chlorine gas to react with an aqueous alkaline solution of the precursor amine see tsao et al u201c novel n halamine disinfectant compounds u201d biotechnol prog 1991 7 60 or worley et al u s pat no 5 057 612 it can also be purchased commercially from the halosource corporation in bothell wash the precursor 2 2 5 5 tetramethyl 4 imidazolidinone is able to be prepared according to the method outlined in tsao et al u201c novel n halamine disinfectant compounds u201d biotechnol prog 1991 7 60 or worley et al u s pat no 5 057 612 compound 2 is able to be prepared by reaction of commercial aldrich chemical company milwaukee wis 2 2 6 6 tetramethyl 4 piperidinol with dilute household bleach the oxidative chlorine contents and hence purities of both compounds are able to be measured using a standard iodometric thiosulfate titration procedure pure compounds 1 and 2 contain 20 1 and 18 5 percent by weight oxidative chlorine respectively their solubilities in water at 22 u00b0 c are 1930 and 6815 mg l respectively the weight percents of oxidative chlorine present under these saturated conditions at 22 u00b0 c for the two compounds are 388 and 1260 mg l respectively both compounds are adequately soluble for a contact lens soaking application in which about 10 to 1000 mg l preferably about 60 mg l would be required to provide adequate disinfection efficacy disposable soft contact lenses such as those manufactured by johnson amp johnson vision care inc acuvue 2 which contain a blue dye for ultraviolet light protection are recommended by the manufacturer to be worn for no more than 14 days or 6 days and nights of continued wear thus it is necessary for an active.