Transcript CH 6-4 Power Point

CH 6-4 SN1 Reaction – Part I
•SN1: “Substitution….Nucleophilic….Unimolecular (RLS)”
•Rate = k [substrate]
(1st order reaction)
The SN1 Mechanism
•Carbocation Mechanism. “Ionization” of the substrate
occurs in the 1st Step:


RLS
(1)
intermediate
sp2;
trigonal
planar
The SN1 Mechanism
•In the 2nd Step the nucleophile “grabs” the Carbocation
forming a new bond.
(2)
intermediate
•If you add together Step 1 + 2 you must get the Net equation:
The SN1 Reaction
•Energy Diagram; minimum of two-steps:
(RLS)
E
R
P
Reaction Progress
The SN1 Transition State: RLS only
CH3
Br
H3C
RLS
H3C
H 3C
CH 3
+
C
C
Br
CH3
ts1
ts2
E
intermediate
R
H3C
CH3
CH3
Reaction Progress
P
“Polar” T.S.
“unimolecular”