Acetaldehyde, a colorless flow liquid , with a pungent odor, soluble in water, alcohol, ether, chloroform, acetone and benzene, flammable & volatile and oxidation into acetic acid. In the presence of a small amount of acid, it is very easy to aggregate into trimers Acetaldehyde (liquid , melting point 124 ℃), or produce polyacetaldehyde at low temperatures. These two polymerization in a small amount of sulfuric acid can happen regeneration and decompose into Acetaldehyde. Ity is mainly produced with ethanol in oxidation method.