CN115819388B - Preparation method of delta-cyclopentalactone - Google Patents

Abstract

The present invention belongs to the technical field of organic synthesis, and provides a method for preparing δ-cyclopentanolactone. Compared with the prior art, 1,5-pentanediol and sodium hypochlorite aqueous solution are used as raw materials, dichloromethane is used as solvent, and the method for preparing δ-cyclopentanolactone by reaction under alkaline conditions is used. The present invention uses 1,5-pentanediol and sodium hypochlorite as raw materials, and uses 2,2,6,6-tetramethylpiperidinyl oxide as a co-oxidant. Without the need for an organic solvent and alkaline conditions, δ-cyclopentanolactone can be obtained, which is beneficial to environmental protection. Meanwhile, 2,2,6,6-tetramethylpiperidinyl oxide is fully contacted with 1,5-pentanediol to improve yield. In addition, the microchannel reaction equipment has a large reaction area, and the raw materials are fully contacted, which further improves the product yield. The embodiment shows that the conversion rate of the preparation method provided by the present invention to δ-cyclopentanolactone is 60.6-99.9%, the selectivity is 70.4-99.9%, and the yield is 99.80%.

Description

A method for preparing delta-cyclopentanolactone

Technical Field

The invention relates to the technical field of organic synthesis, and in particular to a method for preparing delta-cyclopentanolactone.

Background technique

δ-Cyclopentanolactone (δ-valerolactone), also known as tetrahydro-α-pyrone, is a light yellow or colorless liquid with an aromatic odor. It is well miscible with organic solvents such as benzene, acetone, ether, and ethanol, and slightly soluble in water. Its monomers tend to self-polymerize when left standing, so it has strict requirements during storage, such as adding an appropriate amount of inhibitor or storing at low temperatures.

As a very important pharmaceutical intermediate and organic intermediate raw material, δ-cyclopentanolactone is easy to self-polymerize by ring opening. At the same time, it can also be polymerized with other lactone compounds such as caprolactone to obtain high molecular polyester with good plasticity, biodegradability, physiological activity, flexibility and elongation. And this material is widely used in the fields of environmental protection, medicine and liquid crystal materials. The preparation method of δ-valerolactone is mainly the catalytic dehydrogenation method of pentanediol.

However, the pentanediol catalytic dehydrogenation method uses 1,5-pentanediol and sodium hypochlorite aqueous solution as raw materials and dichloromethane as solvent to react under alkaline conditions to obtain δ-cyclopentanolactone, but the yield is low.

Summary of the invention

In view of this, the object of the present invention is to provide a method for preparing δ-cyclopentanolactone, and the yield of the preparation method provided by the present invention is 99.80%.

In order to achieve the above-mentioned invention object, the present invention provides the following technical solutions:

The present invention provides a method for preparing δ-cyclopentanolactone, comprising the following steps:

1,5-pentanediol is used as the first material; a mixed solution of sodium hypochlorite, 2,2,6,6-tetramethylpiperidinyl oxide and water is used as the second material;

The first material and the second material are reacted in a microchannel reaction device to obtain the delta-cyclopentanolactone.

Preferably, the flow ratio of the first material to the second material is 1:(0.4-1.5).

Preferably, the flow ratio of the first material to the second material is 1:(0.6-1.2).

Preferably, the flow rate of the first material is 20-30 g/min.

Preferably, the mass ratio of sodium hypochlorite, 2,2,6,6-tetramethylpiperidinyl oxide and water in the second material is (2900-3750):(8-12):1500.

Preferably, the reaction temperature is -10 to 60°C and the pressure is 0.01 to 0.5 MPa.

Preferably, the reaction temperature is 0-50° C. and the pressure is 0.05-0.3 MPa.

Preferably, the microchannel reaction equipment comprises a microchannel mixer and a microchannel reactor; the microchannel mixer is heart-shaped.

