Pyridine is a chemical compound with the formula C5H5N. It is classified as a heterocyclic organic compound, and is the simplest member of the pyridine family. Pyridine is a colorless gas with a pungent odor. It is widely used in the production of other chemicals. Pyridine is a colorless, crystalline organic compound that is the simplest member of the pyrimidine family. It is used in organic synthesis as a reagent, and is also a precursor to the widely used dye, methylene blue. Pyridine is highly soluble in water, and is widely used as a precursor to dyes and pesticides. It is also used in the production of hydrofluoric acid, and is added to gasoline to improve the combustion of hydrocarbons.