Preparation method of octyloxyglycerol

Abstract

The invention provides a preparation method of octyloxyglycerin, and belongs to the technical field of organic synthesis. The method comprises the following steps: taking isooctanol as an initial raw material, and reacting with a chlorination reagent in the presence of a catalyst to generate an intermediate 3-chloromethylheptane; reacting the intermediate 3-chloromethylheptane with glycerol in the presence of alkali and a phase transfer catalyst to generate an octyloxyglycerol crude product; and carrying out reduced pressure distillation on the octyloxyglycerol crude product to obtain the high-purity octyloxyglycerol. The preparation method of the octyloxyglycerin has the advantages of low raw material price, simplicity in operation, good safety and the like, and a new idea is provided for preparation of the octyloxyglycerin.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and in particular to a method for preparing octoxyglycerol. Background Technology

[0002] Octoxyglycerol, also known as ethylhexylglycerol, has the chemical name 3-[2-(ethylhexyl)oxy]-1,2-propanediol, CAS number 70445-33-9, and molecular formula C642-12-12-propanediol. 11 H 24 O3, with a molecular weight of 204.31, has the following chemical structural formula:

[0003] Octoxyglycerol chemical structural formula

[0004] Octoxyglycerin, in its pure form, is a colorless, transparent liquid with excellent solubility and stability. It is a high-performance, multifunctional cosmetic ingredient with good moisturizing, antibacterial, and emulsifying stability, and is widely used in personal care products such as lotions, creams, and shampoos. Especially in the cosmetics field, octoxyglycerin is an excellent moisturizer and emollient, increasing the skin's hydration capacity, reducing moisture loss, and improving skin softness and smoothness. Simultaneously, octoxyglycerin also has strong antibacterial and microbial growth-inhibiting effects, serving as a preservative substitute and extending the shelf life of cosmetics and skincare products. Furthermore, octoxyglycerin has anti-inflammatory and skin-soothing effects, reducing skin discomfort and sensitivity.

[0005] Patent CN104402682 uses isooctanol as a starting material, and reacts with epichlorohydrin in three steps—condensation, ring closure, and ring opening—to generate octyloxyglycerol. The synthetic route is as follows:

[0006] In the final ring-opening reaction step, patent JP3977109 uses p-toluenesulfonic acid as a catalyst and simultaneously feeds water and octyl glycidyl ether into a tubular reactor at 240 °C to carry out the reaction, thus achieving continuous operation.

[0007] Patent CN108191614 uses isooctanol as a starting material, which reacts with glycidyl acetate in a two-step reaction under the action of liquid alkali to obtain octyloxyglycerol. The synthetic route is as follows:

[0008] Patent CN114380668 reports a method for preparing ethylhexylglycerol by adding a small amount of water to isooctanol, mixing it thoroughly with glycerol, and then feeding the mixture into a reactor loaded with an acidic solid catalyst for intermolecular dehydration reaction. The route is as follows:

[0009] This method requires the use of ion exchange resin, which is relatively expensive and prone to generating byproducts.

[0010] Patent CN112759507 discloses a method for obtaining ethylhexylglycerol by reacting isooctyl alcohol and 3-chloro-1,2-propanediol under alkaline conditions, with a yield of up to 86.3%.

[0011]

[0012] Patent CN112661614 increases the yield of this route to 92.4% and achieves continuous production by using a microchannel reactor.

[0013] The aforementioned methods for synthesizing octyloxyglycerol mostly employ expensive raw materials or involve harsh conditions such as high temperature and high pressure, resulting in problems such as high cost, poor safety, and cumbersome operation. Therefore, developing a synthetic route with inexpensive and readily available raw materials, mild reaction conditions, simple operation, and environmental friendliness is of great significance for reducing the production cost of octyloxyglycerol and promoting its widespread application. Summary of the Invention

[0014] The purpose of this invention is to provide a method for preparing octoxyglycerol to solve the above-mentioned technical problems.

[0015] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing octoxyglycerol, comprising the following steps: 1) Starting with isooctyl alcohol, it reacts with a chlorinating agent in the presence of a catalyst to produce the intermediate 3-chloromethylheptane; 2) The intermediate 3-chloromethylheptane was reacted with glycerol in the presence of a base and a phase transfer catalyst to produce crude octoxyglycerol; 3) High-purity octoxyglycerol was obtained by vacuum distillation of crude octoxyglycerol.

[0016] Furthermore, the chlorinating agent comprises one or more of thionyl chloride, oxalyl chloride, phosphorus oxychloride, phosphorus trichloride, and phosphorus pentachloride; the amount of the chlorinating agent used is 1 to 3 times the mass of isooctyl alcohol.

[0017] Furthermore, the catalyst comprises N,N-dimethylformamide; the amount of the catalyst used is 1-5% of the mass of isooctyl alcohol.

[0018] Furthermore, in step 1), the reaction temperature is 50~80℃ and the reaction time is 2~6h.

[0019] Furthermore, the alkali comprises sodium hydroxide and / or potassium hydroxide, and the amount of the alkali used is 0.9 to 1.2 times the mass of glycerol.

[0020] Furthermore, in step 2), the molar ratio of glycerol to intermediate 3-chloromethylheptane is 1.0~1.6:1, the reaction temperature is 80~110℃, and the reaction time is 4~10h.

[0021] Furthermore, the phase transfer catalyst comprises tetrabutylammonium bromide and / or benzyltriethylammonium chloride, and the amount of phase transfer catalyst added is 1 to 5% of the mass of the intermediate 3-chloromethylheptane.

[0022] Furthermore, in step 3), during vacuum distillation, the fraction at 138~140℃ and 45±5 Pa is collected.

[0023] The beneficial effects of this invention are: (1) The raw materials are cheap and readily available: the starting material isooctyl alcohol is a bulk chemical product, and its cost is much lower than that of other special raw materials.

[0024] (2) The route is short and efficient: it only requires two steps, has high atom economy, and avoids the loss of total yield and purification difficulties caused by multi-step synthesis.

[0025] (3) Mild and controllable conditions: Both steps of the reaction are carried out at normal pressure and medium and low temperature, which makes the operation safe, requires low equipment, and is easy to scale up industrially.

[0026] (4) Good selectivity: The addition of a catalyst improves reaction efficiency and selectivity. Detailed Implementation

[0027] This invention provides a method for preparing octoxyglycerol, comprising the following steps: 1) Starting with isooctyl alcohol, it reacts with a chlorinating agent in the presence of a catalyst to produce the intermediate 3-chloromethylheptane; 2) The intermediate 3-chloromethylheptane was reacted with glycerol in the presence of a base and a phase transfer catalyst to produce crude octoxyglycerol; 3) High-purity octoxyglycerol was obtained by vacuum distillation of crude octoxyglycerol.

[0028] In this invention, the reaction route for synthesizing high-purity octoxyglycerol is as follows:

[0029] In this invention, the chlorination reagent comprises one or more of thionyl chloride, oxalyl chloride, phosphorus oxychloride, phosphorus trichloride, and phosphorus pentachloride, preferably one or more of thionyl chloride, phosphorus trichloride, and phosphorus pentachloride, and more preferably thionyl chloride; the amount of the chlorination reagent is 1 to 3 times the mass of isooctyl alcohol, preferably 1.2 to 2.0 times, and more preferably 1.5 to 2.0 times.

[0030] In this invention, the catalyst is preferably N,N-dimethylformamide; the amount of the catalyst is 1-5% of the mass of isooctyl alcohol, preferably 2-4%, and more preferably 3-4%.

[0031] In this invention, in step 1), the reaction temperature is 50~80℃, preferably 55~75℃, and more preferably 60~70℃; the reaction time is 2~6h, preferably 3~5h, and more preferably 4~5h.

[0032] In this invention, the alkali comprises sodium hydroxide and / or potassium hydroxide, preferably sodium hydroxide; the amount of the alkali used is 0.9 to 1.2 times the mass of glycerol, preferably 1 times.

[0033] In this invention, in step 2), the molar ratio of glycerol to the intermediate 3-chloromethylheptane is 1.0~1.6:1, preferably 1.05~1.5:1, and more preferably 1.05~1.3:1; the reaction temperature is 80~110℃, preferably 85~105℃, and more preferably 90~100℃; the reaction time is 4~10h, preferably 5~9h, and more preferably 6~8h.

[0034] In this invention, the phase transfer catalyst comprises tetrabutylammonium bromide and / or benzyltriethylammonium chloride, preferably tetrabutylammonium bromide; the amount of phase transfer catalyst added is 1 to 5% of the mass of the intermediate 3-chloromethylheptane, preferably 2 to 4%, and more preferably 3 to 4%.

[0035] In this invention, in step 3), the fraction at 138~140℃ and 45±5 Pa is collected during vacuum distillation.

[0036] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0037] Example 1

[0038] (1) Synthesis of 3-chloromethylheptane

[0039] The system is equipped with a stirrer, thermometer, reflux condenser, and exhaust gas absorption device (for absorbing HCl and S). 131.0 g (1.0 mol) of isooctanol and 4.0 g of DMF were added to a 500 mL four-necked flask. Under ice-water bath cooling, 179.0 g (1.5 mol) of thionyl chloride was slowly added dropwise, controlling the dropping rate to keep the reaction temperature below 50 °C. After the addition was complete, the temperature was slowly raised to 65 °C, and the reaction was stirred for 6 hours. After the reaction was complete, excess thionyl chloride was first removed by vacuum distillation, and then the fraction at 55 ± 1 °C was collected under a vacuum of 680 ± 5 Pa to obtain 141.8 g of colorless and transparent 3-chloromethylheptane with a purity of 99.5% and a yield of 94.9% (based on isooctanol).

[0040] (2) Synthesis of octoxyglycerol

[0041] Add 92.5 g (1.0 mol) glycerol, 42 g (1.0 mol) sodium hydroxide, and 1.0 g tetrabutylammonium bromide (TBAB) to a 500 mL four-necked flask equipped with a stirrer, thermometer, and condenser. Heat to 90 °C, and slowly add 134.5 g (0.9 mol) of 3-chloromethylheptane obtained in step (1) dropwise under vigorous stirring. After the addition is complete, continue the reaction at 100 °C for 6 hours. After the reaction is complete, cool the reaction solution, dilute with 150 mL of water, and extract three times with ethyl acetate (100 mL of ethyl acetate each time). Combine the organic phases and remove the solvent by vacuum distillation. Distill the crude product under reduced pressure, collecting the fraction from 138–40 °C at 45 ± 5 Pa to obtain 170.9 g of a pale yellow to colorless viscous liquid, octyloxyglycerol, with a purity of 99.3% and a yield of 92.3% (based on 3-chloromethylheptane), as determined by HPLC.

[0042] The experimental data of the examples obtained by changing the reaction conditions or reaction reagents are summarized in Tables 1 and 2 below.

[0043] Table 1. Chlorination reaction conditions and their effect on 3-chloromethylheptane

[0044] Note: The molar ratio of the substrate epoxide; Calculated as epoxides.

[0045] Table 2. Etherification reaction conditions and their effect on octyloxyglycerol

[0046] Note: The molar ratio is a multiple of the substrate 3-chloromethylheptane; Based on 3-chloromethylheptane.

[0047] As shown in the above embodiments, this invention provides a method for preparing octyloxyglycerol. Using industrially available isooctanol (2-ethylhexanol) as the starting material, the invention first reacts with thionyl chloride under mild conditions to selectively generate the key intermediate 3-chloromethylheptane. Subsequently, this intermediate is efficiently etherified with excess glycerol in the presence of a base and a phase transfer catalyst to produce crude octyloxyglycerol. This crude product is then subjected to high-vacuum distillation to obtain a high-content product. The octyloxyglycerol preparation method of this invention has advantages such as low raw material cost, simple operation, and good safety, providing a new approach for the preparation of octyloxyglycerol.

[0048] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing octoxyglycerol, characterized in that, Includes the following steps: 1) Starting with isooctyl alcohol, it reacts with a chlorinating agent in the presence of a catalyst to produce the intermediate 3-chloromethylheptane; 2) The intermediate 3-chloromethylheptane was reacted with glycerol in the presence of a base and a phase transfer catalyst to produce crude octoxyglycerol; 3) High-purity octoxyglycerol was obtained by vacuum distillation of crude octoxyglycerol.

2. The method for preparing octoxyglycerol according to claim 1, characterized in that, The chlorination reagent comprises one or more of thionyl chloride, oxalyl chloride, phosphorus oxychloride, phosphorus trichloride, and phosphorus pentachloride; the amount of the chlorination reagent used is 1 to 3 times the mass of isooctyl alcohol.

3. The method for preparing octoxyglycerol according to claim 1 or 2, characterized in that, The catalyst contains N,N-dimethylformamide; the amount of the catalyst used is 1-5% of the mass of isooctyl alcohol.

4. The method for preparing octoxyglycerol according to claim 3, characterized in that, In step 1), the reaction temperature is 50~80℃ and the reaction time is 2~6h.

5. The method for preparing octoxyglycerol according to claim 1 or 4, characterized in that, The alkali comprises sodium hydroxide and / or potassium hydroxide, and the amount of the alkali used is 0.9 to 1.2 times the mass of glycerol.

6. The method for preparing octoxyglycerol according to claim 5, characterized in that, In step 2), the molar ratio of glycerol to intermediate 3-chloromethylheptane is 1.0~1.6:1, the reaction temperature is 80~110℃, and the reaction time is 4~10h.

7. The method for preparing octoxyglycerol according to claim 1, 2, or 6, characterized in that, The phase transfer catalyst comprises tetrabutylammonium bromide and / or benzyltriethylammonium chloride, and the amount of phase transfer catalyst added is 1 to 5% of the mass of the intermediate 3-chloromethylheptane.

8. The method for preparing octoxyglycerol according to claim 1, characterized in that, In step 3), during vacuum distillation, the fraction at 138~140℃ and 45±5 Pa is collected.

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