JP2011236165A - Method for producing alkene by deoxidation of epoxy compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing alkene for allowing production of a target compound under a mild condition in excellent yield when producing the corresponding alkene by deoxidation of an epoxy compound.SOLUTION: In the method for producing alkene, the corresponding alkene is prepared when the epoxy compound is deoxidized under a carbon monoxide atmosphere in the presence of a catalyst with gold-immobilized surface, which is obtained by immobilizing gold nanoparticles to the surface of a carrier, and water. Hydrotalcite is preferably used for the carrier.

Description

  The present invention relates to a method for producing an alkene capable of deoxygenating an epoxy compound under mild conditions to obtain a corresponding alkene in a high yield.

  Deoxygenation of epoxy compounds to alkenes is a very important reaction in the field of organic synthesis and biochemistry. Development of stoichiometric reactions using various reagents for deoxygenation of epoxy compounds to alkenes is progressing (Non-Patent Documents 1 and 2 etc.), but it is necessary to use harmful reducing agents for catalytic reactions. However, there remain problems such as the point that the reaction is easily influenced by air and humidity, and the low catalytic activity (Non-Patent Documents 3 and 4).

  That is, a method for producing an alkene by deoxygenation of an epoxy compound, which can be produced efficiently under mild conditions, and an alkene production method having excellent operability and workability has not yet been found. is the current situation.

Atagi, L. M .; Over, D. E .; McAlister, D. R .; Mayer, J. M. J. Am. Chem. Soc. 1991, 113, 870 RajanBabu, T. V .; Nugent, W. A. J. Am. Chem. Soc. 1994, 116, 986 Gable, K. P .; Brown, E. C .; J. Am. Chem. Soc. 2003, 125, 11018 Gable, K. P .; Brown, E. C. Synlett 2003, 14, 2243

  Accordingly, an object of the present invention is a method for producing an alkene characterized by deoxygenating an epoxy compound to produce a corresponding alkene, and the objective compound is produced in an excellent yield under mild conditions. An object of the present invention is to provide a method for producing an alkene.

  As a result of intensive studies to solve the above problems, the present inventors have used carbon monoxide and water as a reducing agent in the presence of a surface gold-immobilized catalyst obtained by supporting gold nanoparticles on a support. Thus, it was found that the corresponding alkene can be obtained in an excellent yield by deoxygenating the epoxy compound under mild conditions. The present invention has been completed based on these findings.

  That is, the present invention is to produce a corresponding alkene by deoxygenating an epoxy compound in a carbon monoxide atmosphere in the presence of a surface gold-immobilized catalyst obtained by immobilizing gold nanoparticles on a support surface and water. A method for producing an alkene is provided.

  As the carrier, hydrotalcite is preferable.

  The alkene production method according to the present invention uses a surface gold-immobilized catalyst obtained by supporting gold nanoparticles on a specific carrier as a catalyst in a deoxygenation reaction of an epoxy compound, and water and monoxide as a reducing agent. Use in combination with carbon. The catalyst exhibits an excellent reaction promoting action, and can selectively produce the target alkene with a very high yield even under mild conditions. In the present invention, since water is used instead of the organic solvent, the cost can be reduced, and problems associated with handling the organic solvent such as explosiveness, flammability and toxicity can be solved. Furthermore, since water has a large heat capacity, the reaction temperature can be easily adjusted, and the product insoluble in water can be easily recovered. Furthermore, in the method for producing alkene according to the present invention, carbon dioxide is by-produced, but since carbon dioxide can be easily removed, purification of the target alkene is easy. According to the alkene production method of the present invention, it is not necessary to use harmful reagents, and the target compound can be efficiently obtained without by-producting harmful substances. Useful alkenes can be produced efficiently.

[Surface gold immobilization catalyst]
The surface gold-immobilized catalyst used in the present invention is obtained by immobilizing gold nanoparticles on the surface of a carrier. Examples of the carrier include hydrotalcite, alumina (Al ₂ O ₃ ), magnesia (MgO), titania (TiO ₂ ), and the like. In the present invention, among these, a carrier made of a basic compound such as hydrotalcite, alumina (Al ₂ O ₃ ), magnesia (MgO) is preferable. In addition, carriers made of non-basic compounds such as titania (TiO ₂ ), silica (SiO ₂ ), activated carbon (C) are bases (for example, sodium carbonate (Na ₂ CO ₃ ), potassium carbonate (K ₂ CO ₃ )). Etc.) can be used as a carrier in the present invention.

  In the present invention, among these, hydrotalcite is preferable because the target compound can be obtained in an extremely high yield. Therefore, as the surface gold-immobilized catalyst in the present invention, a hydrotalcite-immobilized gold nanoparticle catalyst (hereinafter sometimes referred to as “Au / HT”) in which gold nanoparticles are immobilized on the hydrotalcite surface is preferable. .

  The hydrotalcite is not particularly limited, and naturally produced hydrotalcite may be used, or a synthetic hydrotalcite or a synthetic hydrotalcite-like compound may be used.

The hydrotalcite is, for example, the following formula (1)
M ^II _8-X M ^III _X (OH) ₁₆ A · nH ₂ O (1)
( ^Wherein M ^II is at least one selected from Mg ²⁺ , Fe ²⁺ , Zn ²⁺ , Ca ²⁺ , Li ²⁺ , Ni ²⁺ , Co ²⁺ , Cu ²⁺ , and Mn ^2+. M ^III is at least one trivalent metal selected from Al ³⁺ , Fe ³⁺ , Mn ³⁺ , Ru ³⁺ , x is an integer of 1 to 7 A represents a divalent anion, and n represents an integer of 0 to 30)
Or the following formula (2)
[Mg ²⁺ _1-y Al ³⁺ _y (OH) ₂ ] ^{y +} [(D ^s− ) _{y / s} · mH ₂ O] ^y− (2)
(Wherein y represents a number satisfying 0.20 ≦ y ≦ 0.33, D ^s− represents an s-valent anion, and m represents an integer of 0 to 30)
It is represented by As the hydrotalcite in the present invention, in particular, M ^II is Mg ²⁺ , M ^III is Al ³⁺ , and A is CO ₃ ² in the above formula (1) in that the target compound can be obtained in an extremely high yield. ^In particular, hydrotalcite represented by Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O can be suitably used.

  As hydrotalcite in this invention, you may use commercial items, such as a brand name "Tomita AD-500" (made by Tomita Pharmaceutical Co., Ltd.).

The method for immobilizing the gold nanoparticles on the surface of the carrier is not particularly limited. For example, a gold compound such as gold chloride (AuCl ₃ ) or chloroauric acid (HAuCl ₄ ) and a carrier such as hydrotalcite. And the like in a solvent and agitated to immobilize gold ions on the surface of a carrier such as hydrotalcite and then reduce the gold ions by an appropriate method.

  The solvent only needs to dissolve the gold compound to be used, and examples thereof include water, acetone, and alcohols. The concentration of the gold compound in the solution when the gold nanoparticles are immobilized is not particularly limited, and can be appropriately selected from a range of 0.1 to 100 mM, for example. Although the temperature at the time of stirring can be selected from the range of 20-80 degreeC, for example, it is normally performed at room temperature (25 degreeC). Although stirring time changes also with the temperature at the time of stirring, it is 6 to 24 hours, for example, Preferably, it is about 8 to 12 hours. After completion of the stirring, it may be washed with water or an organic solvent as necessary, and dried by vacuum drying or the like.

Examples of the reducing agent include borohydride complex compounds such as sodium borohydride (NaBH ₄ ), lithium borohydride (LiBH ₄ ), potassium borohydride (KBH ₄ ), hydrazine, hydrogen (H ₂ ), Examples include silane compounds such as dimethylphenylsilane, hydroxy compounds, and the like. Examples of the hydroxy compound include alcohol compounds such as primary alcohol and secondary alcohol. The hydroxy compound may have a plurality of hydroxyl groups, and may be any of monohydric alcohol, dihydric alcohol, polyhydric alcohol and the like.

As a reducing agent used when performing the metal immobilization treatment on the hydrotalcite surface in the present invention, sodium borohydride (NaBH ₄ ), lithium borohydride (LiBH ₄ ), potassium borohydride (KBH), among others. ₄ ) and the like are preferable, and potassium borohydride (KBH ₄ ) is particularly preferable. The surface gold-immobilized catalyst obtained by reduction with potassium borohydride (KBH ₄ ) tends to have a smaller average particle size of the immobilized metal particles, thereby increasing the specific surface area. And the catalytic activity can be significantly improved.

  The gold nanoparticle content in the surface gold-immobilized catalyst is, for example, 0.01 to 3 mmol, preferably 0.01 to 0.1 mmol, particularly preferably 0.045 to 1 g of a carrier such as hydrotalcite. 0.1 mmol. When the gold nanoparticle content in the surface gold-immobilized catalyst exceeds the above range, the catalytic action tends to decrease.

