CN111393345A - Preparation method of limonene hydroperoxide - Google Patents

Abstract

The invention discloses a preparation method of limonene hydroperoxide. The method adopts an integrated photochemical microchannel reactor continuous flow reaction device, and through the feed port of the photochemical microchannel reactor, a mixed solution comprising terpinene, a photosensitizer and a solvent is continuously transported to the photochemical microchannel reaction. In the fluid module of the device, oxygen is supplied to the fluid module at the same time, and light is provided to the fluid module, a photosensitive oxidation reaction occurs in the fluid module, and the reaction obtains limonene hydroperoxide. The preparation process of the invention is novel, efficient, green and sustainable, and compared with the traditional batch reaction, it has precise temperature and pressure control, good mass transfer effect, greatly shortened reaction time, high light source utilization rate, less side reactions, and energy consumption. It has the characteristics of low yield and high yield, and has certain industrialization prospects at the same time.

Description

A kind of preparation method of limonene hydroperoxide

technical field

The invention belongs to the technical field of essential oil intermediate synthesis, and in particular relates to a preparation method of limonene hydroperoxide.

Background technique

Limonene hydroperoxide is a key intermediate in the synthesis of terpinene-4-ol by photosensitive oxidation. Terpinene-4-ol, also known as 4-terpineol, is a monocyclic monoterpene alcohol, colorless oily liquid, slightly soluble in water, with a warm peppery fragrance, a lighter earthy fragrance and a lily fragrance. It has anti-inflammatory, detoxification, antibacterial and other functions, especially has strong antibacterial effect on fungi, common pathogenic bacteria and drug-resistant bacteria, and is widely used in the field of preparation of advanced essential oils.

At present, the main source of terpinen-4-ol is obtained by rectifying tea tree oil. With the continuous expansion of the market, people have greater demand for terpinene-4-ol, but due to the limitation of the shortage of tea tree oil raw materials, the situation of short supply is becoming more and more serious. To solve this problem, it is necessary to develop new supply channels of terpinene-4-ol, and artificial chemical synthesis is a new way to solve the shortage of terpinene-4-ol.

So far, there are three main methods for the artificial chemical synthesis of terpinene-4-ol. The first one uses 1,4-cineole as raw material, and terpinene-4-ol is obtained by catalytic ring opening. Simple and efficient method, but it is also limited by the lack of 1,4-cineole raw material; the second one uses terpinolene, one of the components of turpentine, as raw material, and undergoes three steps of epoxidation, isomerization and hydrogenation Obtain terpinene-4-ol, but the catalyst used in this process has poor catalytic performance and is difficult to recover; the third is also taking terpinolene as raw material, and obtains terpinene-4 through three steps of photosensitive oxidation, reduction and hydrogenation -Alcohol, but in the photosensitive oxidation process of terpinene, the experimental setup used is a combination of a glass flask and a high-pressure mercury lamp, which lacks effective gas-liquid contact and uniform irradiation of the reaction solution, and a high-pressure mercury lamp It contains a lot of ultraviolet rays, and long-term irradiation will generate a lot of heat, making the reaction temperature difficult to control and the formation of obvious by-products. In addition, the scale of the reaction is also greatly restricted by the constraints of the experimental setup.

Therefore, it is necessary to find a preparation method that is simple to operate, green and efficient, has short reaction time, high yield, and is easy to produce limonene hydroperoxide on a large scale.

SUMMARY OF THE INVENTION

In order to solve the above limitation, the present invention provides a preparation method of limonene hydroperoxide, which has the advantages of simple operation, green efficiency, short reaction time, high yield, easy large-scale production and the like.

For achieving the above object, the technical scheme of the present invention is:

A preparation method of limonene hydroperoxide, the method adopts a photochemical microchannel reactor continuous flow reaction device, and through the feed port of the photochemical microchannel reactor, the continuous delivery comprises a mixture of terpinene, a photosensitizer and a solvent. The solution is put into the fluid module of the photochemical microchannel reactor, and oxygen is supplied to the fluid module at the same time, and light is provided to the fluid module. The mixed solution undergoes a photosensitive oxidation reaction in the fluid module, and the reaction obtains limonene hydroperoxide. thing.

