Cyanophenol herbicides

The cyanophenol herbicides arrived as an intelligent replacement for Truffaut s dinitro-o-cresol. A typical example is ioxynil (6.71) 2,6-di-iodo-4-cyanophenol (Wain, 1963). It is a contact herbicide which powerfully uncouples oxidative phosphorylation (Section 4.5), in fact much more strongly than 2,4-dinitrophenol does (Kerr and Wain, 1964). It and the less expensive, if slightly slower acting, 2,6-dibromo-4-cyanophenol (bromoxynil), are used against young dicotyledonous weeds in cereal crops. They are also available as the octoate esters, for better penetration. 

---