution, 1.0 g of hydrotalcite ([Mg ₆ Al ₂ (OH) ₁₆ ] CO ₃ .nH ₂ O) having a molar ratio of Mg to Al of 3: 1 was added and stirred at room temperature for 9 hours. Thereafter, filtration and drying were performed to obtain 1.0 g of a rhodium-supported hydrotalcite catalyst.

<Example 2>
(Synthesis of cyclohexanone by dehydrogenation of cyclohexanol)
1 mmol of cyclohexanol was dissolved in 5 ml of methylcyclohexane solvent under a stream of argon. To this solution, 0.2 g of the rhodium-supported hydrotalcite catalyst prepared in Example 1 was added and stirred at 110 ° C. for 72 hours under an argon atmosphere. After cooling, the catalyst was separated by filtration, and the filtrate was diluted with methylcyclohexane. Using this diluted solution, the yield of cyclohexanone was measured by gas chromatography (hereinafter referred to as “GC”). The yield of cyclohexanone relative to the charged cyclohexanol was 92%.

<Example 3>
(Synthesis of cyclooctanone by dehydrogenation of cyclooctanol)
In Example 2, cyclooctanol was obtained in the same manner as in Example 2 except that cyclooctanol was used instead of cyclohexanol and the stirring time was changed to 11 hours. The yield was 99% or more.

<Example 4>
(Synthesis of cyclododecanone by dehydrogenation of cyclododecanol)
In Example 2, cyclododecanone was obtained in the same manner as in Example 2 except that cyclododecanol was used instead of cyclohexanol and the stirring time was 30 hours. The yield was 89%.

<Example 5>
(Synthesis of 2-adamantanone by dehydrogenation of 2-adamantanol)
In Example 2, 2-adamantanol was obtained in the same manner as in Example 2 except that 2-adamantanol was used instead of cyclohexanol and the stirring time was 30 hours. The yield was 74%.

<Example 6>
(Synthesis of 2-octanone by dehydrogenation of 2-octanol)
In Example 2, 2-octanol was obtained in the same manner as in Example 2 except that 2-octanol was used instead of cyclohexanol and the stirring time was changed to 48 hours. The yield was 66%.

<Comparative Example 1>
(Synthesis of cyclooctanone by dehydrogenation of cyclooctanol using hydrotalcite as a catalyst)
1 mmol of cyclooctanol was dissolved in 5 ml of methylcyclohexane solvent under an argon stream. To this solution, 0.2 g of the hydrotalcite before loading rhodium used in Example 1 as a catalyst was added and stirred at 110 ° C. for 10 hours in an argon atmosphere. After cooling, the catalyst was separated by filtration, and the filtrate was diluted with methylcyclohexane. Using this diluted solution, the yield of cyclooctanone was measured by GC. The yield of cyclooctanone was a trace amount.

<Comparative example 2>
(Synthesis of cyclooctanone by dehydrogenation of cyclooctanol using rhodium-supported fluoroapatite catalyst)
1 mmol of cyclooctanol was dissolved in 5 ml of methylcyclohexane solvent under an argon stream. To this solution, 0.2 g of rhodium-supported fluoroapatite was added as a catalyst, and the mixture was stirred at 110 ° C. for 10 hours in an argon atmosphere. After cooling, the catalyst was separated by filtration, and the filtrate was diluted with methylcyclohexane. Using this diluted solution, the yield of cyclooctanone was measured by GC. The yield of cyclooctanone was a trace amount.

Claims (5)

A solid catalyst for alcohol dehydrogenation reaction, comprising a carrier comprising hydrotalcite represented by the following general formula (I) and rhodium supported on the hydrotalcite carrier.
[Mg _8-z Al _z (OH) ₁₆ ] ^{z +} [X ^n- _{z / n} ] ・ mH ₂ O (I)
(In the formula, Z is a real number of 0 <Z ≦ 4, X ⁿ⁻ represents an anion and its charge, n is a natural number of 1 ≦ n ≦ 4, and m is a real number of 0 ≦ m ≦ 12. .) A hydrotalcite represented by the following general formula (I) is added to a solution of a rhodium compound, and the resulting mixture is stirred, solid-liquid separated and dried, and then reduced under a hydrogen atmosphere. 2. A process for producing a solid catalyst for alcohol dehydrogenation according to 1.
[Mg _8-z Al _z (OH) ₁₆ ] ^{z +} [X ^n- _{z / n} ] ・ mH ₂ O (I)
(In the formula, Z is a real number of 0 <Z ≦ 4, X ⁿ⁻ represents an anion and its charge, n is a natural number of 1 ≦ n ≦ 4, and m is a real number of 0 ≦ m ≦ 12. .)   A method for producing a saturated carbonyl compound, comprising dehydrogenating a saturated secondary alcohol compound in the presence of the solid catalyst for alcohol dehydrogenation reaction according to claim 1 without using an oxidizing agent.   The manufacturing method of Claim 3 which performs the said dehydrogenation reaction in a solvent.   A saturated carbonyl compound produced by the method according to claim 3.