abstract |
Compounds of the formula: ##STR1## wherein one of X 1 and X 2 is --CH 2 CH 2 -- and the other is --CH 2 CH 2 -- or a single covalent bond, n ring A is 1,4-phenylene or trans-1,4-cyclohexylene, and n R 1 is straight-chain C 1 -C 12 -alkyl or when positioned on a 1,4-phenylene ring R 1 may also be straight chain C 1 -C 12 -alkoxy. |