Kinetic isotope effects for the benzylic hydrogen atom abstraction reactions of the triplet states of several diarylcarbenes with toluenttoluene-ds in fluid solution were determined by measuring the ratio of 1, 2-diphenylethane to 1, 2-diphenylethane-d7 produced in the reaction. Eight carbenes were studied: dibenzocycloheptadienylidene (DBC); 1- naphthylphenylcarbene (1-NPC), 4-biphenylphenylcarbene (BPC), 2- ...