Method for producing α,β-unsaturated aldehyde

Abstract

To provide a production method which, by using titanium oxide in a cross aldol condensation reaction, can provide a target aldehyde in high yield and suppress generation of by-products while satisfying selectivity.SOLUTION: A method for producing an α,β-unsaturated aldehyde comprises a step of reacting a compound represented by formula (I) and a compound represented by formula (II) in a solvent or without a solvent to obtain a compound represented by formula (III). In the step, titanium oxide is used as a catalyst and an amount of the solvent is 50 pts.mass or less relative to a total amount of 100 pts.mass of the compounds of formula (I) and formula (II).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing an α,β-unsaturated aldehyde.

Background Art

[0002] Aldehydes are compounds useful as raw materials for chemical reactions, fragrances, pharmaceuticals, pesticide intermediates, etc. Among them, α,β-unsaturated aldehydes having a specific molecular weight are useful as fragrance materials by themselves, and are further used as raw materials for derivatives having different fragrance notes.

[0003] As methods for producing aldehydes, dehydrogenation reactions and oxidation reactions using alcohol as a raw material have been known for a long time. Among these, the cross-aldol condensation reaction of two kinds of aldehydes is frequently used as a method for producing α,β-unsaturated aldehydes, and various studies have been made on the reaction conditions.

[0004] For example, Non-Patent Document 1 discloses a method for producing an α,β-unsaturated aldehyde by the cross-aldol reaction of heptanal and benzaldehyde. In this reaction, titanium oxide is used as a catalyst, and a large amount of solvent is used when using a solvent.

[0005] Patent Document 1 discloses a method in the cross-aldol condensation reaction by adjusting the content of water contained in the raw materials used in the reaction to a specific amount.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] In the case of the cross-aldol condensation reaction, it is known that side reactions such as dimerization (self-aldol condensation reaction) and disproportionation (Cannizzaro reaction) of the same type of aldehydes occur. When this side reaction proceeds, there are problems such as difficulty in isolating the target aldehyde and a decrease in the yield.

[0009] An object of the present invention is to provide a method for producing an α,β-unsaturated aldehyde that can obtain the target aldehyde in a high yield while satisfying the selectivity and suppress the generation of by-products.

Means for Solving the Problems

[0010] The present inventors have found that in the cross-aldol condensation reaction, by using a specific catalyst, the target aldehyde can be obtained in a high yield while satisfying the selectivity and the generation of by-products can be suppressed.

[0011] That is, the present invention includes a step of reacting a compound represented by formula (I) (hereinafter sometimes referred to as "the compound of formula (I)") and a compound represented by formula (II) (hereinafter sometimes referred to as "the compound of formula (II)") in a solvent or without a solvent to obtain a compound represented by formula (III) (α,β-unsaturated aldehyde), and provides a method for producing an α,β-unsaturated aldehyde, wherein in the above step, titanium oxide is used as a catalyst and the amount of the solvent is 50 parts by mass or less with respect to 100 parts by mass in total of the compounds of formula (I) and formula (II).

[0012]

Chemical Formula

[0013] In the above formula, R ,

[0011] , , , , ,

[0012] , , , ,<00is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, R 2 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and R 3 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or R 2 and R 3 together with the carbon atom to which they are attached form a 1,3-dioxolane, R 4 , R 5 and R 6 are independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. [Effect of the Invention]

[0014] According to the present invention, there is provided a method for producing an α,β-unsaturated aldehyde, which can obtain the target aldehyde in a high yield while satisfying the selectivity and can suppress the generation of by-products. [Embodiments for Carrying Out the Invention]

[0015] The method for producing an α,β-unsaturated aldehyde of the present invention is a method using titanium oxide as a catalyst in the cross aldol condensation reaction between a compound of formula (I) and a compound of formula (II). In the present invention, the selectivity is the α,β-unsaturated aldehyde selectivity (relative to the compound of formula (II)) determined by the method described in the examples, the yield is the α,β-unsaturated aldehyde yield (relative to the compound of formula (I)) determined by the method described in the examples, and the suppression of the generation of by-products means that the HCA / dimer production ratio described in the examples is high.

