2,5-Diaminobenzenesulfonic acid, also known as 2,5-Diaminobenzenesulfonic acid, is a white to light gray solid powder at room temperature and pressure. It has a certain solubility in water and can dissolve in strong polar organic solvents such as methanol and N,N-dimethylformamide. 2,5-Diaminobenzenesulfonic acid is a kind of benzenesulfonic acid compound, which is mainly used as an intermediate in organic synthesis and as a basic synthetic material for dye molecules in the production process of benzenesulfonic acid dyes.

What is the preparation process?

Research has shown that scientists have synthesized 2,5-Diaminobenzenesulfonic acid using o-phenylenediamine or 2-amino-5-nitrobenzenesulfonic acid as raw materials, with a yield of up to 95%, higher than the former (less than 60%). Studies on the reduction reaction of iron filings have shown that reducing the particle size of iron filings and using appropriate catalysts significantly increase the reaction rate.

What is the condensation reaction?

Figure 1 Condensation reaction of 2,5-Diaminobenzenesulfonic acid

In a dry reaction flask, add 2,5-Diaminobenzenesulfonic acid and urea solution, then heat the resulting reaction mixture to 70-80°C and stir the reaction for about 72 hours at this temperature. After the reaction is completed, slowly add sodium sulfate solution to the resulting reaction mixture, wash the resulting mixture with hot water to remove sodium chloride, dry the resulting mixture at 80°C for 5 hours and wash with acetone, reflux the resulting mixture solution at 50-55°C for about 1 hour, cool and filter the resulting reaction mixture to obtain the target product molecule.

What are the chemical applications?

2,5-Diaminobenzenesulfonic acid is mainly used as an organic synthesis reagent and raw material in the dye industry, especially in benzenesulfonic acid dyes. Due to its excellent color brightness, good color fastness, and uniform dyeing properties, it has a wide range of applications in the dyeing of materials such as cellulose, paper, and feathers. In addition, in the process of synthesizing new pigments and dyes, 2,5-Diaminobenzenesulfonic acid is often used as a basic raw material, and the chemical reactions it participates in include coupling reactions and condensation reactions, which can generate compounds with specific colors and properties.

Reference

[1] Rathod, Gaurav K.; et al, Oriental Journal of Chemistry,2023,39(6),1720-1726.