Desolventizing process for production of ethyl chrysanthemate

Abstract

The invention discloses a desolventizing process for producing ethyl chrysantheate, which comprises the following steps: S1, stirring and desolventizing: opening a cyclizing liquid feeding valve and a vacuum tube valve of an efficient desolventizing tower, pumping a certain amount of cyclizing liquid into the efficient desolventizing tower in vacuum, closing the cyclizing liquid feeding valve and the vacuum tube valve, opening a manual emptying tube emptying valve to enable the interior of the efficient desolventizing tower to return to normal pressure, and then adding a catalyst into the efficient desolventizing tower; opening a gas phase feeding valve, a reflux valve and a circulating water inlet and outlet valve of the condenser of the efficient desolventizing tower; by adopting the three-stage desolventizing system, the removal of the 2, 5-dimethyl-2, 4-hexadiene can be divided into three stages for desolventizing, so that the 2, 5-dimethyl-2, 4-hexadiene with higher purity is separated from the cyclization liquid to the greatest extent, the recovered purity of the solvent and the 2, 5-dimethyl-2, 4-hexadiene is higher, the utilization rate of the raw material is improved, the 2, 5-dimethyl-2, 4-hexadiene is promoted to be recycled, and the yield of the 2, 5-dimethyl-2, 4-hexadiene is increased. The 2, 5-dimethyl-2, 4-hexadiene is low in impurity content, high in quality and capable of being directly recycled, and compared with conventional desolvation, the yield of the ethyl chrysanthemumate can be greatly increased.

Description

Technical Field

[0001] The invention relates to the technical field of chemical processes, in particular to a desolventizing process for producing ethyl chrysanthemate. Background Art

[0002] Chrysanthemic acid ethyl ester, like pyrethrin methyl ester, is also an important intermediate of pyrethroids. It can be used to prepare a variety of hygienic pyrethroids including allethrin, tetramethrin, phenothrin, propylthrin and other insecticides. The reaction of ethyl diazoacetate and 2,5-dimethyl-2,4-hexadiene is one of the most important and industrially valuable synthetic routes.

[0003] In the desolventizing process, the boiling points of 2,5-dimethyl-2,4-hexadiene vary greatly, and when toluene is recovered and desolventized, the temperature in the tower is difficult to control, which leads to a decrease in the desolventizing rate of 2,5-dimethyl-2,4-hexadiene, thereby reducing the recovery purity and resulting in the problem of low chemical yield. Summary of the invention

[0004] The object of the present invention is to provide a desolventizing process for producing ethyl chrysanthemate to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a desolventizing process for producing ethyl chrysanthemate, comprising the following steps:

[0006] S1: Stirring and desolventizing:

[0007] (1) Opening the cyclization liquid feed valve and the high-efficiency desolventizing tower vacuum pipe valve to vacuum-draw a certain amount of cyclization liquid into the high-efficiency desolventizing tower, then closing the cyclization liquid feed valve and the vacuum pipe valve, opening the manual vent pipe vent valve to return the high-efficiency desolventizing tower to normal pressure, and then opening the high-efficiency desolventizing tower condenser gas phase feed valve, reflux valve and circulating water inlet and outlet valves;

[0008] (2) Turn on the agitator of the high-efficiency desolventizing tower, the jacketed steam feed pipe, and the condensate discharge pipe, and start heating and reflux;

[0009] S2: Heating and reflux:

[0010] After reflux for 30 minutes, open the toluene feed valve of the toluene receiving tank and the upper vacuum valve for vacuum distillation, observe the temperature trend balance, adjust the reflux ratio, keep the top temperature below 90°C, and allow toluene to evaporate continuously;

[0011] S3: Stage Escape

[0012] When toluene is recovered to 80%, the toluene feed valve of the toluene receiving tank and its upper vacuum valve are closed to stop receiving toluene, and the 2,5-dimethyl-2,4-hexadiene feed valve of the 2,5-dimethyl-2,4-hexadiene receiving tank is opened to start removing 2,5-dimethyl-2,4-hexadiene. The removal process of 2,5-dimethyl-2,4-hexadiene is divided into three stages:

[0013] (1) The first stage is the removal stage of the first 2,5-dimethyl-2,4-hexadiene, which is atmospheric distillation, and the tower top temperature in this stage is 60-135°C;

[0014] (2) The second stage is the removal stage of 2,5-dimethyl-2,4-hexadiene, which is atmospheric distillation, and the tower top temperature in this stage is 135-138°C;

[0015] (3) The third stage is the stage of vacuum removal of 2,5-dimethyl-2,4-hexadiene. The pressure in the tower is vacuum degree ≥ 0.07Mpa and the temperature is 115-120°C.