[0016] [Compound Represented by Formula (I)] In the compound represented by the above formula (I), R 1 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R 1The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 3 to 8 carbon atoms. From the viewpoint of reactivity in the cross-aldol condensation reaction and the usefulness of the resulting aldehyde as a fragrance material, the alkyl group having 2 or more carbon atoms, more preferably 3 or more carbon atoms, and more preferably 8 or fewer carbon atoms, and more preferably 7 or fewer carbon atoms. The alkyl group having 1 to 10 carbon atoms may be a linear alkyl group or a branched alkyl group, and is preferably a linear alkyl group. Examples of alkyl groups having 1 to 10 carbon atoms include methyl, ethyl, n-propyl, isopropyl, 2-methylpropyl, n-butyl, t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl. Examples of compounds of formula (I) include acetaldehyde, propionaldehyde, butanal, pentanal, hexanal, heptanal, octanal, nonanal, decanal, and dodecanal. The compound of formula (I) is preferably propionaldehyde, butanal, pentanal, hexanal, heptanal, octanal, nonanal, or decanal, more preferably pentanal, hexanal, heptanal, octanal, nonanal, or decanal, and more preferably pentanal, hexanal, heptanal, octanal, or nonanal.

[0017] [Compounds represented by formula (II)] In the compound represented by the above formula (II), R 2 R is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, and 3 R is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 2The C1 to C6 alkyl group is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and more preferably a hydrogen atom. From the viewpoint of reactivity in the cross-aldol condensation reaction and the usefulness of the resulting aldehyde as a fragrance material, the C1 to C6 alkyl group is preferably a C1 or more alkyl group, preferably a C5 or less alkyl group, and more preferably a C4 or less alkyl group. Examples of C1 to C6 alkyl groups include methyl, ethyl, n-propyl, isopropyl, 2-methylpropyl, n-butyl, t-butyl, pentyl, and hexyl. The C1 to C6 alkoxy group is an alkyloxy group having 1 to 6 carbon atoms, such as methoxy, ethoxy, n-propyloxy, isopropyloxy, 2-methylpropyloxy, n-butyloxy, t-butyloxy, pentyloxy, and hexyloxy. From the viewpoint of reactivity in the cross-aldol condensation reaction and the usefulness of the resulting aldehyde as a fragrance material, the C1 to C5 alkoxy group is preferably a C1 to C4 alkoxy group. 3 As described above, this is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, preferably a hydrogen atom. From the viewpoint of the usefulness of the generated aldehyde as a fragrance material, the alkyl group having 1 to 2 carbon atoms is preferred, and more preferably an alkyl group having 1 carbon atom. Examples of alkyl groups having 1 to 3 carbon atoms include methyl, ethyl, n-propyl, and isopropyl.

[0018] In the compound represented by the above formula (II), R 2 and R 3 These may combine with the carbon atoms to which they are bonded to form 1,3-dioxolane. In that case, the compound of formula (II) is represented by the following formula.

[0019] [ka]

[0020] In the above formula, R4 , R 5 and R 6 This is defined in equation (II) as follows:

[0021] In the compound of formula (II) above, R 4 , R 5 and R 6 R is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 4 , R 5 and R 6 The atom is preferably a hydrogen atom. The alkyl group having 1 to 3 carbon atoms is preferably an alkyl group having 1 to 2 carbon atoms, more preferably an alkyl group having 1 carbon atom, from the viewpoint of the usefulness of the resulting aldehyde as a fragrance material. Examples of alkyl groups having 1 to 3 carbon atoms include methyl, ethyl, n-propyl, and isopropyl.

[0022] The following compounds are preferred as the compound of formula (II), and benzaldehyde is preferred.

[0023] [ka]

[0024] [Compounds represented by formula (III)] In the compound represented by formula (III), R 1 This is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R 2 R is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, and 3 is either a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or R 2 and R 3 These, together with the carbon atoms to which they bond, form 1,3-dioxolane. R 4 , R 5 and R 6Each is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. In the compound represented by formula (III), R 1 Preferably, it is an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 3 to 8 carbon atoms. R 2 R is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and more preferably a hydrogen atom. 3 is preferably a hydrogen atom, R 4 , R 5 and R 6 Preferably, it is a hydrogen atom.

[0025] Examples of compounds represented by formula (III) include the following R compounds shown in Table 1. 1 ~R 6 Compounds with this combination are preferred.

