Question

Following each name is the number of Kekulé structures that can be drawn for it. Draw these Kekulé structures and show, using curved arrows, how the first contributing structure for each molecule is converted to the second and so forth. (a) Naphthalene (3) (b) Phenanthrene (5)

Short answer

Question: Draw the Kekulé structures for (a) Naphthalene and (b) Phenanthrene, and show the conversion between these structures using curved arrows.

Step-by-step solution

Draw the basic structure of naphthalene

Naphthalene is a bicyclic aromatic compound with two fused benzene rings. First, draw the two benzene rings connected to each other.

Draw the 3 Kekulé structures for naphthalene

To draw the 3 Kekulé structures for naphthalene, alternate the position of double bonds in each benzene ring, ensuring the double bonds follow the Huckel's rule of 4n+2 pi electrons.

Show the conversion between Kekulé structures using curved arrows

Use curved arrows to show how electrons move from one bond to another, indicating the conversion from one Kekulé structure to the next. Ensure that each curved arrow originates from a double bond and points towards the single bond, which will become a double bond in the next structure. (b) Phenanthrene (5)

Draw the basic structure of phenanthrene

Phenanthrene is a polycyclic aromatic compound with three fused benzene rings. First, draw the three benzene rings connected to each other in a linear arrangement.

Draw the 5 Kekulé structures for phenanthrene

To draw the 5 Kekulé structures for phenanthrene, alternate the position of double bonds in each benzene ring, again ensuring the double bonds follow Huckel's rule of 4n+2 pi electrons.

Show the conversion between Kekulé structures using curved arrows

Use curved arrows to show how electrons move from one bond to another, indicating the conversion from one Kekulé structure to the next. Ensure that each curved arrow originates from a double bond and points towards the single bond, which will become a double bond in the next structure.