what part of the structure difference makes urea and naphthalene behavior differently?

Question

Organic solid such as naphthalene and 1, 4-dichlorobenzene are widely used as mothballs b/c they are toxic to insects ans sublime at a slow rate at atmospheric pressure. Other organic solids such as urea and lactic acid do not have any appreciable vapor pressure under ambient conditions. Explain this behavior in terms of the structure of the molecules.

Answer 1

napthalene and DCB are both aromatic compounds, having as their substrate the benzene ring. Their tendency to sublime is a result of their their triple point (where all 3 phases exist simultaneously) at a temperature in excess of room temperature and a pressure above 1 atm. Hence, the liquid phase is never entered.

Urea, NH2-(C=O)-NH2 and lactic acid are much more polar, and has a higher boiling point .