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