Molecule of the Day: Naphthalene
Naphthalene (C10H8) is a colourless solid with a strong smell of coal tar. It is a common household chemical, and is used as a component of mothballs.
At room temperature, it gradually sublimes to form gaseous naphthalene vapours, which are toxic to moths. It is also used as a fumigant to repel other insects and small animals. However, it is also toxic to humans, since it can damage red blood cells if inhaled in large quantities. It is also rather flammable, so it is being gradually replaced by para-dichlorobenzene in mothballs.
Naphthalene is aromatic, but its electrons are less delocalised than in benzene. As can be seen in the resonance structures below, some bonds have greater p-character due to having a double bond in 2 out of the 3 resonance structures, while others have less due to having a double bond in 1 only.
It can undergo reactions typical of aromatic compounds such as electrophilic substitution, but also undergoes oxidative cleavage of one of the rings, such as by acidified potassium permanganate, to produce phthalic acid.
Naphthalene is industrially produced from the fractional distillation of coal tar.