Method for realizing dehydration of 2-picoline through coupling of extraction and rectification

Abstract

The invention discloses a method for realizing dehydration of 2-picoline through coupling of extraction and rectification, and belongs to the technical field of refinement of organic high molecular compounds. The method is characterized by comprising the following steps: (1) performing mixing: mixing dichloromethane with a to-be-dehydrated 2-picoline solution so as to obtain mixed liquor, wherein the mass ratio of the dichloromethane to the 2-picoline in the mixed liquor is (6-10) to 1; (2) performing extraction and phase separation: placing the mixed liquor in a phase separator for phase separation so as to obtain an aqueous phase and an organic phase and complete extraction once; (3) performing extraction and phase separation once again: detecting the aqueous phase obtained in the step (2), if the 2-picoline is greater than or equal to 1% by mass of the aqueous phase, adding the dichloromethane to the aqueous phase, and when the mass ratio of the dichloromethane to the 2-picoline is (6-10) to 1, executing the step (2) and the step (3); and (4) performing rectification: performing rectification on the organic phase obtained in the step (2) and the step (3), extracting an extraction agent at upper parts, and extracting 2-picoline at lower parts. The dehydration method has the advantages of good separation effects, low production cost, low energy consumption and the like.

Description

technical field [0001] The invention belongs to the technical field of purifying organic polymer compounds, and in particular relates to a method for realizing the dehydration of 2-picoline by coupling extraction and rectification. Background technique [0002] 2-Methylpyridine is an important chemical intermediate and an important raw material for the synthesis of medicines and dyes. At present, a large amount of 2-picoline is used to synthesize 2-vinylpyridine, and 2-vinylpyridine is used to produce butylpyridine latex, which is the skeleton material of rubber products such as tires and conveyor belts. my country's annual demand is tens of thousands of tons and year by year increase, but currently domestic butylpyridine latex mainly relies on imports. [0003] The process of synthesizing 2-vinylpyridine with 2-picoline is as follows: 2-picoline and paraformaldehyde are catalytically added in liquid phase under high pressure or normal pressure to synthesize 2-hydroxyethylpy...

AI Technical Summary

Problems solved by technology

[0006] The dehydration and refining process of 2-picoline commonly used in industry is mainly the alkali-adding stratification method, which realizes the stratification of 2-picoline and water by changing the acidity and alkalinity of the solution, thereby preparing high-purity 2-picoline However, this method has obvious defects: after adding lye, each ton of industrial raw materials needs to stand still for 10-15 hours, and the product purity is not high, the generated lye cannot be directly discharged, and the lye cannot be recycled, so the economy is poor

It is also reported that benzene is used as an entrainer to destroy the azeotropic mixture of 2-picoline and water through its low-boiling azeotrope with water, so as to realize azeotropic distillation and dehydration. However, benzene, as a toxic chemical Reagents are dangerous in actual operation, and the ability of benzene to carry water is limited; in addition, technical means such as barium oxide, calcium oxide, calcium hydride, lithium aluminum hydride, metal sodium, 5A molecular sieve or membrane separation can also be used Dehydration, but it is not suitable when the water content is high and the treatment capacity is large, the operation is relatively cumbersome and other impurities may be introduced

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