[0026] [Table 1]

[0027] As for compounds represented by formula (III), the following compounds are more preferred, for example.

[0028] [ka]

[0029] [Titanium Oxide] Titanium dioxide can be of the anatase type, rutile type, or brookite type, or mixtures thereof. From the viewpoint of yield and selectivity, the titanium dioxide preferably contains the anatase type, more preferably 60% by mass or more of the anatase type relative to the total titanium dioxide, more preferably 80% by mass or more, even more preferably 95% by mass or more, and preferably 100% by mass or less.

[0030] In the present invention, the titanium dioxide is preferably used in an amount of 1% by mass or more, more preferably 2% by mass or more, and even more preferably 5% by mass or more, relative to the compound of formula (I) from the viewpoint of yield and selectivity, and preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, relative to the compound of formula (I). From these viewpoints, the titanium dioxide is preferably used in an amount of 1% by mass or more and 50% by mass or less, more preferably 2% by mass or more and 30% by mass or less, and even more preferably 5% by mass or more and 20% by mass or less, relative to the compound of formula (I).

[0031] That is, from the viewpoint of yield and selectivity, the titanium oxide is preferably used in amounts of 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the compound of formula (I). Furthermore, from the viewpoint of low-cost production, it is preferably used in amounts of 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. From these viewpoints, the titanium oxide is preferably used in amounts of 1 part by mass or more and 50 parts by mass or less, more preferably 2 parts by mass or more and 30 parts by mass or less, and even more preferably 5 parts by mass or more and 20 parts by mass or less, per 100 parts by mass of the compound of formula (I).

[0032] The primary particle size of titanium dioxide is, for example, 1 nm to 50 nm, preferably 3 nm to 40 nm, and more preferably 5 nm to 30 nm. This primary particle size is measured by X-ray diffraction.

[0033] The BET specific surface area of ​​titanium dioxide can be determined by methods such as nitrogen adsorption. For example, the BET specific surface area of ​​titanium dioxide is 30 m². 2 / g or more 500m 2 / g or less, preferably 40m 2 / g or more 400m 2 / g or less, more preferably 50m 2 / g or more 300m 2 It is less than / g.

[0034] The crystallite size of titanium oxide is preferably 80 Å or larger, more preferably 100 Å or larger, and even more preferably 120 Å or larger, from the viewpoint of yield and selectivity. Similarly, it is preferably 500 Å or smaller, more preferably 400 Å or smaller, and even more preferably 300 Å or smaller. Preferably, it is 80 Å to 500 Å, more preferably 100 Å to 400 Å, and even more preferably 120 Å to 300 Å. The crystallite size can be measured by the method described in the examples. In the case of commercially available products, catalog values ​​can also be used.

[0035] Titanium dioxide may be produced by methods such as the sulfuric acid method or the chlorine method, but titanium dioxide produced by the sulfuric acid method is preferred.

[0036] Titanium dioxide may be produced by gas-phase or liquid-phase methods, but it is preferable to produce it by liquid-phase method.

[0037] [solvent] In the above step of the present invention, from the viewpoint of yield and selectivity, when a solvent is used, the amount of solvent is 50% by mass or less relative to the compounds of formula (I) and formula (II). Preferably, the amount of solvent is 30% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, preferably 0% by mass or more, and more preferably substantially 0% by mass. Substantially means not used intentionally and does not exclude cases where it is included unintentionally. From these viewpoints, the amount of solvent is preferably 0 parts by mass or more and 30 parts by mass or less, more preferably 0 parts by mass or more and 10 parts by mass or less, and even more preferably 0 parts by mass or more and 5 parts by mass or less, based on 100 parts by mass of the total of the compounds of formula (I) and formula (II).

[0038] Examples of the aforementioned solvents include alcoholic solvents such as methanol, n- and isopropanol, t-butanol, 1-butanol, 1-hexanol, and glycerin; ketone solvents such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclohexanone, methyl hexyl ketone, diisobutyl ketone, diacetone alcohol, and isophorone; etheric solvents such as diethyl ether, tetrahydrofuran (THF), and dioxane; non-aromatic hydrocarbon solvents such as hexane, petroleum ether, liquid paraffin, squalane, and squalene; and unsubstituted or substituted aromatic hydrocarbon solvents having 6 to 12 carbon atoms such as benzene, toluene, and xylene. The aforementioned solvents preferably include hydrocarbon solvents, and more preferably include aromatic hydrocarbon solvents.

