Method for preparing crystal high-purity phosphorous acid by purifying byproduct phosphorous acid in pivaloyl chloride production

Abstract

The invention belongs to the field of chemical product purification, and particularly relates to a method for preparing crystal high-purity phosphorous acid by purifying byproduct phosphorous acid inpivaloyl chloride production, which comprises the following steps of: 1, diluting phosphorous acid serving as a byproduct of pivaloyl chloride production by using evaporation condensate water; 2, adding porous adsorbents such as activated carbon into the diluted solution, and performing filtering to separate the activated carbon and impurities; 3, vacuumizing the filtered clear liquid into an evaporation and concentration kettle with a stirring function, adopting a steam medium to perform heating in a jacketed manner, and performing evaporating and concentrating under a vacuum condition; 4, performing water evaporation, namely pumping the material into a cooling kettle with a stirring function, introducing circulating cooling water into a jacket, cooling the material, and putting the material liquid into a crystallization barrel for natural crystallization; and 5, naturally cooling the material, crushing the material, and centrifugally separating impurities containing uncrystallized phosphoric acid to obtain a crystal high-purity phosphorous acid product. The method effectively solves the problem that the byproduct phosphorous acid in pivaloyl chloride production is low in concentration and difficult to further utilize.

Description

technical field [0001] The patent of the invention belongs to the field of purification of chemical products, and in particular relates to a method for purifying phosphorous acid, a by-product of pivaloyl chloride production, to prepare crystal high-purity phosphorous acid. Background technique [0002] Present pivaloyl chloride production by-product phosphorous acid purification method for crystal high-purity phosphorous acid has the following problems: [0003] Problem 1: The low concentration of phosphorous acid, a by-product of pivaloyl chloride production, is difficult to further utilize; [0004] Question 2: It is not possible to purify low-concentration phosphorous acid industrial by-products into crystalline high-purity phosphorous acid products, which are not suitable for the production of pharmaceutical intermediates; [0005] Question 3: The evaporating and concentrating kettle is suitable for a reactor that concentrates the solvent, but the feed port of the trad...

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Problems solved by technology

[0003] Problem 1: The low concentration of phosphorous acid, a by-product of pivaloyl chloride production, is difficult to further utilize;

[0004] Question 2: It is not possible to purify low-concentration phosphorous acid industrial by-products into crystalline high-purity phosphorous acid products, which are not suitable for the production of pharmaceutical intermediates;

[0005] Question 3: The evaporating and concentrating kettle is suitable for a reactor that concentrates the solvent, but the feed port of the traditional evaporating and concentrating kettle is vertically downward, which cannot make full use of the inner wall of the reactor for solvent concentration, and the feed will impact the bottom of the kettle Concentrate, affecting the concentration effect;

[0006] Question 4: However, the cooling function of the common cooling kettle is not perfect at present. The heat dissipation speed of the material is relatively slow, resulting in low cooling efficiency. At the same time, it lacks a protection mechanism for the outside world. When the material is cooled, the temperature of the outer wall of the device will increase. , prone to damage to the operator

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