Colorless liquid, has excitant odour. Melting point, boiling point° C 1.35 ° C141 101.3 kPa , ° C (2.0 4.85 kPa), relative density 1.052 (20/20 ° C), flash point (open cups) ° C, refractive index 1.4185 68.3. Soluble in water, alcohol, ether. Yi polymerization, often with 7-hydroxy hydrogen quinone or hydrogen quinone made the polymerization retarder. Acid is strong, have severely corrosive.