Dizotization process for producing ethyl chrysanthemate

Abstract

The invention discloses a diazotization process for producing ethyl chrysantheate, which is characterized in that the reaction ratio of glycine ethyl ester hydrochloride, water, sodium nitrite, water, glacial acetic acid and toluene is (480 + 660) kg: (262.5 + 660) kg: 36.8 kg: 800L, and comprises the following steps: S1, sequentially adding materials: sequentially adding tap water, glycine ethyl ester hydrochloride, acetic acid, toluene and a sodium nitrite aqueous solution into a diazotization kettle; wherein the sodium nitrite aqueous solution is added dropwise; according to the method, high-precision temperature control is performed on the sodium nitrite aqueous solution, so that the sodium nitrite aqueous solution is prepared efficiently and stably, uniform stirring is performed in a dropwise adding manner, the uniformity and the reaction rate of diazotization reaction are improved, sodium nitrite is dropwise added into acetic acid within a specified control range, the reaction stability of diazo liquid is enhanced, and the yield of the diazo liquid is increased. The cyclization reaction rate is improved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical processes, in particular to a diazotization 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 diazotization process, the feeding temperature of the sodium nitrite aqueous solution is difficult to control, which affects the stability of the diazo liquid reaction and reduces the cyclization reaction rate, resulting in a low chemical yield. Summary of the invention

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

[0005] To achieve the above object, the present invention provides the following technical solution: a diazotization process for producing chrysanthemic acid ethyl ester, wherein the diazotization reaction ratio is glycine ethyl ester hydrochloride + water: sodium nitrite + water: glacial acetic acid: toluene = (480 + 660) kg: (262.5 + 660) kg: 36.8 kg: 800 L, comprising the following steps:

[0006] S1: Sequential feeding:

[0007] Tap water, glycine ethyl hydrochloride, acetic acid, toluene and sodium nitrite aqueous solution are added to the diazotization kettle in sequence, wherein the sodium nitrite aqueous solution is added dropwise;

[0008] S2: Process control point:

[0009] (1) Preparation of sodium nitrite solution:

[0010] Dissolving temperature: 30-50°C, stirring time: 30 minutes;

[0011] (2) Reaction process, sodium nitrite solution dropping temperature:

[0012] Dissolving temperature: 10-15°C, dropping time: 4-5 hours

[0013] Insulation temperature: 10-15°C, insulation time: 45 minutes

[0014] pH before addition: 3.5~4.5, pH after addition: 3.5~4.5

[0015] Pressure in the reaction kettle during the reaction process: normal pressure

[0016] S3: Process control operations:

[0017] Preparation of sodium nitrite solution:

[0018] (1) Towards 2m 3 Add 660L of tap water into the preparation kettle, and add 262.5kg of solid sodium nitrite under stirring;

[0019] (2) Stir for 30 minutes to dissolve the sodium nitrite solid. If the liquid temperature is low, steam can be introduced to heat the material to dissolve it;

[0020] (3) Open the vacuum of the sodium nitrite measuring tank and suck the prepared sodium nitrite solution for standby use;

[0021] S4: Diazotization reaction:

[0022] (1) 660 L of tap water, 480 kg of glycine ethyl hydrochloride, and 36.8 kg of acetic acid were placed in a diazotization reactor;

[0023] (2) Stir for 30 minutes to dissolve the solid; stop stirring and measure the pH value to control pH = 3.5-4.5

[0024] (3) 800 L of toluene was put into the reactor;

[0025] (4) Start freezing, and the temperature of the diazotization kettle material drops to 10-15°C;

[0026] (5) Add sodium nitrite solution dropwise. The temperature will rise slightly. Pay attention to adjusting the frozen brine. The addition time is controlled to be 4 to 5 hours. After the addition is completed, keep warm for 45 minutes and control the temperature at 10 to 15°C.

[0027] (6) After the heat preservation is completed, the stirring is stopped and the layers are separated after standing for half an hour. The wastewater in the lower layer is discharged into the waste liquid collection tank.

