Preparation method of 1-phenyl-2-pyrrolidone

Abstract

The invention belongs to the technical field of organic monomer synthesis, and relates to a preparation method of 1-phenyl-2-pyrrolidone. According to the method, gamma-butyrolactone and aniline are used as raw materials, deionized water is used as a reaction catalyst, the raw materials are conveyed into a pipeline through a metering pump and then uniformly mixed through a mixer, the mixture enters an oil bath temperature-controlled tubular reactor under the pressure condition for a reaction, after heat is removed through ice-water bath condensation, a product is collected at the tail end, and 1-phenyl-2-pyrrolidone is obtained. The adopted catalyst replaces a traditional acid catalyst, and the catalyst has high selectivity and is green and environment-friendly; the reaction is carried out under a low-pressure condition, so that the equipment cost and the safety risk are reduced. The preparation method is rapid and efficient, the reaction period is shortened, the technological operation is simple, and the process is convenient to regulate and control.

Description

Technical Field

[0001] The invention relates to a method for preparing 1-phenyl-2-pyrrolidone, and belongs to the technical field of organic monomer synthesis. Background Art

[0002] 1-Phenyl-2-pyrrolidone (NPP) is an important fine chemical and intermediate with a variety of applications, such as medicine, pesticides and other fields. As an intermediate in organic synthesis, NPP shows its important role in chemical synthesis. In terms of industrial applications, copolymers formed by NPP with butadiene and styrene are used as ink dispersants, fuel oil surface dispersants, and rubber modification additives. In addition, it can also be used as an adjuvant to improve the efficacy of pesticides and added to detergents as an emulsifier and fabric softener. At present, there are four main methods for preparing NPP, including N-alkylation reaction of halogenated benzene and pyrrolidone, direct alkylation of pyrrolidone and benzene, cyclization of aniline and monochlorobutyramide as raw materials, and ring-opening and then ring-closing reaction of γ-butyrolactone and aniline.

[0003] The N-alkylation reaction of halogenated benzene and pyrrolidone uses chlorobenzene as raw material. Although chlorobenzene has low cost, its yield is only 3% due to its low activity. Using bromobenzene and iodobenzene as raw materials, the yield is increased to 85%-98%, but the cost of bromine and iodine is high and the reaction time is long. The direct alkylation of pyrrolidone and benzene has a low yield of 16%. Aniline and monochlorobutyramide are used as raw materials to form a ring with a yield of 31%. Not only is the yield low, but the product separation is also difficult. γ-Butyrolactone and aniline are first ring-opened and then ring-closed. When phosphoric acid is used as a catalyst, the yield of synthesized NPP is 96.2%; diatomaceous earth is used as a carrier and impregnated in phosphotungstic acid to prepare a solid-supported heteropoly acid, and the yield is 96% when used as a catalyst; direct synthesis under a hydrogen atmosphere has a yield of 89%, and 1 molecule of 1-cyclohexyl-2-pyrrolidone is generated at the same time. Therefore, the reaction of γ-butyrolactone with aniline is the most meaningful for preparation.

[0004] Zhang Zhide et al. (Fine Chemicals, 2004, 21 (11): 869-871) used phosphoric acid as a catalyst to react γ-butyrolactone with aniline to synthesize NPP. The effects of raw material ratio, catalyst dosage, reaction time, reaction temperature and product separation and purification on the yield of NPP were studied. The reaction was carried out at 180-210℃ for 2h, and the product was separated and purified by vacuum distillation and recrystallization. The yield of NPP was 96.2% and the mass fraction was 99.5%. However, there were problems such as complex product purification operation, difficult catalyst recycling and long reaction time, which were not conducive to industrial production.

[0005] Zhang Lingyu et al. (Chemical Reagents, 2017, 39 (4): 427-430) used fixed bed technology to 2- / M x O yNPP was synthesized by the reaction of γ-butyrolactone and aniline using solid superacid as catalyst, and the effect of fixed bed process conditions on NPP conversion was studied. The experimental results showed that SO4 2- / M x O y The best experimental conditions for the fixed bed synthesis of NPP using solid superacid as catalyst are n (γ-butyrolactone): n (aniline) = 1.2:1, reaction temperature is 300℃, feed rate is 1.2mL / min, and the highest conversion rate of NPP is 98.7%. However, solid superacid catalysts are easily contaminated. Once contaminated, their catalytic activity will decrease rapidly, and it is difficult to regenerate after contamination; the preparation process of solid superacid catalysts is relatively complicated, the stability is relatively poor, and they are easy to lose activity under reaction conditions; in addition, the reaction temperature is high and the energy consumption is large.

