Mass Spectrometry: Fragmentation 
                Ethers & Sulfides   !         !!!! 
                  Ethers 
                     +
                  • M  usually stronger than corresponding alcohol; may be weak/absent 
                  • α-cleavage of an alkyl radical 
                  • Inductive cleavage 
                  • Rearrangement with loss of CHR=CHR’  
                    
                  Aryl Ethers 
                     +
                  • M  strong 
                  • C-O cleavage β to aromatic ring with subsequent loss of CO 
                  • Cleavage adjacent to aryl ring also possible 
                   
                  Sulfides 
                     +
                  • M  usually stronger than corresponding ether 
                  • cleavage pattern similar to ethers 
                       Mass Spectrometry: Fragmentation 
                            Ethers 
                                   fragmentation patterns 
                                           α-cleavage 
                                                                     R CH O R'                                     R         +       H       R'
                                                                              2                                                      H O
                                           inductive cleavage 
                                                                     R CH2 O R'                                   R CH2         +       O R'
                                           rearrangement 
                                                                      H              H                         H
                                                                   H      O CH2 CHR                        H      O H        +     H2C=CHR
               Mass Spectrometry: Fragmentation 
                  Ethers                                                                  O
                                                                                        MW = 88
                       ethyl propyl ether 
                                                         H                          H
                                                       H   O H                   O    H
                                                       m/z = 31                59 
                                                                              M-29 
                                           CH CH           CH2CH2CH3
                                              3  2          m/z = 43 
                                           m/z = 29                                   H
                                                                                    H   O         M (88) 
                                                                                        73 
                                                                                      M-15 
                Mass Spectrometry: Fragmentation                                                     O
                   Ethers                                                                        MW = 130
                        di-sec-butyl ether 
                                                    H
                                                H C   O H
                                                 3
                                                 m/z = 45           m/z = 57 
                                                                                         H
                                                                                    H3C    O
                                                                                         101 
                                                                          H             M-29 
                                                                   CH CH    O H                    H
                                                                     3   2
                                                                     m/z = 59               CH3CH2   O
                                                                                                 115 
                                                                                                 M-15 
                                                                                                       M (130)