1 (939)

Prévia do material em texto

CHAPTER 22 931 
 
22.29. Attack at either C2 or C4 generates an intermediate that exhibits a resonance structure with a nitrogen atom that 
bears a positive charge and lacks an octet (highlighted below). Attack at C3 generates a more stable intermediate 
(carbon is more electropositive than nitrogen so a carbon atom can better stabilize a positive charge associated with an 
unfilled octet): 
 
 
 
 
 
22.30. Attack at the C2 position proceeds via an 
intermediate with three resonance structures: 
 
 
 
In contrast, attack at the C3 position proceeds via an 
intermediate with only two resonance structures: 
 
 
 
The intermediate for C2 attack is lower in energy than 
the intermediate for C3 attack. The transition state 
leading to the intermediate of C2 attack will therefore be 
lower in energy than the transition state leading to the 
intermediate of C3 attack. As a result, C2 attack occurs 
more rapidly, giving the following product: 
 
 
 
22.31. 
(a) The second compound will have an N-H stretching 
signal between 3300 and 3500 cm-1. The first compound 
will not have such a signal. 
(b) When treated with HCl, the first compound will be 
protonated to form an ammonium salt that will produce 
an IR signal between 2200 and 3000 cm-1. The second 
compound is not an amine and will not exhibit the same 
behavior. 
 
22.32. 
(a) The 1H NMR spectrum of the first compound will 
have a singlet resulting from the N-methyl group. The 
1H NMR spectrum of the second compound is not 
expected to exhibit any singlets. 
(b) The 1H NMR spectrum of the first compound will 
have six signals, while the 1H NMR spectrum of the 
second compound will have only three signals. 
22.33. The designation “primary” indicates that two 
hydrogen atoms are attached to the nitrogen atom, while 
www.MyEbookNiche.eCrater.com