A method for synthesizing 2,6-dimethyl-2-hydroxyheptanal

Abstract

The present invention provides a method for synthesizing 2,6-dimethyl-2-hydroxy-heptanal, belonging to the technical field of organic chemistry. 6-Methyl-2-heptanone is reacted with haloacetaldehyde to prepare 2,6-dimethyl-2-hydroxy-heptanal. The present invention adopts a one-step method to prepare 2,6-dimethyl-2-hydroxy-heptanal. The synthesis method is simple, without the need for protecting and deprotecting groups, safe and environmentally friendly, the synthesis conditions are mild, the product yield is high, it is suitable for industrial application, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of organic chemistry, and particularly relates to a method for synthesizing 2,6-dimethyl-2-hydroxy-heptanal. Background Art

[0002] 2,6-Dimethyl-2-hydroxy-heptanal, whose structural formula is shown in Formula I, is an important derivative.

[0003]

[0004] It can enhance the floral or aromatic odor of perfumes or other organic chemicals. For example, 2,6-dimethyl-2-hydroxyheptanal has the aroma of melon, tropical fruits, raspberry-like, and lily of the valley, and can be used as an additive fragrance in tobacco, food, cleaners, soaps, fabric softeners, perfumes, etc.; another example is 2,6-dimethyl-6-methoxyheptanal, which is a colorless to pale yellow viscous liquid with a faint floral fragrance, a slight fruity fragrance, accompanied by the characteristic fragrance of citrus, and also has a fresh herbaceous flavor and a slight melon-like fruity fragrance, and can be used in functional and organic chemical flavorings with floral and herbaceous fragrance notes.

[0005] The current synthesis process is complex, the product yield is low, protection and deprotection groups are required, and the recovery of the protection groups is difficult. Therefore, it is necessary to develop a simple synthesis method. Summary of the Invention

[0006] The present invention overcomes the problems of complex synthesis process, low product yield, the need for protection and deprotection groups, and the difficulty in recovering the protection groups, and provides a simple method for synthesizing 2,6-dimethyl-2-hydroxy-heptanal.

[0007] The technical solution of the present invention is realized as follows:

[0008] The present invention provides a method for synthesizing 2,6-dimethyl-2-hydroxy-heptanal, which reacts 6-methyl-2-heptanone with haloacetaldehyde to obtain 2,6-dimethyl-2-hydroxy-heptanal.

[0009] As a further improvement of the present invention, the haloacetaldehyde is selected from at least one of chloroacetaldehyde and bromoacetaldehyde.

[0010] As a further improvement of the present invention, an alkali is added to the reaction.

[0011] As a further improvement of the present invention, the alkali is selected from at least one of NaOH, KOH, triethylamine, and diethylamine.

[0012] As a further improvement of the present invention, the molar ratio of 6-methyl-2-heptanone to haloacetaldehyde is 1:1.1 - 1.3.

[0013] As a further improvement of the present invention, the molar ratio of 6-methyl-2-heptanone, haloacetaldehyde, and base is 1:1.1 - 1.3:3 - 5.

[0014] As a further improvement of the present invention, the synthesis route is as follows:

[0015]

[0016] wherein X = Cl, Br.

[0017] As a further improvement of the present invention, the temperature of the reaction is 50 - 70°C and the time is 2 - 3 h.

[0018] As a further improvement of the present invention, it specifically includes the following steps: Dissolve 1 molar equivalent of 6-methyl-2-heptanone and 1.1 - 1.3 molar equivalents of haloacetaldehyde in acetonitrile, add 3 - 5 molar equivalents of base, heat to 50 - 70°C, and stir and react for 2 - 3 h to obtain 2,6-dimethyl-2-hydroxy-heptanal.

[0019] As a further improvement of the present invention, the yield of 2,6-dimethyl-2-hydroxy-heptanal is 90 - 97%.

[0020] The present invention has the following beneficial effects: The present invention uses a one-step method to prepare 2,6-dimethyl-2-hydroxy-heptanal. The synthesis method is simple, without the need for protection and deprotection groups, safe and environmentally friendly, the synthesis conditions are mild, the product yield is high, it is suitable for industrial application, and has broad application prospects. Specific Embodiments

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Example 1

[0023] This example provides a method for synthesizing 2,6-dimethyl-2-hydroxy-heptanal, and the synthesis route is as follows:

[0024]

[0025] The specific synthesis method includes the following steps:

[0026] Dissolve 0.1 mol of 6-methyl-2-heptanone and 0.11 mol of chloroacetaldehyde in 100 mL of acetonitrile, add 0.3 mol of base, heat to 50 °C, stir and react for 2 h, remove the solvent and excess reaction raw materials under reduced pressure to obtain 2,6-dimethyl-2-hydroxy-heptanal. ESI-MS calculated value: C9H 19 O3(M+H)+159.13, measured value: 159.1. The purity of the product analyzed by GC (gas chromatography) is 98.6%, and the yield is 93.2%.

[0027] NMR results: 1 H NMR(300 MHz, CDCl3) δ 9.72(s, 1H), 2.0(br, 1H), 1.82(m, 1H), 1.72(t, 2H), 1.42(s, 3H), 1.29(m, 2H), 1.25(m, 2H), 1.02(d, 6H).

[0028] 1 C NMR(300 MHz, CDCl3) δ 203.7, 91.0, 39.7, 36.2, 28.5, 22.3, 20.1, 18.2.

[0029] From the above data, it can be seen that 2,6-dimethyl-2-hydroxy-heptanal was successfully synthesized.

[0030] Example 2

[0031] This example provides a method for synthesizing 2,6-dimethyl-2-hydroxy-heptanal. The synthesis route is as follows:

[0032]

[0033] The specific synthesis method includes the following steps:

[0034] Dissolve 0.1 mol of 6-methyl-2-heptanone and 0.13 mol of chloroacetaldehyde in 100 mL of acetonitrile, add 0.5 mol of base, heat to 70 °C, stir and react for 3 h, remove the solvent and excess reaction raw materials under reduced pressure to obtain 2,6-dimethyl-2-hydroxy-heptanal. The purity of the product analyzed by GC (gas chromatography) is 98.2%, and the yield is 96.5%.

[0035] Example 3

[0036] This example provides a method for synthesizing 2,6-dimethyl-2-hydroxy-heptanal. The synthesis route is as follows:

[0037]

[0038] The specific synthesis method includes the following steps:

[0039] Dissolve 0.1 mol of 6-methyl-2-heptanone and 0.12 mol of chloroacetaldehyde in 100 mL of acetonitrile, add 0.4 mol of base, heat to 60 °C, stir and react for 2.5 h, remove the solvent and excess reaction raw materials under reduced pressure to obtain 2,6-dimethyl-2-hydroxy-heptanal. Analyze the product purity by GC (gas chromatography) to be 98.5%, and the yield is 94.5%.

[0040] Example 4

[0041] This example provides a method for synthesizing 2,6-dimethyl-2-hydroxy-heptanal, and the synthesis route is as follows:

[0042]

[0043] The specific synthesis method includes the following steps:

[0044] Dissolve 0.1 mol of 6-methyl-2-heptanone and 0.115 mol of bromoacetaldehyde in 100 mL of acetonitrile, add 0.35 mol of base, heat to 55 °C, stir and react for 2.5 h, remove the solvent and excess reaction raw materials under reduced pressure to obtain 2,6-dimethyl-2-hydroxy-heptanal. Analyze the product purity by GC (gas chromatography) to be 99.0%, and the yield is 94.1%.

[0045] Example 5

[0046] This example provides a method for synthesizing 2,6-dimethyl-2-hydroxy-heptanal, and the synthesis route is as follows:

[0047]

[0048] The specific synthesis method includes the following steps:

[0049] Dissolve 0.1 mol of 6-methyl-2-heptanone and 0.125 mol of bromoacetaldehyde in 100 mL of acetonitrile, add 0.45 mol of base, heat to 65 °C, stir and react for 2.5 h, remove the solvent and excess reaction raw materials under reduced pressure to obtain 2,6-dimethyl-2-hydroxy-heptanal. Analyze the product purity by GC (gas chromatography) to be 98.8%, and the yield is 95.1%.

[0050] The present invention uses a one-step method to prepare 2,6-dimethyl-2-hydroxy-heptanal. The synthesis method is simple, without the need for protecting and deprotecting groups, safe and environmentally friendly, the synthesis conditions are mild, the product yield is high, ranging from 93.2% to 96.5%, and the purity is high, ranging from 98.2% to 99%. It is suitable for industrial application and has broad application prospects.

[0051] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for synthesizing 2,6-dimethyl-2-hydroxy-heptanal, characterized in that, React 6-methyl-2-heptanone with haloacetaldehyde to obtain 2,6-dimethyl-2-hydroxy-heptanal. An alkali is added to the reaction, and the alkali is selected from at least one of NaOH, KOH, triethylamine, and diethylamine. The molar ratio of 6-methyl-2-heptanone, haloacetaldehyde, and alkali is 1:1.1 - 1.3:3 - 5. The temperature of the reaction is 50 - 70 °C, and the time is 2 - 3 h.

2. The synthesis method according to claim 1, wherein The haloacetaldehyde is selected from at least one of chloroacetaldehyde and bromoacetaldehyde.

3. The synthesis method according to claim 1, wherein Specifically, it includes the following steps: Dissolve 1 molar equivalent of 6-methyl-2-heptanone and 1.1 - 1.3 molar equivalents of haloacetaldehyde in acetonitrile, add 3 - 5 molar equivalents of alkali, heat to 50 - 70 °C, and stir and react for 2 - 3 h to obtain 2,6-dimethyl-2-hydroxy-heptanal.

4. The synthesis method according to claim 3, wherein The yield of the 2,6-dimethyl-2-hydroxy-heptanal is 90 - 97%.

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