Abstract: The use of dihalogeno-hydroxydiphenyl ethers as antimicrobial agents in water treatment processes, such as in purification and decontamination of drinking or waste water, is claimed. Preferably the water treatment is performed in a membrane filtration system. The antimicrobial agents protect the membrane system against bacterial and/or algal decay and assist in maintaining a high efficiency of the membrane filtration process. Methods of maintaining membrane filtration efficiency using dihalogeno-hydroxydiphenylethers as well as aqueous antimicrobial rinsing liquors comprising dihalogeno-hydroxydiphenylethers are also claimed.

Abstract: There is described the preparation of phenylphenol compounds of formula (1) by reaction of a keto compound of formula (3) with dioxolane of formula (4) and with an ammonium compound of formula (5) to from &bgr;-aminoketone compound of formula (6) (reaction step (I)), reaction of the compound of formula (6) with a compound of formula (7) to form a compound of formula (2) (reaction step (II)), and subsequent alkylation to form a compound of formula (1) (reaction step (III)) in accordance with scheme (A); wherein R1, R2, R3, R6 and R7 are each independently of the others hydrogen or C1-C8alkyl; R4, R5 and R8 are each independently of the others hydrogen or C1-C5alkyl; ant Hal is a halogen atom. The compounds prepared in accordance with the invention are suitable as antimicrobial active substances.

Abstract: There is described the preparation of phenylphenol compounds of formula (I) by reaction of a keto compound of formula (3) with dioxolane of formula (4) and with an ammonium compound of formula (5) to form a &bgr;-aminoketone compound of formula (6) (reaction step (I)), reaction of the compound of formula (6) with a compound of formula (7) to form a compound of formula (2) (reaction step (II)), and subsequent alkylation to form a compound of formula (I) (reaction step (III)) in accordance with scheme (A); wherein R1, R2, R3, R6 and R7 are each independently of the others hydrogen or C1-C8-alkyl; R4, R5 and R8 are each independently of the others hydrogen or C1-C5alkyl; and Hal is a halogen atom. The compounds prepared in accordance with the invention are suitable as antimicrobial active substances.