Naphthenes are a group of cyclic, saturated hydrocarbons. Furthermore, in petrochemistry, naphthene is the common name for cycloalkanes occurring in petroleum, such as cyclopentane and cyclohexane, and their alkyl derivatives. Naphthenes are poorly soluble to insoluble in water. They are highly flammable but relatively inert. | Industrially important naphthenes include cyclohexane and methylcyclohexane.