Process for synthesis of hydroxy ethidene diphosphoric acid

Abstract

A method for synthesizing hydroxyl ethylidenediphosphonic acid belongs to synthesis of organo-phosphonic acid and is used in water stabilization. The phsophorus trichloride and acetic acid react at a temperature between 80 DEG C and 150 DEG C with an absolute pressure less than 760 millimeters mercury column, and the byproducts of hydrochloride and a few acetyl chlorides free of condensation are respectively retrieved and reused by combined recovery system of acetic acid and hydrochloric acid. The product of this method is obtained by hydrolyzing the acetylated hydroxyl ethylidenediphosphonic acid at a temperature between 80 DEG C and 150 DEG C with an absolute pressure no more than 760 millimeters mercury column; the collected hydrolysate of acetic acid after the distillation and the condensation is selected as raw material together with the acetic acid solution from the reclamation tower of acetic acid. The autoclave of 1000 litres daily produces products of 2500 kilograms with 60 % of solid content and less than 0.15 % of phosphorous acid; the yield rate of the products is more than 98 % calculated by phsophorus trichloride and is more than 96 % calculated by acetic acid.

Description

technical field [0001] The invention relates to a synthesis method of hydroxyethylene diphosphonic acid, which belongs to the synthesis of organic phosphonic acid. The commonly used method is to obtain phosphorus trichloride and acetic acid as raw materials through acetylation and then hydrolysis. Background technique [0002] Hydroxyethylene diphosphonic acid has a stable structure and strong complexing ability. It is mostly used for water quality stabilization treatment. A kind of production method of hydroxyethylene diphosphonic acid is disclosed in CN-1043044C. Its purpose is to collect the acetyl chloride taken out by the by-product hydrogen chloride. Its measure is to add a secondary Frozen brine condenser. The collected acetyl chloride is added to the acetic acid solution and used as part of the raw material acetic acid. Its shortcoming is that it adds operating procedures, which brings unsafe factors; increases equipment investment and energy consumption, and has...

AI Technical Summary

Problems solved by technology

Its shortcoming is that it adds operating procedures, which brings unsafe factors; increases equipment investment and energy consumption, and has a long production cycle and low equipment production capacity.

Its disadvantage is that it is not safe to add phosphorus trichloride dropwise under normal pressure and high temperature, and a large amount of acetyl chloride and acetic acid are entrained in the by-product hydrogen chloride gas, which needs to be equipped with a huge condensation device. After condensation, the mixture of acetyl chloride and acetic acid is collected. Feeding is inconvenient to use, and by-product recovery is not complete

The ratio of acetic acid to phosphorus trichloride is high, which increases energy consumption, and is faced with the trouble of viscous stirring of materials.