Estabilidade de Carbocátions

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Solutions for Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy
4 Carbocation stability depends first on conjugation (benzylic, allylic), then on degree of carbon 
carrying the positive charge.
1°
2°
3°
1°2°
2°
less significant
contributor
more significant
contributor
equivalent to the
first resonance form
H
C
H
C
CH3H2C
C
H3C
C
CH2
HH3C
C
H H
H
H
H H
H
H
H
H
H
H
C
H2C
C
CH3
HH H3C
C
H
C
CH2H3C
H
C
H
H
H
HH
C C
H3C H
H O
CH2CH3
C C
H3C H
O
CH2CH3
C
H3C
O
H CH2CH3
H O
CH2CH3
C
H3C H
C
H3C H
O
H CH2CH3
C
H3C H
O
CH3CH2
Br
H O
CH2CH3
H3C Br
5
∆
allylic
Two carbons are 
electron deficient 
so the nucleophile 
can attack either.
The most basic 
species in the 
reaction mixture 
will remove this 
proton. The oxygen 
of ethanol is more 
basic than bromide 
ion.
H O
CH2CH3
340