Synthetic method of phenylhydrazine

Abstract

The invention discloses a synthetic method of phenylhydrazine. The synthetic method comprises the following steps: adding dilute sulfuric acid into aniline, dropwise adding ammonium nitrite at 0-5 DEG C, and then performing thermal reaction for 4-6 minutes; then cooling to a temperature between -5 and -10 DEG C, adding a solid reducing agent, and stirring violently; when the temperature of the reaction system naturally rises to be more than 40 DEG C, adding dilute sulfuric acid to adjust the pH value to be 2-4, and heating to 70-100 DEG C to react for 4-6 hours; and separating the obtained reaction product to obtain phenylhydrazine. According to the synthetic process of phenylhydrazine, disclosed by the invention, aniline is used as a raw material, dilute sulfuric acid is used as salt forming and acidifying reagents, ammonium nitrite is used as a diazotization reagent, ammonium sulfite and / or ammonium hydrogen sulfite is used as the reducing agent, ammonia gas is used for neutralizing a reaction solution, phenylhydrazine is finally obtained by virtue of extraction and distillation, and a byproduct salt is single ammonium sulfate.

Description

Technical field

[0001] The present invention relates to a method for synthesizing aromatic hydrazines, in particular to a method for synthesizing phenylhydrazine, a chemical intermediate for organic synthesis. Background technique

[0002] Phenylhydrazine, its molecular formula is C 6 H 8 N 2 , its structural formula is as follows:

[0003]

[0004] Phenylhydrazine is an important fine chemical intermediate. The synthesis method of phenylhydrazine currently mainly uses aniline as raw material, and is obtained through diazotization, reduction, hydrolysis, neutralization, distillation and other steps. Patent WO 2012065062 mentions the use of SnCl 2 The method of reducing diazonium salt to prepare phenylhydrazine is expensive and not suitable for industrial production. In addition, the reducing agents currently used in industry are sodium sulfite, ammonium sulfite, sodium bisulfite and ammonium bisulfite, but a large amount of water is used as sulfite or bisulfite in t...

Examples

Embodiment 1

[0031] Embodiment 1, a kind of preparation method of phenylhydrazine, take aniline, dilute sulfuric acid, ammonium nitrite, ammonium sulfite, ammonium bisulfite, ammonia as raw material, carry out following steps successively:

[0032] 1). Measure 50ml of 50wt% sulfuric acid (0.36mol), add it into a 500ml three-necked flask, weigh 18.63g of aniline (0.20mol) and add it, a large amount of solids are precipitated, and then cool down to 0°C in an ice-salt bath. Add 90ml (2.20mol / L) ammonium nitrite solution dropwise, the dropping time is 30min, the temperature is controlled at 0-5°C during the dropwise addition, keep the temperature for 5min after the dropwise addition, and then cool down to -10°C in the ice-salt bath .

[0033] 2). Weigh 30g (0.26mol) of ammonium sulfite and 18g (0.18mol) of ammonium bisulfite into the three-necked flask directly, stir vigorously (rotating speed is 800-1200rmp), when the temperature of the reaction system naturally rises slowly to 40°C Finally,...

Embodiment 2

[0036] Embodiment 2, a kind of preparation method of phenylhydrazine, take aniline, dilute sulfuric acid, ammonium nitrite, ammonium sulfite, ammonium bisulfite, ammonia as raw material, carry out following steps successively:

[0037] 1). Take 42ml of 60wt% sulfuric acid (0.39mol), add it into a 500ml three-necked flask, weigh 18.63g of aniline (0.20mol) into it, and precipitate a large amount of solids, then cool down to 0°C in an ice-salt bath. Add 90ml (2.20mol / L) ammonium nitrite solution dropwise, the dropping time is 30min, the temperature is controlled at 0-5°C during the dropwise addition, keep the temperature for 5min after the dropwise addition, and then cool down to -10°C in the ice-salt bath .

[0038] 2). Weigh 30g of ammonium sulfite (0.26mol) and 18g of ammonium bisulfite (0.18mol) into the three-necked flask directly, stir vigorously (rotating speed is 800-1200rmp), when the temperature of the reaction system naturally rises slowly to 40°C Finally, 60wt% sulf...

Embodiment 3

[0041] Embodiment 3, a kind of preparation method of phenylhydrazine, take aniline, dilute sulfuric acid, ammonium nitrite, ammonium sulfite, ammonia as raw material, carry out following steps successively:

[0042]1). Measure 60ml of 50wt% sulfuric acid (0.43mol), add it into a 500ml three-neck flask, weigh 18.63g of aniline (0.20mol) and add it, a large amount of solids are precipitated, and then cool down to 0°C in an ice-salt bath. Add 90ml (2.20mol / L) ammonium nitrite solution dropwise, the dropping time is 30min, the temperature is controlled at 0-5°C during the dropwise addition, keep the temperature for 5min after the dropwise addition, and then cool down to -10°C in the ice-salt bath .

[0043] 2). Weigh 45g of ammonium sulfite (0.39mol) and add it directly into a three-necked flask, stir vigorously (rotating speed: 800-1200rmp), when the temperature of the reaction system naturally rises slowly to 40°C, add 50wt% sulfuric acid (about 50ml) The pH was adjusted to 3, ...

Technical field

[0001] The present invention relates to a method for synthesizing aromatic hydrazines, in particular to a method for synthesizing phenylhydrazine, a chemical intermediate for organic synthesis. Background technique

[0002] Phenylhydrazine, its molecular formula is C 6 H 8 N 2 , its structural formula is as follows:

[0003]

[0004] Phenylhydrazine is an important fine chemical intermediate. The synthesis method of phenylhydrazine currently mainly uses aniline as raw material, and is obtained through diazotization, reduction, hydrolysis, neutralization, distillation and other steps. Patent WO 2012065062 mentions the use of SnCl 2 The method of reducing diazonium salt to prepare phenylhydrazine is expensive and not suitable for industrial production. In addition, the reducing agents currently used in industry are sodium sulfite, ammonium sulfite, sodium bisulfite and ammonium bisulfite, but a large amount of water is used as sulfite or bisulfite in t...

Examples

Embodiment 1

[0031] Embodiment 1, a kind of preparation method of phenylhydrazine, take aniline, dilute sulfuric acid, ammonium nitrite, ammonium sulfite, ammonium bisulfite, ammonia as raw material, carry out following steps successively:

[0032] 1). Measure 50ml of 50wt% sulfuric acid (0.36mol), add it into a 500ml three-necked flask, weigh 18.63g of aniline (0.20mol) and add it, a large amount of solids are precipitated, and then cool down to 0°C in an ice-salt bath. Add 90ml (2.20mol / L) ammonium nitrite solution dropwise, the dropping time is 30min, the temperature is controlled at 0-5°C during the dropwise addition, keep the temperature for 5min after the dropwise addition, and then cool down to -10°C in the ice-salt bath .

[0033] 2). Weigh 30g (0.26mol) of ammonium sulfite and 18g (0.18mol) of ammonium bisulfite into the three-necked flask directly, stir vigorously (rotating speed is 800-1200rmp), when the temperature of the reaction system naturally rises slowly to 40°C Finally,...

Embodiment 2

[0036] Embodiment 2, a kind of preparation method of phenylhydrazine, take aniline, dilute sulfuric acid, ammonium nitrite, ammonium sulfite, ammonium bisulfite, ammonia as raw material, carry out following steps successively:

[0037] 1). Take 42ml of 60wt% sulfuric acid (0.39mol), add it into a 500ml three-necked flask, weigh 18.63g of aniline (0.20mol) into it, and precipitate a large amount of solids, then cool down to 0°C in an ice-salt bath. Add 90ml (2.20mol / L) ammonium nitrite solution dropwise, the dropping time is 30min, the temperature is controlled at 0-5°C during the dropwise addition, keep the temperature for 5min after the dropwise addition, and then cool down to -10°C in the ice-salt bath .

[0038] 2). Weigh 30g of ammonium sulfite (0.26mol) and 18g of ammonium bisulfite (0.18mol) into the three-necked flask directly, stir vigorously (rotating speed is 800-1200rmp), when the temperature of the reaction system naturally rises slowly to 40°C Finally, 60wt% sulf...

Embodiment 3

[0041] Embodiment 3, a kind of preparation method of phenylhydrazine, take aniline, dilute sulfuric acid, ammonium nitrite, ammonium sulfite, ammonia as raw material, carry out following steps successively:

[0042]1). Measure 60ml of 50wt% sulfuric acid (0.43mol), add it into a 500ml three-neck flask, weigh 18.63g of aniline (0.20mol) and add it, a large amount of solids are precipitated, and then cool down to 0°C in an ice-salt bath. Add 90ml (2.20mol / L) ammonium nitrite solution dropwise, the dropping time is 30min, the temperature is controlled at 0-5°C during the dropwise addition, keep the temperature for 5min after the dropwise addition, and then cool down to -10°C in the ice-salt bath .

[0043] 2). Weigh 45g of ammonium sulfite (0.39mol) and add it directly into a three-necked flask, stir vigorously (rotating speed: 800-1200rmp), when the temperature of the reaction system naturally rises slowly to 40°C, add 50wt% sulfuric acid (about 50ml) The pH was adjusted to 3, ...

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