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Preparation method for tert-butyl carbazate

A technology of carbazic acid and t-butyl ester, which is applied in the field of industrial preparation of tert-butyl carbazate, can solve the problems of unfavorable industrial use, low safety factor, skin irritation, etc., and achieves low cost, short reaction time, and method simple effect

Inactive Publication Date: 2010-09-08
JIANGSU GRANDCHEM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The shortcoming that above method exists has: use chloroformate in synthesis, safety factor is low; Not conducive to industrial use

Method used

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  • Preparation method for tert-butyl carbazate

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preparation example Construction

[0018] The preparation method of tert-butyl carbazate of the present invention comprises the steps:

[0019] In the first step, first add hydrazine hydrate and isopropanol into the reaction kettle, start stirring, and lower the temperature; 70% to 80%; the temperature of the material in the kettle drops to -5°C when stirring, the purity of hydrazine hydrate is greater than 98% (mass), and the purity of isopropanol is greater than 99% (mass).

[0020] In the second step, the BOC anhydride and isopropanol are transported to the high-position stirring drop tank, and stirred, and the uniformly stirred BOC anhydride and isopropanol mixture is slowly added dropwise to the hydrazine hydrate isopropyl alcohol in the reaction kettle in the first step In the alcohol solution; BOC anhydride accounts for 56-60% of the total weight of the feed, and isopropanol accounts for 40-44% of the total weight of the feed; the purity of BOC anhydride and the purity of isopropanol are greater than 99%...

Embodiment 1

[0026] Turn on the cooling system, extract 50 kg of hydrazine hydrate and add it to the 500-liter reactor, then add 128 kg of isopropanol to the 500-liter reactor, stir at low temperature for 1 hour, and control the temperature in the reactor at about -5°C. Transfer 100 kg of BOC anhydride and 72 kg of isopropanol to a high-level stirring drop tank, and slowly drop the uniformly stirred mixture into a 500-liter reactor. During the dropwise addition, the temperature of the reaction solution in the kettle should not exceed 0°C. The dropwise addition takes about 5 hours. After the dropwise addition, turn off the brine pump, stop the low-temperature cooling, and stir at room temperature for 12 hours. Isopropanol was distilled off. Add 280 kg of dichloromethane, add 10 kg of anhydrous sodium sulfate, and stir at room temperature for 2 hours. Sodium sulfate was filtered out, anhydrous sodium sulfate was washed with dichloromethane, and sodium sulfate was sucked dry. The dichloro...

Embodiment 2

[0028] Turn on the cooling system, extract 100 kg of hydrazine hydrate and add it to the 500-liter reactor, then add 128 kg of isopropanol to the 500-liter reactor, stir at low temperature for 1 hour, and control the temperature in the reactor at about -5°C. Transfer 100 kg of BOC anhydride and 72 kg of isopropanol to a high-level stirring drop tank, and slowly drop the uniformly stirred mixture into a 500-liter reactor. During the dropwise addition, the temperature of the reaction solution in the kettle should not exceed 0°C. The dropwise addition takes about 5 hours. After the dropwise addition, turn off the brine pump, stop the low-temperature cooling, and stir at room temperature for 24 hours. Isopropanol was distilled off. Add 280 kg of dichloromethane, add 10 kg of anhydrous sodium sulfate, and stir at room temperature for 2 hours. Sodium sulfate was filtered out, anhydrous sodium sulfate was washed with dichloromethane, and sodium sulfate was sucked dry. The dichlor...

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Abstract

The invention discloses a preparation method for tert-butyl carbazate, which comprises the following steps that: hydrazine hydrate and isopropyl alcohol are added into a reactor first, agitation is started and temperature is reduced; BOC acid anhydride and isopropyl alcohol are delivered to a high-position agitation and dropping tank and the evenly agitated mixed liquid is slowly dropped into the reactor; a brine pump is shut down after the mixed liquid is completely dropped and normal temperature agitation is conducted; isopropyl alcohol is distilled, dichloromethane is added, anhydrous sodium sulfate is added, room temperature agitation is conducted, sodium sulfate is filtered, the dichloromethane washes the anhydrous sodium sulfate and the sodium sulfate is dried in a pumping way; and distillation is conducted to recover dichloromethane, normal hexane is added, agitated and dissolved, the obtained solution is delivered to a crystallization kettle, cooling, agitation and crystallization are conducted, products are separated out through centrifugation and the products are vacuum-dried to obtain the tert-butyl carbazate. The invention has the advantages that the material selection is scientific, the proportion is proper, the method is simple and the method is suitable for industrialized production; the reaction time is short, the recovery rate is high and the product quality is high; the environmental pollution is reduced, and the cost is low and the tert-butyl carbazate can be conveniently prepared by low cost.

Description

technical field [0001] The invention belongs to the technical field of industrial preparation of tert-butyl carbazate, in particular to a preparation method of tert-butyl carbazate. Background technique [0002] In recent years, tert-butyl carbazate has been used more and more as an important intermediate in organic synthesis, drug synthesis and fine synthesis. It is mainly used as a key intermediate for the preparation of tert-butyl azidocarboxylate, amino acid protecting group, aldehyde protecting group, synthesis of anti-HIV drug atazanavir, etc. Its advantages in synthesis: the protected product is easy to crystallize and has good stability; the protecting group is stable under alkaline conditions; it is easy to remove under acidic conditions; it is easy to synthesize. [0003] With the rapid increase of the dosage, the old process is currently used to synthesize tert-butyl carbazate in two steps, and the final product is purified by distillation. The main methods are:...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C281/02
Inventor 赵学飞蒋世明
Owner JIANGSU GRANDCHEM IND
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