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Preparation method of 4-methyl-5-(2-hydroxyethyl)-thiazole

A hydroxyethyl and methyl technology, applied in the field of chemical synthesis, can solve the problem of low yield and the like, and achieve the effects of low production cost, simple process and mild reaction conditions

Inactive Publication Date: 2011-05-04
NANCHANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of this invention is to provide a kind of chemical synthesis technique of new 4-methyl-5-(2-hydroxyethyl)-thiazole, to overcome the not high deficiency of prior art productive rate

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] 1. The reaction of 3-acetylpropanol and thiourea is carried out in water under the condition of sulfuric acid. The proportioning ratio of 3-acetylpropanol and thiourea is 1:1 mole, the reaction temperature is 100° C., and the reaction time is 4 hours.

[0016] 2. Adjust the pH value of the product solution obtained in step 1 to 8.5 with 20% sodium hydroxide solution, extract with ether, and remove the ether to obtain a dark red viscous liquid.

[0017] 3. Dissolve the dark red viscous liquid in concentrated sulfuric acid solution, cool to -12°C in an ice bath, add sodium nitrite aqueous solution dropwise, and stir at this temperature for 30 minutes. Then it was cooled to -5° C., an aqueous solution of sodium hypophosphite was added dropwise, and the reaction was carried out in an ice bath for 3 hours. The pH value of the reaction mixture was adjusted to 8.5 with a 20% sodium hydroxide solution by mass fraction. .Extract with dichloromethane, remove dichloromethane, the...

Embodiment 2

[0019] 1. The reaction of 3-acetylpropanol and thiourea is carried out in ethanol under the condition of sulfuric acid. The ratio of 3-acetylpropanol to thiourea is 1:1.2 moles, the reaction temperature is 80° C., and the reaction time is 5 hours.

[0020] 2. Adjust the pH value of the product solution obtained in step 1 to 9.0 with a 20% potassium hydroxide solution, extract with ether, and remove the ether to obtain a dark red viscous liquid.

[0021] 3. Dissolve the dark red viscous liquid in concentrated hydrochloric acid solution, cool to -15°C in an ice bath, add sodium nitrite aqueous solution dropwise, and stir at this temperature for 30 minutes. Then it was cooled to -7° C., an aqueous solution of sodium hypophosphite was added dropwise, and the reaction was carried out in an ice bath for 4 hours. The pH value of the reaction mixture was adjusted to 10.0 with a 20% potassium hydroxide solution by mass fraction. Extract with dichloromethane, remove dichloromethane, th...

Embodiment 3

[0023] 1. The reaction of 3-acetylpropanol and thiourea is carried out in propanol under sulfuric acid conditions. The ratio of 3-acetylpropanol to thiourea is 1:1.5 moles, the reaction temperature is 90° C., and the reaction time is 4.5 hours.

[0024] 2. Adjust the pH value of the product solution obtained in step 1 to 10.0 with 30% sodium hydroxide solution, extract with ether, and remove the ether to obtain a dark red viscous liquid.

[0025] 3. Dissolve the dark red viscous liquid in concentrated sulfuric acid solution, cool to -12°C in an ice bath, add sodium nitrite aqueous solution dropwise, and stir at this temperature for 30 minutes. Then it was cooled to -6° C., an aqueous solution of sodium hypophosphite was added dropwise, and the reaction was carried out in an ice bath for 5 hours. The pH value of the reaction mixture was adjusted to 11.0 with a 30% sodium hydroxide solution by mass fraction. Extract with dichloromethane, remove the dichloromethane, then distill...

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Abstract

The invention discloses a preparation method of 4-methyl-5-(2-hydroxyethyl)-thiazole, which comprises the following steps: 3-acetylpropyl alcohol and thiourea react in a solvent under acidic conditionat the temperature of 78 to 100 DEG C for 3 to 8 hours, with the mole ratio of 1:1-2; alkali solution with mass fraction of 10-50 percent is added for adjusting the pH value to 8.5-10.5, ethyl etheris added for extraction and then the ethyl ether is removed; next the mixture is dissolved in acid solution with high concentration, and cooled to -10--20 DEG C; aqueous solution of sodium hypophosphite is added in a dropwise way, and then the mixture is stirred for 30 minutes at the present temperature, and cooled to -5--7 DEG C; the aqueous solution of sodium hypophosphite is added again in a dropwise way, and then the mixture reacts in an ice bath for 3-5 hours; alkali solution with mass fraction of 10-50 percent is added for adjusting the pH value of the reaction mixture to 8.0-11.0; methylene dichloride is added for extraction and then removed; reduced pressure distillation is conducted; and under the pressure of 395-400Pa, distillate with the temperature of 120-127 DEG C is collected. The preparation method has easy-available raw materials, low production cost, simple technique, mild reaction condition and high yield up to 73 percent.

Description

technical field [0001] The invention belongs to the field of chemical synthesis, and in particular relates to a synthesis process of 4-methyl-5-(2-hydroxyethyl)-thiazole, an intermediate of tobacco flavor and vitamin VB1. Background technique [0002] Some synthetic techniques of 4-methyl-5-(2-hydroxyethyl)-thiazole are known, which are described in published patent documents US2,194,179 and US2,654,760. Utilize 3-halo-2-acetylpropanol and thioformamide reaction to obtain 4-methyl-5-(2-hydroxyethyl)-thiazole; Utilize 2-methyl-2,3-dichloro-4,5- Reaction of dihydrofuran and thioformamide gives 4-methyl-5-(2-hydroxyethyl)-thiazole. Known synthetic techniques are different, and a synthetic technique utilizes α,-chloro-α-acetyl-r-butyrolactone to be hydrolyzed into 3-chloro-3-acetylpropanol under acidic conditions, and then combined with thioformamide The reaction yields 4-methyl-5-(2-hydroxyethyl)-thiazole with a yield of 68%; another synthesis process utilizes 2-methyl-2,3-di...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D277/24
Inventor 张小林胡延雷高艳
Owner NANCHANG UNIV