4-(Methylthio)benzoic acid is an aromatic carboxylic acid carrying a lipophilic methylthio group at the para-position. The compound is odourless to faintly sulfurous, air-stable, and readily soluble in common organic solvents (ethanol, methanol, ethyl acetate, chloroform) while only sparingly soluble in cold water.
Key physical data: m.p. 192–196 °C; predicted b.p. 319 °C; predicted density 1.28 g cm⁻³; predicted pKa 4.28; predicted log P 2.74. The substance shows good thermal stability and can be stored indefinitely in a tightly closed container at room temperature away from strong oxidants .
Typical uses:
Versatile building block for the synthesis of aryl-sulfone-type COX-2 inhibitors (e.g., rofecoxib, etoricoxib) via oxidation of the thio-ether to the corresponding sulfone followed by further hetero-cyclisation .
Starting material for the preparation of 4-(methylthio)benzoyl chloride, a key intermediate for agro-chemicals, UV-absorbers, and sulfonamide-based herbicides .
Ligand precursor for metal–organic frameworks (MOFs) and luminescent metal complexes; the methylthio unit can be oxidised to sulfoxide or sulfone to tune the electronic properties of the resulting materials .
Quality specification (commercial grade):
Purity (GC): ≥98 %
Water content (KF): ≤0.3 %
Residue on ignition: ≤0.1 %
Heavy metals: ≤20 ppm
Hazard statement: Causes skin and eye irritation; may cause respiratory irritation. Use gloves, goggles and a dust mask. SDS available on request.