[0039] The amount of the aromatic hydrocarbon is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 10% by mass or less, and even more preferably 5% by mass or less, relative to the compound of formula (I) and the compound of formula (II), and also preferably 0% by mass or more, and more preferably substantially 0% by mass.

[0040] Furthermore, the content of aromatic hydrocarbon solvents in the solvent is preferably 50% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, and even more preferably 95% by mass or more and 100% by mass or less.

[0041] [Reaction process] In the present invention, the step of reacting the compound of formula (I) with the compound of formula (II) to obtain the α,β-unsaturated aldehyde of formula (III) is carried out, for example, by charging the catalyst titanium dioxide, the compound of formula (I), and the compound of formula (II) into a reaction vessel and stirring the reaction mixture. Alternatively, the step may be carried out by charging the catalyst titanium dioxide and the compound of formula (II) into a reaction vessel and adding the compound of formula (I) dropwise thereto.

[0042] In the present invention, the amount of the compound of formula (II) is preferably 0.8 molar equivalents or more, more preferably 1.0 molar equivalent or more, even more preferably 1.2 molar equivalents or more, and even more preferably 1.5 molar equivalents or more, relative to the compound of formula (I), from the viewpoint of yield and selectivity. Furthermore, from the viewpoint of low-cost production, it is preferably 15 molar equivalents or less, more preferably 10 molar equivalents or less, even more preferably 7 molar equivalents or less, and even more preferably 5 molar equivalents or less. From these viewpoints, the amount of the compound of formula (II) is preferably 0.8 molar equivalents or more and 15 molar equivalents or less, more preferably 1.0 molar equivalent or more and 10 molar equivalents or less, even more preferably 1.2 molar equivalents or more and 7 molar equivalents or even more preferably 1.5 molar equivalents or more and 5 molar equivalents or less, relative to the compound of formula (I).

[0043] In the present invention, the step of reacting a compound of formula (I) with a compound of formula (II) to obtain an α,β-unsaturated aldehyde of formula (III) is preferably carried out at a temperature of 20°C or higher, more preferably 25°C or higher, even more preferably 50°C or higher, and also preferably 200°C or lower, more preferably 180°C or lower, even more preferably 160°C or lower, preferably 20°C to 200°C, more preferably 25°C to 180°C, and even more preferably 50°C to 160°C, from the viewpoint of reaction efficiency.

[0044] In the present invention, the step of reacting the compound of formula (I) with the compound of formula (II) to obtain the α,β-unsaturated aldehyde of formula (III) may be carried out under an inert gas atmosphere from the viewpoint of reaction efficiency. From the viewpoint of reaction efficiency, the inert gas is preferably nitrogen or a noble gas (group 18 element), and more preferably nitrogen. Examples of noble gases include argon and helium, with argon being preferred.

[0045] The present invention includes the following embodiments. <1> A method for producing an α,β-unsaturated aldehyde, comprising the step of reacting a compound represented by formula (I) and a compound represented by formula (II) in a solvent or without a solvent to obtain a compound represented by formula (III), A method for producing α,β-unsaturated aldehydes, wherein titanium dioxide is used as a catalyst in the above step, and the amount of solvent is 50 parts by mass or less per 100 parts by mass of the total of the compounds of formula (I) and formula (II).

[0046] [ka]

[0047] [In the above formula, R 1 This is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. R 2 R is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, and 3 is either a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or R 2 and R 3 These, together with the carbon atoms to which they bond, form 1,3-dioxolane. R 4 , R 5 and R 6 [Each is independently a hydrogen atom, or an alkyl group having 1 to 3 carbon atoms.]

[0048] <2> The amount of solvent is 0 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the total of compounds (I) and (II). <1> A method for producing the α,β-unsaturated aldehyde described above.

[0049] <3> The amount of solvent is 0 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the total of compounds (I) and (II). <1> or <2> A method for producing α,β-unsaturated aldehydes as described above.

