2 B or not 2 B

1
2 B or not 2 B?
??? ????? ????? ???????????? ?- SN1 ???? ?- SN2?
SN2 ???? ????? ?????. ???, ?? ??????? ????? ?????
????? ????? SN1.
????? ????? (??"?, ?????? ?????????) ???? SN2
???? ????? ????? SN1.
2
???????? ????? ?????? ?? SN2.
R-X Nu ? R-Nu X
3
?????? ???? ????????.
E
SN1
SN2
Reaction coordinate
4
??????? ????????? ???? ????????
XOR, NR2, SR etc.
? -80 kcal mol-1
? -65 kcal mol-1
5
???? ?????? ?????? ?????
DH (RH, kcal mol-1)
-66.2
-81.2
???? ??????? ??????? ???????? ?? ?????? ????
?????????
6
R-Cl ? R Cl
36
21
15
7
CH3Cl ? CH3 Cl
DH229 kcal mol-1
CH3CH2Cl ? CH3CH2 Cl
DH193 kcal mol-1
CH3 Cl ? CH3Cl
DH-229 kcal mol-1
CH3CH2Cl CH3 Cl? CH3CH2 Cl CH3Cl
DH193-229 -36 kcal mol-1
????? ?????? ???????? ?????? SN2 ??????? SN1.
8
???? ????? ????? ?????? ??? ?????????
9
?????
???? ?????
hyperconjugation
conjugation
10
R (Å), A()
R2
R1 1.531 1.443
R1
A1
R2 1.096 1.112
R3 1.094
R4 1.094

R2
A1 111.4 101.9
A3
R1
A1
A2 114.3
A2
R4
R3
A3 117.6
11
?????
?? ?????!!!
?? ?????!!!
???? ????? ?? R-X
R 1 SN2
R 3 SN1
R 2 SN2 SN1
12

?????? ????? (?????????)
S
RatekS
(?) ???? ???? ?????? ???? ????? SN1?
13
????? ?????? ????? ?? ?????? ??????, ???
??????????? ?????? ?????? ?-180 ?????, ???? ????
?-SN2 ????.
?????, ???????? ????? SN1.
14
??????
??????
DH-36 kcal mol-1
15
E
Reaction coordinate
16
(No Transcript)
17
2-electrons-3-centers
???????? ????
??????? ????????
?????? ????? ????? ?????
18
-Br
H2O -H
????? ?????? ???
CB26 kcal mol-1
DHstrain-20 kcal mol-1
CP6 kcal mol-1
19
-Br
H2O -H