Ove up antibonding thetwo e cts on thep orbital

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: bital to m up. ove up antibonding Thetwo e cts on thep orbital cancel ffe The cancel e othe out; thetwo π orbitals are ach r pushe apart: “e rgy splitting”; d ne im portantly, theπ bonding orbital goes down. down Ethe ne π* π* 0 up Nonbondin g MO 2) p E π unchange d 3) π down Allyl p Orbital Allylic radical is stabilize by 13.5 kcal m -1. d ol Re sulting picture : # of e de nds on pe +,·,- π* 0 ? p E H 2C π H C CH2 Location Location of +,·,iisat s te ini rm te Reactivity of Allylic Position Reactivity A. Radical Haloge nation C CH H HC Me chanism : I nitiation: 1. Br2 hυ or Δ + Br2 Low conc. C C C Br HHH Faste than addition! r + HBr . 2 Br . + Br . CCC HHH CCC HHH + HBr . Propagation: 2. C C H H HC CCC HHH . Br2 . C C C Br + HHH CCC HHH . Br Te ination: rm Te . + . CH CH Br 3. C H Br2 BrC C C HH H . + Br . Br . CH CH 2 C H C CH H HC CC C HH H Anything that traps radicals, including the“dirt” on thewalls of Anything theflask, contribute to te ination. s rm t he A convenient solid brominating agent: convenient N-Bromosuccinimide, NBS Trace s, Trace always pre nt in NBS se Low Low...
View Full Document

Ask a homework question - tutors are online