Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Bromphenol Blue (3′,3",5′,5" -Tetrabromophenolsulfonphthalein; 4,4′-(3H-2,1-Benzoxathiol-3-ylidene)bis[2,6-dibromophenol] S,S-Dioxide) 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
ABSTRACT This monograph for Bromphenol Blue provides, in addition to common physical constants, a general description including typical appearance, typical appearance, applications, change in state (approximate), and aqueous solubility. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Clarity of Solution and Visual Transition Interval.
C19H10Br4O5S (sultone) C19H9Br4O5SNa (sodium salt) C19H9Br4O5SNa (sodium salt)
Formula Wt 669.96 Formula Wt 691.94
CAS No. 115-39-9 CAS No. 34725-61-6
Formula Wt 691.94
CAS No. 62625-28-9
Note: This monograph applies to both the sultone and both salt forms of this indicator.
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4063 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . sultone; pale orange solid Typical appearance . . . . . . . . . . . . . . . . . . . sodium salt (CAS No. 34725-61-6), blue-black solid; sodium salt, CAS No. 62625-28-9, yellow-brown or green powder Applications . . . . . . . . . . . . . . . . . . . . . . . . indicator Change in state (approximate) . . . . . . . . . . . . decomposes at 279 °C Aqueous solubility . . . . . . . . . . . . . . . . . . . . 0.4 g in 100 mL at 25 °C
SPECIFICATIONS Clarity of solution . . . . . . . . . . . . . . . . . . . . Passes test Visual transition interval . . . . . . . . . . . . . . . . pH 3.0 (yellow) to pH 4.6 (blue)
TESTS Clarity of Solution If the indicator is the sultone form, dissolve 0.1 g in 100 mL of alcohol. If the indicator is the salt form, dissolve 0.1 g in 100 mL of water. Not more than a faint trace of turbidity or insoluble matter should remain. Reserve the solution for the test for visual transition interval.
Visual Transition Interval Dissolve 1 g of potassium chloride in 100 mL of water. Adjust the pH of the solution to 3.0 (using a pH meter) with 0.01 N hydrochloric acid. Add 0.10–0.30 mL of the 0.1% solution of the indicator reserved from the test for clarity of solution. The color of the solution should be yellow with a slight greenish hue. Titrate the solution with 0.01 N sodium hydroxide to a pH of 3.4 (using the pH meter). The color of the solution should be green. Continue the titration to pH 4.6. The color of the solution should be blue.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4063 ACS Reagent Chemicals, Part 4
