JPS6345652B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is based on the general formula () The present invention relates to a method for producing an α,β-unsaturated carbonyl compound shown in the following. In the above general formula (), R ¹ and R ² are the same or different, each a hydrogen atom; methyl group, ethyl group, n-propyl group, isobutyl group, pentyl group, 4-methoxy-4-methylpentyl group, 4-
Ethoxy-4-methylpentyl group, hexyl group,
heptyl group, 4,8-dimethylnonyl group, 4,
An alkyl group that may be substituted with a lower alkoxy group or a cycloalkyl group such as an 8,12-trimethyltridecyl group, a cyclohexylmethyl group, or a cyclolabandillyl group; a cyclopentyl group;
Cycloalkyl or cycloalkenyl groups such as cyclopentyl, cyclohexyl, menthyl, 2-cyclohexenyl, 2,6,6-trimethyl-2-cyclohexenyl; 4-methyl-
3-pentenyl group, 3,4-dimethyl-3-pentenyl group, 3-hexenyl group, 4-methyl-3-
hexenyl group, 4,8-dimethyl-3,7-nonadienyl group, 4-ethyl-8-methyl-3,7-
Decadienyl group, 4,8,12-trimethyl-3,
It represents an alkenyl group such as a 7,11-tridecatrienyl group or an alkapolyenyl group; or an aryl group such as a phenyl group, tolyl group, xylyl group, or naphthyl group. Further, R ¹ and R ² may be combined with the carbon atoms to which they are bonded to form a ring. R ³ represents a hydrogen atom; or a lower alkyl group such as a methyl group or an ethyl group, and R ⁴ represents a hydrogen atom; an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or a heptyl group. ; or 3-methyl-2-butenyl group,
3-methyl-3-butenyl group, 4-dimethyl-3
-Represents an alkenyl group such as a pentenyl group, 3-hexenyl group, or 4-methyl-3-hexenyl group. The α,β-unsaturated carbonyl compound represented by the general formula () can not only be used as a fragrance per se, but also a compound useful as an intermediate in the production of fragrances, cosmetic base materials, medicines, agricultural chemicals, and the like. Conventionally, α,β-unsaturated carbonyl compounds have been produced by chemically oxidizing the corresponding α,β-unsaturated alcohol with manganese dioxide or chromic acid, or by dehydrogenating it in the presence of a metal catalyst such as copper or silver. [New Experimental Chemistry Course 15, Oxidation and Reduction (-1), pages 71-77 and pages 120-122 (published by Maruzen Co., Ltd.; see US Pat. No. 2,042,220)]. However, this conventional chemical oxidation method requires a large amount of oxidizing agent, and in order to avoid pollution problems, it is essential to recover the heavy metal compound used as the oxidizing agent after the reaction. This is not an industrially preferred method for producing β-unsaturated carbonyl compounds, and the dehydrogenation method described above requires reaction at a high temperature of 300 to 550°C. Industrial use of α,β-unsaturated carbonyl compounds is difficult due to the fact that decomposition reactions are likely to occur, resulting in a decrease in the yield of the target α,β-unsaturated carbonyl compounds, and that reaction equipment that can withstand high temperatures is required. Not suitable for manufacturing. The present inventors have made extensive studies to solve the above-mentioned problems in conventional methods using α,β-unsaturated alcohols as raw materials and to establish an industrially advantageous method for producing α,β-unsaturated carbonyl compounds. General formula () that is relatively easy to obtain [In the formula, R ¹ , R ² , R ³ and R ⁴ have the same meanings as in the general formula (), and R ⁵ is substituted with an alkyl group, a lower alkoxy group, a cycloalkyl group, a cycloalkenyl group, or an aryl group. represents an optionally substituted alkenyl group or alkapolyenyl group. ] It was discovered that the α,β-unsaturated carbonyl compound represented by the general formula () can be easily produced with good selectivity by using the β,γ-unsaturated ether represented by the formula () as a raw material, and the present invention I've reached it. R ⁵ in the above general formula () specifically includes a methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, 3,7-dimethyloctyl group, 3,7,11-trimethyldodecyl group, etc. alkyl group; or 2-butenyl group, 3-methyl-
