Thiodiglycolic acid is the simplest α,α'-thio-dicarboxylic acid, consisting of two carboxy-methyl groups linked by a sulfur atom. The compound is freely soluble in water, alcohols, ketones and ethyl acetate, and only sparingly soluble in non-polar solvents. Commercial material is normally supplied ≥99 % pure and is stable under ambient conditions.
Key physicochemical data:
Melting point: 128–130 °C
Predicted b.p.: 338 °C (760 mmHg, decomp.)
Density: 1.50 g cm⁻³ (20 °C, solid)
pKa₁: 3.5; pKa₂: 4.5 (25 °C, water)
Log P (octanol/water): –0.4 (predicted)
Typical uses:
Chelating and biodegradable complexing agent for Ca²⁺, Fe³⁺, Cu²⁺ in electroplating, metal-finishing and detergent formulations.
Laboratory reagent for the colorimetric determination of iron and other transition metals.
Building block for thio-glycolic acid esters, sulfoxides/sulfones and sulfur-containing heterocycles used in pharmaceutical and agro-chemical synthesis.
Quality specification (commercial grade):
Purity (HPLC): ≥99 %
Water content (KF): ≤0.3 %
Chloride (Cl⁻): ≤0.01 %
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.
