sn1, sn2, e1, e2

nucleophiles

OH-

OR-

SH-

SR-

CCR-

CN-

I-, Br-, Cl-

N3-

NH3

H2O

ROH

RSH

structure of alkene + sn1/sn2

sn1 - carbocation formation

MOST 3 > 2 > 1 > Me LEAST STABLE

sn2 - steric factors

carbocation stability

MOST

1. 2 allylic / 2 benzyl / 3 allylic / 3 benzyl

2. 3

3. 1 allylic / 1 benzylic

4. 2

5. 1

6. Me+

LEAST

good leaving groups

BEST

1. I-

2. Br-

3. Cl-

4. H2O

5. F-

bad leaving groups

WORST

1. CH3O-

2. OH-

3. CH3OOO

solvents + sn1/sn2

polar protic - sn1

polar aprotic sn2

polar protic solvents

H2O

HCOOH

CH3OH

CH3CH2OH

CH3COOH

polar aprotic solvents

DMSO, DMF, acetone, acetonitrile

good nucleophiles

Br-

I-

CH3S-

RS-

OH-

CH3O-

RO-

RCC-

CN-

moderate nucleophiles

Cl-

F-

CH3COO-

RCOO-

CH3SH

RSH

R2S

NH3

poor nucleophiles

H2O

ROH

CH3OH

CH3OOH

R-COOH

nucleophiles + sn1/sn2

sn2 - acquires good nucleophile

sn1 - doesn’t care about nucleophile type

nucleophilicity + basicity relationship

nucleophilicity parallels basicity

X-CH3 + sn1/sn2

sn2 - yes

sn1 - no

primary carbocation + sn1/sn2

sn2 - yes

sn1 - rare, benzylic and allylic

secondary carbocation + sn1/sn2

sn2 - favored in aprotic, favored for good nucleophile

sn1 - favored in protic, favored for bad nucleophile, carbocation rearrangement

tertiary carbocation + sn1/sn2

sn2 - no

sn1 - yes, carbocation rearrangement

stereochemistry + sn1/sn2

sn2 - inversion

sn1 - racemization

minor product

hoffmann

major product

zaitsef

alkene stability

MOST

1. tetrasubstituted

2. trisubstituted

3. disubstituted (trans)

4. disubstituted (cis)

5. monosubstituted

heat + sn1/sn2/e1/e2

heat means elimination reaction will be favored