C₁₂H₁₁Hg₂NO₄

Chemical name. Nitratophenylmercury; (nitrato-O)phenylmercury; CAS Reg. No. 55-68-5.

Description. White, lustrous plates or a white, crystalline powder; odourless.

Solubility. Very slightly soluble in water; slightly soluble in ethanol (~750 g/l) TS; soluble in glycerol R and in fixed oils.

Category. Antimicrobial preservative.

Storage. Phenylmercuric nitrate should be kept in a tightly closed container, protected from light.

Additional information. Phenylmercuric nitrate is affected by light. It melts at about 188 °C with decomposition.

Requirements

Definition. Phenylmercuric nitrate is a mixture of phenylmercuric nitrate and phenylmercuric hydroxide.

Phenylmercuric nitrate contains not less than 98.0% and not more than the equivalent of 101.0% of C₁₂H₁₁Hg₂NO₄, calculated with reference to the dried substance.

Identity tests

A. To 10 mL of a saturated solution add 2 drops of sodium sulfide TS; a white precipitate is produced. Boil the mixture and allow to stand; the precipitate becomes black.

B. Heat 0.5 g with 0.5 g of zinc R powder, 0.5 g of reduced iron R, and 5 mL of sodium hydroxide (~200 g/l) TS. Place a piece of moistened red litmus paper R over the vapours; the colour of the paper changes to blue.

C. To 10 mL of a saturated solution add 1 mL of hydrochloric acid (~70 g/l) TS and heat to boiling; a white precipitate is produced. Filter, and to 5 mL of the filtrate add 2 mL of ferrous sulfate (15 g/l) TS; it yields reaction A described under 2.1 General identification tests as characteristic of nitrates.

Mercuric salts and heavy metals. Heat 0.1 g with 15 mL of water, cool, filter, and add 0.1 mL of sodium sulfide TS to the filtrate; a precipitate is produced, the colour of which remains unchanged.

Residue on ignition. Not more than 5.0 mg/g.

Loss on drying. Dry to constant mass at 105 °C; it loses not more than 10 mg/g.

Acidity. To a 0.2 mg/mL solution add 3 drops of bromocresol green/ethanol TS; the solution is neutral (green).

Assay. Transfer about 0.2 g, accurately weighed, to a conical flask, and dissolve in 90 mL of water and 10 mL of nitric acid (~1000 g/l) TS. Add 2 mL of ferric ammonium sulfate (45 g/l) TS and titrate with ammonium thiocyanate (0.05 mol/l) VS.

Each mL of ammonium thiocyanate (0.05 mol/l) VS is equivalent to 0.01586 g of C₁₂H₁₁Hg₂NO₄.