Alcohols are compounds that have hydroxyl groups bonded to saturated,sp3-hybridized carbon atoms, while phenol are compounds that have hydroxyl groups bonded to aromatic rings. Both can be thought of as organic derivatives of water in which one of the water hydrogens is replaced by an organic group:H-O-H versus R-O-H or Ar-O-H. Note that enols, compounds with an -OH group bonded to a vinylic carbon, are purposely excluded from discussion in this chapter beacause their chemistry is so diffent. We'll look at enols in Chapter 22.