metalation, any chemical process by which a metal atom is introduced into an organic molecule to form an organometallic compound, but more commonly the process involving a hydrogen–metal exchange. An example is the metalation of benzene (C6H6) by reaction with ethylsodium (C2H5Na), forming phenylsodium (C6H5Na) and ethane (C2H6). Metalation by means of hydrogen–metal exchange is a very powerful method of removing a hydrogen atom (in the form of its cation, H+) from a chemical compound; the reaction, therefore, is useful in studying the relative acidities of such extremely weak acids as the hydrocarbons.