1. A Review of General Chemistry

Draw resonance contributors for each of the following species and rank them in order of decreasing contribution to the resonance hybrid. Then draw the resonance hybrid.

d.

Draw resonance contributors for each of the following species and rank them in order of decreasing contribution to the resonance hybrid. Then draw the resonance hybrid.

f.

Which of the following has delocalized electrons?

a.

b.

c.

Draw all resonance structures of the following carbanion and carbocation.

(a)

(b)

How many atoms share the unpaired electron in semiquinone?

Draw the resonance contributors for the following radicals:

a.

Another way the preceding might be presented is to say that the minor resonance structure(s) reveal the reactivity of a molecule. Show how the minor resonance structure(s) can help us understand that the following reactions occur with the regioselectivity shown.

(a)

(b)

(c)

A carboxylic acid has two oxygen atoms, each with two nonbonding pairs of electrons.

(a) Draw the resonance forms of a carboxylic acid that is protonated on the hydroxy oxygen atom.

(b) Compare the resonance forms with those given previously for an acid protonated on the carbonyl oxygen atom.

(c) Explain why the carbonyl oxygen atom of a carboxylic acid is more basic than the hydroxy oxygen.

Draw the resonance contributors of the peptide bond in the less stable configuration.

Draw all possible resonance structures for the reactive intermediates shown.

(b)

Draw the important resonance contributors for both resonance-stabilized cations (in brackets) in the mechanism for acid-catalyzed hydrolysis of an amide.

Draw two important resonance structures involving the lone pair on oxygen for the molecule shown. Which carbons are most likely to act as nucleophiles?

Draw two important resonance structures involving the C―O π bond for the molecule shown. To which carbons would you expect a nucleophile to add?

Use resonance forms to show delocalization of the negative charge in the Ruhemann's purple anion.

Draw all possible resonance structures for the reactive intermediates shown.

(c)