HETEROCYCLIC 
    HETEROCYCLIC 
    COMPOUNDS 
    COMPOUNDS 
   DEFINITION OF HETEROCYCLIC COMPOUNDS: 
   Heterocyclic compounds are cyclic compounds which contains 
   one/more atoms of other elements along with carbon atoms. 
   DEFINITION OF HETEROATOM: 
   Hetero atoms are those which contains an atom other than 
   carbon such as nitrogen, sulphur, phosphorus etc.
                  CLASSIFICATION: 
                   CLASSIFICATION: 
   Depending upon the size of heterocyclic ring, they are classified into 
   diferent types. 
     Five membered heterocyclic compounds: 
          NH           S          O          O         NH         N
            N                      N                         N    N
                     N                                         N
                            isooxazole                         H
      pyrazole    thiazole               furan     pyrrole    tetrazole
      Six membered heterocyclic compounds: 
              N
                                NH              S
                                            N
        Pyridine          piperidine      thiazine
                                  Fused heterocyclic compounds:                                                                                        
                                                   N
                                                                                   N
                                                                                             N
                                                                                             H
                                         quinoline                  isoquinoline                 indole
             Condensed ring systems:                                                                                                     
                              H
                              N
                              N
                              benzimidazole
                          NOMENCLATURE 
      Systematic nomenclature system is used for naming 3-10 membered
       monocyclic heterocyclics of various degree of the unstauration containing
       one/more  heteroatoms. 
      It specifies the following characters such as:                                                 
       
        - the ring size                                                                                                
                                               
        -the nature                                                                                                    
                                        
        -the type of heteroatom                                                                                
                                
        - the position of heteroatom etc.