[0028] (7) Add 400 L of water to the upper layer, stir for 15 minutes, let stand for 15 minutes, and discharge the lower water layer into the waste liquid collection tank;

[0029] (8) Use vacuum to pump the diazo liquid into a diazo liquid metering tank for later use.

[0030] Preferably, the sodium nitrite solution is controlled by dropwise addition, wherein the dissolution temperature is 10-15° C., the dropwise addition time is 4-5 hours, and the insulation temperature is 10-15° C., and the insulation time is 45 minutes.

[0031] Preferably, the diazotization kettle is provided with a drain valve, which is opened after the feeding is completed in sequence to ensure smooth draining.

[0032] Preferably, when the diazotization temperature is too high or too low, the dropping is suspended or the frozen brine is adjusted to make the temperature tend to normal before dropping, and the dropping temperature is lower than 8 degrees and can not be dropped. The steam is slightly opened to raise the temperature to 8 degrees and then the dropping is continued. The dropping must be stopped when the temperature exceeds 14 degrees, and the dropping is continued after the temperature drops to 13 degrees.

[0033] Preferably, the dosage of acetic acid is controlled at a pH value between 3.5 and 4.5, and sodium nitrite is added dropwise after accurate control.

[0034] Preferably, the diazo liquid must be placed in a diazotization reactor and stored at low temperature.

[0035] The diazotization process for producing ethyl chrysanthemate proposed by the present invention has at least the following beneficial effects:

[0036] The sodium nitrite aqueous solution is prepared efficiently and stably by high-precision temperature control of the sodium nitrite aqueous solution, and is stirred evenly by dripping, thereby improving the uniformity and reaction rate of the diazotization reaction, and ensuring that the sodium nitrite is dripped into acetic acid within a specified control range, thereby enhancing the reaction stability of the diazotization solution and improving the cyclization reaction rate. DETAILED DESCRIPTION

[0037] 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.

[0038] The embodiment provided by the present invention is a diazotization process for producing chrysanthemic acid ethyl ester, wherein the reaction ratio of diazotization is glycine ethyl ester hydrochloride + water: sodium nitrite + water: glacial acetic acid: toluene = (480 + 660) kg: (262.5 + 660) kg: 36.8 kg: 800 L, comprising the following steps:

[0039] S1: Sequential feeding:

[0040] Tap water, glycine ethyl hydrochloride, acetic acid, toluene and sodium nitrite aqueous solution are added to the diazotization kettle in sequence, wherein the sodium nitrite aqueous solution is added dropwise;

[0041] S2: Process control point:

[0042] (1) Preparation of sodium nitrite solution:

[0043] Dissolving temperature: 30-50°C, stirring time: 30 minutes;

[0044] (2) Reaction process, sodium nitrite solution dropping temperature:

[0045] Dissolving temperature: 10-15°C, dropping time: 4-5 hours

[0046] Insulation temperature: 10-15°C, insulation time: 45 minutes

[0047] pH before addition: 3.5~4.5, pH after addition: 3.5~4.5

[0048] Pressure in the reaction kettle during the reaction process: normal pressure

[0049] S3: Process control operations:

[0050] Preparation of sodium nitrite solution:

[0051] (1) Towards 2m 3 Add 660L of tap water into the preparation kettle, and add 262.5kg of solid sodium nitrite under stirring;

[0052] (2) Stir for 30 minutes to dissolve the sodium nitrite solid. If the liquid temperature is low, steam can be introduced to heat the material to dissolve it;

[0053] (3) Open the vacuum of the sodium nitrite measuring tank and suck the prepared sodium nitrite solution for standby use;

[0054] S4: Diazotization reaction:

[0055] (1) 660 L of tap water, 480 kg of glycine ethyl hydrochloride, and 36.8 kg of acetic acid were placed in a diazotization reactor;

[0056] (2) Stir for 30 minutes to dissolve the solid; stop stirring and measure the pH value to control pH = 3.5-4.5

[0057] (3) 800 L of toluene was put into the reactor;

[0058] (4) Start freezing, and the temperature of the diazotization kettle material drops to 10-15°C;

[0059] (5) Add sodium nitrite solution dropwise. The temperature will rise slightly. Pay attention to adjusting the frozen brine. The addition time is controlled to be 4 to 5 hours. After the addition is completed, keep warm for 45 minutes and control the temperature at 10 to 15°C.

[0060] (6) After the heat preservation is completed, the stirring is stopped and the layers are separated after standing for half an hour. The wastewater in the lower layer is discharged into the waste liquid collection tank.

[0061] (7) Add 400 L of water to the upper layer, stir for 15 minutes, let stand for 15 minutes, and discharge the lower water layer into the waste liquid collection tank;

[0062] (8) Use vacuum to pump the diazo liquid into a diazo liquid metering tank for later use.

[0063] Furthermore, the sodium nitrite solution is controlled by dripping, wherein the dissolution temperature is 10-15° C., the dripping time is 4-5 hours, and the insulation temperature is 10-15° C., and the insulation time is 45 minutes, which makes the reaction rate of the sodium nitrite solution controlled by dripping more efficient.

[0064] Furthermore, the diazotization kettle is provided with a drain valve, which is opened after the feeding is completed in sequence to ensure smooth draining.

[0065] Furthermore, when the diazotization temperature is too high or too low, the dripping can be suspended or the frozen brine can be adjusted to make the temperature tend to normal before dripping. If the dripping temperature is lower than 8 degrees, no dripping can be done. The steam can be slightly opened to raise the temperature to 8 degrees before continuing the dripping. If the temperature exceeds 14 degrees, the dripping must be stopped and the temperature must be dropped to 13 degrees before continuing the dripping to improve the accuracy of temperature control.

[0066] Furthermore, the dosage of acetic acid is controlled within the pH range of 3.5 to 4.5, and sodium nitrite is added dropwise after the pH value is accurately controlled. When the pH value is not within the pH range of 3.5 to 4.5, the dosage of acetic acid is increased until the control range is reached.

[0067] Furthermore, the diazo liquid must be placed in the diazotization reactor and stored at low temperature, and taken out according to the use requirements so that it can be used immediately.

[0068] Embodiment 1, the chemical reaction equation of diazotization reaction (endothermic reaction) is as follows:

[0069] NH2CH2COOC2H5.HC1+NaNO2=N2CHCOOC2H5+NaCl+2H2O

[0070] △H=-8.69KJ.mol -1 .

[0071] Example 2, notes:

[0072] (1) The entire set of equipment, pipelines, valves and raw materials used in the diazotization reaction must ensure that they are free of copper ions or metallic copper.

[0073] (2) The amount of acetic acid added must be accurate. If the pH value after adding the materials is not between 3.5 and 4.5, the amount of acetic acid can be increased until it reaches the control range before adding sodium nitrite. (Acetic acid is a buffer solution for adjusting pH and does not participate in the reaction itself).

[0074] (3) After adding the materials, remember to open the drain valve of the diazotization reactor and ensure that the drain is unobstructed.

[0075] (4) When the diazotization temperature is too high or too low, you can stop dropping or adjust the frozen brine to make the temperature normal before adding. If the dropping temperature is lower than 8 degrees, do not add. Slightly open the steam to raise the temperature to 8 degrees and then continue to add. If the temperature exceeds 14 degrees, stop adding and continue to add after the temperature drops to 13 degrees.

[0076] Diazo liquid is unstable. If the plant is temporarily shut down for a long time due to special reasons, the diazo liquid must be placed in the diazotization reactor and stored at low temperature. Generally, it must be used immediately after it is made.

[0077] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0078] 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., indicating the orientation or positional relationship, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0079] 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 diazotization process for producing ethyl chrysanthemate, characterized in that: The reaction ratio of the diazotization is glycine ethyl ester hydrochloride + water: sodium nitrite + water: glacial acetic acid: toluene = (480 + 660) kg: (262.5 + 660) kg: 36.8 kg: 800 L, comprising the following steps: S1: Sequential feeding: Tap water, glycine ethyl hydrochloride, acetic acid, toluene and sodium nitrite aqueous solution are added to the diazotization kettle in sequence, wherein the sodium nitrite aqueous solution is added dropwise; S2: Process control point: (1) Preparation of sodium nitrite solution: Dissolving temperature: 30-50°C, stirring time: 30 minutes; (2) Reaction process, sodium nitrite solution dropping temperature: Dissolving temperature: 10-15°C, dropping time: 4-5 hours Insulation temperature: 10-15°C, insulation time: 45 minutes pH before addition: 3.5~4.5, pH after addition: 3.5~4.5 Pressure in the reaction kettle during the reaction process: normal pressure S3: Process control operations: Preparation of sodium nitrite solution: (1) Towards 2m 3 Add 660L of tap water into the preparation kettle, and add 262.5kg of solid sodium nitrite under stirring; (2) Stir for 30 minutes to dissolve the sodium nitrite solid. If the liquid temperature is low, steam can be introduced to heat the material to dissolve it; (3) Open the vacuum of the sodium nitrite measuring tank and suck the prepared sodium nitrite solution for standby use; S4: Diazotization reaction: (1) 660 L of tap water, 480 kg of glycine ethyl hydrochloride, and 36.8 kg of acetic acid were placed in a diazotization reactor; (2) Stir for 30 minutes to dissolve the solid; stop stirring and measure the pH value to control pH = 3.5-4.5 (3) 800 L of toluene was put into the reactor; (4) Start freezing, and the temperature of the diazotization kettle material drops to 10-15°C; (5) Add sodium nitrite solution dropwise. The temperature will rise slightly. Pay attention to adjusting the frozen brine. The addition time is controlled to be 4 to 5 hours. After the addition is completed, keep warm for 45 minutes and control the temperature at 10 to 15°C. (6) After the heat preservation is completed, the stirring is stopped and the layers are separated after standing for half an hour. The wastewater in the lower layer is discharged into the waste liquid collection tank. (7) Add 400 L of water to the upper layer, stir for 15 minutes, let stand for 15 minutes, and discharge the lower water layer into the waste liquid collection tank; (8) Use vacuum to pump the diazo liquid into a diazo liquid metering tank for later use.

2. The diazotization process for producing ethyl chrysanthemate according to claim 1, wherein: The sodium nitrite solution is controlled by dropwise addition, wherein the dissolution temperature is 10-15° C., the dropwise addition time is 4-5 hours, and the insulation temperature is 10-15° C., and the insulation time is 45 minutes.

3. The diazotization process for producing ethyl chrysanthemate according to claim 1, characterized in that: The diazotization kettle is provided with a drain valve, which is opened after the feeding is completed in sequence to ensure smooth draining.

4. The diazotization process for producing ethyl chrysanthemate according to claim 1, characterized in that: When the diazotization temperature is too high or too low, the dropping is suspended or the frozen brine is adjusted to make the temperature tend to normal before dropping. If the dropping temperature is lower than 8 degrees, no dropping is allowed. The steam is slightly turned on to raise the temperature to 8 degrees before continuing the dropping. If the temperature exceeds 14 degrees, the dropping must be stopped and the dropping will be continued after the temperature drops to 13 degrees.

5. The diazotization process for producing ethyl chrysanthemate according to claim 1, characterized in that: The dosage of the acetic acid is controlled to be between pH 3.5 and 4.5, and sodium nitrite is added dropwise after the pH value is accurately controlled.

6. The diazotization process for producing ethyl chrysanthemate according to claim 1, characterized in that: The diazo liquid must be placed in a diazotization reactor and stored at low temperature.