[0006] Hu Shanling et al. (Chemical Technology, 2006, 14 (6): 9-12) used microwave radiation technology to prepare a solid heteropolyacid catalyst by impregnating diatomaceous earth as a carrier in phosphotungstic acid, and synthesized NPP with γ-butyrolactone and aniline as raw materials, and studied the effect of microwave process conditions on the reaction yield. When the phosphotungstic acid loading was 17.6%, the catalyst mass fraction was 1.5%, the microwave power was 325W, the irradiation time was 14min, and n (γ-butyrolactone): n (aniline) = 1.0: 1.25, under this condition, the NPP yield reached more than 96%. However, since the impregnation of phosphotungstic acid catalyst is mainly adsorption and solidification, the interaction between phosphotungstic acid and the carrier is weak, and it is easy to fall off during the reaction, resulting in the loss of active components of the catalyst and a short service life. Summary of the invention

[0007] In order to overcome the problems existing in the current 1-phenyl-2-pyrrolidone preparation process, the present invention provides a method for preparing 1-phenyl-2-pyrrolidone, specifically a new method for continuously synthesizing 1-phenyl-2-pyrrolidone through a tubular reactor. The catalyst used in the method is highly selective and green and environmentally friendly; the synthesis method is fast and efficient, shortening the reaction cycle; reducing the reaction temperature in the synthesis process; the operating pressure is low; and the process operation is simple, and the process is easy to control.

[0008] The specific scheme of the present invention is as follows: A method for preparing 1-phenyl-2-pyrrolidone comprises the following steps: γ-butyrolactone and aniline are used as raw materials, which are respectively transported into pipelines through metering pumps and then mixed through a "T"-type mixer; deionized water is used as a reaction catalyst, which is pumped into the mixer through a metering pump, and a one-way valve is introduced into each transport pipeline to prevent the solution from flowing back during the reaction; γ-butyrolactone, aniline and deionized water are evenly mixed in the mixer to obtain a mixed material; the back pressure valve is adjusted to apply back pressure to the entire reaction system, and the mixed material enters a reaction section of a tubular reactor controlled by an oil bath for full reaction, and the reaction product is condensed in an ice-water bath to remove heat and then collected at the tail end to obtain 1-phenyl-2-pyrrolidone.

[0009] Preferably, the molar ratio of γ-butyrolactone to aniline is 1:0.8-1.2.

[0010] Preferably, the feed amount of deionized water as a catalyst is 0.3-0.4 mL / min; the feed amount of γ-butyrolactone is 0.46-0.77 mL / min; and the feed amount of aniline is 0.54-0.88 mL / min.

[0011] Preferably, the reaction temperature of the mixed material in the tubular reactor is 240-260° C., and the reaction time is 40-60 min.

[0012] Preferably, the back pressure valve is adjusted to keep the system pressure at 2-3 MPa.

[0013] Preferably, the tubular reactor is a serpentine tubular reactor, the inner diameter of the serpentine tube is 0.2-0.4 cm, and the tube length is 4-6 m.

[0014] Preferably, the inlet end of the tubular reactor is connected to the mixer through a stainless steel pipe, and the outlet end is connected to the condensation tank through a stainless steel pipe.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses a serpentine tubular reactor. When the reaction system is stabilized at a certain pressure, γ-butyrolactone and aniline are catalyzed by deionized water to continuously synthesize 1-phenyl-2-pyrrolidone, thereby replacing the traditional acid catalyst, reducing the catalyst preparation cost, and generating no catalyst solid waste, which is more environmentally friendly.

[0016] (2) The present invention reduces the reaction temperature to 240°C, shortens the reaction time to 40 min, and reduces the total energy consumption of the reaction.

[0017] (3) The present invention utilizes a tubular reactor to carry out the reaction under 2 MPa. The low pressure is beneficial to reducing equipment costs and safety risks.

[0018] (4) During the experiment of the present invention, the raw material metering pump can be adjusted at any time, which is convenient for adjusting the feed flow rate and easy to operate; two mixers are used to make the materials mixed more evenly and in more sufficient contact with each other.

[0019] (5) The present invention adopts a serpentine tubular reactor. The spiral pipeline increases the heating area of ​​the material in the reaction zone, so that the material can fully react at the reaction temperature. The synthesis reaction time is less than 60 minutes, and the product yield reaches more than 96%, thereby improving the reaction efficiency and the utilization rate of raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The process flow chart of continuous synthesis of 1-phenyl-2-pyrrolidone is shown in FIG. 1-aniline metering pump, 2-γ-butyrolactone metering pump, 3-deionized water metering pump, 4-check valve, 5-T-type mixer, 6-mixer, 7-tubular reactor, 8-condensation tank, 9-back pressure valve, 10-sample bottle. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below by means of reaction examples. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0022] Embodiment 1: A method for preparing 1-phenyl-2-pyrrolidone, the process flow of which is as follows Figure 1 As shown: γ-butyrolactone and aniline are used as raw materials, the feed molar ratio is 1:0.8, the flow rate of the γ-butyrolactone metering pump is set to 0.77mL / min, and the flow rate of the aniline metering pump is set to 0.73mL / min. The two materials are fed into the feed pump pipeline, sent to the T-type mixer through a one-way valve, and then enter the mixer; deionized water is used as a reaction catalyst and pumped into the mixer at a flow rate of 0.3mL / min through a metering pump, so that each reaction material is fully mixed in the mixer to obtain a mixed material. The back pressure valve is adjusted to stabilize the pressure of the reaction system at 2MPa, and the mixed material enters the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor is a serpentine tubular reactor with an inner diameter of 0.4cm and a tube length of 5m. The reaction temperature is 250℃, and the reaction time of the material is 40min. The reacted material enters the condensation tank, and is collected in a sample bottle at the outlet of the reaction system after removing heat through ice water bath condensation to obtain 1-phenyl-2-pyrrolidone.

[0023] After the sample was treated, the yield of NPP was analyzed by gas chromatography area normalization method and found to be 96.1%.

[0024] Embodiment 2: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline were used as raw materials, and the feed molar ratio was 1:1. The flow rate of the γ-butyrolactone metering pump was set to 0.69 mL / min, and the flow rate of the aniline metering pump was set to 0.81 mL / min. The two materials were fed into the feed pump pipeline, sent to the T-type mixer through a one-way valve, and then entered the mixer; deionized water was pumped into the mixer at a flow rate of 0.3 mL / min through a metering pump as a reaction catalyst, so that each reaction material was fully mixed in the mixer to obtain a mixed material. The back pressure valve was adjusted to stabilize the pressure of the reaction system at 2 MPa, and the mixed material entered the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor was a serpentine tubular reactor with an inner diameter of 0.4 cm and a tube length of 5 m. The reaction temperature was 250 ° C, and the reaction time of the material was 40 min. The reacted material entered the condensation tank, and after removing the heat through ice water bath condensation, it was collected in a sample bottle at the outlet of the reaction system to obtain 1-phenyl-2-pyrrolidone.

[0025] After the sample was treated, the yield of NPP was analyzed by gas chromatography area normalization method and found to be 97.9%.

[0026] Embodiment 3: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline are used as raw materials, the feed molar ratio is 1:1.2, the flow rate of the γ-butyrolactone metering pump is set to 0.62mL / min, and the flow rate of the aniline metering pump is set to 0.88mL / min. The two materials are fed into the feed pump pipeline, sent to the T-type mixer through a one-way valve, and then enter the mixer; deionized water is used as a reaction catalyst and pumped into the mixer at a flow rate of 0.3mL / min through a metering pump, so that each reaction material is fully mixed in the mixer to obtain a mixed material. The back pressure valve is adjusted to stabilize the pressure of the reaction system at 2MPa, and the mixed material enters the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor is a serpentine tubular reactor with an inner diameter of 0.4cm and a length of 5m. The reaction temperature is 250℃, and the reaction time of the material is 40min. The reacted material enters the condensation tank, and after removing heat through ice water bath condensation, it is collected in a sample bottle at the outlet of the reaction system to obtain 1-phenyl-2-pyrrolidone.

[0027] After the sample was treated, the yield of NPP was analyzed by gas chromatography area normalization method and found to be 96.8%.

[0028] Embodiment 4: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline are used as raw materials, the feed molar ratio is 1:1, the flow rate of the γ-butyrolactone metering pump is set to 0.46mL / min, and the flow rate of the aniline metering pump is set to 0.54mL / min. The two materials are fed into the feed pump pipeline, sent to the T-type mixer through a one-way valve, and then enter the mixer; deionized water is used as a reaction catalyst and pumped into the mixer at a flow rate of 0.3mL / min through a metering pump, so that each reaction material is fully mixed in the mixer to obtain a mixed material. The back pressure valve is adjusted to stabilize the pressure of the reaction system at 2MPa, and the mixed material enters the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor is a serpentine tubular reactor with an inner diameter of 0.4cm and a length of 5m. The reaction temperature is 250℃, and the reaction time of the material is 60min. The reacted material enters the condensation tank, and is collected in a sample bottle at the outlet of the reaction system after removing heat through ice water bath condensation to obtain 1-phenyl-2-pyrrolidone.

[0029] After the sample was treated, the yield of NPP was analyzed by gas chromatography area normalization method and found to be 98.1%.

[0030] Embodiment 5: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline are used as raw materials, the feed molar ratio is 1:1, the flow rate of the γ-butyrolactone metering pump is set to 0.69mL / min, and the flow rate of the aniline metering pump is set to 0.81mL / min. The two materials are fed into the feed pump pipeline, sent to the T-type mixer through a one-way valve, and then enter the mixer; deionized water is used as a reaction catalyst and pumped into the mixer through a metering pump at a flow rate of 0.4mL / min, so that each reaction material is fully mixed in the mixer to obtain a mixed material. The back pressure valve is adjusted to stabilize the pressure of the reaction system at 2MPa, and the mixed material enters the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor is a serpentine tubular reactor with an inner diameter of 0.4cm and a tube length of 5m. The reaction temperature is 250℃, and the reaction time of the material is 40min. The reacted material enters the condensation tank, and is collected in a sample bottle at the outlet of the reaction system after removing heat through ice water bath condensation to obtain 1-phenyl-2-pyrrolidone.

[0031] After the sample was treated, the yield of NPP was analyzed by gas chromatography area normalization method and found to be 96.1%.

[0032] Embodiment 6: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline are used as raw materials, the feed molar ratio is 1:1, the flow rate of the γ-butyrolactone metering pump is set to 0.69mL / min, and the flow rate of the aniline metering pump is set to 0.81mL / min. The two materials are fed into the feed pump pipeline, sent to the T-type mixer through a one-way valve, and then enter the mixer; deionized water is used as a reaction catalyst and pumped into the mixer through a metering pump at a flow rate of 0.3mL / min, so that each reaction material is fully mixed in the mixer to obtain a mixed material. The back pressure valve is adjusted to stabilize the pressure of the reaction system at 2MPa, and the mixed material enters the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor is a serpentine tubular reactor with an inner diameter of 0.4cm and a tube length of 5m. The reaction temperature is 260℃, and the reaction time of the material is 40min. The reacted material enters the condensation tank, and is collected in a sample bottle at the outlet of the reaction system after removing heat through ice water bath condensation to obtain 1-phenyl-2-pyrrolidone.

[0033] After the sample was treated, the yield of NPP was analyzed by gas chromatography area normalization method and found to be 96.9%.

[0034] Embodiment 7: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline are used as raw materials, the feed molar ratio is 1:1, the flow rate of the γ-butyrolactone metering pump is set to 0.69mL / min, and the flow rate of the aniline metering pump is set to 0.81mL / min. The two materials are fed into the feed pump pipeline, sent to the T-type mixer through a one-way valve, and then enter the mixer; deionized water is used as a reaction catalyst and pumped into the mixer through a metering pump at a flow rate of 0.3mL / min, so that each reaction material is fully mixed in the mixer to obtain a mixed material. The back pressure valve is adjusted to stabilize the pressure of the reaction system at 2MPa, and the mixed material enters the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor is a serpentine tubular reactor with an inner diameter of 0.4cm and a tube length of 5m. The reaction temperature is 240℃, and the reaction time of the material is 40min. The reacted material enters the condensation tank, and after removing heat through ice water bath condensation, it is collected in a sample bottle at the outlet of the reaction system to obtain 1-phenyl-2-pyrrolidone.

[0035] After the sample was treated, the yield of NPP was analyzed by gas chromatography area normalization method and was found to be 97.0%.

[0036] Embodiment 8: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline are used as raw materials, the feed molar ratio is 1:1, the flow rate of the γ-butyrolactone metering pump is set to 0.69mL / min, and the flow rate of the aniline metering pump is set to 0.81mL / min. The two materials are fed into the feed pump pipeline, sent to the T-type mixer through a one-way valve, and then enter the mixer; deionized water is used as a reaction catalyst and pumped into the mixer at a flow rate of 0.3mL / min through a metering pump, so that each reaction material is fully mixed in the mixer to obtain a mixed material. The back pressure valve is adjusted to stabilize the pressure of the reaction system at 3MPa, and the mixed material enters the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor is a serpentine tubular reactor with an inner diameter of 0.4cm and a tube length of 5m. The reaction temperature is 250℃, and the reaction time of the material is 40min. The reacted material enters the condensation tank, and is collected in a sample bottle at the outlet of the reaction system after removing heat through ice water bath condensation to obtain 1-phenyl-2-pyrrolidone.

[0037] After the sample was treated, the yield of NPP was analyzed by gas chromatography area normalization method and was found to be 97.3%.

[0038] Comparative Example 1: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline are used as raw materials, the feed molar ratio is 1:1, the flow rate of the γ-butyrolactone metering pump is set to 0.69mL / min, and the flow rate of the aniline metering pump is set to 0.81mL / min. The two materials are fed into the pipeline through the feed pump, sent to the T-type mixer through a one-way valve, and then enter the mixer; no deionized water is added during the process. The back pressure valve is adjusted to make the reaction system pressure-free, and the mixed material enters the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor is a serpentine tubular reactor with an inner diameter of 0.4cm and a tube length of 5m. The reaction temperature is 250℃, and the reaction time of the material is 40min. The reacted material enters the condensation tank, and after removing the heat through ice-water bath condensation, it is collected in a sample bottle at the outlet of the reaction system to obtain 1-phenyl-2-pyrrolidone.

[0039] After the sample was treated, the yield of NPP was analyzed by gas chromatography area normalization method and was found to be 49.8%.

[0040] Comparative Example 2: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline are used as raw materials, the feed molar ratio is 1:1, the flow rate of the γ-butyrolactone metering pump is set to 0.69mL / min, and the flow rate of the aniline metering pump is set to 0.81mL / min. The two materials are fed into the feed pump pipeline, sent to the T-type mixer through a one-way valve, and then enter the mixer; deionized water is used as a reaction catalyst and pumped into the mixer through a metering pump at a flow rate of 0.3mL / min, so that each reaction material is fully mixed in the mixer to obtain a mixed material. The back pressure valve is adjusted to make the reaction system pressure-free, and the mixed material enters the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor is a serpentine tubular reactor with an inner diameter of 0.4cm and a tube length of 5m. The reaction temperature is 250℃, and the reaction time of the material is 40min. The reacted material enters the condensation tank, and is collected in a sample bottle at the outlet of the reaction system after removing heat through ice water bath condensation to obtain 1-phenyl-2-pyrrolidone.

[0041] After the sample was treated, the yield of NPP was 56.2% analyzed by gas chromatography area normalization method.

[0042] Comparative Example 3: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline are used as raw materials, the feed molar ratio is 1:1, the flow rate of the γ-butyrolactone metering pump is set to 0.69mL / min, and the flow rate of the aniline metering pump is set to 0.81mL / min. The two materials are fed into the pipeline through the feed pump, sent to the T-type mixer through a one-way valve, and then enter the mixer; no deionized water is added during the process. The back pressure valve is adjusted to stabilize the pressure of the reaction system at 2MPa, and the mixed material enters the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor is a serpentine tubular reactor with an inner diameter of 0.4cm and a tube length of 5m. The reaction temperature is 250℃, and the reaction time of the material is 40min. The reacted material enters the condensation tank, and is collected in a sample bottle at the outlet of the reaction system after removing heat through ice-water bath condensation to obtain 1-phenyl-2-pyrrolidone.

[0043] After the sample was treated, the yield of NPP was analyzed by gas chromatography area normalization method and found to be 80.2%.

[0044] Comparative Example 4: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline are used as raw materials, the feed molar ratio is 1:1, the flow rate of the γ-butyrolactone metering pump is set to 0.69mL / min, and the flow rate of the aniline metering pump is set to 0.81mL / min. The two materials are fed into the feed pump pipeline, sent to the T-type mixer through a one-way valve, and then enter the mixer; deionized water is used as a reaction catalyst and pumped into the mixer through a metering pump at a flow rate of 0.2mL / min, so that each reaction material is fully mixed in the mixer to obtain a mixed material. The back pressure valve is adjusted to stabilize the pressure of the reaction system at 2MPa, and the mixed material enters the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor is a serpentine tubular reactor with an inner diameter of 0.4cm and a tube length of 5m. The reaction temperature is 250℃, and the reaction time of the material is 40min. The reacted material enters the condensation tank, and is collected in a sample bottle at the outlet of the reaction system after removing heat through ice water bath condensation to obtain 1-phenyl-2-pyrrolidone.

[0045] After the sample was treated, the yield of NPP was analyzed by gas chromatography area normalization method and it was found to be 94.6%.

[0046] Comparative Example 5: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline are used as raw materials, the feed molar ratio is 1:1, the flow rate of the γ-butyrolactone metering pump is set to 0.69mL / min, and the flow rate of the aniline metering pump is set to 0.81mL / min. The two materials are fed into the feed pump pipeline, sent to the T-type mixer through a one-way valve, and then enter the mixer; deionized water is used as a reaction catalyst and pumped into the mixer through a metering pump at a flow rate of 0.3mL / min, so that each reaction material is fully mixed in the mixer to obtain a mixed material. The back pressure valve is adjusted to stabilize the pressure of the reaction system at 2MPa, and the mixed material enters the reaction section of the tubular reactor controlled by oil bath temperature. The tubular reactor is a serpentine tubular reactor with an inner diameter of 0.4cm and a tube length of 5m. The reaction temperature is 230℃, and the reaction time of the material is 40min. The reacted material enters the condensation tank, and is collected in a sample bottle at the outlet of the reaction system after removing heat through ice water bath condensation to obtain 1-phenyl-2-pyrrolidone.

[0047] After the sample was treated, the yield of NPP was analyzed by gas chromatography area normalization method and found to be 82.8%.

[0048] Comparative Example 6: A kind of preparation method of 1-phenyl-2-pyrrolidone γ-butyrolactone and aniline were used as raw materials, with a feed molar ratio of 1:1. The flow rate of the γ-butyrolactone metering pump was set to 0.69 mL / min, and the flow rate of the aniline metering pump was set to 0.81 mL / min. The two materials were fed into the feed pump pipeline, sent to the T-type mixer through a one-way valve, and then entered the mixer; deionized water was pumped into the mixer at a flow rate of 0.3 mL / min through a metering pump as a reaction catalyst, so that each reaction material was fully mixed in the mixer to obtain a mixed material. The back pressure valve was adjusted to stabilize the pressure of the reaction system at 2 MPa, and the mixed material entered the reaction section of a traditional straight tube reactor. The reaction temperature was 250 ° C, and the reaction time of the material was 40 min. The reacted material entered the condensation tank, and after removing the heat through ice water bath condensation, it was collected in a sample bottle at the outlet of the reaction system to obtain 1-phenyl-2-pyrrolidone.

[0049] After the sample was treated, the yield of NPP was 75.3% by gas chromatography area normalization method.

