Compounds 2 and 7 are structurally similar except their acylium part and the obvious activity difference may be due to an additional acetal formation by hydroxyl group present on benzene ring in acylium part of molecule 2, whereas its lacks in compound 7.
Contrary the compounds 3, 20, 23 and 25 have same acylium group but having p-chloro, o-hydroxy, o-bromo in 3,23 and 25, respectively, and compound 20 have anaphthyl group, caused the complete loss of activity.
Compounds 1, 5, 13, 15, 22, and 23 containing ortho hydroxyl groups in benzilidium part of the molecules but having different acylium part were found to be completely inactive due to steric hindrance.
Compounds 8 and 12 having the same benzilidium part but acylium part is para-chloro substituted benzene in compound 8 while in compound 12 it is methyl subsituted instead of chloro group.
Compounds 3, 18-21, and 24-26 were found completely inactive due to inappropriate substituted benzilidium as well as acylium parts of the compounds which is prerequisite in this type of molecules and already been established in the foregoing discussion.