Method for determining content of formaldehyde in glycolonitrile product

Abstract

The invention relates to a method for determining the content of formaldehyde in a glycolonitrile product. The method is characterized by comprising the following steps: accurately weighing a defined amount of glycolonitrile product sample to prepare an experiment solution, after regulating the experiment solution to be neutral, rapidly adding excessive sodium sulfite solution with the pH being 9.2, and immediately titrating a sulfuric acid standard titration solution until the pH is equal to 9.16-9.20 as an end point. The method has the advantages of simplicity and convenience in operation, rapidness, good reproducibility, high accuracy, and the like, and can be used for controlling the quality of the glycolonitrile product.

Description

technical field [0001] The invention relates to the determination of impurity content in hydroxyacetonitrile products, in particular to a method for determining formaldehyde content in hydroxyacetonitrile products. Background technique [0002] Hydroxyacetonitrile, also known as glycolonitrile, is a formaldehyde derivative and the simplest cyanohydrin. Hydroxyacetonitrile is highly toxic and is easily decomposed into formaldehyde and hydrocyanic acid. It is unstable to heat, has reducibility, and is easy to polymerize. In industry, it usually has a concentration of 40% or 50% by weight at a pH of 2 to 3.5. save. Hydroxyacetonitrile is an important organic synthesis intermediate, which is used in the synthesis of amino acid, glyphosate, indigo dye and malononitrile, etc., and is also used in the production of chelating agent, flotation agent, high-efficiency cleaning agent, etc. At present, hydrocyanic acid and formaldehyde are mainly synthesized in China, so hydroxyacetoni...

AI Technical Summary

Problems solved by technology

However, it is difficult to accurately measure the formaldehyde content in industrial hydroxyacetonitrile products, because hydroxyacetonitrile is easy to decompose to produce formaldehyde, the longer the time, the higher the temperature, and the higher the pH value, the faster the decomposition of hydroxyacetonitrile, so the conventional measurement operation is difficult. Accurate Determination of Formaldehyde Content in Hydroxyacetonitrile Products

For example, oxidation-reduction methods such as sodium bisulfite addition oxidation method, sodium hypochlorite oxidation method, and silver salt oxidation method in the commonly used chemical measurement methods are not suitable, because hydroxyacetonitrile itself has reducing properties, which will interfere with the measurement results; use hydroxylamine The time required for the oximation method is long; the commonly used spectrophotometric method not only takes a long time to develop color, but also easily changes hydroxyacetonitrile under the condition of color development, which interferes with the determination. For example, the color development of the acetylacetone method takes 50 to 60 minutes, and The color produced by the hydroxyacetonitrile reaction is almost consistent with the yellow color produced by the reaction with formaldehyde, which interferes with the determination; the AHMT method reacts under strong alkaline conditions, and the hydroxyacetonitrile will decompose to produce formaldehyde, making the measured value higher than the actual value; GC method and HPLC method usually needs to be determined after derivatization, which is too time-consuming and the analysis cost is high

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