Requirements for each reaction Flashcards
SN1 steps
LG, NA (other steps can take place too)
SN2 steps
H+ transfer, NA, H+ transfer
Weak nucleophiles
F-, H2O, ROH
Strong nucleophiles
I-, Br-, Cl-, HS-, H2S, RSH, HO-, RO, NC, H3O+
SN2 uses _____ nucleophiles
Strong
Inversion- ______ process
SN2
SN1 products
Enantiomers
(MOST IMPORTANT FACTOR) Less sub e-phile favors
SN2
(MOST IMPORTANT FACTOR) More sub e-phile favors
SN1
Strong nucleophile points to
SN2
Good LGs are critical for both, but especially for
SN1
Less than 7 membered ring can only be
cis
Bredt’s rule
You can’t have a double bond at a bridgeheaded carbon in a ring with less than 8 members (spine of book)
How do you know if an alkene is E or Z
Look at either side of 2x bond
Is trans or cis more stable?
Trans
E2 mechanism
Base attacks H, causing proton transfer. Then LLG, making alkene and LG-
Rate of elimination rxn __________ with subs
Increases
Hoffman product
Less stable
Zaitsev product
More stable
E1 mechanism
LLG, Base attacks H creating double bond erasing + charge
E1 prefers Zaitsev (more sub) or hoffman (less sub)
Zaitsev
More polarizable nucleophiles are
More effective
Strong bases
H, DBN, DBU
Strong nuc/strong base
OH, MeO, EtO
Weak nuc, weak base
H2O, MeOH, EtOH
Nucleophile only, 1 or 2 sub
SN2
Nucleophile only, 2 or 3 sub
SN1
Base only
E2
strong base and strong nuc
E2 (Major for 2)
strong base and strong nuc, 1 and 2
E2 (major for 1)
Weak nuc, weak base, 1
SN2, E2 (slow)
Weak nuc, weak base, 2
SN2, SN1 (slow), E2, E1
Weak nuc, weak base, 3
SN1, E1
