SN2, SN2, E1, E2, strong/weak base/nuc, protic and aprotic

SN2

me>1°>2°

Strong Nucleophile

Polar aprotic

LG: OTs- > I- > Br- >Cl-

Rearrangement: NO

Stereochem: Inversion

Concerted one step

SN1

3°> 2°

Weak nucleophile

Polar protic

LG: OTs- > I- > Br- > Cl-

Rearrangement: Possible

Stereochem: Racemization

Carbocation formation—> Multistep

E2

3°> 2°> 1°

Strong base

Polar aprotic** —> faster in aprotic but more likely in protic

LG: OTs- > I- > Br- > Cl-

Rearrangement: NO

Stereochem: B-Hydrogen has to be Anti!!!

Concerted 1 step

E1

3°>2°

Weak base (water/alc most common)

Polar protic

LG: OTs- > I- > Br- > Cl-

Rearrangement: Possible

Stereochem: None

Carbocation formation—> multistep

Weak Nuc/ Weak base

H2O, ROH, RCOOH

SN1/E1

Strong nuc/ weak base:

CN-, N3-, Cl-, Br-, I-, RS-, HS-, RSH, H2S, RNH2, R3P

SN2

Strong nuc/ Strong base

OH-, RO- and HONC with neg charge

SN2, E2

Strong/ Bulky base:

t-BuO-, DBN, DBU, LDA

E2—> can do SN2 on methyl halide

Super bases (strong bases)

NaH, NaNH2, LiCH2CH2CH2CH3

E2

Polar Protic

Water, Alcohol, Carboxylic acid

Polar Aprotic

Acetone, DMSO, acetonitrile, DMF, THF, HMPA, Diethyl ether

• Can’t H bond (Doesn’t have H attached to O or N)

SN1, E1 Rate

Rate= k[Substrate]^x

SN2 Rate

Rate= k[substrate]^x [nucleophile]^y

E2 rate

Rate= k[substrate]^x [base]^y

For ranking nucleophiles:

The stronger the base, the better the nuc (down a group, larger atoms more polarizable

For leaving groups:

The weaker the base, the better the leaving group