{TAIL ~ R25} is hydrogen, alkyl of {HEAD ~ 1 6 carbon atoms}, or aralkyl of 7 10 carbon atoms 
{ TAIL ~ R25 } is hydrogen , alkyl of { HEAD ~ 1 6 carbon atoms } , or aralkyl of 7 10 carbon atoms
TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH