2,2'-Dithio salicylic acid is a bis-(o-hydroxyaryl) disulfide in which two salicylic acid units are linked through the sulfur atoms at the 2-position. The material is air-stable, freely soluble in hot ethanol, methanol, aqueous alkali and DMF, sparingly soluble in cold water, and practically insoluble in non-polar solvents. Commercial product is supplied ≥98 % pure.
Key physicochemical data:
Melting point: 220–223 °C (dec.)
Predicted b.p.: >450 °C (decomp.)
Density: 1.54 g cm⁻³ (20 °C, solid)
pKa (carboxylic, 25 °C): ~3.2; phenolic ~9.0
Log P (octanol/water): 3.6 (predicted)
Typical uses:
Chelating and biodegradable complexing agent for Fe³⁺, Cu²⁺, Zn²⁺ in electroplating, metal-finishing and anti-oxidant formulations.
Laboratory reagent for colorimetric determination of iron and other transition metals.
Building block for thio-salicylate esters, metal-chelating polymers and sulfur-containing pharmaceutical intermediates.
Quality specification (commercial grade):
Purity (HPLC): ≥98 %
Water content (KF): ≤0.3 %
Residue on ignition: ≤0.1 %
Heavy metals: ≤20 ppm
Hazard statement:
Causes skin and eye irritation (H315 + H319). Harmful if swallowed (R22). Avoid inhalation of dust; use gloves, goggles and adequate ventilation. Store in a cool, dry place away from oxidants. SDS available on request.
