Long-chain unsaturated olefine aldehyde and preparation method thereof

Abstract

The invention relates to the technical field of artificial synthesis of insect sex pheromones, in particular to a preparation method of long-chain unsaturated olefine aldehyde, which comprises the following steps: by taking a copper-containing compound as a catalyst and 2, 2 '-dipyridyl as a ligand, adding alkali, and by taking 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine-1-oxygen free radical and air oxygen as oxidants, reacting at the temperature of 60-80 DEG C to obtain the long-chain unsaturated olefine aldehyde. And converting the long-chain unsaturated enol into long-chain unsaturated olefine aldehyde. The preparation method of the long-chain unsaturated olefine aldehyde provided by the invention can be used for reaction at room temperature, and has the obvious advantages of mild reaction conditions, easily available raw materials, extremely low cost, suitability for industrial production and the like.

Description

Technical Field

[0001] The invention relates to the technical field of artificial synthesis of insect sex pheromones, in particular to a long-chain unsaturated olefinic aldehyde and a preparation method thereof. Background Art

[0002] Insect sex pheromones, as trace signal molecules released from insects, have a powerful ability to accurately attract insects of the opposite sex of the same species to mate. This is a unique and precise way of interspecies communication in nature, characterized by extremely high sensitivity, strong specificity, environmental friendliness (non-toxic and pollution-free), and harmlessness to natural enemies. In addition, the application of this sex pheromone can significantly reduce the application of chemical pesticides, thereby slowing down the speed at which pests develop resistance to pesticides. By using the disorientation strategy, that is, using insect sex pheromones to interfere with the natural chemical signal exchange between male and female adults, their mating and reproduction processes can be effectively controlled, achieving the goal of ecological control and prevention of pests.

[0003] So far, about two thousand insect sex pheromones have been documented. The chemical structure of these substances is generally composed of a long-chain skeleton consisting of 6 to 20 carbon atoms, and characteristically contains one or more double bonds. From the functional group classification of organic compounds, these sex pheromones can be subdivided into several major categories, including long-chain unsaturated aldehydes, long-chain unsaturated enols, long-chain unsaturated enol acetates, long-chain unsaturated ketones, and long-chain unsaturated epoxides. Among them, long-chain unsaturated aldehyde compounds, as the key component of insect sex pheromones, occupy a particularly important position. For example, (cis-11)-hexadecenal (abbreviated as Z11-16:Ald) is the main component of the sex pheromone of the vegetable pest Plutella xylostella, (cis-9)-hexadecenal (abbreviated as Z9-16:Ald) is the main component of the sex pheromone of cotton bollworm and tobacco budworm, (cis-13)-octadecenal (abbreviated as Z13-18:Ald) is the main component of the sex pheromone of the rice pest Cnaphalocrocis medinalis, and (cis-10)-hexadecenal (abbreviated as Z10-16:Ald) is the main component of the sex pheromone of the fruit pest Concha borella.

[0004] Since the amount of sex pheromones naturally secreted by insects is extremely small, only reaching the nanogram to microgram level, the market widely adopts the method of artificially synthesizing insect sex pheromones to effectively control pests. The synthesis of long-chain unsaturated enal sex pheromones is usually obtained by oxidation of the corresponding long-chain unsaturated enols. Commonly used oxidants include PCC, manganese dioxide, oxalyl chloride / dimethyl sulfoxide (Swern oxidation), 2,2,6,6-tetramethyl-1-piperidinyl oxide (TEMPO), etc.

[0005] PCC oxidant can oxidize secondary alcohols to corresponding aldehydes. The reaction conditions are mild, the generated products are relatively simple, and over-oxidation will not occur. However, since pyridinium chlorochromate is a heavy metal salt, it will cause pollution to the environment, so the post-treatment is relatively troublesome and not suitable for large-scale preparation and industrial production. The conditions for manganese dioxide oxidation are relatively mild, but the efficiency of heterogeneous reactions is not high, and obvious solid waste residues will be produced, which is also not suitable for large-scale preparation. Swern oxidation is commonly used in organic synthesis reactions. DMSO (dimethyl sulfoxide) and triethylamine are used to synergize with oxalyl chloride under low temperature conditions to oxidize primary alcohols or secondary alcohols to corresponding aldehydes or ketones with relatively high yields. However, the Swern oxidation reaction needs to be carried out at a low temperature of -78 ° C, especially the smell of its byproduct dimethyl sulfide is too bad, which makes it difficult to use for large-scale preparation.

