Abstract: Bi-aromatic esters have the formula ##STR1## wherein R.sub.1 represents H, OH, --CH.sub.3, --CH.sub.2 OH, --CH(OH)CH.sub.3, --COOR.sub.9, ##STR2## or SO.sub.2 R.sub.10 ; R.sub.9 represents H, C.sub.1 -C.sub.6 alkyl or monoor polyhydroxyalkyl; R.sub.10 represents OH, C.sub.1 -C.sub.6 alkyl or ##STR3## r' and r" represent H, C.sub.1 -C.sub.6 alkyl, aryl, aralkyl, mono or polyhydroxyalkyl, or r' and r" taken together form a heterocycle; R.sub.2 represents H, C.sub.1 -C.sub.6 alkyl, OR.sub.9, F or --CF.sub.3 ; R.sub.3, R.sub.4 and R.sub.5 represent H, F, OH, --CH.sub.3, --OCH.sub.3, --CF.sub.3, --COOH or --CH.sub.2 OH; R.sub.6 and R.sub.8 represent H, .alpha.-substituted C.sub.3 -C.sub.15 alkyl, .alpha.,.alpha.'-disubstituted C.sub.4 -C.sub.12 alkyl, C.sub.3 -C.sub.12 cycloalkyl, C.sub.5 -C.sub.12 mono or polycyclic cycloalkyl whose linking carbon is trisubstituted, --SR.sub.11, --SO.sub.2 R.sub.11 or --SOR.sub.11 ; R.sub.11 represents C.sub.1 -C.sub.6 alkyl or cycloalkyl; R.sub.6 and R.sub.