Method for producing α,β-unsaturated aldehyde

Abstract

The object of the present invention is to provide a manufacturing method, which, in a cross-aldol condensation reaction, can obtain a target aldehyde in a high yield while satisfying the selectivity by using titanium oxide, and can suppress the generation of by-products. The present invention is a method for manufacturing an α, β-unsaturated aldehyde, wherein the method for manufacturing the above-mentioned α, β-unsaturated aldehyde includes: reacting a compound represented by formula (I) with a compound represented by formula (II) in a solvent or in the absence of a solvent to obtain a compound represented by formula (III), in which titanium oxide is used as a catalyst, and the amount of solvent is 50 parts by mass or less relative to 100 parts by mass of the total amount of the compounds of formula (I) and formula (II). #imgabs0#

Description

Technical Field

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

[0002] Aldehydes are useful compounds as raw materials for chemical reactions, fragrances, pharmaceuticals, pesticide intermediates, etc. Among them, α,β-unsaturated aldehydes with specific molecular weights are useful not only as raw materials for fragrances but also as raw materials for derivatives with different fragrance notes.

[0003] Known methods for producing aldehydes include dehydrogenation reactions and oxidation reactions using conventional alcohols as raw materials. Among these, a cross-aldol condensation reaction of two aldehydes is often used as a method for producing α,β-unsaturated aldehydes, and various studies have been conducted on the reaction conditions.

[0004] For example, Org. Lett. 2010, 12(5), 948 (Non-Patent Document 1) discloses a method for producing α,β-unsaturated aldehydes based on a cross-aldol reaction of heptanal and benzaldehyde. In this reaction, titanium oxide is used as a catalyst, and when a solvent is used, a large amount of solvent is used.

[0005] Japanese Patent Application Laid-Open No. 2019-104718 (Patent Document 1) discloses a method in which, in a cross aldol condensation reaction, the content of water contained in the raw materials used in the reaction is adjusted to a specific amount. Summary of the Invention

[0006] The present invention provides a method for producing an α,β-unsaturated aldehyde, comprising: 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 in the absence of a solvent to obtain a compound represented by formula (III) (α,β-unsaturated aldehyde);

[0007] In the above step, titanium oxide is used as a catalyst, and the amount of solvent is 50 parts by mass or less relative to 100 parts by mass of the total of the compounds of formula (I) and formula (II).

[0008]

[0009] In the above formula,

[0010] R 1 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms,

[0011] 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 3is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or

[0012] R 2 and R 3 Together with the carbon atoms to which they are bonded, they form 1,3-dioxolane,

[0013] R 4 、R 5 and R 6 Each of the groups is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. DETAILED DESCRIPTION

[0014] Cross-aldol condensation is known to cause side reactions such as dimerization (self-aldol condensation) and disproportionation (Cannizzaro reaction) between aldehydes of the same type. These side reactions make isolation of the target aldehyde difficult, leading to reduced yields.

[0015] The technical problem of the present invention is to provide a method for producing α,β-unsaturated aldehydes, which can obtain the target aldehyde in high yield while satisfying the selectivity and can suppress the generation of by-products.

[0016] The present inventors have found that, by using a specific catalyst in a cross-aldol condensation reaction, the target aldehyde can be obtained in a high yield while satisfying the selectivity and suppressing the formation of by-products.

[0017] That is, the present invention provides a method for producing an α,β-unsaturated aldehyde, comprising: 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 in the absence of a solvent to obtain a compound represented by formula (III) (α,β-unsaturated aldehyde);

[0018] In the above step, titanium oxide is used as a catalyst, and the amount of solvent is 50 parts by mass or less relative to 100 parts by mass of the total of the compounds of formula (I) and formula (II).

[0019]

[0020] In the above formula,

[0021] R 1 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms,

[0022] 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 R3 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or

[0023] R 2 and R 3 Together with the carbon atoms to which they are bonded, they form 1,3-dioxolane,

[0024] R 4 、R 5 and R 6 Each of the groups is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0025] According to the present invention, a method for producing an α,β-unsaturated aldehyde can be provided, which can obtain a target aldehyde in a high yield with satisfactory selectivity and can suppress the generation of by-products.

[0026] 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 of a compound of formula (I) and a compound of formula (II). In the present invention, the term "selectivity" refers to the selectivity of the α,β-unsaturated aldehyde (relative to the compound of formula (II)) determined by the method described in the Examples; the term "yield" refers to the yield of the α,β-unsaturated aldehyde (relative to the compound of formula (I)) determined by the method described in the Examples; and "suppressed by-product formation" refers to a high HCA / dimer formation ratio as described in the Examples.

[0027] [Compound represented by formula (I)]

[0028] 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. 1An alkyl group having 1 to 10 carbon atoms is preferred, and an alkyl group having 3 to 8 carbon atoms is more preferred. As the alkyl group having 1 to 10 carbon atoms, from the perspective of the reactivity of the cross-aldol condensation reaction and the usefulness of the generated aldehyde as a fragrance raw material, an alkyl group having 2 to 10 carbon atoms is preferred, and more preferably 3 to 3 carbon atoms is preferred, and an alkyl group having 8 to 8 carbon atoms is preferred, and more preferably 7 to 7 carbon atoms is preferred. As the alkyl group having 1 to 10 carbon atoms, it can be a straight-chain alkyl group or a branched alkyl group, and is preferably a straight-chain alkyl group. As the alkyl group having 1 to 10 carbon atoms, methyl, ethyl, n-propyl, isopropyl, 2-methylpropyl, n-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc. can be mentioned. Compounds of formula (I) are, for example, acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, hexanal, heptanal, octanal, nonanal, decanal, dodecanal, etc. From the viewpoint of reactivity of the cross-aldol condensation reaction, the compound of the above formula (I) is preferably propionaldehyde, butyraldehyde, valeraldehyde, hexanal, heptanal, octanal, nonanal, and decanal, more preferably valeraldehyde, hexanal, heptanal, octanal, nonanal, and decanal, and more preferably valeraldehyde, hexanal, heptanal, octanal, nonanal, and decanal.

[0029] [Compound represented by formula (II)]

[0030] In the compound represented by the above formula (II), 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. 2 Preferably, it is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom. As the alkyl group having 1 to 6 carbon atoms, from the viewpoint of the reactivity of the cross-aldol condensation reaction and the usefulness of the generated aldehyde as a fragrance raw material, it is preferably an alkyl group having 1 or more carbon atoms, preferably 5 or less carbon atoms, and more preferably 4 or less carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, 2-methylpropyl, n-butyl, tert-butyl, pentyl, and hexyl. The alkoxy group having 1 to 6 carbon atoms is an alkyloxy group having 1 to 6 carbon atoms, for example, methoxy, ethoxy, n-propoxy, isopropoxy, 2-methylpropoxy, n-butoxy, tert-butoxy, pentyloxy, and hexyloxy. The alkoxy group having 1 to 6 carbon atoms is preferably an alkoxy group having 1 to 5 carbon atoms, and more preferably an alkoxy group having 1 to 4 carbon atoms, from the viewpoint of the reactivity of the cross-aldol condensation reaction and the usefulness of the generated aldehyde as a fragrance raw material. 3It is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, preferably a hydrogen atom. As the alkyl group having 1 to 3 carbon atoms, from the viewpoint of the usefulness of the generated aldehyde as a fragrance raw material, an alkyl group having 1 to 2 carbon atoms is preferred, and an alkyl group having 1 carbon atom is more preferred. Examples of the alkyl group having 1 to 3 carbon atoms include methyl, ethyl, n-propyl, and isopropyl.

[0031] In the compound represented by the above formula (II), R 2 and R 3 Together with the carbon atoms to which they are bonded, they form a 1,3-dioxolane ring. In this case, the compound of formula (II) is represented by the following formula.

[0032]

[0033] In the above formula, R 4 、R 5 and R 6 represents the meanings as defined below in formula (II).

[0034] In the compound of formula (II), 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 A hydrogen atom is preferred. The alkyl group having 1 to 3 carbon atoms is preferably an alkyl group having 1 to 2 carbon atoms, and more preferably an alkyl group having 1 carbon atom, from the perspective of the usefulness of the generated aldehyde as a fragrance raw material. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.