2-butenyl group, 3-cyclohexyl-2-butenyl group, 3-(2,6,6-trimethyl-2-cyclohexenyl)-2-propenyl group, cinnamyl group, 2-hexenyl group, 3-methyl-2- hexenyl group, 2-octenyl group, 7-methoxy-
3,7-dimethyl-2-octenyl group, 3,7-
Dimethyl-2,6-octadienyl group, 3-ethyl-7-methyl-2,6-nonadienyl group, 2-
Decenyl group, 3,7,11-trimethyl-2,6,
Substituted with a lower alkoxy group such as a 10-dodecatrienyl group, a 3,7,11,15-tetramethyl-2,6,10,14-hexadecatetraenyl group, a cycloalkyl group, a cycloalkenyl group or an aryl group an alkenyl group or an alkapolyenyl group which may be
These are alkenyl groups such as butenyl group and 3-methyl-3-butenyl group. Representative examples of the β,γ-unsaturated ether represented by the general formula () include allyl methyl ether, 2
-butenyl methyl ether, 3-methyl-2-butenyl methyl ether, 3-methyl-2-butenyl methyl ether, 3-methyl-2-butenyl
3'-methyl-3'-butenyl ether, di(3-methyl-2-butenyl) ether, 3,7-dimethyl-2,6-octadienyl methyl ether,
Examples include 3,7-dimethyl-7-methoxy-2-octenyl methyl ether. According to the present invention, β represented by the general formula (),
The γ-unsaturated ether is oxidized in the liquid phase with molecular oxygen (triplet oxygen) in the presence or absence of a radical initiator, and the oxidation product is then catalytically reduced or chemically reduced in the presence of water. By doing so, the α,β-unsaturated carbonyl compound represented by the general formula () can be produced. The method of the present invention can be shown by the following reaction formula. (In the formula, R ¹ , R ² , R ³ , R ⁴ and R ⁵ are as defined above.) Oxidizing the β, γ-unsaturated ether represented by the general formula () with molecular oxygen in the liquid phase. The oxidation product represented by the above general formula () is obtained. Although this oxidation reaction can be carried out without a catalyst, it is preferably carried out in the presence of a radical reaction initiator. As a radical reaction initiator, azobisisobutyronitrile, azobisdimethylvaleronitrile, benzoyl peroxide, acetyl peroxide,
Di-tert-butyl peroxide, tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl perphthalate,
Examples include tert-butyl hydroperoxide, cumene hydroperoxide, and raw allyl ether-1-hydroperoxide, but in particular low-temperature decomposable azobisdimethylvaleronitrile, azobisisobutyronitrile, etc. are used. is preferred. The amount of radical reaction initiator used is approximately 0.01 to 5% relative to β, γ-unsaturated ether.
% by weight, preferably about 0.1-1% by weight. The reaction temperature is suitably in the range of about 10 to 100°C, particularly preferably in the range of about 30 to 80°C. If the temperature is too low, the reaction rate will be slow, and if the temperature is too high, epoxy compounds and the like will be more likely to be produced as by-products. Further, this oxidation reaction can be carried out in the presence or absence of a solvent, and an inert catalyst such as benzene, toluene, hexane, heptane, acetone, etc. is used as the solvent. Usually, this oxidation reaction is carried out under normal pressure while blowing molecular oxygen into the reaction system, or under pressure in the presence of molecular oxygen. This molecular oxygen may be diluted with nitrogen, argon, etc., and can also be oxidized using air, for example. In order to carry out the oxidation reaction in the present invention advantageously, it is preferable to use a low-temperature decomposable radical reaction initiator to react at a relatively low temperature and to stop the reaction within a short time. In the reaction in a solvent, the conversion rate of β, γ-unsaturated ether is preferably kept below 30%. After the oxidation reaction, dissolved oxygen is removed from the reaction mixture, and the reaction mixture containing the oxidation product represented by the general formula () is directly subjected to a reduction reaction to produce α,β-unsaturation represented by the general formula (). Carbonyl compounds can be obtained. Oxidation products of the general formula () can be produced by a catalytic hydrogenation reaction in the presence of a metal catalyst or by a chemical reduction reaction using an organic reducing agent in the presence of water.
