Resonance and Delocalization - Organic Chemistry Concepts: An EFL Approach - page 61

Q 4.2. Study the pairs of resonance structures in Q 4.1 and try to evaluate their
relative contribution to the overall hybrid.
PROGRAM 11 Resonance in Conjugated Systems
A Programs 9 and 10 show how electron pairs are moved from atoms to adjacent
bonds. This program shows that it is possible to move these pairs from bond to
adjacent bond. Study the positively charged species below.
Write resonance forms for these carbocations.
B You should have drawn the following.
The first example is the allylic system. It shows two equal resonance forms. The second
example gives two unequal structures. Note how the lone pairs on the oxygen are used
in the curly arrow electron movements.
Now use the same method to draw resonance forms for the uncharged systems
below.