Solubility in ethanol at
The presence of the hydroxyl group,
The nonpolar naphthalene molecules will be attracted to the nonpolar ethyl groups and allow for some degree of solubility to exist.
By comparison, naphthalene is virtually insoluble in water, a much more polar compound than ethanol.
At the same temperature, naphthalene has a solubility of 31.6 mg per liter of water.