Location effect of an OH group on the chemiluminescence efficiency of 4-hydroperoxy-2-(o-, m-, or p-hydroxyphenyl)-4,5-diphenyl-4H-isoimidazoles

In studying the location effect of an OH group on the chemiluminescence efficiency of 4-hydroperoxy-2-(o-, m-, or p-hydroxyphenyl)-4,5-diphenyl-4H-isoimidazoles 4, we found that the efficiency of 4a with o-OH was 0.28 times that of lophine peroxide on initiation with KOH/MeOH. When the trigger base was changed to TBAF/THF, efficiency was 530-fold in dry DMF. The efficiency of 4b with m-OH or 4c with p-OH showed no such dramatic change.