Preferably, the inner diameter of the microchannel of the microchannel reaction device is 0.01 to 0.018 mm.

The present invention provides a method for preparing δ-cyclopentanolactone, comprising the following steps: using 1,5-pentanediol as a first material; a mixed solution of sodium hypochlorite, 2,2,6,6-tetramethylpiperidinyl oxide and water as a second material; reacting the first material and the second material in a microchannel reaction device to obtain the δ-cyclopentanolactone. Compared with the prior art method of using 1,5-pentanediol and sodium hypochlorite aqueous solution as raw materials, dichloromethane as solvent, and reacting under alkaline conditions to prepare δ-cyclopentanolactone, the present invention uses 1,5-pentanediol and sodium hypochlorite as raw materials, and 2,2,6,6-tetramethylpiperidinyl oxide as a co-oxidant, and can obtain δ-cyclopentanolactone without the need for an organic solvent and alkaline conditions, which is beneficial to environmental protection; at the same time, 2,2,6,6-tetramethylpiperidinyl oxide is fully contacted with 1,5-pentanediol to improve the yield; in addition, the microchannel reaction device has a large reaction area, and the raw materials are fully contacted, which further improves the product yield.

The data of the examples show that the conversion rate of the preparation method provided by the present invention for δ-cyclopentanolactone is 60.6-99.9%, the selectivity is 70.4-99.9%, and the yield is 99.80%.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic structural diagram of a microchannel mixer;

FIG. 2 is a flow chart of preparing δ-cyclopentanolactone using a microchannel reaction apparatus.

Detailed ways

The present invention provides a method for preparing δ-cyclopentanolactone, comprising the following steps:

1,5-pentanediol is used as the first material; a mixed solution of sodium hypochlorite, 2,2,6,6-tetramethylpiperidinyl oxide (TEPMO) and water is used as the second material;

The first material and the second material react in a microchannel reaction device to obtain the delta-cyclopentanolactone.

In the present invention, unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

In the present invention, the mass ratio of sodium hypochlorite, 2,2,6,6-tetramethylpiperidinyl oxide (TEPMO) and water in the second material is preferably (2900-3750):(8-12):1500, and more preferably 3250:(8-12):1500.

In the present invention, the flow rate ratio of the first material to the second material is preferably 1: (0.4-1.5), more preferably 1: (0.6-1.2), and more preferably 1: 1. In the present invention, the flow rate of the first material is preferably 20-30 g/min.

In the present invention, the reaction temperature is preferably -10 to 60°C, more preferably 0 to 50°C; the pressure is preferably 0.01 to 0.5 MPa, more preferably 0.05 to 0.3 MPa.

In the present invention, the microchannel reaction device comprises a microchannel mixer and a microchannel reactor. In the present invention, the microchannel mixer is preferably a heart-shaped device, and the structure is shown in FIG1 .

In the present invention, the inner diameter of the microchannel of the microchannel reaction device is preferably 0.01 to 0.018 mm.

In the present invention, the reaction process of the first material and the second material in the microchannel reaction device is preferably:

The first material and the second material enter the microchannel mixer in the microchannel reaction device through two inlets respectively for mixing, and then flow into the microchannel reactor for reaction. The reaction temperature and pressure defined above in the present invention refer to the conditions for reaction in the microchannel reactor.

After the reaction, the present invention preferably further comprises post-treating the obtained reaction liquid to obtain the δ-cyclopentanolactone.

In the present invention, the post-treatment preferably includes standing the obtained reaction liquid for stratification, and distilling the obtained organic phase to obtain the δ-cyclopentanolactone. The present invention does not specifically limit the operation of the distillation, and the operation well known to those skilled in the art can be used.

FIG. 2 is a flow chart of preparing δ-cyclopentanolactone using a microchannel reaction apparatus.

The preparation method of δ-cyclopentanolactone provided by the present invention is described in detail below in conjunction with the examples, but they should not be construed as limiting the scope of protection of the present invention.

