Page 471 - Advanced Organic Chemistry Part A - Structure and Mechanisms, 5th ed (2007) - Carey _ Sundberg

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CHAPTER 4
Nucleophilic Substitution

TS endo

3.7 kcal mol –1
including ground state forward
energy difference TS exo reverse reaction:
associattion: ΔH = 5.3
‡
‡
forward ΔH = 5.6 kcal mol –1
kcal mol –1
reaction: ‡
‡
ΔH = 2.8 reverse
kcal mol –1 associattion:
‡
ΔH = 1.9
kcal mol –1
+
2 (X = OH )
2
(1.2(1.6)
–1
+
1 (X = OH ) 6 kcal mol )
2
–1
(0.0 kcal mol ) (0.9 (–2.3)
–1
kcal mol )
∗
Fig. 4.14. Computational energy diagram (B3LYP)/6-311+G ) for intermediates and transition states in
ionization and rearrangement of protonated 2-norbornanol. Reproduced from J. Org. Chem., 62, 4216
(1997), by permission of the American Chemical Society.
Scheme 4.5. Examples of Bridged Carbocations
+ + +
+
+ +

Bicyclobutonium ion a Bicyclo[3.1.0]hex-3-ylium b Bicyclo[2.2.2]hex-2-ylium c

+ + +
+ + +

Octahydrodimethano- Pentacyclo[4.3.0.0 2,4 .- 1-Methyl-2-adamantyl
naphthylium 0 3,8 .0 5,7 -non-9-ylium e cation f

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