（式中、Ｒ¹、Ｒ^1'、Ｒ²、Ｒ^2'は同一又は異なって、水素原子又は炭化水素基を示す。Ｒ¹、Ｒ^1'、Ｒ²、Ｒ^2'から選択された２つが互いに結合して、エポキシ環を形成する炭素原子と共に環を形成していてもよい。尚、Ｒ¹、Ｒ^1'、Ｒ²、Ｒ^2'のうち、少なくとも１つは炭化水素基である）
で表される。 [Epoxy compound]
In the method for producing alkene according to the present invention, the epoxy compound serving as a substrate is represented by the following formula (3):

Wherein R ¹ , R ^{1 ′} , R ² and R ^{2 ′} are the same or different and each represents a hydrogen atom or a hydrocarbon group. 2 selected from R ¹ , R ^{1 ′} , R ² and R ^{2 ′} May be bonded to each other to form a ring together with carbon atoms forming an epoxy ring, wherein at least one of R ¹ , R ^{1 ′} , R ² and R ^{2 ′} is a hydrocarbon group. )
It is represented by

Examples of the hydrocarbon group in R ¹ , R ^{1 ′} , R ² , and R ^{2 ′} include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and a group in which these are bonded. . The hydrocarbon group includes a hydrocarbon group having a substituent.

  Examples of the aliphatic hydrocarbon group include alkyl groups having about 1 to 4 (preferably 1 to 3) carbon atoms such as methyl, ethyl, propyl, isopropyl, and butyl groups.

  Examples of the alicyclic hydrocarbon group include about 3 to 12 members (preferably 3 to 8 members, particularly preferably 5 to 8 members) such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. A cycloalkyl group; a cycloalkenyl group of about 3 to 8 members (preferably 5 to 8 members) such as a cyclopentenyl group.

  Examples of the aromatic hydrocarbon group include an aromatic hydrocarbon group having about 6 to 14 (preferably 6 to 10) carbon atoms such as a phenyl group.

Examples of the hydrocarbon group in which an aliphatic hydrocarbon group and an alicyclic hydrocarbon group are bonded include cycloalkyl-alkyl groups such as cyclopentylmethyl, cyclohexylmethyl, and 2-cyclohexylethyl groups (for example, C _3-12 cyclohexane). Alkyl-C _1-4 alkyl group, etc.).

The hydrocarbon group in which an aliphatic hydrocarbon group and an aromatic hydrocarbon group are bonded to each other includes an aralkyl group (for example, a C _7-18 aralkyl group) and an alkyl-substituted aryl group (for example, about 1 to about 4). And a phenyl group substituted with a C _1-4 alkyl group).

  The hydrocarbon group may have various substituents such as a halogen atom, an oxo group, a hydroxyl group, a substituted oxy group (for example, an alkoxy group, an aryloxy group, an aralkyloxy group, etc.). Further, the hydroxyl group may be protected with a protecting group commonly used in the field of organic synthesis.

Specific examples of the epoxy compound that is suitably used include the following compounds (3a) to (3i).

  In the present invention, among them, aromatic epoxy compounds (for example, compounds represented by the above formulas (3a) to (3h)) are preferable in that the desired alkene can be obtained with high yield. In particular, styrene oxide derivatives (for example, compounds represented by the above formulas (3a) to (3f)) are preferable in that the substrate is rapidly converted.

（式中、Ｒ¹、Ｒ^1'、Ｒ²、Ｒ^2'は上記に同じ） [Alkene production method]
The method for producing an alkene according to the present invention comprises deoxidizing an epoxy compound in a carbon monoxide atmosphere in the presence of a surface gold immobilization catalyst obtained by immobilizing gold nanoparticles on a support surface and water, and the corresponding alkene. It is characterized by manufacturing. When a compound represented by the following formula (3) is used as the epoxy compound, a corresponding alkene represented by the following formula (4) is obtained.

(Wherein R ¹ , R ^{1 ′} , R ² , R ^{2 ′} are the same as above)

The alkene production method according to the present invention is considered to proceed according to the reaction mechanism shown below. In addition, although the case where Au / HT is used as a catalyst will be described, the same applies to the case where a surface gold-immobilized catalyst obtained by immobilizing gold nanoparticles on another carrier is used. In the formula, BS represents a base site of hydrotalcite. R ¹ , R ^{1 ′} , R ² and R ^{2 ′} are the same as above.

  The amount of the surface gold immobilization catalyst used is, for example, about 0.0001 to 50 mol%, particularly about 0.01 to 20 mol%, particularly about 0.1 to 5 mol% with respect to the epoxy compound. preferable.

  The above reaction is performed in the presence of water. For example, the amount of water used is preferably within a range where the concentration of the substrate is about 0.5 to 2.0% by weight.

  The above reaction is performed in a carbon monoxide atmosphere. The carbon monoxide atmosphere refers to a state in which carbon monoxide gas or carbon monoxide gas is supplied (bubbled). When the reaction is performed in carbon monoxide, the pressure during the reaction is not particularly limited and may be normal pressure or increased pressure, but is preferably 0.1 to 1.0 MPa (in particular, 0.1 to 0.5 MPa). Is preferred). Furthermore, the above reaction can be carried out by a conventional method such as a batch system, a semi-batch system, or a continuous system.

  The method for producing alkene according to the present invention allows the reaction to proceed smoothly even under mild conditions. The reaction temperature can be appropriately adjusted according to the type of substrate and the type of target product, and is, for example, about 10 to 100 ° C, preferably about 10 to 50 ° C, and particularly preferably about 10 to 40 ° C. . The reaction time can be appropriately adjusted according to the reaction temperature and pressure, and is, for example, about 10 minutes to 48 hours, preferably about 1 hour to 48 hours, and particularly preferably about 4 hours to 30 hours.

  After completion of the reaction, the reaction product can be separated and purified by separation means such as filtration, concentration, distillation, extraction, crystallization, recrystallization, column chromatography, etc., or a separation means combining these.

  According to the method for producing alkene of the present invention, the deoxygenation reaction of the epoxy compound can be performed under mild conditions, and the corresponding alkene can be produced with high yield.

  In addition, since the surface gold-immobilized catalyst used in the reaction is supported on a carrier, the metal supported in the organic synthesis reaction is not easily eluted into the reaction solution. For example, physical reaction such as filtration or centrifugation from the reaction solution is performed. Can be easily recovered by a conventional separation method. The recovered surface gold-immobilized catalyst is reused as it is or after being washed and dried. The washing treatment can be performed by a method of washing several times (for example, 2 to 3 times) with an appropriate solvent (for example, water).

  The recovered surface gold-immobilized catalyst can exhibit almost the same catalytic ability as an unused surface gold-immobilized catalyst. Even if the use-regeneration is repeated a plurality of times, for example, the use-regeneration is performed about 5 times. Even if it repeats, the fall of the catalyst ability can be suppressed remarkably. Therefore, according to the alkene production method of the present invention, the surface gold-immobilized catalyst that occupies a large proportion of the production cost can be recovered and repeatedly used, so that the production cost can be greatly reduced.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited by these Examples.

Production Example 1
In a 50 mL eggplant-shaped flask, 0.1 mmol of chloroauric acid (HAuCl ₄ ) and 50 mL of ion-exchanged water are added, and 1.0 g of hydrotalcite (trade name: AD-500, manufactured by Tomita Pharmaceutical Co., Ltd.) is added to the solution. After stirring at room temperature for 2 minutes, ammonia (5 mmol) was added, and the mixture was further stirred for 12 hours. Thereafter, the mixture was filtered with suction, washed with deionized water (1 L), and vacuum-dried to obtain Au / HT (Au: trivalent) (Au: 0.045 mmol / g) as a yellow powder.
In a 50 mL eggplant-shaped flask, KBH ₄ (0.9 mmol) was dissolved by adding water (50 mL), and 0.9 g of the obtained Au / HT (Au: trivalent) was added thereto, and the mixture was added at room temperature under an argon atmosphere. For 1 hour. After stirring, it is filtered by suction, washed with 1 L of deionized water, and vacuum-dried for 24 hours to obtain a purple powder of Au / HT (Au: 0 valent) (Amount of Au supported on 1 g of carrier: 0.045 mmol / g). Obtained.

Production Example 2
A catalyst (Au / Al ₂ O ₃ ) having gold nanoparticles immobilized on the alumina surface was obtained in the same manner as in Preparation Example 1 except that alumina (Al ₂ O ₃ ) was used instead of hydrotalcite.

Production Example 3
A catalyst (Au / MgO) in which gold nanoparticles were immobilized on the magnesia surface was obtained in the same manner as in Preparation Example 1 except that magnesia (MgO) was used instead of hydrotalcite.

Production Example 4
A catalyst (Au / TiO ₂ ) having gold nanoparticles immobilized on the titania surface was obtained in the same manner as in Preparation Example 1, except that titania (TiO ₂ ) was used instead of hydrotalcite.

