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Solutions for Amines
57 continued
O(b)
H A C
O
H
C
O
H N
H
C OH
N H
A
C OH
N
H AC OH
N
H
– H2OC
N
A
C
N
H
H
To this point, everything is the same in the two mechanisms.
But now, there is no H on the N to remove to form the imine.
The only H that can be removed to form a neutral intermediate
is the H on C next to the carbocation.
C
N
H
enamine
(c) A secondary amine has only one H to give, which it loses in the first half of the mechanism to form the 
neutral intermediate called a hemiaminal, equivalent to a hemiacetal. In the second half of the mechanism, 
the H on an adjacent carbon is removed to form the neutral product, the enamine. The type of product 
depends entirely on whether the amine begins with one or two hydrogen atoms.
A– is the conjugate 
base of the acid HA.
called a hemiaminal
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