In a process for producing phenol and cyclohexanone, a feed comprising cyclohexylbenzene is oxidized to produce an oxidation reaction product comprising cyclohexyl-1-phenyl-1-hydroperoxide. At least a portion of the oxidation reaction product is then cleaved to produce a cleavage reaction product comprising phenol, cyclohexanone, and at least one contaminant. At least a portion of the cleavage reaction product is contacted with an acidic material to convert at least a portion of the at least one contaminant to a converted contaminant and thereby produce a modified reaction product.