Acrylic acid (IUPAC: prop-2-enoic acid) is an organic compound with the formula CH2=CHCO2H. It is the simplest unsaturatedcarboxylic acid, consisting of a vinyl group connected directly to a carboxylic acid terminus. This colorless liquid has a characteristic acrid or tart smell. It is miscible with water, alcohols, ethers, and chloroform. More than a thousand kilotons are produced annually.