[0050] <4> The amount of solvent is 0 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the total of compounds (I) and (II). <1> ~ <3> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0051] <5> The amount of solvent is substantially 0 parts by mass relative to the total of 100 parts by mass of the compounds of formula (I) and formula (II). <1> ~ <4> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0052] <6> In the above step, the amount of the compound represented by formula (II) is 0.8 molar equivalents or more and 15 molar equivalents or less relative to the compound represented by formula (I). <1> ~ <5> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0053] <7> In the above step, the amount of the compound represented by formula (II) is 1.0 molar equivalent or more and 10 molar equivalent or less relative to the compound represented by formula (I). <1> ~ <6> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0054] <8> In the above step, the amount of the compound represented by formula (II) is 1.2 molar equivalents or more and 7 molar equivalents or less relative to the compound represented by formula (I). <1> ~ <7> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0055] <9> R 1 This is an alkyl group having 3 to 8 carbon atoms. <1> ~ <8> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0056] <10> R 2 R is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and 3 This is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. <1> ~ <9> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0057] <11> The compound represented by formula (II) is a compound represented by any of the following formulas: <1> ~ <10> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0058] [ka]

[0059] <12> The titanium dioxide includes anatase-type titanium dioxide. <1> ~ <11> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0060] <13> The crystallite size of the titanium oxide is 80 Å or more and 500 Å or less. <1> ~ <12> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0061] <14> The crystallite size of the titanium oxide is 100 Å or more and 500 Å. <1> ~ <13> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0062] <15> The crystallite size of the titanium oxide is 100 Å or more and 400 Å or less. <1> ~ <14> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0063] <16> The crystallite size of the titanium oxide is 120 Å or more and 300 Å or less. <1> ~ <15> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0064] <17> The titanium oxide is used in an amount of 1 to 50 parts by mass per 100 parts by mass of the compound of formula (I). <1> ~ <16> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0065] <18> The titanium oxide is used in amounts of 2 to 30 parts by mass per 100 parts by mass of the compound of formula (I). <1> ~ <17> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0066] <19> The titanium oxide is used in amounts of 5 to 20 parts by mass per 100 parts by mass of the compound of formula (I). <1> ~ <18> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0067] <20> The solvent includes hydrocarbon solvents. <1> ~ <19> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0068] <21> The solvent includes aromatic hydrocarbon solvents. <1> ~ <20> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0069] <22> The content of aromatic hydrocarbon solvents in the solvent is 50% by mass or more and 100% by mass or less. <1> ~ <21> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0070] <23> The content of aromatic hydrocarbon solvents in the solvent is 80% by mass or more and 100% by mass or less. <1> ~ <22> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0071] <24> The content of aromatic hydrocarbon solvents in the solvent is 95% by mass or more and 100% by mass or less. <1> ~ <23> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0072] <25> The above process is carried out at a temperature of 20°C or higher and 200°C or lower. <1> ~ <24> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0073] <26> The above process is carried out at a temperature of 25°C to 180°C. <1> ~ <25> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0074] <27> The above process is carried out at a temperature of 50°C to 160°C. <1> ~ <26> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0075] <28> The compound represented by formula (I) is octanal, the compound represented by formula (II) is benzaldehyde, and the compound represented by formula (III) is hexyl cinnamic aldehyde. <1> ~ <27> A method for producing α,β-unsaturated aldehydes as described in any of the following.

[0076] [Examples] In the following examples and comparative examples, "%" refers to "mass%" unless otherwise specified.

[0077] The following raw materials were used in the reaction. Benzaldehyde: Manufactured by Wako Pure Chemical Industries, Ltd., Wako Special Grade. Octanal: Manufactured by Kao Corporation. Toluene: Manufactured by Wako Pure Chemical Industries, Ltd., Wako Special Grade. Tetradecane: Manufactured by Wako Pure Chemical Industries, Ltd., Wako Special Grade. Diethyl ether: Manufactured by Wako Pure Chemical Industries, Ltd., Wako Special Grade.