[0035] As the compound of the above formula (II), for example, the compounds shown below are preferred, and benzaldehyde is preferred.

[0036]

[0037] [Compound represented by formula (III)]

[0038] In the compound represented by formula (III), R 1 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms,

[0039] 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 3is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, or

[0040] R 2 and R 3 Together with the carbon atoms to which they are bonded, they form 1,3-dioxolane,

[0041] R 4 、R 5 and R 6 Each of the groups is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0042] In the compound represented by formula (III), R 1 It is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 3 to 8 carbon atoms,

[0043] R 2 It is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and more preferably a hydrogen atom. 3 Preferably, a hydrogen atom, R 4 、R 5 and R 6 Preferred is a hydrogen atom.

[0044] As the compound represented by formula (III), for example, the following R shown in Table 1 are preferred: 1 ~R 6 A compound of a combination of.

[0045] [Table 1]

[0046]

[0047] As the compound represented by formula (III), for example, the following compounds are more preferable.

[0048]

[0049] [Titanium oxide]

[0050] Titanium oxide can be anatase, rutile or brookite, or mixtures thereof. From the viewpoint of yield and selectivity, the titanium oxide preferably contains anatase, and the content of the anatase relative to the total amount of titanium oxide is more preferably 60% by mass or more, more preferably 80% by mass or more, further preferably 95% by mass or more, and preferably 100% by mass or less.

[0051] In the present invention, from the viewpoint of yield and selectivity, the amount of the titanium oxide used relative to the compound of formula (I) is preferably 1% by mass or more, more preferably 2% by mass or more, and further preferably 5% by mass or more. In addition, from the viewpoint of low manufacturing cost, it is preferably 50% by mass or less, more preferably 30% by mass or less, and further preferably 20% by mass or less. From these viewpoints, the amount of the titanium oxide used relative to the compound of formula (I) is preferably 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 further preferably 5% by mass or more and 20% by mass or less.

[0052] That is, from the viewpoint of yield and selectivity, the amount of the titanium oxide is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and further preferably 5 parts by mass or more, relative to 100 parts by mass of the compound of formula (I). In addition, from the viewpoint of low-cost manufacturing, it is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 20 parts by mass or less. From these viewpoints, the amount of the titanium oxide is preferably 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 further preferably 5 parts by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the compound of formula (I).

[0053] The primary particle size of titanium oxide 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.

[0054] The BET specific surface area of ​​titanium oxide can be determined by nitrogen adsorption method or the like. The BET specific surface area of ​​titanium oxide is, for example, 30 m 2 / g and above and 500m 2 / g or less, preferably 40m 2 / g and above and 400m 2 / g or less, more preferably 50m 2 / g and above and 300m 2 / g or less.

[0055] From the viewpoint of yield and selectivity, the crystallite diameter of titanium oxide is More preferably Above, more preferably From the same viewpoint as above, it is preferred The following are more preferably The following is more preferably The following are preferably Above and The following are more preferably Above and The following is more preferably Above and The crystal grain size can be measured by the method described in the Examples. In the case of commercially available products, the values ​​described in the catalog can also be used.

[0056] Titanium oxide can be produced by a sulfuric acid method, a chlorine method, or the like, and titanium oxide produced by a sulfuric acid method is preferred.

[0057] Titanium oxide can be produced by a gas phase method, a liquid phase method, or the like, but titanium oxide produced by a liquid phase method is preferred.

[0058] [Solvent]

[0059] In the above-mentioned process of the present invention, from the viewpoint of yield and selectivity, when using a solvent, relative to the compound of formula (I) and formula (II), solvent amount is 50 mass % or less, preferably 30 mass % or less, more preferably 10 mass % or less, further preferably 5 mass % or less, and, preferably more than 0 mass %, more preferably substantially 0 mass %. "Substantially" refers to the situation that is not deliberately used, and does not exclude the situation that is included as nothing. From these viewpoints, relative to 100 mass parts totaling the compound of formula (I) and formula (II), above-mentioned solvent amount is preferably more than 0 mass part and less than 30 mass parts, more preferably more than 0 mass part and less than 10 mass parts, further preferably more than 0 mass part and less than 5 mass parts.

