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