[0078] <Example 1> Production of hexyl cinnamic aldehyde (formula (III-1))

[0079] [ka]

[0080] Titanium dioxide (manufactured by Sakai Chemical Industry Co., Ltd., SSP-M, anatase-type titanium dioxide, produced by the sulfuric acid method (liquid phase method), 0.19 g, 10% by mass relative to octanal, 10 parts by weight per 100 parts by mass of compound (I)), octanal (formula (I-1), 1.9 g, 15.0 mmol), benzaldehyde (formula (II-1), 8.0 g, 75.0 mmol, 5 molar equivalents relative to octanal), and tetradecane (GC internal standard, 0.2 g) were added as catalysts to a reaction tube with an inner diameter of 34 mm fitted with a condenser. After purging the reaction tube with nitrogen, the mixture in the reaction tube was stirred at 150°C for 4 hours. Thereafter, the reaction tube was cooled to 30°C to terminate the reaction.

[0081] The reaction results were calculated using the composition of each component in the reactant obtained by quantitative analysis of the filtered reactant by gas chromatography (GC) using the internal standard method, according to the following formula. Tetradecane was used as the internal standard, and diethyl ether was used as the solvent. The calculated hexyl cinnamic aldehyde yield (vs. octanal), hexyl cinnamic aldehyde selectivity (vs. benzaldehyde), and HCA / dimer production ratio are shown in Table 2 below.

[0082] Specifically, 0.2 mL of the reaction solution was sampled, placed in a screw-cap tube, and accurately weighed. This reaction solution was diluted with 4 mL of diethyl ether. The solution was filtered through a membrane filter (polytetrafluoroethylene (PTFE), 0.2 μm) to remove the catalyst, and the resulting filtrate was subjected to GC analysis.

[0083] GC analysis was performed using both DB-1 columns (GC column, 100% dimethylpolysiloxane, manufactured by Agilent Technologies, Inc.) and DB-WAX columns (GC column, polyethylene glycol, manufactured by Agilent Technologies, Inc.).

[0084] [Hexyl cinnamic aldehyde yield (vs. octanal)] The yield of the target hexyl cinnamic aldehyde (compared to octanal) was calculated according to the following formula. A higher value indicates a better yield.

[0085]

number

[0086] [Hexyl cinnamic aldehyde selectivity (vs. benzaldehyde)] The selectivity of hexyl cinnamic aldehyde (vs. benzaldehyde), a measure of aldehyde disproportionation, was calculated according to the following formula. A higher value indicates better selectivity.

[0087]

number

[0088] [HCA / Dimer Production Ratio] The ratio of HCA formation between the aldehyde dimer and the target product was calculated according to the following formula. A larger value indicates fewer by-products.

[0089]

number

[0090] <Example 2> The procedure was the same as in Example 1, except that titanium dioxide (Teika Co., Ltd., AMT-600, anatase-type titanium dioxide, produced by the sulfuric acid method (liquid phase method)) was used as a catalyst instead of titanium dioxide (Sakai Chemical Industry Co., Ltd., SSP-M). The evaluation results of the obtained products are shown in Table 2.

[0091] <Example 3> The procedure was carried out in the same manner as in Example 1, except that titanium dioxide (manufactured by Ishihara Sangyo, MC-150, anatase-type titanium dioxide, produced by the sulfuric acid method (liquid phase method)) was used as a catalyst instead of titanium dioxide (manufactured by Sakai Chemical Industry, SSP-M). The evaluation results of the obtained products are shown in Table 2.

[0092] <Example 4> The procedure was carried out in the same manner as in Example 1, except that titanium dioxide (manufactured by Ishihara Sangyo, MC-50, anatase-type titanium dioxide, produced by the sulfuric acid method (liquid phase method)) was used as a catalyst instead of titanium dioxide (manufactured by Sakai Chemical Industry, SSP-M). The evaluation results of the obtained products are shown in Table 2.

[0093] <Example 5> The procedure was carried out in the same manner as in Example 1, except that titanium dioxide (manufactured by Ishihara Sangyo, MC-90L, anatase-type titanium dioxide, produced by the sulfuric acid method (liquid phase method)) was used as a catalyst instead of titanium dioxide (manufactured by Sakai Chemical Industry, SSP-M). The evaluation results of the obtained products are shown in Table 2.

[0094] <Example 6> The procedure was carried out in the same manner as in Example 1, except that 1.5 molar equivalents of benzaldehyde were used relative to octanal instead of 5 molar equivalents. The evaluation results of the obtained product are shown in Table 2.