[0016] S4: Cooling and discharging:

[0017] After the removal of 2,5-dimethyl-2,4-hexadiene is completed, the steam feed valve, condensate discharge valve and vacuum valve of the 2,5-dimethyl-2,4-hexadiene receiving tank of the high-efficiency desolventizing tower are closed, and the circulating water of the jacket of the high-efficiency desolventizing tower is opened to start cooling. When the material temperature in the high-efficiency desolventizing tower drops to 50-70°C, the lower discharge valve of the high-efficiency desolventizing tower is opened to start barreling and weighing to obtain crude chrysanthemum acid ethyl ester.

[0018] Preferably, the removal of 2,5-dimethyl-2,4-hexadiene is mainly divided into three stages, wherein the first and second stages are the atmospheric distillation removal stages of 2,5-dimethyl-2,4-hexadiene, and the third stage is the vacuum removal stage of 2,5-dimethyl-2,4-hexadiene.

[0019] Preferably, a discharge valve and a discharge pipe are provided at the bottom of the high-efficiency desolventizing tower, and the crude ethyl chrysanthemate is discharged through the discharge pipe for weighing.

[0020] Preferably, the top temperature of the high-efficiency desolventizing tower is controlled below 90° C., and when the toluene is continuously evaporated and the toluene is recovered to 80%, the receiving of toluene is stopped.

[0021] Preferably, after the agitator of the high-efficiency desolventizing tower, the jacket steam feed pipe and the condensed water discharge pipe are opened, the cyclization liquid is allowed to start heating and reflux.

[0022] Preferably, the high-efficiency desolventizing tower is cooled by circulating water in the jacket to reduce the material temperature in the tower body to 50-70°C.

[0023] The desolventizing process for producing ethyl chrysanthemate proposed by the present invention has at least the following beneficial effects:

[0024] By adopting a three-stage desolventizing system, the removal of 2,5-dimethyl-2,4-hexadiene can be divided into three stages for desolventizing, so as to separate it from the cyclization liquid to the greatest extent and obtain 2,5-dimethyl-2,4-hexadiene with higher purity, so that the purity of the recovered solvent and 2,5-dimethyl-2,4-hexadiene is higher, the utilization rate of raw materials is improved, and the impurity content of 2,5-dimethyl-2,4-hexadiene is low, the quality is high, and it can be directly reused. Compared with conventional desolventizing, the yield of chrysanthemic acid ethyl ester can be greatly improved. DETAILED DESCRIPTION

[0025] The following will be combined with the description of the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The embodiment provided by the present invention: a desolventizing process for producing ethyl chrysanthemate, comprising the following steps:

[0027] S1: Stirring and desolventizing:

[0028] 1. Open the cyclization liquid feed valve and the high-efficiency desolventizing tower vacuum pipe valve to vacuum-draw a certain amount of cyclization liquid into the high-efficiency desolventizing tower, then close the cyclization liquid feed valve and the vacuum pipe valve, open the manual vent pipe vent valve to return the high-efficiency desolventizing tower to normal pressure, and then open the high-efficiency desolventizing tower condenser gas phase feed valve, reflux valve and circulating water inlet and outlet valves;

[0029] 2. Turn on the agitator of the high-efficiency desolventizing tower, the jacketed steam feed pipe and the condensed water discharge pipe, and start heating and reflux;

[0030] S2: Heating and reflux:

