Liquid Ortho Xylene also known as o-xylene, is a clear, colorless liquid with a sweet, aromatic odor. It is a type of xylene isomer, which is a mixture of three isomers of dimethylbenzene. Ortho-xylene is the most reactive and least stable isomer of the three. This is commonly used in the chemical industry as a solvent, particularly for the production of phthalic anhydride, which is used in the production of plasticizers, polyester resins, and alkyd resins. Liquid Ortho Xylene is also a volatile organic compound (VOC) and contributes to the formation of ground-level ozone and smog.