Isotope effect criteria for reaction mechanism

The thermal fragmentation of t-butyl ethyl ether into ethanol and isobutylene was studied by temperature-dependent isotope effects and shown to involve a transition state characterized by linear hydrogen transfer accompanied by a large degree of quantum mechanical tunneling. The kinetic isotope effect of natural abundance sulfur-34 was used to verify a mechanism involving increased bonding at a sulfur in the transition state of the thioallylic rearrangement of α-methylallyl phenyl sulfide. Inverse kinetic secondary deuterium isotope effects were demonstrated for the addition of various reagents to the double bond of norbornene.. Correlations of these effects with transition state models were made