[0060] Examples of the solvent include alcohol solvents such as methanol, n-propanol, isopropanol, tert-butanol, 1-butanol, 1-hexanol, and glycerol; ketone solvents such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclohexanone, methyl hexyl ketone, diisobutyl ketone, diacetone alcohol, and isophorone; ether 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 solvent preferably includes a hydrocarbon solvent, and more preferably includes an aromatic hydrocarbon solvent.

[0061] From the viewpoint of yield and selectivity, the amount of the above-mentioned aromatic hydrocarbons relative to the compound of formula (I) and the compound of formula (II) is preferably 50% by mass or less, more preferably 30% by mass or less, further preferably 10% by mass or less, further preferably 5% by mass or less, and preferably 0% by mass or more, more preferably substantially 0% by mass.

[0062] In addition, the content of the aromatic hydrocarbon solvent in the above solvents 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.

[0063] [Reaction process]

[0064] 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 adding titanium oxide as a catalyst, the compound of formula (I), and the compound of formula (II) into a reaction vessel and stirring the reaction mixture. Alternatively, the step of reacting the compound of formula (I) with titanium oxide as a catalyst and the compound of formula (II) into a reaction vessel may be carried out, and the compound of formula (I) may be added dropwise thereto.

[0065] In the present invention, from the viewpoint of yield and selectivity, relative to the compound of formula (I), the amount of the compound of formula (II) is preferably 0.8 molar equivalents or more, more preferably 1.0 molar equivalents or more, further preferably 1.2 molar equivalents or more, and further preferably 1.5 molar equivalents or more. In addition, from the viewpoint of low-cost manufacturing, it is preferably 15 molar equivalents or less, more preferably 10 molar equivalents or less, further preferably 7 molar equivalents or less, and further preferably 5 molar equivalents or less. From these viewpoints, relative to the compound of formula (I), 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 equivalents or more and 10 molar equivalents or less, further preferably 1.2 molar equivalents or more and 7 molar equivalents or less, and further preferably 1.5 molar equivalents or more and 5 molar equivalents or less.

[0066] In the present invention, from the viewpoint of reaction efficiency, when 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, the temperature is preferably 20°C or higher, more preferably 25°C or higher, and even more preferably 50°C or higher. In addition, it is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower. It is preferably 20°C or higher and 200°C or lower, more preferably 25°C or higher and 180°C or lower, and even more preferably 50°C or higher and 160°C or lower.

[0067] In the present invention, from the viewpoint of reaction efficiency, 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, the inert gas is preferably nitrogen or a rare gas (Group 18 element), more preferably nitrogen. Examples of the rare gas include argon and helium, with argon being preferred.

[0068] The present invention includes the following aspects.

[0069] <1> A method for producing an α,β-unsaturated aldehyde, comprising: 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);

[0070] In the above step, titanium oxide is used as a catalyst, and the amount of solvent is 50 parts by mass or less relative to 100 parts by mass of the total of the compounds of formula (I) and formula (II).

[0071]

[0072] In the above formula,

[0073] R 1 is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms,

[0074] 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

[0075] R 2 and R 3 Together with the carbon atoms to which they are bonded, they form 1,3-dioxolane,

[0076] R 4 、R 5 and R 6 Each of the groups is independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0077] <2> The method for producing an α,β-unsaturated aldehyde according to <1>, wherein the amount of the solvent is 0 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the total of the compounds of formula (I) and formula (II).

[0078] <3> The method for producing an α,β-unsaturated aldehyde according to <1> or <2>, wherein the amount of the solvent is 0 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the total of the compounds of formula (I) and formula (II).

[0079] <4> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <3>, wherein the amount of the solvent is 0 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the total of the compounds of formula (I) and formula (II).

[0080] <5> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <4>, wherein the amount of the solvent is substantially 0 parts by mass relative to 100 parts by mass of the total of the compounds of formula (I) and formula (II).

