Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Phenol Part 4, Monographs for Reagent Chemicals: General Descriptions, Specifications, and Tests eISBN: 9780841230460 Tom Tyner Chair, ACS Committee on Analytical Reagents James Francis Secretary, ACS Committee on Analytical Reagents
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ABSTRACT This monograph for Phenol provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), aqueous solubility, density, and pKa. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Freezing Point, Clarity of Solution, Residue after Evaporation, and Water.
C6H5OH
Formula Wt 94.11
CAS No. 108-95-2
Note: Phenol that conforms to this specification may contain a stabilizer. If a stabilizer is present, its presence should be stated on the label.
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . colorless hygroscopic solid; may become pink on exposure to air Applications . . . . . . . . . . . . . . . . . . . . . . . . pH indicator Change in state (approximate) . . . . . . . . . . . . when free from water and cresol, it congeals at 41 °C and melts at 43 °C; boiling point, 182 °C Aqueous solubility . . . . . . . . . . . . . . . . . . . . 8.2 g in 100 mL at 15 °C; very soluble in hot water Density . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.07 pKa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.9
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥99.0% C6H5OH
© 2017 American Chemical Society
A
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4263 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Freezing point . . . . . . . . . . . . . . . . . . . . . . Not below 40.5 °C (dry basis) Clarity of solution . . . . . . . . . . . . . . . . . . . . Passes test Maximum Allowable Residue after evaporation . . . . . . . . . . . . . . . 0.05% Water (H2O) . . . . . . . . . . . . . . . . . . . . . . . . 0.5%
TESTS
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Assay (By iodometry after bromination of hydroxyl groups). Weigh accurately about 1.5 g, and dissolve in sufficient water to make exactly 1 L. Transfer 25 mL into a 500 mL glass-stoppered iodine flask, add 30 mL of 0.1 N bromine solution and 5 mL of hydrochloric acid, and immediately stopper the flask. Shake frequently during 30 min, and allow to stand for 15 min. Then quickly add 10 mL of 10% potassium iodide reagent solution, being careful that no bromine escapes, and stopper immediately. Shake, add 1 mL of chloroform, and titrate the liberated iodine (which represents the excess of bromine) with 0.1 N sodium thiosulfate volumetric solution, using 3 mL of starch indicator solution. One milliliter of 0.1 N bromine corresponds to 0.001569 g of C6H5OH.
Freezing Point Dry the sample by adding 15 g of molecular sieve zeolite having 4A-size pores to 100 g of molten sample in a 400 mL conical flask. (The zeolite may be in the form of a powder or of cylindrical granules about 3 mm in diameter.) Stopper the flask loosely, and maintain the mixture at 55–60 °C for 20 min with frequent stirring. Quickly transfer a portion of the dried sample to a jacketed test tube, filling the tube to a depth of 8 cm. Insert a suitable thermometer, graduated in 0.1 °C units, and stir until the temperature falls to 10 °C above the expected freezing point. Immerse the tube in a water bath that is adjusted to about 4 °C below the expected freezing point and clamp in a vertical position. Insert a ring-type stirrer around the thermometer that is clamped to place the bottom of the bulb about 0.5 cm above the bottom of the test tube. Stir the sample continuously until crystallization occurs and the temperature does not change more than 0.05 °C in 2 min or, if supercooling occurs, the temperature rises rapidly to maximum accompanied by rapid crystallization. Record the constant temperature or the maximum temperature as the freezing point.
Clarity of Solution Dissolve 5.0 g in 100 mL of water. The solution should be free of turbidity and insoluble residue.
Residue after Evaporation [Part 2: Gravimetric Methods; Residue after Evaporation]. Evaporate 10.0 g to dryness in a tared, preconditioned dish on a hot plate (~100 °C), and dry the residue at 105 °C for 30 min.
Water [Part 2: Titrimetric Methods; Water by the Karl Fischer Method; Volumetric Procedure; Volumetric Procedure for Samples Using Karl Fischer Reagent, Method 1]. Use 25.0 g of molten sample.
© 2017 American Chemical Society
B
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4263 ACS Reagent Chemicals, Part 4
