Is free halogen necessary for disinfection?

Abstract

The principle of Le Chatelier was used in demonstrating that 3-chloro-4,4-dimethyl-2-oxazolidinone (compound 1) itself kills Staphylococcus aureus rather than the very small amount of free chlorine in hydrolysis equilibrium with compound 1. On the other hand, when the N-bromo analog of compound 1 (compound 1B) was used as the disinfectant, the mixture of combined compound 1B and free bromine formed in the hydrolysis equilibrium provided disinfection. When the hydrolysis equilibrium for 1B was suppressed to the level at which a negligible amount of free bromine remained in solution, combined compound 1B was much more efficacious than combined compound 1 at killing S. aureus.

New Biocide with Both N‐Chloramine and Quaternary Ammonium Moieties Exerts Enhanced Bactericidal Activity

“…As the dissociation constant of amide N ‐chloramine is less than 10 −9 ,21 its biocidal function is believed to proceed in a direct‐contact manner 22. As for the N‐Cl form of 3 , either free or after immobilization, the nature of N‐Cl is identical to that of 1 .…”

Unlocking the Latent Antimicrobial Potential of Biomimetically Synthesized Inorganic Materials

“…Examples of such damage include the oxidation of sulfur‐containing amino acid residues (e.g., the oxidation of cysteine to cysteic acid), the chlorination of tyrosine side chains and other aromatic compounds, lipid peroxidation, and the N‐chlorination of nucleic acid bases and amino acid side chains 53, 54. Though the regeneration of hypochlorous acid from halamine compounds is possible (Scheme ), the most predominant mode of action by these compounds is the direct transfer of Cl from the intact N‐Cl compound 55…”

Effect of organic N-halamines on selected membrane functions in intact Staphylococcus aureus cells

“…Disinfectant (10 ppm of total chlorine [final concentration]) was added to the cell suspension 5 to 10 min before the acid pulse. It should be noted that the ratio of cells to disinfectant was approximately 100 to 500 times that ratio used when disinfection kinetics experiments were performed (22)(23)(24).…”

“…However, at least one of the compounds examined in these laboratories, 3-chloro-4,4dimethyl-2-oxazolidinone, does not hydrolyze to form a free halogen residual in order to be an effective biocide. In fact, free halogen was shown to not be the mode of attack of this compound (22). The N,N'-dihalamine, 1,3-dichloro-4,4,5,5tetra-methyl-2-imidazolidinone, can be assumed to behave in a manner similar to that of 3-chloro-4,4-dimethyl-2-oxazolidinone in that there is no measurable free chlorine formed as a result of equilibrium hydrolysis (data not shown).…”