Example 1

A mixture of 1,5-pentanediol as the first material and TEPMO: sodium hypochlorite and water in the second material in a mass ratio of 10:3250:1500 was prepared; the first material and the second material were pumped into a microchannel mixer for mixing, and the flow rates of the first material and the second material were both 20 g/min; then the mixture was put into a microchannel reactor at a temperature of 10°C and a pressure of 0.2 MPa, and the reactor temperature was 10°C. After reacting for 10 minutes, the reaction liquid in the microchannel reactor was extracted for static stratification, and the obtained organic phase was subjected to The crude product of δ-cyclopentanolactone is obtained by distillation. 10 mg of the crude product is added into 100 mL of ethanol. 9.98 mg of δ-cyclopentanolactone, 0.01 mg of 1,5-pentanediol and 0.01 mg of by-products are obtained by liquid chromatography injection. The conversion rate is 10.37/10.38=99.90%, the selectivity is 9.98/9.99=99.9%, and the yield is 99.9%*99.9%=99.80%. The inner diameter of the microchannel in the microchannel reaction device is 0.015 mm. The shape of the microchannel mixer is a heart shape.

Example 2

1,5-pentanediol was used as the first material, and the second material was a mixture of TEPMO: sodium hypochlorite and water in a mass ratio of 8:3250:1500. The first material and the second material were pumped into a microchannel mixer for mixing by a pump. The flow rates of the first material and the second material were both 20 g/min. The first material and the second material then entered a microchannel reactor at a temperature of 10°C and a pressure of 0.2 MPa. At this time, the reactor temperature was 10°C. After a stable reaction for 10 minutes, the reaction liquid in the microchannel reactor was extracted for static stratification, and the obtained organic phase was subjected to The δ-cyclopentanolactone was obtained by distillation, 10 mg of the crude product was added into 100 mL of ethanol, and 7.32 mg of δ-cyclopentanolactone, 2.05 mg of 1,5-pentanediol, and 0.62 mg of by-products were obtained by liquid chromatography injection, with a conversion rate of 8.26/10.31=80.1%, a selectivity of 7.32/7.94=92.2%, and a yield of 80.1%*92.2%=73.85%. The inner diameter of the microchannel in the microchannel reaction device is 0.015 mm; and the shape of the microchannel mixer is a heart shape.

Example 3

1,5-pentanediol was used as the first material, and the second material was a mixture of TEPMO: sodium hypochlorite and water in a mass ratio of 12:3250:1500. The first material and the second material were pumped into a microchannel mixer for mixing by a pump. The flow rates of the first material and the second material were both 20 g/min. The first material and the second material then entered a microchannel reactor at a temperature of 10°C and a pressure of 0.2 MPa. At this time, the reactor temperature was 10°C. After a stable reaction for 10 minutes, the reaction liquid in the microchannel reactor was extracted for static stratification, and the obtained organic phase was subjected to The δ-cyclopentanolactone was obtained by distillation, 10 mg of the crude product was added into 100 mL of ethanol, and 6.85 mg of δ-cyclopentanolactone, 0.27 mg of 1,5-pentanediol, and 2.88 mg of by-products were obtained by liquid chromatography injection, with a conversion rate of 10.12/10.39=97.4%, a selectivity of 6.85/9.73=70.4%, and a yield of 97.4%*70.4%=68.57%. The inner diameter of the microchannel in the microchannel reaction device is 0.015 mm; and the shape of the microchannel mixer is a heart shape.

Example 4

1,5-pentanediol was used as the first material, and the second material was a mixture of TEPMO: sodium hypochlorite and water in a mass ratio of 10:3750:1500. The first material and the second material were pumped into a microchannel mixer for mixing by a pump. The flow rates of the first material and the second material were both 20 g/min. The first material and the second material then entered a microchannel reactor at a temperature of 10°C and a pressure of 0.2 MPa. At this time, the reactor temperature was 10°C. After reacting for 10 minutes, the reaction liquid in the microchannel reactor was extracted for static stratification, and the obtained organic phase was subjected to The δ-cyclopentanolactone was obtained by distillation, 10 mg of the crude product was added into 100 mL of ethanol, and 7.45 mg of δ-cyclopentanolactone, 1.66 mg of 1,5-pentanediol, and 0.89 mg of by-products were obtained by liquid chromatography injection, with a conversion rate of 8.67/10.33=83.9%, a selectivity of 7.45/8.34=89.3%, and a yield of 83.9%*89.3%=74.9%. The inner diameter of the microchannel in the microchannel reaction device is 0.015 mm; and the shape of the microchannel mixer is a heart shape.

Example 5

1,5-pentanediol was used as the first material, and the second material was a mixed solution of TEPMO: sodium hypochlorite and water in a mass ratio of 10:2900:1500. The first material and the second material were pumped into a microchannel mixer for mixing by a pump. The flow rates of the first material and the second material were both 20 g/min. The first material and the second material then entered a microchannel reactor at a temperature of 10°C and a pressure of 0.2 MPa. At this time, the reactor temperature was 10°C. After reacting for 10 minutes, the reaction liquid in the microchannel reactor was extracted for static stratification, and the obtained organic phase was subjected to The δ-cyclopentanolactone was obtained by distillation, 10 mg of the crude product was added into 100 mL of ethanol, and 7.27 mg of δ-cyclopentanolactone, 2.54 mg of 1,5-pentanediol, and 0.19 mg of by-products were obtained by liquid chromatography injection. The conversion rate was 7.76/10.3=75.3%, the selectivity was 7.27/7.46=97.5%, and the yield was 75.3%*97.5%=73.42%. The inner diameter of the microchannel in the microchannel reaction device was 0.015 mm. The shape of the microchannel mixer was a heart shape.

Example 6

1,5-pentanediol was used as the first material, and the second material was a mixture of TEPMO: sodium hypochlorite and water in a mass ratio of 10:3250:1500 g. The first material and the second material were pumped into a microchannel mixer for mixing by a pump. The flow rates of the first material and the second material were both 20 g/min. The first material and the second material then entered a microchannel reactor at a temperature of 30°C and a pressure of 0.2 MPa. At this time, the reactor temperature was 30°C. After reacting for 10 minutes, the reaction liquid in the microchannel reactor was extracted for static stratification, and the obtained organic phase was subjected to The δ-cyclopentanolactone was obtained by distillation. 10 mg of the crude product was added into 100 mL of ethanol. 5.85 mg of δ-cyclopentanolactone, 2.73 mg of 1,5-pentanediol and 1.42 mg of by-products were obtained by liquid chromatography injection. The conversion rate was 7.56/10.29=73.5%, the selectivity was 5.85/7.27=80.5%; the yield was 73.5%*80.5%=59.17%; the inner diameter of the microchannel in the microchannel reaction device was 0.015 mm; and the shape of the microchannel mixer was a heart shape.

Example 7

1,5-pentanediol was used as the first material, and the second material was a mixture of TEPMO: sodium hypochlorite and water in a mass ratio of 10:3250:1500. The first material and the second material were pumped into a microchannel mixer for mixing by a pump. The flow rates of the first material and the second material were both 20 g/min. The first material and the second material then entered a microchannel reactor at a temperature of 0°C and a pressure of 0.2 MPa. At this time, the reactor temperature was 0°C. After reacting for 10 minutes, the reaction liquid in the microchannel reactor was extracted and allowed to stand for stratification. The obtained organic phase was subjected to purification. distillation to obtain the δ-cyclopentanolactone, take 10 mg of the crude product and add it into 100 mL of ethanol, and inject by liquid chromatography to obtain 6.62 mg of δ-cyclopentanolactone, 1.53 mg of 1,5-pentanediol, and 1.85 mg of by-products, with a conversion rate of 8.81/10.34=85.2%, a selectivity of 6.62/8.47=78.2%, and a yield of 85.2%*78.2%=66.63%; the inner diameter of the microchannel in the microchannel reaction device is 0.015 mm; the shape of the microchannel mixer is a heart shape.