[0006] In 1997, A. De Mico et al. reported a highly selective method for oxidizing alcohols to corresponding carbonyl compounds, using a catalytic amount of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) combined with bis(acetoxy)iodobenzene (BAIB) as a stoichiometric oxidant. This method is effective for most traditional solvents at room temperature, has high selectivity for the oxidation of primary alcohols, and has no obvious peroxidation effect in carboxyl compounds. This method is used to oxidize long-chain unsaturated enols with high yields, but there is an obvious problem: the polarity of the iodobenzene produced by the reaction is very close to that of the product enal, making it difficult to separate. If distillation is used, iodobenzene is easily decomposed by heat, and the product becomes dark black. Moreover, the iodine produced will cause the cis double bonds in the unsaturated enal to isomerize, seriously affecting the purity of the sex pheromone.

[0007] In view of this, how to provide a method for preparing long-chain unsaturated olefins under mild reaction conditions is a technical problem that urgently needs to be solved. Summary of the invention

[0008] In order to solve the problem of harsh reaction conditions of long-chain unsaturated olefins in the prior art, the present invention provides a method for preparing long-chain unsaturated olefins, wherein the method comprises the following steps: using 2,2'-bipyridine (BPY) as a ligand and in the presence of a base, using 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl radical (HO-TEMPO) and air to efficiently convert long-chain unsaturated olefins into corresponding long-chain unsaturated olefins under the action of a copper catalyst. The method has the obvious advantages of mild reaction conditions, easy availability of raw materials, extremely low cost, and being very suitable for industrial production, and solves the problem of harsh reaction conditions of long-chain unsaturated olefins in the prior art.

[0009] The technical solution adopted by the present invention to solve its technical problem is: A method for preparing a long-chain unsaturated olefin aldehyde comprises the following steps: using a copper-containing compound as a catalyst, using 2,2'-bipyridine as a ligand, adding a base, and using 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl free radical and air oxygen as oxidants to convert a long-chain unsaturated olefin alcohol into a long-chain unsaturated olefin aldehyde.

[0010] Optionally, the long-chain unsaturated ene alcohol is selected from at least one of (cis-11)-hexadecene-1-ol, (trans-11)-hexadecene-1-ol, (cis-9)-hexadecene-1-ol, (cis-9)-tetradecene-1-ol, (cis-8)-dodecene-1-ol, and (cis-13)-octadecene-1-ol.

[0011] Optionally, the copper-containing compound is selected from at least one of cuprous bromide, cuprous chloride, cupric bromide, and tetraacetonitrile copper (I) trifluoromethanesulfonate.

[0012] Optionally, the base is an organic base.

[0013] Optionally, the organic base is selected from at least one of methylimidazole, potassium tert-butoxide, pyridine, triethylamine, and 4-dimethylaminopyridine.

[0014] Optionally, the copper-containing compound is used in an amount of 2%-7% by mole relative to the long-chain unsaturated ene alcohol.

[0015] Optionally, the amount of the 2,2'-bipyridine used is 3%-8% by mole relative to the long-chain unsaturated ene alcohol.

[0016] Optionally, the amount of the 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl free radical used is 2%-7% by mole relative to the long-chain unsaturated enol.

[0017] Optionally, the amount of the base used is 5%-10% relative to the molar percentage of the long-chain unsaturated ene alcohol.

[0018] Another object of the present invention is to provide a long-chain unsaturated alkenal, which is prepared by the above-mentioned method for preparing the long-chain unsaturated alkenal.

[0019] The beneficial effects of the present invention are: The method for preparing the long-chain unsaturated olefinic aldehyde provided by the present invention can be reacted at room temperature, has the obvious advantages of mild reaction conditions, readily available raw materials, extremely low cost, and is very suitable for industrial production. DETAILED DESCRIPTION

[0020] The present invention is now further described in detail. The embodiments described below are exemplary and intended to be used to explain the present invention, but cannot be understood as limiting the present invention. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0021] In order to solve the problem of harsh reaction conditions of long-chain unsaturated olefins in the prior art, the present invention provides a method for preparing long-chain unsaturated olefins, the preparation process of which is as follows: taking long-chain unsaturated olefin alcohol as a substrate, taking a copper-containing compound as a catalyst, taking 2,2'-bipyridine (BPY) as a ligand, adding a base, taking 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl free radical (HO-TEMPO) and air oxygen as oxidants, the long-chain unsaturated olefin alcohol is converted into a long-chain unsaturated olefin.

[0022] Preferably, in the preparation method provided by the present invention, the reaction solvent is selected from at least one of acetonitrile, acetonitrile / water, dichloromethane and dimethylformamide, and preferably the reaction solvent is acetonitrile.

