Molecular formula C3H4O2, molecular weight 72.06. Colorless liquid with irritating odor, corrosive and strong acidity. Soluble in water, ethanol and ether, and also soluble in benzene, acetone, chloroform, etc. The melting point is 13.5 ° C, the boiling point is 140.9 ° C, and the density (20/4 ° C) is 1.0611 g / cm3. Chemically lively. It is easy to polymerize in air and can be reduced to propionic acid by hydrogenation. Addition with hydrogen chloride produces 2-chloropropionic acid. For the preparation of acrylic resins and other organic synthesis. It can be obtained by oxidation of acrolein or hydrolysis of acrylonitrile. It can also be produced by carbon monoxide, acetylene and water under the action of a nickel catalyst.