It is derived from the α,β-unsaturated carbonyl compound represented by As a metal catalyst, Raney nickel,
Nickel-based catalysts such as platinum Raney nickel, Urushihara nickel, and reduced nickel; Palladium-based catalysts such as palladium-attached calcium carbonate, palladium-attached barium sulfate, palladium-attached activated carbon, Lindlar catalyst, colloidal palladium, and palladium black; platinum oxide, platinum inert carbon, and colloids. Platinum-based catalysts such as platinum and platinum black; Raney cobalt,
Those normally used in catalytic hydrogenation reactions, such as reduced cobalt and reduced copper, can be used. The amount of metal catalyst used is about 0.001 to 5% by weight, preferably about 0.1 to 1% by weight, based on the oxidation product. This catalytic hydrogenation reaction is carried out under normal pressure or increased pressure, usually at a temperature around room temperature. Examples of organic reducing agents include trivalent phosphorus compounds such as trimethylphosphite, triethylphosphite, trioctylphosphine, triphenylphosphine, tri-n-butylphosphine, hexamethylphosphorustriamide, and hexaethylphosphorustriamide; methyl sulfide,
Examples include alkyl sulfides such as ethyl sulfide. The amount of these reducing agents used is about 1 to 1.5 equivalents relative to the oxidized product. This chemical reduction reaction is usually carried out in the presence of water while keeping the temperature around room temperature. When the oxidation product represented by the general formula () is chemically reduced in the absence of water, the desired α,β-unsaturated carbonyl compound cannot be obtained.
When chemical reduction is carried out in the present invention, it is necessary to have water in the system, and an equimolar amount to the oxidation product is sufficient, but an excessive amount of water may be used. There is nothing wrong with that. After the reduction reaction is completed, the α,β-unsaturated carbonyl compound represented by the general formula () can be isolated by distilling the reaction mixture. β shown by the general formula () used as a raw material,
γ-unsaturated ethers can be expressed, for example, by the general formula () [In the formula, R ² , R ³ and R ⁴ have the same meanings as in the general formula (), and R is a group such that the R-CH ₂ - group is the same as R ¹ in the general formula (). means. ] The conjugated diene compound represented by the general formula () R ⁵ OH...() [wherein R ⁵ has the same meaning as in the bond (). ] Alcohols shown in sulfuric acid, phosphoric acid, boric acid,
It can be easily produced by reacting in the presence of an acidic catalyst such as p-toluenesulfonic acid or a cationic ion exchange resin. For example, by reacting isoprene and methanol at a temperature of 50 to 60°C in the presence of a cationic ion exchange resin (Diaion PK206), a high yield of about 85% can be obtained.
-Methyl-2-butenyl methyl ether is obtained. Hereinafter, the present invention will be specifically explained with reference to Examples. Example 1 30 g of 3-methyl-2-putenyl methyl ether and 0.15 g of azobismethylpareronitrile were placed in a 100 ml glass autoclave, and the inside of the autoclave was replaced with oxygen. After the temperature was set to 50 to 55°C, the oxygen pressure was set to 7 Kg/cm ² G, and the mixture was stirred at 700 rpm for 7 hours. After the obtained reaction mixture was cooled to 10° C., the inside of the system was purged with nitrogen. The amount of peroxide in the reaction mixture was determined by iodometric titration and was found to be 53.2 mmol. Next, the reaction mixture was transferred to a 100 ml atmospheric hydrogenation device, 0.2 g of Lindlar catalyst (manufactured by Nippon Engelhard) was added thereto, the system was replaced with hydrogen, and the hydrogenation reaction was carried out at 15 to 20°C. Summer. After confirming the disappearance of peroxide in the reaction mixture by iodometric titration, gas chromatography analysis of the reaction mixture revealed that the conversion rate of 3-methyl-2-butenyl methyl ether was 20%, indicating that it was selected. rate 80
% of senesion aldehyde was obtained. Example 2 In Example 1, azobisisobutyronitrile was used instead of 0.15 g of azobisdimethylvaleronitrile.