[0095] <Example 7> The procedure was carried out in the same manner as in Example 1, except that toluene (3.0 g, 30% by mass relative to the total amount of compound (I) and compound (II)) was added to the reaction tube along with the catalyst, octanal, benzaldehyde, etc. The evaluation results of the obtained products are shown in Table 2.

[0096] <Example 8> Titanium dioxide (manufactured by Ishihara Sangyo, MC-90L, anatase-type titanium dioxide, produced by sulfuric acid method (liquid phase method), 19.2 g, 30% by mass relative to octanal, 30 parts by weight per 100 parts by mass of compound (I)) and benzaldehyde (formula (II-1), 80.0 g, 0.75 mol, 1.5 molar equivalent relative to octanal) were added as catalysts to a 200 mL separable flask. A mechanical stirrer, thermometer, Dean-Stark trap, condenser, nitrogen line, and aldehyde supply line were attached to the separable flask. The octanal supply line was connected to a dropping pump to allow for a constant rate supply of octanal. After purging the reaction tube with nitrogen, the temperature was raised to 150°C and the mixture in the separable flask was stirred. After reaching 150°C, octanal (formula (I-1)) was supplied to the reaction mixture in the separable flask using a dropping pump. For the first three hours, the supply rate was 12.8 g / h, and for the last three hours, it was 8.5 g / h, for a total of 64 g (0.5 mol) of octanal was supplied to the reaction mixture over a period of 6 hours. After that, the reaction mixture was stirred at 150°C for 0.5 hours, and then the separable flask was cooled to 30°C to terminate the reaction. The evaluation results of the obtained product are shown in Table 2.

[0097] <Example 9> The procedure was the same as in Example 1, except that titanium dioxide (Teika Co., Ltd., TK-1460, anatase-type titanium dioxide, produced by the sulfuric acid method (liquid phase method)) was used as a catalyst instead of titanium dioxide (Sakai Chemical Industry Co., Ltd., SSP-M). The evaluation results of the obtained products are shown in Table 2.

[0098] <Comparative Example 1> The procedure was carried out in the same manner as in Example 1, except that magnesium oxide (Kyowa Chemical Industry Co., Ltd., KyowaMag 30, 0.19 g, 10% by mass relative to octanal) was used as a catalyst instead of titanium oxide (Sakai Chemical Industry Co., Ltd., SSP-M, 0.19 g, 10% by mass relative to octanal). The evaluation results of the obtained product are shown in Table 3.

[0099] <Comparative Example 2> The procedure was carried out in the same manner as in Example 1, except that hydrotalcite (Kyowa Chemical Industry Co., Ltd., hydrotalcite, 0.19 g, 10% by mass relative to octanal) was used as a catalyst instead of titanium dioxide (Sakai Chemical Industry Co., Ltd., SSP-M, 0.19 g, 10% by mass relative to octanal). The evaluation results of the obtained product are shown in Table 3.

[0100] <Comparative Example 3> The procedure was carried out in the same manner as in Example 1, except that aluminophosphate (Kanto Chemical Co., Ltd., aluminophosphate, 0.19 g, 10% by mass relative to octanal) was used as a catalyst instead of titanium dioxide (Sakai Chemical Industry Co., Ltd., SSP-M, 0.19 g, 10% by mass relative to octanal). The evaluation results of the obtained product are shown in Table 3.

[0101] <Comparative Example 4> The procedure was carried out in the same manner as in Example 1, except that silicoaluminophosphate zeolite (JGC Catalysts & Chemicals, SAPO-34, 0.19 g, 10% by mass relative to octanal) was used as a catalyst instead of titanium dioxide (Sakai Chemical Industry Co., Ltd., SSP-M, 0.19 g, 10% by mass relative to octanal). The evaluation results of the obtained product are shown in Table 3.

[0102] <Comparative Example 5> The procedure was carried out in the same manner as in Example 1, except that toluene (7.4 g, 75% by mass relative to the total amount of compound (I) and compound (II)) was added to the reaction tube along with the catalyst, octanal, benzaldehyde, etc. The evaluation results of the obtained product are shown in Table 3.

[0103] The reaction conditions and results for Examples 1-9 and Comparative Examples 1-5 are summarized in Tables 2 and 3 below. The primary particle size, sulfur content, BET specific surface area, and crystallite size of the titanium dioxide used as a catalyst are also shown in Table 2.

