Page 2 - Microsoft Word - Lesson note-1(haloalkanes and haloarenes)
P. 2

(2) Slimination reaction: [dehydrologenation]
                                             alc.KOH
                                                                                  
                                                               
                                                           
                                  
                                      
                           CH  CH CH CH       CH  CH CH CH    CH  CH  CH CH
                                                      3
                             3
                                          2
                                                                       3
                                                                            2
                                                                                     2
                                                                   3
                                 |  |  |                 (81%)             (19%)
                                H   Br  H
                                        Saytseff’s rule
                    (3) Reaction with metal:
                              Dry ether
                                       
                        
                     
                    R X Mg       R Mg X
                                            
                                    Dry ether
                                             
                                                
                    R X 2Na X R        R R 2NaX
                             
                     
                        
                                
                    (wurtz reaction)
                    (4) Redution:
                                Zn/HCl(conc.)
                                                
                    R X 2(H)        R H HX
                     
                        
                                             
                                  
                               or Zn Cu/C 2 5 H OH
                    Preparation of Haloarenes:
                    (a) By direct halogenations of benzene


                    (b) From diazonium salts:
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