Further, in the process of the photosensitive oxidation, the temperature in the fluid module is -10℃～50℃, preferably 10℃～30℃, more preferably 20℃; the internal pressure is 0～18bar, preferably 6～ 12 bar, more preferably 8 bar.

Further, the residence time of the photosensitive oxidation reaction is 30s-150s, preferably 50s-80s.

Further, the photosensitizer is rose bengal, methylene blue, tetraphenylporphyrin and derivatives, phthalocyanine and derivatives or eosin, preferably rose bengal, methylene blue or tetraphenylporphyrin derivatives.

Further, the substance ratio of the used photosensitizer to terpinolene is 0.0001-0.1, preferably 0.002-0.01.

Further, the solvent is methanol, ethanol, isopropanol, dichloromethane or water, preferably ethanol or isopropanol.

Further, the mass ratio of solvent to terpinolene in the mixed solution is 1-100 times, preferably 5-60 times.

Further, the step of "supplying oxygen into the fluid module" is specifically, supplying pure oxygen or a gas containing oxygen into the fluid module, preferably the oxygen purity is 99.999%.

Further, the light source used for "providing illumination" is selected from one of halogen lamps, xenon lamps, mercury lamps, and LED lamps, preferably LEDs are used as the light source.

Further, the photochemical microchannel reactor includes one or more fluid modules connected in series, and each fluid module is illuminated by a light source; the inner channel depth of the photochemical microchannel reactor is 100 μm˜10 mm.

Further, the fluid module structure in the photochemical microchannel reactor is a microtubular structure, a trough structure, a T-shaped structure, a spherical structure, an umbrella-shaped structure or a heart-shaped structure; the material of the fluid module is special glass, silicon carbide , corrosion-resistant alloys or fluoropolymers.

Beneficial effects of the present invention:

(1) In the photochemical microchannel reactor, the mass transfer and heat transfer efficiency are high, the temperature and pressure of the whole process are precisely controlled, and the reaction time is short, which significantly improves the conversion rate and selectivity of the reaction.

(2) Using LED as the light source, low heat dissipation, low energy consumption, pure light source, and can provide 6 specific wavelengths and adjustable light intensity, so as to select the best light source according to the absorption spectrum of the photosensitizer, and improve the utilization rate of the light source .

(3) The method is simple in operation, efficient in production, does not cause pollution to equipment and the environment, and can be scaled up seamlessly, is suitable for large-scale continuous preparation, and is convenient for industrial utilization.

Description of drawings

Fig. 1 is the structural representation of the photochemical microchannel reactor continuous flow reaction device in Example 1;

Fig. 2 is the hydrogen spectrogram of the limonene hydroperoxide obtained in Example 1;

Fig. 3 is the carbon spectrogram of the limonene hydroperoxide obtained in Example 1;

In the picture: 1-syringe pump, 2-mass flow controller, 3-photochemical microchannel reactor, 4-fluidic module, 5-LED light source, 6-product collector.

Detailed ways

The present invention will be further described below with reference to specific preferred examples, but the protection scope of the present invention is not limited to the following examples.

Example 1

(1) Preparation of solution: Mix 5g of terpinolene with 276g of ethanol to obtain a solution of terpinolene, then add 0.071g of rose bengal to the solution, stir evenly to obtain a photosensitization reaction solution.

(2) As shown in FIG. 1, the photochemical microchannel reactor continuous flow reaction device includes a photochemical microchannel reactor 3, and the photochemical microchannel reactor 3 is provided with a fluid module 4 and an LED light source 5. The fluid module 4 is: Microtubular structure, the left part of the photochemical microchannel reactor 3 is provided with a feeding port, and the syringe pump 1 for transporting the photosensitized reaction solution and the mass flow controller 2 for transporting oxygen are respectively connected with the feeding port, The right part of the photochemical microchannel reactor is provided with a discharge port connected with the product collector 6 .

