2-Methyl-4-Isothiazolin-3-One is a technically defined substance with the molecular formula C4H4ClNOS and a molecular weight of 149.60. It exhibits a Melting Point range of 54-55 °C. For a mixture of 5-chloro-2-methyl-3(2H)-isothiazolone and 2-methyl-3(2H)-isothiazolone, it presents as a clear light amber liquid with a density of 1.256 - 1.296 g/mL at 20-25 °C and a viscosity of 11.4 cP at 25.7 °C. The hazard signal word for this substance is Warning.

• CAS Number: 2682-20-4
• Molecular Weight: 149.60
• Molecular Formula: C4H4ClNOS
• Melting Point: 54-55 °C
• Exact Mass: 148.9702126
• GHS Signal Word: Warning
• Density: For a mixture of 5-chloro-2-methyl-3(2H)-isothiazolone and 2-methyl-3(2H)-isothiazolone: Clear light amber liquid; density: 1.256 - 1.296 g/mL at 20-25 °C; viscosity: 11.4 cP at 25.7 °C
• Hazard Statements:
• H300: Fatal if swallowed [Danger Acute toxicity, oral]
• H317: May cause an allergic skin reaction [Warning Sensitization, Skin]