Preferred Label : entering group; 
IUPAC definition : An atom or group that forms a bond to what is considered to be the main part of the
               substrate during a reaction. For example: the attacking nucleophile in a bimolecular
               nucleophilic substitution reaction.; 
         
         
            Origin ID : E02130; 
 Automatic exact mappings (from CISMeF team) Automatic exact mappings (from CISMeF team)
 See also See also
 
         
         
         An atom or group that forms a bond to what is considered to be the main part of the
            substrate during a reaction. For example: the attacking nucleophile in a bimolecular
            nucleophilic substitution reaction.