{HEAD ~ Organic ring compounds} which can be used are {TAIL ~ acetanilides}, such as para aminoacetanilide or para nitroacetanilide 
used are
{ HEAD ~ Organic ring compounds } which can be used are { TAIL ~ acetanilides } , such as para aminoacetanilide or para nitroacetanilide
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH