Dihydroxybenzoic acid is a class of benzoic acid derivatives containing two hydroxyl groups. It primarily includes the following six compounds:

2,3-Dihydroxybenzoic acid (CAS: 303-38-8)

2,4-Dihydroxybenzoic acid (CAS: 89-86-1)

2,5-Dihydroxybenzoic acid (CAS: 490-79-9)

2,6-Dihydroxybenzoic acid (CAS: 303-07-1 )

‌3,4-Dihydroxybenzoic acid‌ (CAS: 99-50-3)

‌3,5-Dihydroxybenzoic acid‌ (CAS: 99-10-5)

Typical Representative Substances

Take 2,4-dihydroxybenzoic acid as an example. Its molecular formula is C₇H₆O₄ (or simply C₇H₆O₄), with a melting point of 208-211°C. It is crystalline at room temperature, slightly soluble in water (8g/L) and freely soluble in organic solvents such as ethanol and ether.

Main uses

It is primarily used as a dye and pharmaceutical intermediate. For example, the production of acid mordant pink 3BM dye consumes approximately 157 kg of this compound per ton. Some derivatives are also used as chemical analysis reagents for elements such as iron and titanium.