[0023] The method for preparing the long-chain unsaturated olefinic aldehyde provided by the present invention can be reacted at room temperature, has the obvious advantages of mild reaction conditions, readily available raw materials, extremely low cost, and is very suitable for industrial production.

[0024] The present invention preferably uses at least one of the long-chain unsaturated ene alcohol selected from (cis-11)-hexadecene-1-ol, (trans-11)-hexadecene-1-ol, (cis-9)-hexadecene-1-ol, (cis-9)-tetradecene-1-ol, (cis-8)-dodecene-1-ol and (cis-13)-octadecene-1-ol.

[0025] In order to ensure the smooth progress of the reaction and take into account the economic efficiency, the copper-containing compound is preferably selected from cuprous bromide, cuprous chloride, cupric bromide, tetraacetonitrile trifluoromethanesulfonate copper (I) ([Cu(MeCN) 4 ](OTf)); and further preferably, the copper-containing compound is cuprous bromide.

[0026] A 2,2-bipyridine (BPY)-cuprous / TEMPO catalyst system has been reported that can efficiently and selectively oxidize a variety of primary alcohols, including allylic alcohol, benzyl alcohol, and fatty alcohols, to the corresponding aldehydes at room temperature using readily available reagents and ambient air as an oxidant. The catalyst system is compatible with a variety of functional groups and has high selectivity for primary alcohols; however, the cuprous catalyst used in this method is copper (I) tetraacetonitrile trifluoromethanesulfonate, [Cu(MeCN) 4 ](OTf) is expensive and difficult to use directly for large-scale preparation.

[0027] The preparation method provided by the present invention can use cuprous bromide or cuprous chloride as a copper catalyst, which greatly reduces the cost and helps to achieve large-scale production.

[0028] The preferred base of the present invention is an organic base, and the organic base is preferably at least one selected from methylimidazole, potassium tert-butoxide, pyridine, triethylamine, and 4-dimethylaminopyridine, and the organic base is further preferably 4-dimethylaminopyridine.

[0029] In order to take into account both production efficiency and economy, the present invention preferably uses a copper-containing compound in an amount of 2%-7% by mole percentage relative to the long-chain unsaturated enol, and further preferably uses a copper-containing compound in an amount of 5% by mole percentage relative to the long-chain unsaturated enol; preferably uses 2,2'-bipyridine in an amount of 3%-8% by mole percentage relative to the long-chain unsaturated enol, and further preferably uses 5%; preferably uses 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl radical in an amount of 2%-7% by mole percentage relative to the long-chain unsaturated enol, and further preferably uses 5%; preferably uses a base in an amount of 5%-10% by mole percentage relative to the long-chain unsaturated enol, and further preferably uses 7%.

[0030] The method for preparing long-chain unsaturated olefinic aldehyde provided by the present invention uses 2,2'-bipyridine (BPY) as a ligand, and in the presence of a base, 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl radical (HO-TEMPO) and air to efficiently convert long-chain unsaturated olefinic alcohol into corresponding long-chain unsaturated olefinic aldehyde under the action of a copper catalyst. The reaction is carried out at room temperature, and the method has the obvious advantages of mild reaction conditions, easy availability of raw materials, extremely low cost, and being very suitable for industrial production.

[0031] Another object of the present invention is to provide a long-chain unsaturated alkenal, which is prepared by the above-mentioned method for preparing the long-chain unsaturated alkenal.

[0032] The long-chain unsaturated olefin aldehyde provided by the present invention can be prepared at room temperature, has the advantages of mild reaction conditions, easy availability of raw materials, extremely low cost, and is very suitable for industrial production.

[0033] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0034] This embodiment provides a method for preparing a long-chain unsaturated olefinic aldehyde, and the preparation method is as follows: In a 10mL reaction tube, weigh (cis-11)-hexadecene-1-ol Z11-16OH (0.24g, 1mmol), add CuBr (0.0072g, 0.05mmol, 0.05eq), add BPY (0.0078g, 0.05mmol, 0.05eq), add 4-HO-TEMPO (0.0085g, 0.05mmol, 0.05eq), add methylimidazole (0.0057g, 0.07mmol, 0.07eq), add acetonitrile (3mL). Place on a magnetic stirrer and stir evenly at room temperature. Detect the conversion rate of Z11-16OH and the yield of (cis-11)-hexadecene-1-aldehyde (Z11-16:Ald) by gas chromatography at regular intervals. After 5 hours, the conversion of Z11-16OH was 81.97% and the yield of Z11-16:Ald was 70.48%.

