page 41-42 Flashcards
What type of reaction mechanism is shown in the slide?
A: An
SN2 (substitution nucleophilic bimolecular) mechanism.
What does the rate equation for the
SN2 reaction depend on?
A: The concentrations of both reactants:
[
C
H
3
B
r
]
[CH
3
Br] and
[
C
H
3
C
O
O
−
]
[CH
3
COO
−
].
What does second-order kinetics imply about the reaction mechanism?
A: It suggests a one-step, bimolecular mechanism.
In the reaction, what is the nucleophile?
A: The acetate ion (
C
H
3
C
O
O
−
CH
3
COO
−
).
What is the leaving group in the reaction?
A: Bromide ion (
B
r
−
Br
−
).
What product is formed from the reaction of methyl bromide (
C
H
3
B
r
CH
3
Br) and acetate (
C
H
3
C
O
O
−
CH
3
COO
−
)?
A: Methyl acetate (
C
H
3
C
O
O
C
H
3
CH
3
COOCH
3
).
How does the
S
N
2
S
N
2 mechanism occur?
A: Bond breaking and bond making occur simultaneously in a single step.
Why are both reactants involved in the rate equation for
S
N
2
S
N
2?
A: Because the nucleophile and the substrate interact in the same step.
What role does the acetate ion play in the
S
N
2
S
N
2 mechanism?
A: It acts as a nucleophile, attacking the carbon attached to bromine.
What characterizes the transition state in an
S
N
2
S
N
2 mechanism?
A: A pentavalent carbon where the incoming nucleophile and leaving group are partially bonded.
What type of mechanism does Reaction 2 follow?
A: An
SN1 (substitution nucleophilic unimolecular) mechanism.
What does the rate of Reaction 2 depend on?
A: The concentration of the alkyl halide
(
C
H
3
)
3
C
B
r
(CH
3
)
3
CBr only.
What is the rate equation for Reaction 2?
A:
rate
=
k
[
(
C
H
3
)
3
C
B
r
]
rate=k[(CH
3
)
3
CBr] (first-order kinetics).
How many steps are involved in the
SN1 mechanism?
A: Two steps.
What is the rate-determining step in the
SN1 mechanism?
A: The step involving the dissociation of the alkyl halide to form a carbocation and a bromide ion.
What intermediate is formed during the
SN1 reaction?
A: A carbocation.
Why is the mechanism called “unimolecular”?
A: Because the rate-determining step involves only one reactant, the alkyl halide.
What product is formed when acetate reacts with the carbocation?
A: The ester
(
C
H
3
)
3
C
O
C
O
C
H
3
(CH
3
)
3
COCOCH
3
.
What is the leaving group in Reaction 2?
A: Bromide ion (
B
r
−
Br
−
).
How does the stability of the carbocation affect the
S
N
1
S
N
1 mechanism?
A: The reaction favors the formation of stable carbocations, such as tertiary carbocations like
(
C
H
3
)
3
C
+
(CH
3
)
3
C
+
