Sec-butyl, or secondary butyl, is a type of hydrocarbon compound with the chemical formula C4H10. It is an isomer of butane, meaning it has the same molecular formula but a different structure. In sec-butyl, the four carbon atoms are arranged in a branched formation, which affects its physical and chemical properties. This compound is commonly used in various industrial applications, including as a solvent and in the production of certain chemicals. Sec-butyl is also a component in the synthesis of plastics and rubber, contributing to the versatility of these materials in everyday products.