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CH1012
REGIOSELECTIVITY
A regioselective reaction is one where one region of bond-making or bond-breaking is preferred over all others.
CH3CH2CH3 + Br. ® CH3CHCH3. + HBr
With propane there are different Eact values for the chain propagation step if the 1o or 2o H’s are attacked by the Br. radical.
The 2o H abstraction route has the lower Eact and therefore occurs at a higher rate than the other route thereby explaining the regioselectivity. (k = A e-Ea/RT)
