Isopentane is more stable than pentane by 1.8 kcal/mol, and neopentane by 5 kcal/mol. [1] A related cycloalkane is cyclopentane, although this is not an isomer of pentane as its molecular formula is different, cyclopentane is an isomer of the pentenes. Uses Being an unfunctionalized hydrocarbon, pentane is a commodity chemical.