Phenothiazine Prills

CAS Number: 92-84-2
Empirical formula: C12H9NS

Achieving the highest performance

WeylChem Allessa is the world's largest producer of Phenothiazine Prills, an amine-based radical scavenger with versatile functionality as a monomer stabilizer for unsaturated compounds, antioxidant, and building-block in pharmaceutical synthesis.

Our prills offer optimal processing quality and improved stability in storage and handling and can be used at high temperatures and under oxygen-free conditions.

Improved solubility in acrylic acid and acrylates
Optimal processing quality
Improved storage
Uniform particle size gives improved solubility in acrylic acid and acrylate production
Greater bulk density liberates more storage space
Spherical shape and low dust content significantly reduce stickiness of material

Applications in the chemical and pharmaceutical industries

  • Monomer stabilizer for unsaturated compounds (monomers), protecting them from uncontrolled polymerization. The addition of 200 – 3000 ppm of phenothiazine is sufficient in most cases to inhibit premature polymerization of acrylic acid, methacrylic acid, acrylates, and vinyl compounds and thereby increases their stability during production and storage.
  • Antioxidant increasing the lifetime of synthetic rubber (chloroprene) and synthetic lubricating oils in order to improve their durability.
  • Building-block in pharmaceuticals synthesis or as an API in veterinary medicine.



Phenothiazine Prills



92 - 84 -2





Molecular weight (g/mol)




Yellow to greenish prills


Assay (% a/a)

≥ 99.5


Diphenylamine ( % a/a)

≤ 0.5


Particles size (% > 500 μm)

≥ 98.0


Melting point (°C)

≥ 184.0


Heating loss (%)

≤ 0.2


Ash (%)

≤ 0.1


*CoA: listed on Certificate of Analysis; each lot is tested.

TD: Technical Data: Not routinely examined, therefore no certification possible.

Phenothiazine prills

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