R11 and R12 are each, independently, hydrogen, alkyl of 1 6 carbon atoms, {TAIL ~ aralkyl} of 7 10 carbon atoms, cycloalkyl of {HEAD ~ 3 8 carbon atoms}, halogen, or trifluoromethyl 
R11 and R12 are each , independently , hydrogen , alkyl of 1 6 carbon atoms , { TAIL ~ aralkyl } of 7 10 carbon atoms , cycloalkyl of { HEAD ~ 3 8 carbon atoms } , halogen , or trifluoromethyl
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH