Method for recovering pyridine from pyridine hydrochloride water solution

A technology of pyridine hydrochloride and aqueous solution, which is applied in the chemical industry and can solve problems such as difficult separation, unsatisfactory pyridine recovery rate, and difficult separation

Active Publication Date: 2013-04-03
HEFEI XINGYU CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since pyridine and water form an azeotrope, it is actually difficult to separate the two by azeotropic distillation. An extractant is added to it. This extractant is insoluble in water but miscible with pyridine. Theoretically, Pyridine can be separated by multiple extractions, but in actual production, the recovery rate of pyridine using this method is not satisfactory, and the impurity content is high, making it difficult to separate in the later stage

Method used

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  • Method for recovering pyridine from pyridine hydrochloride water solution

Examples

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Comparison scheme
Effect test

Embodiment 1

[0027] Embodiment 1 reclaims pyridine from pyridine hydrochloride aqueous solution

[0028] Take 500 mL of an aqueous solution of pyridine hydrochloride with a specific gravity of 1.2000 g / mL and a pyridine content of about 14.5%, slowly add 30% NaOH solution under stirring, control the temperature at 55°C, adjust the pH to 10, and stir for 20 minutes to obtain the first solution;

[0029] Add 90 mL of dichloroethane into the first solution, stir it for 10 minutes, and then carry out the first atmospheric distillation, and stop at reflux to 100°C to obtain the first fraction of 194 mL, which is collected for later use;

[0030] Add 90 mL of dichloroethane to the distillation waste liquid of the first atmospheric distillation, and then carry out the second atmospheric distillation after stirring for 10 minutes, and stop at reflux to 100 ° C to obtain the second fraction 139 mL, and combine the first fraction with the second The two fractions are mixed to obtain the second solut...

Embodiment 2

[0033] Embodiment 2 reclaims pyridine from pyridine hydrochloride aqueous solution

[0034] Take 500mL of pyridine hydrochloride aqueous solution with a specific gravity of 1.2000g / mL (pyridine hydrochloride aqueous solution is the waste liquid produced by the preparation of bentazon), the content of pyridine is about 10%, slowly add 50% NaOH solution under stirring, and the temperature is controlled at 60°C , adjust the pH to 10, and stir for 20 minutes to obtain the first solution;

[0035] Add 64mL of dichloroethane into the first solution, stir it for 10 minutes, then carry out the first atmospheric distillation, and stop at reflux to 100°C to obtain the first fraction of 138mL, which is collected for later use;

[0036] Add 64mL of dichloroethane to the distillation waste liquid of the first atmospheric distillation, and then carry out the second atmospheric distillation to it after stirring for 10 minutes, and return to 98°C to stop to obtain the second fraction 99mL, an...

Embodiment 3

[0039] Embodiment 3 reclaims pyridine from pyridine hydrochloride aqueous solution

[0040] Take 500 mL of an aqueous solution of pyridine hydrochloride with a specific gravity of 1.2000 g / mL and a pyridine content of about 20%, slowly add 30% NaOH solution under stirring, control the temperature at 57°C, adjust the pH to 9, and stir for 20 minutes to obtain the first solution;

[0041] Add 127mL of dichloroethane to the first solution, stir it for 10 minutes, then carry out the first atmospheric distillation, and stop at reflux to 100°C to obtain the first fraction of 274mL, which is collected for later use;

[0042] Add 127mL of dichloroethane to the distillation waste liquid of the first atmospheric distillation, and then carry out the second atmospheric distillation to it after stirring for 10 minutes, return to 100°C to stop, and obtain the second fraction 196mL, and combine the first fraction with the second The two fractions are mixed to obtain the second solution for s...

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Abstract

The invention relates to the field of chemical engineering, particularly a method for recovering pyridine from a pyridine hydrochloride water solution, which comprises the following steps: by using dichloroethane as an extractant, carrying out extraction distillation twice, and rectifying to obtain the pyridine with higher recovery rate (up to 90-95%). The invention can reduce the waste of resources, and does not pollute the environment, thereby reducing the production cost and enhancing the economic benefit.

Description

technical field [0001] The invention relates to the field of chemical industry, in particular to a method for recovering pyridine from an aqueous solution of pyridine hydrochloride. Background technique [0002] Bentazon, also known as bentazone, is a pesticide herbicide. A large amount of pyridine hydrochloride aqueous solution is produced in the relatively common production method at present, and the aqueous solution contains about 15% pyridine hydrochloride, and the pH is strongly acidic. [0003] Pyridine is a six-membered heterocyclic compound containing a nitrogen heteroatom, with a boiling point of 115.3°C and is miscible with water. Pyridine and its homologs exist in bone tar, coal tar, gas, shale oil, and petroleum. In addition to being used as a solvent, pyridine can also be used industrially as a denaturant, a dyeing aid, and a starting material for the synthesis of a series of products (including medicines, disinfectants, dyes, food seasonings, adhesives, explo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/16C07D213/127
Inventor 王龙江文王兰兰孙东艳
Owner HEFEI XINGYU CHEM
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