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