4-Methylbenzophenone is an aromatic ketone carrying a methyl group at the para-position of one phenyl ring. The extended π-system provides strong UV-A/UV-B absorption (λmax ≈ 330 nm, log ε 3.9) together with excellent thermal and photochemical stability. It is practically insoluble in water (< 0.1 mg L⁻¹ at 25 °C), freely soluble in toluene, chloroform and most acrylic monomers, and can be recrystallised from ethanol or methanol. Commercial material is supplied at ≥ 99 % purity and remains stable for ≥ 2 years when stored at room temperature in tightly closed containers away from light.
Key Physicochemical Data:
Melting point: 56.5–57 °C (lit.)
Boiling point: 326 °C / 760 mmHg (lit.)
Density: 0.9926 g cm⁻³ (25 °C)
Flash point: 143 °C (closed cup)
Log P (octanol/water): 3.69 (25 °C)
Vapour pressure: 0.059 Pa at 25 °C
Typical Uses:
Type II photoinitiator for UV-LED curing of clear coatings, over-print varnishes, wood finishes and structural adhesives; especially suited for thick-section or pigmented formulations .
UV-absorbing additive in food-contact packaging, cosmetic containers and optical-grade polymers .
Reference standard for GC/MS and HPLC determination of migrants from packaging materials .
Quality Specification (Commercial Grade):
Purity (GC): ≥ 99 %
Water content (KF): ≤ 0.3 %
Individual impurity (GC): ≤ 0.5 %
Total impurities (GC): ≤ 1.0 %
Heavy metals: ≤ 20 ppm
Hazard Statement:
Causes skin and eye irritation (H315 + H319); harmful if swallowed (H302) or inhaled (H332) . Avoid dust formation; use gloves, goggles and adequate ventilation. Store in a cool, dry place away from oxidants and strong acids. SDS available on request.
