Unformatted text preview: /\ If you have a 3° substarate, then the reaction will go via an with racemization.
What do you do if the substrate is 2°? You move on to factor 2.
There is one other way to stabilize a carbocation — by resonance. lf a carbocation is resonance stabilized, than it will be easier to form that carbocation: Cl Mﬁ/Q/KBM This carbocation is stabilized by resonance so, LG is willing to leave, and we can have an SNl reaction. Same happens with benzylic position. + Factor 2- The nucleophile In many cases we can determine from the substrate alone whether we will get 8N1 or 8N2 (3° —SN1 ; 1°
-SN2). What do we do if the substrate is 2°? We move on to factor 2 — the nucleophile.
There are 3 categories of nucleophiles: ' Very strong-Imth negative charge that IS not stabilizen. '- charge IS not on a halogen, and there is no resonance that spreads the charge out. RO‘ R/ I?\R 0,166 CHECJH? (Riv ‘ Moderate l- nucleophiles with a negative char e that is very stable. The halogens (F, Cl, Br,
are excellent examples. Other examples represent resonance—stabilized ions, where the
_ ___._.—_._.____...—«- charge is spread out over more than one electronegative atom. ...
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- Summer '08
- Organic chemistry