[0035] The difference between this example and Example 1 is that potassium tert-butoxide (0.0078 g, 0.07 mmol, 0.07 eq) is used instead of methylimidazole (0.0057 g, 0.07 mmol, 0.07 eq). After 5 hours, the conversion rate of Z11-16OH is 35.06%, and the yield of Z11-16:Ald is 24.03%.

[0036] The difference between this example and Example 1 is that pyridine (0.0055 g, 0.07 mmol, 0.07 eq) is used instead of methylimidazole (0.0057 g, 0.07 mmol, 0.07 eq). After 5 hours, the conversion rate of Z11-16OH is 69.80%, and the yield of Z11-16:Ald is 65.09%.

[0037] The difference between this example and Example 1 is that triethylamine (0.0070 g, 0.07 mmol, 0.07 eq) is used instead of methylimidazole (0.0057 g, 0.07 mmol, 0.07 eq). After 5 hours, the conversion rate of Z11-16OH is 65.82%, and the yield of Z11-16:Ald is 59.07%.

[0038] The difference between this example and Example 1 is that 4-dimethylaminopyridine (0.0085 g, 0.07 mmol, 0.07 eq) is used instead of methylimidazole (0.0057 g, 0.07 mmol, 0.07 eq). After 5 hours, the conversion rate of Z11-16OH is 93.73%, and the yield of Z11-16:Ald is 85.23%.

[0039] The above Examples 1-5 show the effects of different bases on the catalytic effect of converting (cis-11)-hexadecene-1-ol into the corresponding aldehyde at room temperature. The catalytic data are shown in Table 1.

[0040] Table 1 According to the data in Table 1, in the reaction system provided by the present invention, the catalytic effect of 4-dimethylaminopyridine on the conversion of (cis-11)-hexadecene-1-ol into the corresponding enal is significantly better than that of other organic bases.

[0041] The difference between this example and Example 1 is that CuBr (0.0072 g, 0.05 mmol, 0.05 eq) is replaced by CuCl (0.0049 g, 0.05 mmol, 0.05 eq). After 5 hours, the conversion rate of Z11-16OH is 60.06%, and the yield of Z11-16:Ald is 53.71%.

[0042] The difference between this embodiment and embodiment 1 is that CuBr 2 (0.0111 g, 0.05 mmol, 0.05 eq) replaced CuBr (0.0072 g, 0.05 mmol, 0.05 eq). After 5 hours, the conversion of Z11-16OH was 30.96% and the yield of Z11-16:Ald was 25.13%.

[0043] The difference between this embodiment and embodiment 1 is that [Cu(MeCN) 4 ](OTf) (0.0188 g, 0.05 mmol, 0.05 eq) replaced CuBr (0.0072 g, 0.05 mmol, 0.05 eq). After 5 hours, the conversion of Z11-16OH was 72.32% and the yield of Z11-16:Ald was 67.94%.

[0044] Examples 1, 6-8 show the effects of different Cu catalysts on the catalytic conversion of (cis-11)-hexadecene-1-ol to the corresponding aldehyde at room temperature. The catalytic data are shown in Table 2.

[0045] Table 2 According to the data in Table 2, in the reaction system provided by the present invention, CuBr has the best catalytic effect on the conversion of (cis-11)-hexadecene-1-ol into the corresponding enal.

[0046] The difference between this example and Example 1 is that acetonitrile (3 mL) is replaced with acetonitrile:water = 4:1 (3 mL). After 5 hours, the conversion rate of Z11-16OH is 13.81%, and the yield of Z11-16:Ald is 7.61%.

[0047] The difference between this example and Example 1 is that dichloromethane (3 mL) is used instead of acetonitrile (3 mL). After 5 hours, the conversion rate of Z11-16OH is 28.61%, and the yield of Z11-16:Ald is 22.18%.

[0048] The difference between this example and Example 1 is that dimethylformamide (3 mL) is used instead of acetonitrile (3 mL). After 5 hours, the conversion rate of Z11-16OH is 27.97%, and the yield of Z11-16:Ald is 21.68%.

[0049] Examples 1, 9-11 show the effects of different solvents on the catalytic conversion of (cis-11)-hexadecene-1-ol to the corresponding aldehyde at room temperature. The catalytic data are shown in Table 3.

[0050] Table 3 According to the data in Table 3, in the reaction system provided by the present invention, acetonitrile has the best catalytic effect on the conversion of (cis-11)-hexadecene-1-ol into the corresponding enal.

[0051] The difference between this example and Example 5 is that (trans-11)-hexadecene-1-ol (E11-16OH) is used instead of (cis-11)-hexadecene-1-ol. After 5 hours, the conversion rate of E11-16OH is 89.94%, and the yield of the product E11-16:Ald is 88.41%.

