An optical isomer, or a racemic mixture of optical isomers of a sulfone selected from the group consisting of: (a) a compound of the formula: wherein the carbon atom designated * constitutes a center of chirality Y is C> = O, CH2, CO2 or CH2C> = O each of R1, R2, R3 and R4, independently of the others, is hydrogen, halo, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, nitro, cyano, hydroxy or -NR8R9 or any two of R1, R2, R3 and R4 in adjacent carbon atoms, together with the phenylene ring represented, are naphthylidene each of R5 and R6, independently of the other, is hydrogen, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, cyano, or cycloalkoxy of up to 18 carbon atoms R7 is hydroxy, alkyl of 1 to 8 carbon atoms, phenyl, benzyl or NR8R9 each of R8 and R9 taken independently of the other hydrogen, alkyl of 1 to 8 carbon atoms, phenyl or benzyl, or one of R8 and R9 is hydrogen and the other is -COR10 or -SO2R10 or -NHCOR10, or R8 and R9 taken together are tetramethylene, pentamethylene, hexamethylene or -H2CH2X12CH2CH2-, wherein X1 is -O-, -S - or -NH- and each of R8 and R9 taken independently of the other hydrogen, alkyl of 1 to 8 carbon atoms, phenyl or benzyl, or one of R8 and R9 is hydrogen and the other is -COR10 or - SO2R10 or -NHCOR10, or R8 and R9 taken together are tetramethylene, pentamethylene, hexamethylene or -CH2CH2X2CH2CH2- in which X2 is -O-, -S- or -NH-. R10 is hydrogen, alkyl of 1 to 8 carbon atoms or phenyl and R10 is hydrogen, alkyl of 1 to 8 carbon atoms or phenyl and (b) the addition salts of said compounds which acid contains a nitrogen atom susceptible of protonation.Un isómero óptico, o una mezcla racémica de isómeros ópticos, de una sulfona seleccionada del grupo que consiste en: (a) un compuesto de la fórmula: en la cual el átomo de carbono señalado con * constituye un centro de quiralidad Y es C>=O, CH2, CO2 o CH2C>=O cada uno de R1, R2, R3 y R4, independientemente de los otros, es hidrógeno, halo, alquilo de 1 a