[0081] <6> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <5>, wherein in the above step, the amount of the compound represented by the above formula (II) is 0.8 molar equivalents or more and 15 molar equivalents or less relative to the compound represented by the above formula (I).

[0082] <7> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <6>, wherein in the above step, the amount of the compound represented by the above formula (II) is 1.0 molar equivalent or more and 10 molar equivalents or less relative to the compound represented by the above formula (I).

[0083] <8> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <7>, wherein in the above step, the amount of the compound represented by the above formula (II) is 1.2 molar equivalents or more and 7 molar equivalents or less relative to the compound represented by the above formula (I).

[0084] <9> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <8>, wherein R 1 It is an alkyl group having 3 or more and 8 or less carbon atoms.

[0085] <10> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <9>, wherein R 2 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R 3 It is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0086] <11> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <10>, wherein the compound represented by the formula (II) is a compound represented by any one of the following formulae:

[0087]

[0088] <12> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <11>, wherein the titanium oxide comprises anatase-type titanium oxide.

[0089] <13> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <12>, wherein the crystallite diameter of the titanium oxide is Above and the following.

[0090] <14> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <13>, wherein the crystallite diameter of the titanium oxide is above the following.

[0091] <15> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <14>, wherein the crystallite diameter of the titanium oxide is above the following.

[0092] <16> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <15>, wherein the crystallite diameter of the titanium oxide is Above and the following.

[0093] <17> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <16>, wherein the titanium oxide is used in an amount of 1 part by mass to 50 parts by mass based on 100 parts by mass of the compound of formula (I).

[0094] <18> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <17>, wherein the titanium oxide is used in an amount of 2 parts by mass to 30 parts by mass based on 100 parts by mass of the compound of formula (I).

[0095] <19> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <18>, wherein the titanium oxide is used in an amount of 5 parts by mass to 20 parts by mass based on 100 parts by mass of the compound of formula (I).

[0096] <20> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <19>, wherein the solvent contains a hydrocarbon solvent.

[0097] <21> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <20>, wherein the solvent contains an aromatic hydrocarbon solvent.

[0098] <22> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <21>, wherein the content of the aromatic hydrocarbon solvent in the solvent is 50% by mass or more and 100% by mass or less.

[0099] <23> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <22>, wherein the content of the aromatic hydrocarbon solvent in the solvent is 80% by mass or more and 100% by mass or less.

[0100] <24> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <23>, wherein the content of the aromatic hydrocarbon solvent in the solvent is 95% by mass or more and 100% by mass or less.

[0101] <25> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <24>, wherein the step is performed at a temperature of 20°C to 200°C.

[0102] <26> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <25>, wherein the step is performed at a temperature of 25°C to 180°C.

[0103] <27> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <26>, wherein the step is performed at a temperature of 50° C. to 160° C.

[0104] <28> The method for producing an α,β-unsaturated aldehyde according to any one of <1> to <27>, 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 hexylcinnamaldehyde.

[0105] [Example]

[0106] In the following Examples and Comparative Examples, “%” means “mass %” unless otherwise specified.

[0107] The following components were used as the raw materials used in the reaction.

[0108] Benzaldehyde: manufactured by Wako Pure Chemical Industries, Ltd., Wako Special Grade.

[0109] Octanal: manufactured by Kao Corporation.

[0110] Toluene: manufactured by Wako Pure Chemical Industries, Ltd., Wako Special Grade.

[0111] Tetradecane: manufactured by Wako Pure Chemical Industries, Ltd., Wako Special Grade.

[0112] Diethyl ether: manufactured by Wako Pure Chemical Industries, Ltd., Wako Special Grade.

[0113] <Example 1>

[0114] Production of hexylcinnamaldehyde (Formula (III-1))

[0115]

[0116] In a reaction tube with an inner diameter of 34 mm equipped with a capacitor, titanium oxide (SSP-M, anatase-type titanium oxide manufactured by Sakai Chemical Industry Co., Ltd., produced by the sulfuric acid method (liquid phase method), 0.19 g, 10% by mass relative to octanal, 10 parts by weight relative to 100 parts by mass of the compound of formula (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 a catalyst. After nitrogen substitution in the reaction tube, the mixed solution in the reaction tube was stirred at 150° C. for 4 hours. Then, the reaction tube was cooled to 30° C. to terminate the reaction.

