Answer to Question #120492 in Organic Chemistry for Fadi Geogre

Question

Compare between (propanal / isopropanal) and ( propanol / isopropanol) with respect to
physical properties

Answer 1

Alcohols are able to form hydrogen bonds, which explains their relatively high boiling and freezing temperatures: 97 ^oC and -126 ^oC for propanol, and 82 ^oC and -89 ^oC for isopropanol. Propanal and isopropanal are not capable of forming hydrogen bonds, so they are more volatile, boiling and freezing poins is 49 ^oC and -81 ^oC for propanal and 57 ^oC and -95 ^oC for isopropanal. The ability to form hydrogen bonds also explains the very high solubility of propanol and isopropanol in water - they are indefinitely miscible with it. Acetone also(isopropanal) mixes indefinitely with water due to its high dipole moment. Propanal is poorly soluble in water - 20 g in 100 ml, because its dipole moment is smaller than that of acetone due to the asymmetry of the molecule.