Ar is an optionally mono or di substituted group selected from ##STR41## in which the optional substituents are selected from {HEAD ~ the group} consisting of alkyl of 1 6 carbon atoms, aralkyl of 7 10 carbon atoms, alkoxy of 1 6 carbon atoms, cyano, halo, nitro, carbalkoxy of 2 7 carbon atoms, or {TAIL ~ perfluoroalkyl} of 1 6 carbon atoms 
consisting of
Ar is an optionally mono or di substituted group selected from # # STR41 # # in which the optional substituents are selected from { HEAD ~ the group } consisting of alkyl of 1 6 carbon atoms , aralkyl of 7 10 carbon atoms , alkoxy of 1 6 carbon atoms , cyano , halo , nitro , carbalkoxy of 2 7 carbon atoms , or { TAIL ~ perfluoroalkyl } of 1 6 carbon atoms
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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