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