2.13 Drawing the resonance structure of the following compound requires one curved arrow. The head of this curved arrow is placed on the oxygen atom, and the tail of the curved arrow can only be placed in one location without violating the rules for drawing curved arrows. Draw this curved arrow.
2.14 Polyhydroxybutyric acid (PHB) is a component of biodegradable plastics that can be used in dissolving sutures or as a scaffold for skin regeneration. PHB is synthesized by linking together hydroxybutyric acid molecules. Inspect the arrows drawn for possible hydroxybutyric acid resonance and determine whether each curved arrow violates either of the two rules for drawing curved arrows in resonance structures. Describe any violations that occur.
2.15 For each of the structures below, draw the resonance structure that is indicated by the curved arrows. Be sure to include formal charges.