Use the syringe pump 1 to pump the photosensitized reaction solution prepared in step (1) into the fluid module 4 in the photochemical microchannel reactor 3 at a flow rate of 1.5mL/min, then open the oxygen valve, and control the mass flow rate The device 2 regulates its flow rate to 10mL/min, the module reaction temperature is set to 20°C, the system pressure is controlled to 8bar, the 4000K LED light source 5 is turned on, the light source intensity is adjusted to 100%, and the light source cooling temperature is set to 20°C. After initiating the photosensitive oxidation reaction, the residence time is 60s, and the crude product of limonene hydroperoxide is obtained at the discharge port of the photochemical microchannel reactor 3 . Detected by high performance liquid chromatography (HPLC), the conversion rate of terpinolene calculated by external standard method was 100%, and the selectivity of limonene hydroperoxide was 61.2%.

Example 2

(1) Preparation of solution: Mix 5g of terpinolene with 276g of ethanol to obtain a solution of terpinolene, then add 0.048g of methylene blue to the solution, stir evenly to obtain a photosensitization reaction solution.

(2) Use the continuous flow reaction device of the photochemical microchannel reactor in Figure 1: use the syringe pump 1 to pump the photosensitized reaction solution prepared in step (1) into the photochemical microchannel reactor at a flow rate of 1.5 mL/min In the fluid module 4 in 3, then open the oxygen valve, adjust its flow rate to 10mL/min through the mass flow controller 2, the module reaction temperature is set to 20°C, the system pressure is controlled to 8bar, and the LED light source with a wavelength of 610nm is turned on, Adjust the light source intensity to 100%, and set the light source cooling temperature to 20°C. After initiating the photosensitive oxidation reaction, the residence time is 60s, and the crude product of limonene hydroperoxide is obtained at the discharge port of the photochemical microchannel reactor 3 . Detected by high performance liquid chromatography (HPLC), the conversion rate of terpinolene calculated by external standard method was 100%, and the selectivity of limonene hydroperoxide was 59.8%.

Example 3

(1) Preparation of solution: Mix 5g of terpinolene with 276g of ethanol to obtain a solution of terpinolene, then add 0.057g of meso-tetrakis (4-carboxyphenyl) porphyrin to the solution, stir well , to obtain a photosensitization reaction solution.

(2) Use the continuous flow reaction device of the photochemical microchannel reactor in Figure 1: use the syringe pump 1 to pump the photosensitized reaction solution prepared in step (1) into the photochemical microchannel reactor at a flow rate of 1.5 mL/min In the fluid module 4 in 3, then open the oxygen valve, control its flow rate to 10mL/min through the mass flow controller 2, the module reaction temperature is set to 20°C, the system pressure is controlled to 8bar, and the LED light source with a wavelength of 405nm is turned on, Adjust the light source intensity to 100%, and set the light source cooling temperature to 20°C. After initiating the photosensitive oxidation reaction, the residence time is 60s, and the crude product of limonene hydroperoxide is obtained at the discharge port of the photochemical microchannel reactor 3 . The conversion rate of terpinolene was 100% and the selectivity of limonene hydroperoxide was 50.8% calculated by external standard method.

Example 4

(1) Preparation of solution: Mix 10g of terpinolene with 549g of isopropanol to obtain a solution of terpinolene, then add 0.0213g of rose bengal to the solution, stir evenly to obtain a photosensitization reaction solution.

(2) Using the continuous flow reaction device of the photochemical microchannel reactor in Figure 1: use the syringe pump 1 to pump the photosensitized reaction solution prepared in step (1) into the photochemical microchannel reactor 3 at a flow rate of 2 mL/min In the fluid module 4, the oxygen valve is opened, the flow rate is regulated to 10mL/min by the mass flow controller 2, the module reaction temperature is set to 20°C, the system pressure is controlled to 8bar, the 4000K LED light source is turned on, and the intensity of the light source is adjusted. is 100%, and the cooling temperature of the light source is set to 20°C. After initiating the photosensitive oxidation reaction, the residence time is 50s, and the crude product of limonene hydroperoxide is obtained at the discharge port of the photochemical microchannel reactor 3 . The conversion rate of terpinolene was 100% and the selectivity of limonene hydroperoxide was 62.3% calculated by external standard method.

