Method for detecting process and end point of sulfur trioxide sulfonation

Abstract

The invention discloses a method for detecting process and end point of sulfur trioxide sulfonation. The method comprises the following steps that: (1) a conductance-detecting electrode is inserted into reactant subjected to sulfonation; the conductance of the reactant is detected and displayed in real time; the conductance of the reactant decreases along with the process of sulfonation; and sulfur dioxide gas is adopted as a sulfonating agent in the sulfonation; and (2) when the conductance of the reactant is detected to decrease to zero, the sulfonation reaches the end for sure. The method has the advantages of tracking the process of the sulfonation in real time through the conductance change of sulfonation solution, accurately judging the end point of the sulfonation, reminding operators in real time, ensuring that reaction cannot exceed the end point, leaving out the trouble of chemical sampling detection and avoiding the phenomenon that the chemical sampling detection is not timely and accurate enough in results.

Description

technical field [0001] The invention relates to a method for detecting the process and end point of sulfonation reaction, in particular to a method for detecting the process and end point of sulfur trioxide sulfonation. Background technique [0002] The introduction of sulfonic acid groups into organic molecules can increase the water solubility and acidity of the product, and most water-soluble dyes (such as direct dyes, acid dyes and reactive dyes, etc.) contain sulfonic acid groups. The reaction of introducing sulfonic acid groups (-SO3H) into organic molecules is called sulfonation reaction. At present, in the production of domestic organic chemical products, some manufacturers use sulfur trioxide gas as a sulfonating agent for sulfonation reaction. Sulfur trioxide gas is continuously added to the reaction material liquid. The organic matter is less and less, and the sulfonation reaction is getting closer and closer to the end point. In order to judge the end point of ...

AI Technical Summary

Problems solved by technology

In order to judge the end point of the sulfonation reaction, chemical sampling and detection measures are generally taken. However, chemical sampling and detection is not only troublesome, but also takes a certain time for the sampling and detection process, which cannot realize real-time detection, and is prone to errors, resulting in inaccurate results.

If the sulfonation reaction has reached the end of the reaction, sulfur trioxide gas is still added continuously, which will cause the increase of reaction by-products, the decrease of product yield, and even the serious consequences of unqualified product quality.