Example 8

1,5-pentanediol was used as the first material, and the second material was a mixture of TEPMO: sodium hypochlorite and water in a mass ratio of 10:3250:1500. The first material and the second material were pumped into a microchannel mixer for mixing by a pump. The flow rates of the first material and the second material were both 30 g/min. The first material and the second material then entered a microchannel reactor at a temperature of 10°C and a pressure of 0.2 MPa. At this time, the reactor temperature was 10°C. After reacting for 10 minutes, the reaction liquid in the microchannel reactor was extracted for static stratification, and the obtained organic phase was further subjected to The δ-cyclopentanolactone was obtained by distillation, 10 mg of the crude product was added into 100 mL of ethanol, and 5.32 mg of δ-cyclopentanolactone, 4.03 mg of 1,5-pentanediol, and 0.65 mg of by-products were obtained by liquid chromatography injection, with a conversion rate of 6.20/10.23=60.6%, a selectivity of 5.32/5.97=89.1%, and a yield of 60.6%*89.1%=54.0%. The inner diameter of the microchannel in the microchannel reaction device is 0.015 mm; and the shape of the microchannel mixer is a heart shape.

Comparative Example 1

1500g of 1,5-pentanediol, 10g of TEPMO and 3250g of sodium hypochlorite are added to 1500g of water, mixed, stirred to be fully mixed, added to a high-pressure reactor, the temperature is controlled at 10°C, and the reaction is carried out at a constant temperature for 40 hours. The reaction system is allowed to stand for stratification, and the obtained organic phase is distilled to obtain the δ-cyclopentanolactone. 850.3g of the prepared product can be collected, the conversion rate is 1104/1500=73.6%, the selectivity is 850.3/1061.55=80.1%, and the yield is 73.6%*80.1%=58.95%.

Comparative Example 2

The difference from Example 1 is that the flow rate of the second material is 5 g/min.

10 mg of the crude product was added to 100 mL of ethanol, and 4.01 mg of δ-cyclopentanolactone, 5.26 mg of 1,5-pentanediol, and 0.73 mg of by-products were obtained by liquid chromatography injection. The conversion rate was 4.93/10.19=48.4%, the selectivity was 4.01/4.74=84.6%, and the yield was 48.4%*84.6%=40.95%.

Comparative Example 3

The difference from Example 1 is that the flow rate of the second material is 35 g/min.

10 mg of the crude product was added to 100 mL of ethanol, and 5.82 mg of δ-cyclopentanolactone, 1.07 mg of 1,5-pentanediol, and 3.11 mg of by-products were obtained by liquid chromatography injection. The conversion rate was 9.29/10.36=89.7%, the selectivity was 5.82/8.93=65.2%, and the yield was 89.7%*65.2%=58.48%.

The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims (1)

1. A method for preparing δ-cyclopentanolactone, characterized in that it comprises the following steps: 1,5-pentanediol is used as the first material; a mixed solution of sodium hypochlorite, 2,2,6,6-tetramethylpiperidinyl oxide and water is used as the second material; The first material and the second material are reacted in a microchannel reaction device to obtain the delta-cyclopentanolactone; The mass ratio of sodium hypochlorite, 2,2,6,6-tetramethylpiperidinyl oxide and water in the second material is (2900-3750):(8-12):1500; The flow rate of the first material is 20g/min; The flow rate of the second material is 20g/min; The reaction temperature is 10°C and the pressure is 0.2MPa; The microchannel reaction equipment comprises a microchannel mixer and a microchannel reactor; the microchannel mixer is heart-shaped; The inner diameter of the microchannel of the microchannel reaction device is 0.015 mm.