Freon is a colorless gas at room temperature orvolatile liquid, slightly aroma, low toxicity, stable chemicalproperties. One of the most important is dichlorodifluoromethaneCCl2F2 (F - 12). Dichlorodifluoromethane for colorless gas undernormal temperature atmospheric pressure; Melting point - 158degrees Celsius, the boiling point 29.8 degrees Celsius, density1.486 g/cm (30 degrees Celsius); Slightly soluble in water, solublein ethanol, ethyl ether; Do not reaction with acid, alkali.Dichlorodifluoromethane can be made of carbon tetrachloride andanhydrous hydrogen fluoride in the reaction system in the presenceof catalyst, the reaction product is dichlorodifluoromethane, andCCl3F and CClF3 will CCl2F2 separated by fractionation.