Physicochemical properties: Phenothiazine is an organic aromatic compound composed of sulfur and nitrogen atoms connected by two benzene rings (phenothiazine parent nucleus), recrystallized from ethanol or benzene for orthorhomeric yellow or grain-green prismatic crystals, precipitated from toluene or butanol for yellow leaf crystals, volatilizing with water vapor. Relative molecular mass 199.28. Melting point 186 ~ 189℃. Boiling point 371℃, 290℃(5.333×103Pa), 130℃(0.133×103Pa) sublimation. Insoluble in water, petroleum ether and chloroform, slightly soluble in ethanol and mineral oil, soluble in ether and acetone, easily soluble in benzene and hot acetic acid, solubility at 25℃ (g/100g) : acetone 25.40, ethanol 3.40, benzene 32.0. In the sun and in the air, the color becomes darker, and 0.3% methylamine can be added to protect it when stored. The color also tends to darken when there are impurities. It decomposes when exposed to acid and acid vapor, and produces toxic nitrogen oxide and sulfur oxide gases. Phenothiazine has sublimation, weak odor, irritation to the skin, can cause maculae, can also be absorbed through the skin, causing visceral disorders. Rat transoral LD505,000 mg/kg. The maximum allowable concentration in the workplace is 5mg/m3. The laboratory obtains this by heating diphenylamine with sulfur at the same time until the hydrogen sulfide free gas is released.

Chemical properties: yellow or gray-green small flake crystals or powders. Melting point 185.5℃, boiling point 371℃(decomposition), 290℃(5.33kPa), insoluble in petroleum ether, chloroform and water, soluble in ether and hot acetic acid. Air oxidizes when exposed to light. It has sublimation. There is a faint odor. It irritates the skin.

Uses: This product is mainly used as an excellent inhibitor of alken-based monomer, widely used in the production of acrylic acid, acrylic acid ester, methacrylate, vinyl acetate. It is also used in the synthesis of drugs, dyes, and auxiliaries for synthetic materials (such as polymerization inhibitor of vinyl acetate grease, raw material for rubber antioxidant).