Method for continuously synthesizing 3, 5-dimethylpyrazole

A technology of dimethylpyrazole and hydrazine hydrate, which is applied in organic chemistry and other fields, can solve problems such as safety risks, poor work efficiency, and unfavorable operation, and achieve accurate material ratio control, high product selectivity, and increased reaction temperature Effect

Pending Publication Date: 2022-08-05
潍坊润安化学科技有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The existing 3,5-dimethylpyrazole preparation method has certain disadvantages in use. First of all, it is a batch operation when it is used, and it cannot be produced continuously, which is troublesome. Acetylacetone or hydrazine hydrate needs to be added dropwise , Hydrazine hydrate is very toxic and has been included in the management of highly toxic drugs. It has potential safety risks and is not conducive to people's operation. It must be closed and automatically controlled for operation. It also has a long reaction time, poor work efficiency, and high temperature is prone to side reactions. , affecting product quality

Method used

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  • Method for continuously synthesizing 3, 5-dimethylpyrazole

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] A method for continuous preparation of 3,5-dimethylpyrazole, comprising the following operation steps:

[0026] S1: Select a shell-and-tube reactor suitable for this experiment, equipped with a low-temperature circulating tank, the liquid holding capacity of the reactor is 30ml, and a sufficient amount of acetylacetone liquid is selected. The acetylacetone is a colorless liquid with a boiling point of 30 ml. 140℃, can also be used as an organic intermediate;

[0027] S2: Select a sufficient amount of hydrazine hydrate, which is a colorless liquid with a boiling point of 120°C; select a metering pump for backup, and the metering pump can be set to flow rate;

[0028] S3: drive acetylacetone into the tubular reactor through a metering pump, and the flow rate of acetylacetone is 50 mL / min;

[0029] S4: pass 40% hydrazine hydrate into the tubular reactor through a metering pump, and the flow rate of hydrazine hydrate is 250 mL / min;

[0030] S5: In the steps of S3 and S4, ...

Embodiment 2

[0034] A method for continuous preparation of 3,5-dimethylpyrazole, comprising the following operation steps:

[0035] S1: Select a shell-and-tube reactor suitable for this experiment, equipped with a low-temperature circulating tank, the liquid holding capacity of the reactor is 30mL, and a metering pump is selected for standby. The metering pump can be set to flow rate;

[0036] S2: Weigh enough hydrazine hydrate and acetylacetone liquid;

[0037] S3: drive acetylacetone into the tubular reactor through a metering pump, and the flow rate of acetylacetone is 20mL / min;

[0038] S4: pass 45% hydrazine hydrate into the tubular reactor with a metering pump, and the flow rate of hydrazine hydrate is 100 mL / min;

[0039] S5: acetylacetone and hydrazine hydrate are simultaneously reacted in a tubular reactor;

[0040] S6: The molar ratio of acetylacetone to hydrazine hydrate is 1:1.10. After the internal reaction of the tubular reactor is completed, high-purity 3,5-dimethylpyrazol...

Embodiment 3

[0043] A method for continuous preparation of 3,5-dimethylpyrazole, comprising the following operation steps:

[0044] S1: Select a shell-and-tube reactor suitable for this experiment, equipped with a low-temperature circulation tank, the liquid holding capacity of the reactor is 30mL, and a sufficient amount of acetylacetone liquid is weighed;

[0045] S2: Weigh a sufficient amount of hydrazine hydrate; select a metering pump for backup, and the metering pump can set the flow rate;

[0046] S3: drive acetylacetone into the tubular reactor through a metering pump, and the flow rate of acetylacetone is 15mL / min;

[0047] S4: pass the 50% hydrazine hydrate metering pump into the tubular reactor, and the hydrazine hydrate flow rate is 75 mL / min;

[0048] S5: In the steps of S3 and S4, acetylacetone and hydrazine hydrate are simultaneously reacted in the tubular reactor;

[0049] S6: The molar ratio of acetylacetone to hydrazine hydrate is 1:1.15. After the reaction in the tubul...

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Abstract

The invention relates to a method for continuously preparing 3, 5-dimethylpyrazole, and belongs to the technical field of chemical preparation. Comprising the following operation steps: (1) selecting hydrazine hydrate with the content required to be 20-80% and acetylacetone with the content required to be more than 99%, which are suitable for the experiment; (2) a micro-channel reactor, a shell tubular reactor capable of heating and cooling and module reactors made of various materials can be selected, a stainless steel tubular reactor and two metering pumps are recommended to be used, the flow can be controlled, and a low-temperature circulating tank is used for controlling the temperature; the method for continuously preparing the 3, 5-dimethylpyrazole is suitable for continuous production, high in product selectivity and almost free of byproducts, the conversion rate of the raw material acetylacetone reaches 100%, the reaction time is greatly shortened to be within 10 seconds from 3 hours, the method is suitable for industrial amplification production, and better use prospects are brought.

Description

technical field [0001] The invention belongs to the technical field of chemical preparation, in particular to a method for continuous synthesis of 3,5-dimethylpyrazole. Background technique [0002] The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not necessarily be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art. [0003] The existing 3,5-dimethylpyrazole preparation method has certain drawbacks in use. First of all, it is intermittent operation when using, which cannot be continuously produced, which is relatively troublesome, and acetylacetone or hydrazine hydrate needs to be added dropwise. , Hydrazine hydrate is very toxic and has been included in the management of highly toxic drugs. It has potential safety risks and is not conducive to people's operations. It must be cl...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D231/12
CPCC07D231/12
Inventor 邓德才邱彬
Owner 潍坊润安化学科技有限公司
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