alkyl group having 1-5 carbon atoms, a straight-chain or branched alkoxy group having 1-5 carbon atoms, or a straight-chain or branched haloalkyl group having 1-5 carbon atoms; and n is 0 or an integer of 1-3; ##STR5## wherein R11 is a hydrogen atom, a halogen atom, a straight-chain or branched alkyl group having 1-5 carbon atoms, an aralkyl group or a trifluoromethyl group; R12 is a straight-chai