R3 will represent alkyl, substituted alkyl, aryl or {TAIL ~ substituted aryl} and {HEAD ~ its formula} will be determined by the make up of R1 and R2 
R3 will represent alkyl , substituted alkyl , aryl or { TAIL ~ substituted aryl } and { HEAD ~ its formula } will be determined by the make up of R1 and R2
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH