1 2 or 3 and the substitution pattern is meta and or para particularly para i e a 4 position substituent exemplified compounds include those where r 2 is 4 trifluoromethyl or 4 trifluoromethoxy r 3 and r 4 may be the same or different and are methyl ethyl n propyl or n butyl of particular interest are those compounds of formula i where r 3 and r 4 are the same and are methyl or ethyl methyl is of particular interest r 5 may be hydrogen c 1 6 alkyl which is a straight chain or branched of particular interest is methyl ethyl propyl isopropyl n butyl sec butyl iso butyl t butyl n pentyl or n hexyl the compounds of formula i may be prepared in crystalline or non crystalline form and if crystalline may be solvated e g as the hydrate this invention includes within its scope stoichiometric solvates e g hydrates certain of the compounds described herein may contain one or more chiral atoms or may otherwise be capable of existing as two enantiomers the compounds claimed below include mixtures of enantiomers as well as purified enantiomers or enantiomerically enriched mixtures also included within the scope of the invention are the individual isomers of the compounds represented by formula i or claimed below as.