[0117] The reaction results were quantitatively analyzed using GC (gas chromatography) and the internal standard method on the filtered reactants. The composition of each component in the resulting reactants was calculated according to the following formula. It should be noted that tetradecane was used as the internal standard substance, and diethyl ether was used as the solvent. The calculated hexylcinnamaldehyde yield (relative to octanal), hexylcinnamaldehyde selectivity (relative to benzaldehyde), and HCA / dimer formation ratio are shown in Table 2 below.

[0118] Specifically, 0.2 mL of the reaction solution was sampled, placed in a screw-capped bottle, and accurately weighed. 4 mL of diethyl ether was added to the reaction solution for dilution. The liquid was filtered through a membrane filter (polytetrafluoroethylene (PTFE), 0.2 μm) to remove the catalyst, and the resulting filtrate was subjected to GC analysis.

[0119] GC analysis was performed using both a DB-1 column (GC column, 100% dimethylpolysiloxane, manufactured by Agilent Technologies, Inc.) and a DB-WAX column (GC column, polyethylene glycol, manufactured by Agilent Technologies, Inc.).

[0120] [Yield of hexylcinnamaldehyde (relative to octanal)]

[0121] The yield of the target hexylcinnamaldehyde (p-octanal) was calculated according to the following formula. A larger value indicates a better yield.

[0122]

[0123] [Selectivity of hexylcinnamaldehyde (relative to benzaldehyde)]

[0124] The selectivity of hexylcinnamaldehyde (relative to benzaldehyde), which is a measure of aldehyde disproportionation, was calculated according to the following formula: A larger value indicates a better selectivity.

[0125]

[0126] [HCA / dimer formation ratio]

[0127] The production ratio of the dimer of aldehyde, i.e., the dimer, to the target product HCA was calculated according to the following formula. A larger value indicates a smaller amount of by-products.

[0128]

[0129] <Example 2>

[0130] The same procedure as in Example 1 was repeated except that titanium oxide (AMT-600, manufactured by Tayca, anatase-type titanium oxide, produced by the sulfuric acid method (liquid phase method)) was used instead of titanium oxide (SSP-M, manufactured by Sakai Chemical Industry) as the catalyst.

[0131] <Example 3>

[0132] The same procedure as in Example 1 was repeated except that titanium oxide (manufactured by Ishihara Sangyo, MC-150, anatase-type titanium oxide, produced by the sulfuric acid method (liquid phase method)) was used instead of titanium oxide (manufactured by Sakai Chemical Industry, SSP-M) as the catalyst. The evaluation results of the obtained products are shown in Table 2.

[0133] <Example 4>

[0134] The same procedure as in Example 1 was repeated except that titanium oxide (manufactured by Ishihara Sangyo, MC-50, anatase-type titanium oxide, produced by the sulfuric acid method (liquid phase method)) was used instead of titanium oxide (manufactured by Sakai Chemical Industry, SSP-M) as the catalyst. The evaluation results of the obtained products are shown in Table 2.

[0135] <Example 5>

[0136] The same procedure as in Example 1 was repeated except that titanium oxide (manufactured by Ishihara Sangyo, MC-90L, anatase-type titanium oxide, produced by the sulfuric acid method (liquid phase method)) was used instead of titanium oxide (manufactured by Sakai Chemical Industry, SSP-M) as the catalyst. The evaluation results of the obtained products are shown in Table 2.

[0137] <Example 6>

[0138] The same procedure as in Example 1 was carried out except that 1.5 molar equivalents of benzaldehyde were used instead of 5 molar equivalents of benzaldehyde relative to octanal. The evaluation results of the obtained products are shown in Table 2.

[0139] <Example 7>

[0140] The reaction tube was charged with the catalyst, octanal, benzaldehyde, etc., and a solvent of toluene (3.0 g, 30% by mass relative to the total amount of the compound of formula (I) and the compound of formula (II)). The same procedure as in Example 1 was followed except that the catalyst, octanal, benzaldehyde, etc., and a solvent of toluene (3.0 g, 30% by mass relative to the total amount of the compound of formula (I) and the compound of formula (II)) were added. The evaluation results of the obtained product are shown in Table 2.

