Acetanilide in water

Water can accept a hydrogen bond from the hydrogen of the N-H bond, and can donate a hydrogen bond to the oxygen of the CAO bond as well as to the nitrogen.  This hydrogen bonding tends to solubilize acetanilide in water. In contrast, the CH3 group and the phenyl ring cannot form hydrogen bonds with water; subsequently, these apolar ("greasy") groups tend to make acetanilide insoluble.

 Groups such as alkyl and phenyl groups that reduce water solubility are sometimes termed hydrophobic groups.