Sodium Hypochlorite

Abstract

[7681-52-9] ClNaO (MW 74.44) (versatile and easily handled oxidizing agent;1 can oxidize alcohols,2 aldehydes,3 electron deficient alkenes,4 amines,5 and transition metal catalysts;6 reagent for N-chlorination,7 oxidative coupling,8 and degradation reactions9) Physical Data: most commonly used in aqueous solution; NaOCl·5H2O: mp 18 °C. Solubility: pentahydrate: 293 g L−1 in H2O (0 °C). Form Supplied in: commercially available as aqueous solutions with 5.25–12.5% available oxidant (w/v) (0.74–1.75 M). Concentration is expressed in % available chlorine, since half of the chlorine in bleach is present as NaCl. The pH of commercial bleach is typically 11–12.5, and it may be adjusted and buffered.6a Analysis of Reagent Purity: active oxidant may be assayed by iodometric10 or potentiometric11 titration. Preparative Methods: solutions may be generated in situ by passing Chlorine gas through aq Sodium Hydroxide solution,12 or electrochemically.13 Purification: commercial solutions are generally used without purification. Handling, Storage, and Precautions: higher concentration sodium hypochlorite (12.5%), sometimes referred to as ‘swimming pool chlorine,’ tends to decrease in concentration by 20% per month upon storage and therefore should be titrated prior to use.1b The concentration of oxidant in household bleach (5.25%) tends to remain constant upon prolonged storage; titration is generally not necessary with brand names (e.g. Clorox®). Solid NaOCl is explosive as the pentahydrate or the anhydride, and therefore it is very rarely employed in those forms. Aqueous solutions are very stable. Bleach is a household item, and it is quite easy and safe to handle. Still, it is a strong oxidant, and precaution should be taken to avoid prolonged skin exposure or inhalation.14 May react violently with NH3.