R9 is hydrogen, alkyl of 1 6 carbon atoms, or {HEAD ~ aralkyl} of {TAIL ~ 7 10 carbon atoms} 
R9 is hydrogen , alkyl of 1 6 carbon atoms , or { HEAD ~ aralkyl } of { TAIL ~ 7 10 carbon atoms }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL