Nature of Transition State:The Hammond Postulate
If two states, for example, a transition state and an unstable intermediate, occur
consecutively during a reaction process and have nearly the same energy content,
their interconversion will involve only a small reorganisation of molecular structure.
Or in other words...a reactive intermediate resembles the transition state the more the
closer the intermediate is in energy to the transition state in question.
Evidence for intermediacy of
The electrophile in this case is:
A linear molecule, isoelectronic with carbon dioxide.NO2+ can be isolated as salts
which are extremely powerful nitrating agents (commercially available):
Evidence for a two step process:
-120oC
HSO3F
BF-
4
can be isolated as a
bright yellow solid
H2O
H2SO4
HNO3
NO2+
HSO4-
NO2+
O2N
+H2O