(fee' nol).
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C6H6O 94.11

Phenol [108-95-2].
»Phenol contains not less than 99.0 percent and not more than 100.5 percent of C6H6O, calculated on the anhydrous basis. It may contain a suitable stabilizer.
Caution—Avoid contact with skin, since serious burns may result.
Packaging and storage— Preserve in tight, light-resistant containers.
Labeling— Label it to indicate the name and amount of any substance added as a stabilizer.
Clarity of solution and reaction— A solution (1 in 15) is clear, and is neutral or acid to litmus paper.
A: To a solution add bromine TS: a white precipitate is formed, and it dissolves at first but becomes permanent as more of the reagent is added.
B: To 10 mL of a solution (1 in 100) add 1 drop of ferric chloride TS: a violet color is produced.
Congealing temperature 651: not lower than 39.
Water, Method I 921: not more than 0.5%.
Limit of nonvolatile residue— Heat about 5 g, accurately weighed, in a tared porcelain dish on a steam bath until it has evaporated, and dry the residue at 105 for 1 hour: not more than 0.05% of residue remains.
Assay— Place about 2 g of Phenol, accurately weighed, in a 1000-mL volumetric flask, dilute with water to volume, and mix. Pipet 20 mL of the solution into an iodine flask, add 30.0 mL of 0.1 N bromine VS, then add 5 mL of hydrochloric acid, and immediately insert the stopper. Shake the flask repeatedly during 30 minutes, allow it to stand for 15 minutes, add quickly 5 mL of potassium iodide solution (1 in 5), taking precautions against the escape of bromine vapor, and at once insert the stopper in the flask. Shake thoroughly, remove the stopper, and rinse it and the neck of the flask with a small quantity of water, so that the washing flows into the flask. Add 1 mL of chloroform, shake the mixture, and titrate the liberated iodine with 0.1 N sodium thiosulfate VS, adding 3 mL of starch TS as the endpoint is approached. Perform a blank determination (see Residual Titrations under Titrimetry 541). Each mL of 0.1 N bromine is equivalent to 1.569 mg of C6H6O.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Feiwen Mao, M.S.
Senior Scientific Liaison
(SM32010) Monographs - Small Molecules 3
USP35–NF30 Page 4288