We
have uncovered a way in which dynamic
effects can be important in ordinary
organic reactions in solution. The
key is that the reaction must involve
two successive transition states without
an intervening intermediate. That
may sound impossible; in fact, it is
likely quite common. Our goal is
to experimentally test for dynamic
effects in diverse organic reactions,
pinning down the breadth of chemistry
for which our most fundamental concepts
and assumptions fail.
Most of the mechanistic probes in
chemistry - such as kinetics,
substituent effects, isotope effects,
and activation parameters- define the
transition state. When defining the
transition state does not define the
mechanism, everything we think we know
about reaction mechanisms needs to be
reconsidered.