            —C—OH
                                                                                                    ‖
                                                                                                    O
      —              CHC—OH     
                                                                                                                                           ‖
O
CHCHCHC—OH        
                 ‖
                 O
HO—C—C—OH        
            ‖    ‖
            O      O
            CHC—OH
            |     ‖
                  O
OH—C—C—OH      
            |       ‖
                    O
               CHC—OH
                    ‖
                     O
                       
     CH—C—OH＋NAOH  →CHC－ONa＋HO
                ‖                                         ‖
O                                                           C
                                      
                     
                                                                
CHCHOH＋O→ CHC－OH＋HO
                         ‖
                  O          
                                     