Substituted diphenyl ethers

Novel compounds of the formula (wherein R1 and R2 are OH, alkoxy of at most 5 carbon atoms or NR3R4, in which R3 and R4 are H or C1- 5 alkyl; and (CH2)m and (CH2)n are straight or branched alkylene radicals, m and n being integers of from 2 to 8 and m+n being at least 5) and salts of the free acids are prepared by reduction of the corresponding ketones, i.e. compounds wherein the methylene groups adjacent to the benzene rings are replaced by carbonyl groups. The free acids thus obtained can be converted to salts, esters and amides by standard methods.