Page 61 - Pharmaceutical Organic Chemmistry-3 (Theoritical book) 24-25
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Clinical Pharmacy PharmD - 2024/2025                  Level 2                Pharmaceutical Organic Chemistry-3 (PC 305)
                                               Pyridine Derivatives


            1) Pyridine-N-oxide (pyridine-1-oxide)

                Pyridine-N-oxide  is  a  very  reactive  compound  and  undergoes  many  types  of

                reactions  which  cannot  be  given  with  pyridine.  The  resonance  structures  of

                pyridine-N-oxide are as follows:



                                                                     +

                                    +                   +                             +
                                    N              N                N                N
                                    O -            O -              O -              O -

                               electron-
                               withdrawing                  nucleophilic attack
                               effect

                                                                       -


                               +                  +   -                +             -   +
                               N                 N                     N                 N
                               O -               O                     O                 O
                           electron-
                           donating
                           effect                          electrophilic attack


                                                    Br  / oleum               Br
                                                       2
                                                         o
                                                      70 C              +
                                                                        N
                                           +                            O -
                                           N
                                                                              SO H
                                                                                 3
                                           O -     oleum / HgSO  4
                                                         o
                                                     240 C              +
                                                                        N
                                                                        O -



            2) Alkyl derivatives:

            Methyl derivatives of pyridine are called as follows:

                   Monomethyl derivatives: picolines

                   Dimethyl derivatives     : lutidines

                   Trimethyl derivatives    : collidines
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