Production Example 5
To a 200 mL eggplant-shaped flask, 1 mmol of silver nitrate (AgNO ₃ ) and 150 mL of ion-exchanged water were added, 2.0 g of hydrotalcite was added thereto, and the mixture was stirred at room temperature for 6 hours. After stirring, the mixture was filtered with suction, washed with 1 L of deionized water, and vacuum-dried for 24 hours to obtain Ag / HT (Ag: monovalent).
Furthermore, water (150 mL) was added to and dissolved in KBH ₄ (9 mmol) in a 200 mL eggplant-shaped flask, and 1.8 g of the obtained Ag / HT (Ag: 1 valence) was added thereto. For 1 hour. After stirring, it is filtered by suction, washed with 1 L of deionized water, and vacuum-dried for 24 hours to give a green powder of Ag / HT (Ag: 0 valence) (Ag load on 1 g of carrier: 0.3 mmol / g) Got.

Production Example 6
Pd / HT (Pd: 0 valence) (Pd supported on 1 g of carrier: 0.1 mmol / g) in the same manner as in Production Example 1 except that Na ₂ PdCl ₄ was used instead of chloroauric acid (HAuCl ₄ ). )

Production Example 7
Pt / HT (Pt: 0 valence) (Pt supported on 1 g of carrier: 0.1 mmol / g) in the same manner as in Production Example 1 except that Na ₂ PtCl ₄ was used instead of chloroauric acid (HAuCl ₄ ). )

Production Example 8
Rh / HT (Rh: 0 valence) (Rh loading relative to 1 g of carrier: 0.1 mmol / g) was carried out in the same manner as in Production Example 1 except that RhCl ₃ was used instead of chloroauric acid (HAuCl ₄ ). Obtained.

Production Example 9
Ru / HT (Ru: 0 valence) (Ru supported on 1 g of carrier: 0.1 mmol) in the same manner as in Production Example 1 except that RuCl ₃ .xH ₂ O was used instead of chloroauric acid (HAuCl ₄ ). / G).

Example 1
Au / HT obtained in Production Example 1 (Au: 0.9 mol% with respect to styrene oxide), water (5 mL), and styrene oxide (0.5 mmol) were added to a glass pressure-resistant reaction tube, and under a CO atmosphere (1 atm), 27 Stirring was carried out at 6 ° C. for 6 hours to obtain styrene (yield 99% or more, selectivity 99% or more). In addition, the standard measuring method by a liquid chromatography was used for the measurement of a yield and a selectivity.

Example 2
Instead of Au / HT obtained in Production Example 1, after completion of the reaction of Example 1, the reaction solution was filtered to separate the catalyst, and the separated catalyst was washed twice with water, and then room temperature (25 Styrene) was obtained in the same manner as in Example 1 except that [Au / HT] ′ obtained by drying under reduced pressure at 0 ° C. was used (yield 99%, selectivity 99% or more).

Example 3
Instead of Au / HT obtained in Production Example 1, after completion of the reaction of Example 3, the reaction solution was filtered to separate the catalyst, and the separated catalyst was washed twice with water, and then room temperature (25 Styrene) was obtained in the same manner as in Example 1 except that [Au / HT] '' obtained by drying under reduced pressure at 0 ° C. was used (yield 97%, selectivity 99% or more).

Examples 4-7, Comparative Examples 1-8
Instead of Au / HT obtained in Production Example 1, styrene was obtained in the same manner as in Example 1 except that the catalysts described in Table 1 below were used. In addition, Example 4 is Production Example 2, Example 5 is Production Example 3, Example 6 is Production Example 4, Comparative Example 4 is Production Example 5, Comparative Example 5 is Production Example 6, Comparative Example 6 is Production Example 7, Comparative Example 7 used the catalyst obtained in Production Example 8 and Comparative Example 8 used in Production Example 9. In Example 7, the catalyst obtained in Production Example 4 was used, and 1.5 mmol of Na ₂ CO ₃ was added.

Example 8
Styrene was obtained in the same manner as in Example 1 except that the amount of Au / HT used was changed from 0.9 mol% to 1.40 mol% with respect to styrene oxide (yield 99% or more, selectivity 99% or more). ).

Examples 9-14
The corresponding alkene was obtained in the same manner as in Example 8 except that the substrate and reaction time were changed to those shown in Table 2 below.

Comparative Example 9
Cinnamyl alcohol (yield 82%, selectivity 82%) was obtained in the same manner as in Example 12 except that toluene was used instead of water as a solvent.

Comparative Example 10
Cinnamyl alcohol (yield 36%, selectivity 36%) was obtained in the same manner as in Example 12 except that tetrahydrofuran was used instead of water and the reaction time was changed from 16 hours to 24 hours. It was.

Claims (2)

  An alkene having a surface gold immobilization catalyst obtained by immobilizing gold nanoparticles on a support surface and a corresponding alkene by deoxygenating an epoxy compound in a carbon monoxide atmosphere in the presence of water. Production method.   The method for producing an alkene according to claim 1, wherein hydrotalcite is used as a carrier.