This reductive or cathodic dimerization was first practiced on a commercial scale in the USA in 1965. Other plants have been built in the USA and, since 1978, also in Western Europe. This electrochemical approach was also developed to a commercial process by Phillips Petroleum, and in Europe by ICI, Rh6ne- Poulenc, and UCB. In Japan, Asahi Chemical has practiced its own technology in a 26000 tonne-per-year plant since 1971.