Oxidation of Aldehydes
         •     Aldehydes oxidize readily to form carboxylic acids. 
         •     Ketones do not undergo oxidation.
     General, Organic, and Biological Chemistry: Structures of Life, 5/e                                                             © 2016 Pearson Education, Inc.
     Karen C. Timberlake
     Tollens’ Test: Silver Mirror
     Tollens’ test
     •  may be used to distinguish between aldehydes and 
        ketones.
                                                                        +
     •  utilizes Tollens’ reagent, which is a solution of Ag  (AgNO3)  
        and ammonia.
     •  oxidizes aldehydes but not ketones.
     •  reduces Ag+, as the aldehyde is oxidized and forms a layer 
        called a “silver mirror” on the inside of the container.
   General, Organic, and Biological Chemistry: Structures of Life, 5/e  © 2016 Pearson Education, Inc.
   Karen C. Timberlake
         Benedict’s Test
          Benedict’s test
          • gives a positive result with 
               compounds that have an 
               aldehyde functional group and an 
               adjacent hydroxyl group.
          • utilizes Benedict’s solution, which 
                                            2+ 
               contains Cu (CuSO4). When the 
               solution is added to this type of 
               aldehyde and heated, a brick-red 
               solid of Cu2O forms 
          • is negative with simple aldehydes 
               and ketones.
     General, Organic, and Biological Chemistry: Structures of Life, 5/e                                                             © 2016 Pearson Education, Inc.
     Karen C. Timberlake
         Benedict’s Test: 2-Hydroxy Aldehyde 
         Because sugars such as glucose contain this type of aldehyde 
         grouping, Benedict’s reagent can be used to determine the 
         presence of glucose in blood or urine.
     General, Organic, and Biological Chemistry: Structures of Life, 5/e                                                             © 2016 Pearson Education, Inc.
     Karen C. Timberlake
     Reduction of Aldehydes and Ketones
     Aldehydes and ketones 
     •   are reduced by hydrogen (H ) or sodium borohydride 
                                                2
         (NaBH ) and a catalyst such as nickel, platinum, or 
                   4
         palladium.
     •   are reduced to alcohols by decreasing the number of 
         carbon–oxygen bonds.
   General, Organic, and Biological Chemistry: Structures of Life, 5/e      © 2016 Pearson Education, Inc.
   Karen C. Timberlake