[0052] The difference between this example and Example 5 is that (cis-9)-hexadecene-1-ol (Z9-16OH) is used instead of (cis-11)-hexadecene-1-ol. After 5 hours, the conversion rate of Z9-16OH is 84.40%, and the yield of the product Z9-16:Ald is 62.76%.

[0053] The difference between this example and Example 5 is that (cis-9)-tetradecene-1-ol (Z9-14OH) is used instead of (cis-11)-hexadecene-1-ol. After 5 hours, the conversion rate of Z9-14OH is 88.60%, and the yield of the product Z9-14:Ald is 86.05%.

[0054] The difference between this example and Example 5 is that (cis-8)-dodecene-1-ol (Z8-12OH) is used instead of (cis-11)-hexadecene-1-ol. After 5 hours, the conversion rate of Z8-12OH is 86.88%, and the yield of the product Z8-12:Ald is 61.62%.

[0055] The difference between this example and Example 5 is that (cis-13)-octadecene-1-ol (Z13-18OH) is used instead of (cis-11)-hexadecene-1-ol. After 5 hours, the conversion rate of Z13-18OH is 84.49%, and the yield of the product Z13-18:Ald is 67.49%.

[0056] Examples 5, 12-16 show the effect of 4-dimethylaminopyridine on the catalytic conversion of different long-chain unsaturated enols into corresponding enals at room temperature. The catalytic data are shown in Table 4.

[0057] Table 4 Note: The reaction conditions were substrate enolate (1 mmol), CuBr (5 mol%), BPY (5 mol%), 4-HO-TEMPO (5 mol%), DMAP (7 mol%), acetonitrile (3 mL), room temperature, 5 h.

[0058] According to the data in Table 4, the synthesis of related pheromones from different long-chain unsaturated enols catalyzed by CuBr (5 mol%), BPY (5 mol%), 4-HO-TEMPO (5 mol%), DMAP (7 mol%), and acetonitrile (3 mL) at room temperature is universal.

[0059] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for preparing a long-chain unsaturated olefinic aldehyde, characterized in that: The preparation process is as follows: a copper-containing compound is used as a catalyst, 2,2'-bipyridine is used as a ligand, a base is added, and 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl free radical and air oxygen are used as oxidants to convert a long-chain unsaturated enolate into a long-chain unsaturated enolate.

2. The method for preparing a long-chain unsaturated olefinic aldehyde according to claim 1, wherein The long-chain unsaturated ene alcohol is selected from at least one of (cis-11)-hexadecene-1-ol, (trans-11)-hexadecene-1-ol, (cis-9)-hexadecene-1-ol, (cis-9)-tetradecene-1-ol, (cis-8)-dodecene-1-ol, and (cis-13)-octadecene-1-ol.

3. The method for preparing a long-chain unsaturated olefinic aldehyde according to claim 1, wherein The copper-containing compound is selected from at least one of cuprous bromide, cuprous chloride, cupric bromide, and tetraacetonitrile copper (I) trifluoromethanesulfonate.

4. The method for preparing a long-chain unsaturated olefinic aldehyde according to claim 1, wherein The base is an organic base.

5. The method for preparing a long-chain unsaturated olefinic aldehyde according to claim 4, characterized in that: The organic base is selected from at least one of methylimidazole, potassium tert-butoxide, pyridine, triethylamine, and 4-dimethylaminopyridine.

6. The method for preparing a long-chain unsaturated olefinic aldehyde according to any one of claims 1 to 5, characterized in that: The amount of the copper-containing compound used is 2%-7% by mole relative to the long-chain unsaturated ene alcohol.

7. The method for preparing a long-chain unsaturated olefinic aldehyde according to any one of claims 1 to 5, characterized in that: The molar percentage of the 2,2'-bipyridine used relative to the long-chain unsaturated ene alcohol is 3%-8%.

8. The method for preparing a long-chain unsaturated olefinic aldehyde according to any one of claims 1 to 5, characterized in that: The amount of the 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl free radical used is 2%-7% by mole relative to the long-chain unsaturated enol.

9. The method for preparing a long-chain unsaturated olefinic aldehyde according to any one of claims 1 to 5, characterized in that: The amount of the base used is 5%-10% by mole relative to the long-chain unsaturated ene alcohol.

10. A long-chain unsaturated olefinic aldehyde, characterized in that: The method is prepared by the method for preparing the long-chain unsaturated olefinic aldehyde according to any one of claims 1 to 9.

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