[0141] <Example 8>

[0142] Titanium oxide (MC-90L, anatase-type titanium oxide manufactured by Ishihara Sangyo, produced by the sulfuric acid method (liquid phase method), 19.2 g, 30% by mass relative to octanal, 30 parts by weight relative to 100 parts by mass of the compound of formula (I)) and benzaldehyde (formula (II-1), 80.0 g, 0.75 mol, 1.5 molar equivalents relative to octanal) were added to a 200 mL separable flask as a catalyst. A mechanical stirrer, a thermometer, a Dean-Stark trap, a capacitor, a nitrogen line and an aldehyde supply line were installed in the separable flask. The octanal supply line was connected to a drip pump, which could supply octanal at a constant rate. After nitrogen substitution in the reaction tube, 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 drip pump. 64 g (0.5 mol) of octanal was added to the reaction mixture over a total of 6 hours at a rate of 12.8 g / h for the first half of the 3 hours and 8.5 g / h for the second half of the 3 hours. The reaction mixture was then stirred at 150°C for 0.5 hours, after which the separable flask was cooled to 30°C to terminate the reaction. The evaluation results of the resulting product are shown in Table 2.

[0143] <Example 9>

[0144] The same procedure as in Example 1 was followed except that titanium oxide (TK-1460, manufactured by Tayca, anatase-type titanium oxide, produced by the sulfuric acid method (liquid phase method)) was used instead of titanium oxide (SSP-M, manufactured by Sakai Chemical Industry) as the catalyst.

[0145] <Comparative Example 1>

[0146] The same procedure as in Example 1 was followed except that magnesium oxide (Kyowa Chemical Industry Co., Ltd., KYOWAMAG30, 0.19 g, 10% by mass relative to octanal) was used as the 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 products are shown in Table 3.

[0147] Comparative Example 2

[0148] The same procedure as in Example 1 was followed except that hydrotalcite (manufactured by Kyowa Chemical Industry, hydrotalcite, 0.19 g, 10% by mass relative to octanal) was used as the catalyst instead of titanium oxide (manufactured by Sakai Chemical Industry, SSP-M, 0.19 g, 10% by mass relative to octanal). The evaluation results of the obtained products are shown in Table 3.

[0149] Comparative Example 3

[0150] The same procedure as in Example 1 was carried out except that aluminum phosphate (manufactured by Kanto Chemical, aluminum phosphate, 0.19 g, 10% by mass relative to octanal) was used as the catalyst instead of titanium oxide (manufactured by Sakai Chemical Industry, SSP-M, 0.19 g, 10% by mass relative to octanal). The evaluation results of the obtained products are shown in Table 3.

[0151] <Comparative Example 4>

[0152] The same procedure as in Example 1 was followed except that silicoaluminophosphate zeolite (manufactured by JGC Catalysts & Chemicals, SAPO-34, 0.19 g, 10% by mass relative to octanal) was used as the catalyst instead of titanium oxide (manufactured by Sakai Chemical Industry, SSP-M, 0.19 g, 10% by mass relative to octanal). The evaluation results of the obtained product are shown in Table 3.

[0153] <Comparative Example 5>

[0154] The reaction tube was charged with the catalyst, octanal, benzaldehyde, etc., and a solvent of toluene (7.4 g, 75% by mass relative to the total amount of the compound of formula (I) and the compound of formula (II)). The same procedure as in Example 1 was followed except that the reaction tube was charged with the catalyst, octanal, benzaldehyde, etc., and a solvent of toluene (7.4 g, 75% by mass relative to the total amount of the compound of formula (I) and the compound of formula (II)). The evaluation results of the obtained product are shown in Table 3.

[0155] The reaction conditions and results of Examples 1 to 9 and Comparative Examples 1 to 5 are summarized in the following Tables 2 and 3. Table 2 also shows the primary particle size, sulfur content, BET specific surface area, and crystallite diameter of the titanium oxide used as the catalyst.

