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CH1012
SN2 MECHANISM
1o alkyl halides RCH2-X always SN2
2o alkyl halides R(R’)CH-X        generally SN2
Experimentally
    Rate (of subs.)    =    k [RCH2X] [Nu:-]
Proposed Mechanism
chiral centre
S
R
nucleophile       leaving
                            group
TS
plane
(Et = C2H5)