Semicarbazone synthesis method

A synthetic method and semicarbazone technology, applied in chemical instruments and methods, preparation of urea derivatives, preparation of organic compounds, etc., can solve the problems of trimethylsilyl isocyanate dependence on imports, low equipment level, and human health hazards. Achieve non-flammable and explosive safety, easy operation and handling, and beneficial to industrial production

Inactive Publication Date: 2006-04-26
ZHEJIANG UNIV OF TECH
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  • Abstract
  • Description
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Problems solved by technology

Among the above three methods, the semicarbazide hydrochloride prepared by method one has a relatively large solubility in water, and can only be obtained by evaporation and concentration, which has high energy consumption, low yield, high raw material cost, and due to excessive hydration Hydrazine is discharged along with the waste liquid and causes serious environmental pollution
Method 2: Trimethylsilyl isocyanate, one of the raw materials, relies on imports, and the production cost is high, which has a great impact on large-scale industrial production
The raw material nitrourea used in method three must be self-made, and it is easy to explode, which is very unf

Method used

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  • Semicarbazone synthesis method

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Embodiment 1

[0024] Embodiment 1 is synthesized in the benzaldehyde semicarbazone in ionic liquid

[0025] Add urea (10g, 0.167mol) and 50% hydrazine hydrate (9g, 0.09mol) successively into a 100mL three-necked round-bottomed flask equipped with a thermometer and a condenser, react at 100°C for 4h, cool to room temperature, and adjust the pH with concentrated hydrochloric acid 3~4, dropwise add the mixed solution of benzaldehyde (9mL, 0.085mol) and 10mL 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid, a white precipitate is formed immediately, after the addition, stir at room temperature for 2h , heated to reflux for 1 h, cooled and filtered to obtain white crystals, 12.1 g, yield 95.8%, melting point 220-221 °C. The filtrate was extracted with dichloromethane, and the solvent was evaporated to obtain 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid, which was recycled for use.

Embodiment 2

[0026] Embodiment 2 is synthesized in the benzaldehyde semicarbazone under ultrasonic promotion

[0027] Add urea (10g, 0.167mol) and 50% hydrazine hydrate (9g, 0.09mol) successively into a 100mL three-necked round-bottomed flask equipped with a thermometer and a condenser, react at 95°C for 4h, cool to room temperature, and adjust the pH with concentrated hydrochloric acid 3~4, dropwise add the mixed solution of benzaldehyde (9mL, 0.085mol) and 10mL 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid, a white precipitate is formed immediately, after the addition, the reaction is promoted by ultrasonic waves 0.5h, heated to reflux for 1h, cooled and filtered to obtain white crystals, 12.2g, yield 96.4%, melting point 219-220°C. The filtrate was extracted with dichloromethane, and the solvent was evaporated to obtain 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid, which was recycled for use.

Embodiment 3

[0028] The synthesis of benzaldehyde semicarbazone under the microwave radiation of embodiment 3

[0029] Add urea (10g, 0.167mol) and 50% hydrazine hydrate (9g, 0.09mol) successively into a 100mL three-necked round-bottomed flask equipped with a thermometer and a condenser, react at 100°C for 4h, cool to room temperature, and adjust the pH with concentrated hydrochloric acid 3~4, dropwise add the mixed solution of benzaldehyde (9mL, 0.085mol) and 10mL 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid, immediately a white precipitate is formed, after the addition, react under 125W microwave After 10 minutes, cool and filter to obtain white crystals, 12.4 g, yield 98.0%, melting point 219-222°C. The filtrate was extracted with dichloromethane, and the solvent was evaporated to obtain 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid, which was recycled for use.

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Abstract

The synthesis process of semicarbazone includes the following steps: 1. reaction of hydrazine hydrate and urea at 90-100 deg.c and regulating the pH value of the reacted liquid with concentrated hydrochloric acid to 3-4; and 2. adding aldehyde and ionic liquid to the reacted liquid, reflux reaction, cooling and filtering to obtain the destination compound. The synthesis process is superior in that the ionic liquid has less trend of volatilization, combustion and explosion, excellent dissolving property on both organic and inorganic matters, and easy recovering, and the reaction in homogeneous phase condition is easy to operate and high in yield; that the condensation may be microwave heated for shortened reaction time, raised yield, high product purity and low power consumption; and that the condensation may be ultrasonically promoted.

Description

(1) Technical field [0001] The invention relates to a method for synthesizing a semicarbazone. (2) Background technology [0002] The semicarbazone produced by the reaction of aldehyde and semicarbazide is an important fine chemical intermediate, which is mainly used in the synthesis of furantidine, an antibacterial drug for urinary tract infection. [0003] Taking the synthesis of benzaldehyde semicarbazone as an example, there are currently three synthetic routes. Method 1: react hydrazine hydrate and urea to obtain semicarbazide, then use concentrated hydrochloric acid to precipitate and separate to obtain semicarbazide hydrochloride, and condense semicarbazide hydrochloride with benzaldehyde or diethyl benzylidene malonate to obtain benzaldehyde amino urea. A large number of bubbles are generated during the reflux stage of the condensation reaction, which often causes the material to overflow and adhere to the wall of the vessel, which brings difficulties to the operat...

Claims

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Application Information

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IPC IPC(8): C07C273/18C07C281/10C07C281/14C07D207/335C07D213/53C07D231/12C07D277/28C07D307/52C07D333/22
Inventor 裴文孙莉孙孟展
Owner ZHEJIANG UNIV OF TECH
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