- ▸ Type II thioether-benzophenone photoinitiator with extended absorption, used with amine synergists in UV coatings (Coatings & Construction)
- ▸ Improves cure speed and surface cure of UV/UV-LED inks and varnishes (Industrial Manufacturing)
- ▸ Sensitizes cure of UV-curable plastics and adhesives (Plastics & Polymers)
A grade-specific Safety Data Sheet (SDS) — with the complete hazard classification, handling precautions, and transport information — is supplied with every shipment and available on request. Confirm all safety and regulatory details against the SDS for your specific grade.
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4-Benzoyl-4′-methyldiphenyl sulfide (BMS) is a thioether-substituted Type II benzophenone photoinitiator. The sulfur group red-shifts absorption to longer UV, giving efficient surface cure and self-sensitizing behavior — used with an amine synergist. Identity: CAS 83846-85-9.
What it is
4-Benzoyl-4′-methyldiphenyl sulfide (CAS 83846-85-9) is a benzophenone bearing a methyl-phenyl thioether, a pale solid. The thioether extends absorption into longer UV, similar in spirit to thioxanthones.
How it cures
A Type II initiator that abstracts hydrogen from an amine co-initiator under UV. Its red-shifted absorption makes it more efficient than plain benzophenone in many systems and a useful sensitizer; pair with an amine synergist such as EDB or EHA.
Applications
Used for surface cure of UV coatings and inks, including slightly pigmented systems, where a longer-UV benzophenone is wanted, alongside a Type I initiator for through cure. Compare the thioxanthone ITX and DETX.
Forms, grades and handling
BMS is supplied as a pale solid. Photoinitiators are light-sensitive — store cool, dry and dark, away from light and ignition sources. Handle per the current Safety Data Sheet (SDS); each lot ships with a Certificate of Analysis (CoA) and Technical Data Sheet (TDS).
Bulk supply and RFQ
RawSource sources 4-Benzoyl-4′-methyldiphenyl Sulfide direct from producers in bulk, with CoA, TDS and SDS per lot. Tell us your lamp (mercury or LED wavelength), system (clear or pigmented) and cure target, and we will quote the right grade. Compare the full range and selection logic in the photoinitiators guide.
Typical Properties
Typical reference values, not a specification; the Certificate of Analysis (CoA) for the lot governs.
| Property | Typical Value |
|---|---|
| Chemical / type | Photoinitiator (Type II, thioether benzophenone) |
| Photoinitiator type | Type II (H-abstraction) |
| Absorption | Red-shifted UV (thioether) |
| CAS Number | 83846-85-9 |
| Molecular Formula | C20H16OS |
| Molecular Weight | 304.4 g/mol |
| Handling | Light-sensitive; refer to the current SDS |
Regulatory & registration requirements
- TSCA (US):
- REACH (EU):
- EC number: 281-064-9
TSCA Inventory flag PMN: a commenced PMN (premanufacture notice) substance (EPA flag legend).
Source: EPA TSCA Inventory (July 2025 release) · ECHA CHEM — retrieved 2026-07-12
Frequently Asked Questions
What is 4-benzoyl-4′-methyldiphenyl sulfide used for?
BMS (CAS 83846-85-9) is a Type II benzophenone-type photoinitiator with thioether-red-shifted absorption, used for efficient UV surface cure with an amine synergist, often in slightly pigmented systems.
How is bulk BMS supplied and quoted?
RawSource supplies BMS in bulk with CoA, TDS and SDS per lot. Pricing is quote-based on grade and volume; submit an RFQ with your target quantity.
What is the REACH and TSCA regulatory status of 4-Benzoyl-4'-methyldiphenyl sulfide (BMS)?
4-Benzoyl-4'-methyldiphenyl sulfide (BMS) (CAS 83846-85-9) is subject to U.S. TSCA Inventory requirements; supplying it into the EU requires valid REACH registration ((EC) No 1907/2006). RawSource cannot verify a third-party supplier's registrations — buyers should require documented TSCA and REACH compliance for their jurisdiction and volume (EC 281-064-9).