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Method for preparing benzyl carbazate

A technology of benzyl carbazate and benzyl chloroformate, which is applied in the field of preparing benzyl carbazate, can solve the problems of low yield of benzyl carbazate, low yield of transesterification, difficult purification of products, etc., and achieve degradation Controllable, waste-free, mild reaction conditions

Inactive Publication Date: 2021-09-03
新沂市永诚化工有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although dimethyl carbonate is safe and suitable for operation, the yield of transesterification is low and the production cost is high, so it needs to be improved when it is applied to industrial production
[0008] In the prior art, the yield of benzyl carbazate prepared by one-step synthesis is low, and the product is not easy to purify

Method used

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  • Method for preparing benzyl carbazate
  • Method for preparing benzyl carbazate
  • Method for preparing benzyl carbazate

Examples

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Effect test

Embodiment 1

[0034] The technical process of the preparation method of benzyl carbazate in the present invention is as figure 1 shown.

[0035] A method for preparing benzyl carbazate, comprising the steps of:

[0036] The first step: add dichloromethane solvent into the reaction kettle, then add hydrazine hydrate and stir until dissolved, then add the catalyst, and continue to stir for at least 5 minutes; the hydrazine hydrate and solvent are in the order of 1:6 by weight; the catalyst is potassium carbonate , sodium carbonate, lithium carbonate, triethylamine, potassium hydroxide or sodium hydroxide;

[0037] The second step: slowly drop benzyl chloroformate into the reaction kettle at 20±2°C, the dropping time is controlled at 10 minutes, and continue to keep warm for 2 hours; hydrazine hydrate, catalyst and benzyl chloroformate are in sequence according to the molar ratio 16:1:4;

[0038] The third step: heat-preserve and divide the obtained reaction liquid through a liquid separati...

Embodiment 2

[0046] A method for preparing benzyl carbazate, comprising the steps of:

[0047] The first step: add dichloromethane solvent into the reaction kettle, then add hydrazine hydrate and stir until dissolved, then add the catalyst, and continue stirring for at least 5 minutes; the hydrazine hydrate and solvent are in the order of 1:7 by weight; the catalyst is potassium carbonate , sodium carbonate, lithium carbonate, triethylamine, potassium hydroxide or sodium hydroxide;

[0048] Step 2: Slowly add benzyl chloroformate to the reaction kettle dropwise at 25±2°C, and the dropping time is controlled at 12 minutes, and continue to keep warm for 2 hours; The ratio is 16:1:4 in turn;

[0049] The third step: heat-preserve and divide the obtained reaction liquid through a liquid separation device, recover the hydrazine hydrate after the water division, and use the organic phase obtained after the water division for subsequent use;

[0050] Step 4: add hydrochloric acid with a concent...

Embodiment 3

[0057] A method for preparing benzyl carbazate, comprising the steps of:

[0058] The first step: add dichloromethane solvent into the reaction kettle, then add hydrazine hydrate and stir until dissolved, then add the catalyst, and continue to stir for at least 5 minutes; the hydrazine hydrate and solvent are in the order of 1:8 by weight; the catalyst is potassium carbonate , sodium carbonate, lithium carbonate, triethylamine, potassium hydroxide or sodium hydroxide;

[0059] The second step: slowly drop benzyl chloroformate into the reaction kettle at 20±2°C, the dropping time is controlled at 15 minutes, and continue to keep warm for 2 hours; The ratio is 16:1:4 in turn;

[0060] The third step: heat-preserve and divide the obtained reaction liquid through a liquid separation device, recover the hydrazine hydrate after the water division, and use the organic phase obtained after the water division for subsequent use;

[0061] Step 4: add hydrochloric acid with a concentra...

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Abstract

The invention provides a method for preparing benzyl carbazate. The method comprises the following steps: (1) adding a dichloromethane solvent and hydrazine hydrate into a reaction kettle, stirring until the dichloromethane solvent and hydrazine hydrate are dissolved, adding a catalyst, and stirring for at least 5 minutes; (2) slowly dropwise adding benzyl chloroformate into the reaction kettle, and carrying out heat preservation reaction for 2 hours; (3) carrying out heat preservation and water separation on the obtained reaction liquid through a liquid separation device, and recycling hydrazine hydrate after water separation; (4) adding hydrochloric acid into an organic phase obtained after water separation, and carrying out acidification refining; (5) adding a sodium carbonate aqueous solution into the acidified and refined solution for neutralization, carrying out cooling crystallization on the neutralized solution, centrifuging, separating the filtrate to remove water, recycling the organic phase, and collecting the crystallized solid for later use; and (6) recrystallizing the collected crystal solid with water to obtain benzyl carbazate. The benzyl carbazate with higher purity is obtained by adding a cooling crystallization method, and the cooling crystallization method is simple, easy to operate and safer for operators.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, in particular to a method for preparing benzyl carbazate. Background technique [0002] The English name of benzyl carbazate is benzyl carbazate, and the molecular formula is C 8 h 10 N 2 o 2 , the molecular weight is 166.18, CAS number: 5331-43-1, this substance has serious damage to the eyes. Its structural formula is: [0003] [0004] Benzyl carbazate is an important organic intermediate, which can be used to prepare plant protection agents and transaminase inhibitors, and has a wide range of uses in the synthesis of pesticides and medicines. The method for preparing benzyl carbazate disclosed at home and abroad mainly contains following several kinds: [0005] The first one uses benzyl alcohol as the starting material, uses phosgene to synthesize benzyl chloroformate intermediate, and then reacts with hydrazine hydrate to generate benzyl carbazate. The severe toxicity of ...

Claims

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Application Information

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IPC IPC(8): C07C281/02
CPCC07C281/20
Inventor 徐西之
Owner 新沂市永诚化工有限公司
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