[0104] [Primary particle size] The primary particle size was measured by X-ray diffraction using an X-ray diffractometer (Rigaku Corporation, model number "MiniFlex600") and calculated from the peaks at 2Θ = 25-26°. [BET specific surface area] The BET specific surface area was measured using a specific surface area measuring device (Micromeritics, model number "FlowSorbIII").

[0105] [Method for measuring the crystallite size of titanium oxide by powder X-ray diffraction] The crystallite size of titanium dioxide is determined by powder X-ray diffraction measurement using a powder X-ray diffractometer (product name: "MiniFlex600", manufactured by Rigaku Corporation), measuring the full width at half maximum of the peak with 2θ of 25-26°, and calculating it using Scherrer's equation, which is expressed by the following general formula (S) (in general formula (S), K=0.9, λ=1.5418 [Å]).

[0106]

number

[0107] In general formula (S), D is the crystallite size [Å], λ is the X-ray wavelength [Å], K is Scherrer's constant, β represents the full width at half maximum (FMAX) of the peak when 2θ is between 25 and 26°. Note that the units for β and θ are radians.

[0108] [Table 2]

[0109] [Table 3]

[0110] From Tables 2 and 3, it was confirmed that when titanium dioxide is used as a catalyst to react the compound of formula (I) with the compound of formula (II) to obtain the α,β-unsaturated aldehyde of formula (III), the selectivity of the α,β-unsaturated aldehyde (against the compound of formula (II)) and the yield of the α,β-unsaturated aldehyde (against the compound of formula (I)) are high, and the formation of by-products can be suppressed. [Industrial applicability]

[0111] According to the manufacturing method of the present invention, the target aldehyde can be obtained in high yield while satisfying selectivity, and the formation of by-products can be suppressed, thus enabling the efficient and pure production of α,β-unsaturated aldehydes. Such a manufacturing method can be suitably used as a method for producing aldehydes useful as fragrance materials.

Claims

1. A method for producing an α,β-unsaturated aldehyde, comprising the step of reacting a compound represented by formula (I) with a compound represented by formula (II) in a solvent or without a solvent to obtain a compound represented by formula (III), In the above step, titanium oxide is used as a catalyst, and the amount of the solvent is 50 parts by mass or less per 100 parts by mass of the total of the compounds of formula (I) and formula (II). 【Transformation 8】 [wherein R 1 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, R 2 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, and R 3 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or R 2 and R 3 together with the carbon atoms to which they are attached to form 1,3-dioxolane, R 4 , R 5 and R 6 are independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

2. The method for producing an α,β-unsaturated aldehyde according to claim 1, wherein the amount of the solvent is 0 to 30 parts by mass per 100 parts by mass of the total of the compounds of formula (I) and formula (II).

3. The method for producing an α,β-unsaturated aldehyde according to claim 1 or 2, wherein the amount of the solvent is 0 to 10 parts by mass per 100 parts by mass of the total of the compounds of formula (I) and formula (II).

4. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 3, wherein in the step, the amount of the compound represented by formula (II) is 0.8 molar equivalents or more and 15 molar equivalents or less relative to the compound represented by formula (I).

5. R 1 The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 4, wherein is an alkyl group having 3 to 8 carbon atoms.

6. R 2 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R 3 The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 5, wherein is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

7. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 6, wherein the compound represented by formula (II) is a compound represented by any one of the following formulas: 【Chemistry 9】

8. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 7, wherein the titanium oxide comprises anatase type titanium oxide.

9. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 8, wherein the titanium oxide has a crystallite diameter of 80 Å to 500 Å.

10. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 9, wherein the titanium oxide has a crystallite diameter of 100 Å or more and 400 Å or less.

11. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 10, wherein the titanium oxide is used in an amount of 1 part by mass or more and 50 parts by mass or less per 100 parts by mass of the compound of formula (I).

12. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 11, wherein the titanium oxide is used in an amount of 2 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the compound of formula (I).

13. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 12, wherein the step is carried out at a temperature of 20°C or higher and 200°C or lower.

14. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 13, wherein the compound represented by formula (I) is octanal, the compound represented by formula (II) is benzaldehyde, and the compound represented by formula (III) is hexyl cinnamic aldehyde.