4,4'-Thiobisbenzenethiol is a trifunctional aromatic thio-ether bearing two thiol groups para to the central sulfur bridge. It is air-sensitive when moist, freely soluble in ethanol, ethyl acetate, aqueous alkali and DMF, sparingly soluble in cold water, and practically insoluble in hydrocarbons. Commercial product is supplied ≥98 % pure with ≤0.3 % water.
Key physicochemical data:
Melting point: 108–111 °C (lit.)
Predicted b.p.: >400 °C (decomp.)
Density: 1.38 g cm⁻³ (20 °C, solid)
pKa (thiol, 25 °C): ~7.8
Flash point: >200 °C
Log P (octanol/water): 4.5 (predicted)
Typical uses:
High-performance chain-transfer agent and sulfur donor for thiol-ene, thiol-epoxy and UV-curable formulations.
Precursor for poly(phenylene sulfide) (PPS) oligomers, high-refractive-index optical resins and flame-retardant epoxy hardeners.
Chelating ligand for heavy-metal sequestration and as a building block for symmetrical diaryl sulfoxides/sulfones.
Quality specification (commercial grade):
Purity (GC): ≥98 %
Water content (KF): ≤0.3 %
Free H₂S: ≤0.05 %
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/vapour; use gloves, goggles and adequate ventilation. Store under nitrogen with desiccant. SDS available on request.