[0156] [Primary particle size]

[0157] The primary particle size was measured by X-ray diffraction using an X-ray diffractometer (manufactured by Rigaku Corporation, model: MiniFlex 600) and calculated from the peak at 2θ=25 to 26°.

[0158] [BET specific surface area]

[0159] The BET specific surface area was measured using a specific surface area measuring apparatus (manufactured by Micromeritics, model: FlowSorb III).

[0160] [Method for measuring the crystallite diameter of titanium oxide by powder X-ray diffraction measurement]

[0161] The crystallite diameter of titanium oxide was measured by powder X-ray diffraction using a powder X-ray diffractometer (trade name: MiniFlex 600, manufactured by Rigaku Corporation). The half-value width of the peak at 2θ of 25 to 26° was measured and the crystallite diameter was calculated by the Scherrer formula represented by the following general formula (S) (where K = 0.9, calculate.

[0162] D=λK / (βcosθ) (S)

[0163] In the general formula (S),

[0164] D represents the grain diameter

[0165] λ represents the wavelength of X-rays

[0166] K represents the Scherrer constant,

[0167] β represents the half-value width of the peak at 2θ of 25 to 26°.

[0168] It should be noted that the unit of β and θ is radian.

[0169]

[0170]

[0171] Tables 2 and 3 show that when the compound of formula (I) is reacted with the compound of formula (II) to obtain the α, β-unsaturated aldehyde of formula (III), when titanium oxide is used as a catalyst, the selectivity for α, β-unsaturated aldehyde (relative to the compound of formula (II)) and the yield of α, β-unsaturated aldehyde (relative to the compound of formula (I)) are high, and the formation of by-products can be suppressed.

[0172] The production method of the present invention can obtain the target aldehyde in high yield while satisfying selectivity and suppressing the formation of by-products, thereby enabling efficient and high-purity production of α,β-unsaturated aldehydes. This production method is suitable for use as a method for producing aldehydes useful as fragrance raw materials.

Claims

1. A method for producing an α,β-unsaturated aldehyde, wherein: include: a step of reacting the compound represented by formula (I) with the compound represented by formula (II) in a solvent of an aromatic hydrocarbon having 6 to 12 carbon atoms or in the absence of 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 relative to 100 parts by mass of the total of the compounds of formula (I) and formula (II). The titanium oxide is anatase titanium oxide, The titanium oxide has a crystallite diameter of 120 Å or more and 300 Å or less. In the formula, 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 bonded, they form 1,3-dioxolane, R 4 、R 5 and R 6 Each of the groups is 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 parts by mass or more and 30 parts by mass or less relative to 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, wherein The amount of the solvent is 0 parts by mass or more and 10 parts by mass or less relative to 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 The amount of the solvent is 0 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of the total of the compounds of formula (I) and formula (II).

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

6. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 3, wherein In the above step, the amount of the compound represented by the above formula (II) is 1.0 molar equivalent or more and 10 molar equivalents or less relative to the compound represented by the above formula (I).

7. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 3, wherein In the above step, the amount of the compound represented by the above formula (II) is 1.2 molar equivalents or more and 7 molar equivalents or less relative to the compound represented by the above formula (I).

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

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

10. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 3, wherein The compound represented by formula (II) is a compound represented by any one of the following formulae: 。 11. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 3, wherein The titanium oxide is used in an amount of 1 part by mass to 50 parts by mass based on 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 3, wherein The titanium oxide is used in an amount of 2 parts by mass or more and 30 parts by mass or less based on 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 3, wherein The titanium oxide is used in an amount of 5 parts by mass or more and 20 parts by mass or less based on 100 parts by mass of the compound of formula (I).

14. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 3, wherein The above process is performed at a temperature of 20° C. to 200° C.

15. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 3, wherein The above process is performed at a temperature of 25° C. to 180° C.

16. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 3, wherein The above process is performed at a temperature of 50° C. to 160° C.

17. The method for producing an α,β-unsaturated aldehyde according to any one of claims 1 to 3, 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 hexylcinnamaldehyde.

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