Chapter 9 Reactions

Question 1

Sn1

Reactants (including conditions/catalysts), Products, Intermediates, Regioselectivity, Stereoselectivity

Answer 1

Reactants: Electrophile (R-X), Weak Nucleophile (Nu-)
Catalysts/Conditions: Polar,protic solvent (ex: H2O, R-OH,)

Products: Product (R-Nu), Leaving Group (X-)
Intermediate: Carbocation
Regioselectivity: 3>2, doesn’t occur with 1/methyl
Stereoselectivity: Inversion (faster) AND Retention (slower) of stereochemistry

Question 2

E1

Reactants (including conditions/catalysts), Products, Intermediates, Regioselectivity, Stereoselectivity

Answer 2

Reactants: Electrophile (R-R-X) and Base
Catalysts/Conditions: polar protic solvent

Products: Alkene and HX
Intermediate: Carbocation
Regioselectivity: Zaitsev major, Hoffman minor
Stereoselectivity: none

Question 3

Sn2

Reactants (including conditions/catalysts), Products, Intermediates, Regioselectivity, Stereoselectivity

Answer 3

Reactants: Electrophile (R-X), Good Nucleophile (Nu-)
Catalysts/Conditions: polar, aprotic solvent (ex. DMF, DMSO, acetone, acetonitrile, THF)

Products: Product (R-Nu), Leaving Group (X-)
Intermediate: No intermediate (no rearrangements)
Regioselectivity: methyl>1>2, doesn’t occur with 3
Stereoselectivity: Inversion of Stereochem

Question 4

E2

Reactants (including conditions/catalysts), Products, Intermediates, Regioselectivity, Stereoselectivity

Answer 4

Reactants: Electrophile (R-X), Good Nucleophile (Nu-)
Catalysts/Conditions: polar, aprotic

Products: Alkene and HX
Intermediate: None
Regioselectivity: Small Base: Zaitsev, Bulky Base: Hoffman
Stereoselectivity: B-H and LG must be anti and coplanar

Question 5

Leaving Group notes

Answer 5

L.G is a stable anion
> anion stability = >size = >L.G. ability = >Sn2 rate
Good L.Gs are generally weak bases

Question 6

Nucleophile notes

Answer 6

Generally, nucleophilicity parallels basicity (unless bulky base)
(-) charged species > neutral species
more E.N = less nucleophilicity

Question 7

___ and ___ always occur together

Answer 7

Sn1 and E1

Question 8

Rate of Sn1/E1

Answer 8

Rate = k[electrophile]

Question 9

Rate of Sn2/E2

Answer 9

Rate = k[electrophile][nucleophile]