Diquaternary ammonium compounds

There are described diquaternary ammonium compounds of the general formula 1 wherein R 1 and R 4 are each independently of the other C 4 -C 16 alkyl, phenyl or phenyl-C 1 -C 10 . alkyl, R 2 , R 3 , R 5 and R 6 are each independently of the others C 1 -C 4 alkyl, and A is a monovalent anion. The compounds exhibit a pronounced action against gram-positive and gram-negative bacteria, and also against yeast, molds and algae. They are accordingly suitable for the antimicrobial treatment of surfaces and for the preservation and disinfection of materials and cosmetic products, and especially also for the preparation of solid or liquid formulations and for the preservation of foodstuffs and drinks. The compounds are furthermore suitable for imparting antimicrobial properties to technical plant and for antimicrobial water treatment.