Du Pont, which was the largest producer of adiponitrile based on 1,4-dichlorobutene, independently developed the direct hydro- cyanation of butadiene, thereby avoiding an alkali chloride elec- trolysis and the pollution problems inherent with NaCl. For the near future at least, benzene, the third type of feedstock, has the bleakest prospects. The reduction of the lead content in gasoline, already under way in many countries, makes an addi- tion of aromatics essential to improve the octane number. This could lead to a shortage of aromatics.