[0031] After reflux for 30 minutes, open the toluene feed valve of the toluene receiving tank and the upper vacuum valve for vacuum distillation, observe the temperature trend balance, adjust the reflux ratio, keep the top temperature below 90°C, and allow toluene to evaporate continuously;

[0032] S3: Stage Escape

[0033] When toluene is recovered to 80%, the toluene feed valve of the toluene receiving tank and its upper vacuum valve are closed to stop receiving toluene, and the 2,5-dimethyl-2,4-hexadiene feed valve of the 2,5-dimethyl-2,4-hexadiene receiving tank is opened to start removing 2,5-dimethyl-2,4-hexadiene. The removal process of 2,5-dimethyl-2,4-hexadiene is divided into three stages:

[0034] 1. The first stage is the removal stage of the first 2,5-dimethyl-2,4-hexadiene. This stage is atmospheric distillation, and the tower top temperature in this stage is 60-135°C;

[0035] 2. The second stage is the removal stage of 2,5-dimethyl-2,4-hexadiene, which is atmospheric distillation, and the tower top temperature is 135-138°C;

[0036] 3. The third stage is the stage of vacuum removal of 2,5-dimethyl-2,4-hexadiene. The pressure in the tower is vacuum degree ≥ 0.07Mpa and the temperature is 115-120℃.

[0037] S4: Cooling and discharging:

[0038] After the removal of 2,5-dimethyl-2,4-hexadiene is completed, the steam feed valve, condensate discharge valve and vacuum valve of the 2,5-dimethyl-2,4-hexadiene receiving tank of the high-efficiency desolventizing tower are closed, and the circulating water of the jacket of the high-efficiency desolventizing tower is opened to start cooling. When the material temperature in the high-efficiency desolventizing tower drops to 50-70°C, the lower discharge valve of the high-efficiency desolventizing tower is opened to start barreling and weighing to obtain crude chrysanthemum acid ethyl ester.

[0039] Furthermore, the removal of 2,5-dimethyl-2,4-hexadiene is mainly divided into three stages, wherein the first and second stages are the atmospheric distillation removal stages of 2,5-dimethyl-2,4-hexadiene, and the third stage is the vacuum removal stage of 2,5-dimethyl-2,4-hexadiene.

[0040] Furthermore, a discharge valve and a discharge pipe are provided at the bottom of the high-efficiency desolventizing tower, and the crude chrysanthemic acid ethyl ester is discharged through the discharge pipe for weighing.

[0041] Furthermore, the top temperature of the high-efficiency desolventizing tower is controlled below 90° C., and when toluene is continuously evaporated and toluene is recovered to 80%, the receiving of toluene is stopped.

[0042] Furthermore, after the agitator of the high-efficiency desolventizing tower and the jacketed steam feed pipe and the condensed water discharge pipe are opened, the cyclization liquid begins to heat up and reflux.

[0043] Furthermore, the high-efficiency desolventizing tower is cooled by circulating water in the jacket to reduce the material temperature in the tower body to 50-70°C.

[0044] Example 1, when the crude chrysanthemic acid ethyl ester begins to be barreled and weighed through the discharge valve, the crude chrysanthemic acid ethyl ester weighing a specified weight is vacuum-drawn into the still pot through the feed valve and the still pot vacuum pipe valve, and after the crude chrysanthemic acid ethyl ester is drawn in, the crude chrysanthemic acid ethyl ester feed valve and the vacuum pipe valve are closed, and the manual vent pipe vent valve is opened to return the still pot to normal pressure:

[0045] In Example 2, the desolventizing structure with staged desolventizing is used to promote the use of atmospheric distillation in both the first and second stages, and the tower top temperatures in different stages are controlled respectively. In the third stage, the high vacuum system is opened by opening the gas phase feed valve, liquid phase discharge valve, circulating water inlet and outlet valves, fore fraction receiving tank feed valve and upper vacuum valve of the still condenser. In this state, the pressure in the still is maintained at a vacuum degree of ≥0.08MPa and a temperature of 115-120°C, thereby utilizing a three-stage continuous system to carry out comprehensive desolventizing of 2,5-dimethyl-2,4-hexadiene.

[0046] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

[0047] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. indicate positions or positional relationships based on the positions or positional relationships shown, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0048] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms connected and connected should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. A desolventizing process for producing ethyl chrysanthemate, characterized in that: The following steps are involved: S1: Stirring and desolventizing: (1) Open the cyclization liquid feed valve and the high-efficiency desolventizing tower vacuum pipe valve to vacuum-draw a certain amount of cyclization liquid into the high-efficiency desolventizing tower, then close the cyclization liquid feed valve and the vacuum pipe valve, open the manual vent pipe vent valve to return the high-efficiency desolventizing tower to normal pressure, and then open the high-efficiency desolventizing tower condenser gas phase feed valve, reflux valve and circulating water inlet and outlet valves; (2) Turn on the agitator of the high-efficiency desolventizing tower, the jacketed steam feed pipe, and the condensate discharge pipe, and start heating and reflux; S2: Heating and reflux: After reflux for 30 minutes, open the toluene feed valve of the toluene receiving tank and the upper vacuum valve for vacuum distillation, observe the temperature trend balance, adjust the reflux ratio, keep the top temperature below 90°C, and allow toluene to evaporate continuously; S3: Stage Escape When toluene is recovered to 80%, the toluene feed valve of the toluene receiving tank and its upper vacuum valve are closed to stop receiving toluene, and the 2,5-dimethyl-2,4-hexadiene feed valve of the 2,5-dimethyl-2,4-hexadiene receiving tank is opened to start removing 2,5-dimethyl-2,4-hexadiene. The removal process of 2,5-dimethyl-2,4-hexadiene is divided into three stages: (1) The first stage is the removal stage of the first 2,5-dimethyl-2,4-hexadiene, which is atmospheric distillation and the tower top temperature is 60-135°C; (2) The second stage is the removal stage of 2,5-dimethyl-2,4-hexadiene, which is atmospheric distillation, and the tower top temperature in this stage is 135-138°C; (3) The third stage is the stage of vacuum removal of 2,5-dimethyl-2,4-hexadiene. The pressure in the tower is vacuum degree ≥ 0.07Mpa and the temperature is 115-120°C. S4: Cooling and discharging: After the removal of 2,5-dimethyl-2,4-hexadiene is completed, the steam feed valve, condensate discharge valve and vacuum valve of the 2,5-dimethyl-2,4-hexadiene receiving tank of the high-efficiency desolventizing tower are closed, and the circulating water of the jacket of the high-efficiency desolventizing tower is opened to start cooling. When the material temperature in the high-efficiency desolventizing tower drops to 50-70°C, the lower discharge valve of the high-efficiency desolventizing tower is opened to start barreling and weighing to obtain crude chrysanthemum acid ethyl ester.

2. The desolventizing process for producing ethyl chrysanthemate according to claim 1, characterized in that: The removal of 2,5-dimethyl-2,4-hexadiene is mainly divided into three stages, wherein the first and second stages are the atmospheric distillation removal stages of 2,5-dimethyl-2,4-hexadiene, and the third stage is the vacuum removal stage of 2,5-dimethyl-2,4-hexadiene.

3. The desolventizing process for producing ethyl chrysanthemate according to claim 1, characterized in that: A discharge valve and a discharge pipe are arranged at the bottom of the high-efficiency desolventizing tower, and the crude chrysanthemic acid ethyl ester is discharged through the discharge pipe for weighing.

4. The desolventizing process for producing ethyl chrysanthemate according to claim 1, characterized in that: The top temperature of the high-efficiency desolventizing tower is controlled below 90° C. When the toluene is continuously evaporated and the toluene is recovered to 80%, the receiving of toluene is stopped.

5. The desolventizing process for producing ethyl chrysanthemate according to claim 1, characterized in that: After the agitator of the high-efficiency desolventizing tower, the jacket steam feed pipe and the condensed water discharge pipe are opened, the cyclized liquid begins to heat up and reflux.

6. The desolventizing process for producing ethyl chrysanthemate according to claim 1, characterized in that: The high-efficiency desolventizing tower is cooled by circulating water in the jacket to reduce the material temperature in the tower body to 50-70°C.