[0050] The results of the above specific examples are shown in Table 1. Combined with the examples, it can be seen that different molar ratios of γ-butyrolactone and aniline will affect the yield of NPP in the continuous synthesis reaction.

[0051] Table 1 Yield and selectivity of each embodiment and comparative example

[0052] Compared with Comparative Example 1 and Comparative Example 3, by adjusting the back pressure valve to make the reaction system higher than a certain pressure, the material conversion rate and selectivity can be effectively improved. Compared with Comparative Example 4, increasing the reaction temperature and extending the reaction time are conducive to the reaction. When the reaction temperature is 250°C and the reaction time is 40-60min, the NPP yield can be above 96%. Compared with Comparative Example 5, the serpentine tubular reactor increases the heating area and reaction time of the material in the reaction zone, which is more conducive to the reaction.

[0053] γ-Butyrolactone and aniline are mixed and reacted under certain temperature and pressure conditions to obtain 1-phenyl-2-pyrrolidone. From the perspective of chemical equilibrium, removing the water generated in the reaction is beneficial to the reaction. Examples 1 and 5 and Comparative Examples 3 and 4 show that the presence of water is beneficial to the system proceeding in the positive direction of the reaction. Moreover, as the amount of water increases, the yield of the reactant gradually increases, but when it exceeds a certain amount, the conversion rate and selectivity of the reaction are reduced.

[0054] An analysis of the experimental process of this study shows that the amino group of aniline acts as a nucleophile to attack the carbonyl carbon of γ-butyrolactone to form a tetrahedral intermediate. This step is the key to the reaction and must be supported by a large energy barrier △E value. A catalyst is needed to reduce this activation energy. Adding an appropriate amount of water to the reaction can play a catalytic role. It can be analyzed from a kinetic point of view, that is, the catalytic effect of water can effectively reduce the activation energy barrier and effectively inhibit the formation of by-products. However, if the amount of water is too large during the reaction, it will affect the chemical equilibrium and the expected effect cannot be achieved. Therefore, if you want to increase the yield of 1-phenyl-2-pyrrolidone products, you must focus on controlling the amount of water. It catalyzes the reaction by reducing the E value and increases the reaction rate from a kinetic point of view.

Claims

1. A method for preparing 1-phenyl-2-pyrrolidone, characterized in that: The preparation method comprises the following steps: γ-butyrolactone and aniline are used as raw materials, which are respectively transported into pipelines through metering pumps and then mixed through a "T"-type mixer; deionized water is used as a reaction catalyst, which is pumped into the mixer through a metering pump, and a one-way valve is introduced into each transport pipeline; γ-butyrolactone, aniline and deionized water are evenly mixed in the mixer to obtain a mixed material; the back pressure valve is adjusted to apply back pressure to the entire reaction system, and the mixed material enters a reaction section of a tubular reactor controlled by an oil bath for full reaction, and the reaction product is condensed in an ice-water bath to remove heat and then collected at the tail end to obtain 1-phenyl-2-pyrrolidone.

2. The preparation method according to claim 1, characterized in that: The molar ratio of the gamma-butyrolactone to the aniline is 1:0.8-1.

2.

3. The preparation method according to claim 1, characterized in that The feed amount of the γ-butyrolactone is 0.46-0.77 mL / min; the feed amount of the aniline is 0.54-0.88 mL / min.

4. The preparation method according to claim 1, characterized in that The feed amount of deionized water as catalyst is 0.3-0.4 mL / min.

5. The preparation method according to claim 1, characterized in that The reaction temperature of the mixed material in the tubular reactor is 240-260° C., and the reaction time is 40-60 min.

6. The preparation method according to claim 1, characterized in that The back pressure of the regulating back pressure valve on the entire reaction system is 2-3 MPa.

7. The preparation method according to claim 1, characterized in that The tubular reactor is a serpentine tubular reactor, the inner diameter of the serpentine tube is 0.2-0.4 cm, and the tube length is 4-6 m.

8. The preparation method according to claim 1, characterized in that: The inlet end of the tubular reactor is connected to the mixer through a stainless steel pipe, and the outlet end is connected to the condensation tank through a stainless steel pipe.

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