This invention provides aromatic diimines which have imino hydrocarbylidene groups with at least two carbon atoms, and aromatic secondary diamines which have amino hydrocarbyl groups with at least two carbon atoms. Both the aromatic diimines and the aromatic secondary diamines either are in the form of one phenyl ring, or are in the form of two phenyl rings connected by an alkylene bridge; each position ortho to an imino group or an amino group bears a hydrocarbyl group. When in the form of one phenyl ring, there are two imino groups on the ring or two amino groups on the ring; the imino groups or amino groups are meta or para relative to each other. When in the form of two phenyl rings connected by an alkylene bridge, there is either one imino group or one amino group on each phenyl ring. Also provided are processes for forming diimines and secondary diamines.