R6 and R9 are each, independently, hydrogen, {TAIL ~ alkyl} of 1 6 carbon atoms, or aralkyl of {HEAD ~ 7 10 carbon atoms} 
R6 and R9 are each , independently , hydrogen , { TAIL ~ alkyl } of 1 6 carbon atoms , or aralkyl of { HEAD ~ 7 10 carbon atoms }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD