Carbon four, namely butane (C4H10), also known as n-butane, is a general term for two alkanes hydrocarbons with the same molecular formula (C4H10).Including: n-butane and isobutane (2-methylpropane).Carbon four is a flammable, colorless, easily liquefied gas. It is an important raw material for the development of petrochemical and organic raw materials, and its use has been paid more and more attention.

Carbon five refers to the number of carbon atoms is 5 alkane compounds, molecular formula C5H12, molecular weight 72.146, there are n-pentane , isopentane , neopentane  three isomers, commonly known as carbon five. Carbon five has a wide range of applications in the chemical industry, as a raw material and solvent for organic synthesis, as well as for refining petroleum products and manufacturing rubber. In addition, the by-product C-5 fraction in the process of petroleum cracking to ethylene can also be used to make synthetic rubber, coatings and other petrochemical products and fine chemical products.