Unformatted text preview: Review: SN2. bimolecular exothermic reaction - transition state involves I
both the nucleophile and electrophile ° "“ (9,16) L.
l Rem-ﬂmte So for the rates of these reactions depend upon the following: - The Nature of the Leaving Group - - weak base Free Energy - The Reactivity of the Nucleophile All strong unhindered bases are good nucleophiles eg. CH30 6) Strong hindered bases are poor nucleophiles eg. (CH3)3CO G
Weak polarizable bases are good nucleophiles eg. I, Br Weak less polarizable bases are poor nucleophiles e.g. CH30H, H20 . The Solvent Polar aprotic
For a SN2 reaction to proceed quickly you want to Free L J
choose a solvent that make the nucleophile more energy f__
reactive. Since the nucleophile has a —ve or partial —ve (G) L“;
charge polar aprotic solvents will speed up the Polar protic
reaction. Polar protic solvents that hydrogen bond to
the nucleophile imped the movement of the —
nucleophile and stabilize the nucleophile. Ream“ °°°'di"at° 5.1 — Substitution 32 ...
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- Fall '07
- Organic chemistry