A compound of the formulae ##STR64## wherein A is phenyl or cyclohexyl;B is a group of the formulae ##STR65## X is --CF3, --CF2 CF3, --CF2 (CH2)t CH3, --CF2 (CH2)t COOR1, --CF2 (CH2)t CONHR1, --CF2 (CH2)t CH2 OR1 or --CF2 (CH2)v CH=CH2 ; R is H or --CH3 ; R1 is H or C1-6 alkyl; n is zero or one; t is the integer 2, 3 or 4; v is the integer 1, 2 or 3;or a stereoisomer or mixture thereof, a hydrate