Comparative Example 1

(1) Preparation of solution: Mix 5g of terpinolene with 276g of ethanol to obtain a solution of terpinolene, then add 0.071g of rose bengal to the solution, stir evenly to obtain a photosensitization reaction solution.

(2) Put the photosensitized reaction solution into a traditional batch photochemical reactor, use a high-pressure mercury lamp to illuminate the reactor, and supply oxygen to the reactor to initiate a photosensitive oxidation reaction. Detected by liquid chromatography (HPLC), the conversion rate of terpinolene calculated by external standard method reached 68%, and the selectivity of limonene hydroperoxide reached 35%.

Comparative Example 1 Compared with Example 1, the conversion rate of terpinolene and the selectivity of limonene hydroperoxide in Example 1 are higher than those in Comparative Example 1; The mass and heat transfer efficiency and its precise temperature control can effectively avoid the decomposition of limonene hydroperoxide caused by the temperature rise during the reaction process; it can also accurately control the irradiation time of the light source through the flow rate of the pump, which can effectively avoid the long-term Irradiation leads to further oxidation of limonene hydroperoxide, which greatly improves the conversion of terpinene and the selectivity of limonene hydroperoxide.

The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All the technical solutions under the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those skilled in the art, improvements and modifications without departing from the principles of the present invention should also be regarded as the protection scope of the present invention.

Claims (10)

1. A preparation method of limonene hydroperoxide is characterized by comprising the following steps: continuously conveying a mixed solution containing terpinolene, a photosensitizer and a solvent to a fluid module of the photochemical microchannel reactor through a feed inlet of the photochemical microchannel reactor, simultaneously supplying oxygen to the fluid module, and providing illumination to the fluid module, wherein the mixed solution is subjected to a photosensitive oxidation reaction in the fluid module to obtain the limonene hydroperoxide.

2. The method for preparing limonene hydroperoxide according to claim 1, wherein during said photosensitive oxidation reaction, the temperature in said fluid module is-10 ℃ to 50 ℃ and the pressure is 0 bar to 18 bar.

3. The process for the preparation of limonene hydroperoxide according to claim 1 or 2, wherein said photo sensitive oxidation reaction has a residence time of 30-150 s.

4. The process for the preparation of limonene hydroperoxide according to claim 1 or 2, wherein said photosensitizer is rose bengal, methylene blue, tetraphenylporphyrin and derivatives, phthalocyanine and derivatives or eosin.

5. The method for producing limonene hydroperoxide according to claim 1, wherein the amount ratio of photosensitizer to terpinolene in said mixed solution is 0.0001-0.1.

6. The method of claim 1, wherein the solvent of the mixed solution is methanol, ethanol, isopropanol, dichloromethane or water.

7. The method for producing limonene hydroperoxide according to claim 1, wherein the mass ratio of the solvent to terpinolene in said mixed solution is 1-100.

8. The method according to claim 1, wherein the light source for providing light is selected from a halogen lamp, a xenon lamp, a mercury lamp, and an L ED lamp.

9. The method of claim 1, wherein the photochemical microchannel reactor comprises one or more fluidic modules connected in series, each fluidic module being illuminated by a light source; the depth of the internal channel of the photochemical microchannel reactor is 100 mu m-10 mm.

10. The method of claim 9, wherein the structure of the fluid module in the photochemical microchannel reactor is a microtubular structure, a channel-type structure, a T-type structure, a spherical structure, an umbrella-type structure, or a heart-type structure; the fluid module is made of special glass, silicon carbide, corrosion-resistant alloy or fluorine-containing polymer.

Images