An oxidation reaction was carried out in the same manner as in Example 1, except that 0.15 g was used, the reaction temperature was 67 to 70°C, and the reaction time was 3 hours, followed by a hydrogenation reaction. As a result of gas chromatography analysis, 3-methyl-2-
The conversion rate of butenyl methyl ether is 24%,
Senesionaldehyde was obtained with a selectivity of 70%. Example 3 An oxidation reaction was carried out in the same manner as in Example 1, except that 0.15 g of azobisdimethylvaleronitrile was not added, the reaction temperature was 77 to 80°C, and the reaction time was 2.5 hours, followed by hydrogenation. The reaction was carried out. As a result of gas chromatography analysis, 3-
The conversion rate of methyl-2-butenyl methyl ether is
23%, and senection aldehyde was obtained with a selectivity of 63%. Example 4 30 g of di(3-methyl-2-butenyl) ether and 0.05 g of azobisdimethylvaleronitrile were placed in a 100 ml glass autoclave, and the inside of the autoclave was replaced with oxygen. After the temperature was set to 50 to 51°C, the oxygen pressure was set to 5 Kg/cm ² G, and the mixture was stirred at 700 rpm for 2 hours. After the obtained reaction mixture was cooled to 10° C., the inside of the system was purged with nitrogen. The amount of peroxide in the reaction mixture was determined by iodometric titration and was 41.7 mmol.
It was hot. Then, the reaction mixture was transferred to a 100 ml atmospheric hydrogenation apparatus, 0.1 g of Lindlar catalyst (manufactured by Nippon Engelhard) was added thereto, the system was replaced with hydrogen, and a hydrogenation reaction was carried out at room temperature. After confirming the disappearance of peroxide in the reaction mixture by iodometric titration, gas chromatography analysis of the reaction mixture revealed that the conversion rate of di(3-methyl-2-butenyl) ether was 32.4%. selection rate
Senesionaldehyde was obtained at 62.5%. Examples 5 to 19 Various β,γ-unsaturated ethers () are oxidized under the same conditions as in Example 1, and the obtained peroxides are subjected to hydrogenation reaction under the same conditions as in Example 1. As a result, an α,β-unsaturated carbonyl compound () was obtained. The results are shown in Table 1.

【table】

【table】

[Table] Example 20 3-Methyl-2 under the same reaction conditions as Example 1
-To 10 g of the reaction mixture obtained by oxidizing butenyl methyl ether (peroxide content: 15.2 mmol), 0.5 g of water was added under a nitrogen atmosphere, and then the temperature was lowered.
Triphenylphosphine 4.5g while keeping at 10℃
10 g of an acetone solution in which . After the dropwise addition was completed, stirring was continued for 1 hour at room temperature. After confirming the disappearance of peroxide in the reaction mixture by iodometric titration, gas chromatography analysis of the reaction mixture revealed that the conversion rate of 3-methyl-2-butenyl methyl ether was 20%, indicating that it was selected. Senesional aldehyde was obtained with a yield of 85%. Example 21 Under reaction conditions similar to Example 13, 1-methyl-3
10 g of the reaction mixture obtained by oxidizing -(2,6,6-trimethyl-2-cyclohexenyl)-2-propenyl methyl ether (peroxide content
9.5 mmol) under nitrogen atmosphere, add 0.5 g of water,
Then, while maintaining the temperature at 10° C., 6 g of an acetone solution containing 2.5 g of triphenylphosphine was added dropwise. After the dropwise addition was completed, stirring was continued for 1 hour at room temperature.
After confirming the disappearance of peroxide in the reaction mixture by iodometric titration, gas chromatography analysis of the reaction mixture revealed that the conversion rate of the raw material ether was 20%, and the selectivity was 73%, indicating that α-ionone was Obtained.

Claims (1)

[Claims] 1. General formula (In the formula, R ¹ and R ² are the same or different and each is a hydrogen atom, an alkyl group optionally substituted with a lower alkoxy group or a cycloalkyl group, a cycloalkyl group, a cycloalkenyl group, an alkenyl group, an alkapolyenyl group, or represents an aryl group, and
R ¹ and R ² may form a ring together with the carbon atom to which they are bonded. R ³ represents a hydrogen atom or a lower alkyl group, R ⁴ represents a hydrogen atom, an alkyl group, or an alkenyl group, and R ⁵
represents an alkyl group, an alkenyl group or an alkapolyenyl group which may be substituted with a lower alkoxy group, a cycloalkyl group, a cycloalkenyl group or an aryl group. ) is oxidized with molecular oxygen in the liquid phase in the presence or absence of a radical initiator, and the oxidation product is then catalytically reduced or chemically treated in the presence of water. General formula characterized by reduction (In the formula, R ¹ , R ² , R ³ and R ⁴ are as defined above.) A method for producing an α,β-unsaturated carbonyl compound represented by the following.