Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Tetrabutylammonium Bromide (TBAB) 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 Tetrabutylammonium Bromide provides, in addition to common physical constants, a general description including typical appearance and applications. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Tributylamine, Tributylamine Hydrobromide, and Polarographic Test.
(CH3CH2CH2CH2)4NBr
Formula Wt 322.38
CAS No. 1643-19-2
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . white solid Applications . . . . . . . . . . . . . . . . . . . . . . . . ion pair reagent
SPECIFICATIONS General Use Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥98.0% (CH3CH2CH2CH2)4NBr Maximum Allowable Tributylamine (Bu3N) . . . . . . . . . . . . . . . . . 0.5% Tributylamine hydrobromide (Bu3N · HBr) . . . . 0.5%
Specific Use Polarographic test . . . . . . . . . . . . . . . . . . . Passes test
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4394 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By argentimetric titration of bromide content). Weigh accurately about 1.0 g, and dissolve in a 250 mL conical flask with 50 mL of water. Add 0.05 g of sodium bicarbonate and 0.2 mL of eosin Y reagent solution. Titrate with 0.1 N silver nitrate volumetric solution to the first color change. One milliliter of 0.1 N silver nitrate volumetric solution corresponds to 0.03224 g of tetrabutylammonium bromide.
Tributylamine and Tributylamine Hydrobromide (By potentiometric titration, [Part 2: Titrimetric Methods; Potentiometric Titrations]).
S a m p l e Pr e p a r a t i o n . Accurately weigh and dissolve 20.0 g of sample in 90 mL of isopropyl alcohol in a 400 mL beaker. Measure the pH of the sample solution on a standardized pH meter. If the pH is less than 5, then no tributylamine is present. Potentiometrically titrate with 1 N sodium hydroxide volumetric solution to determine the tributylamine hydrobromide content. The first inflection point, A mL, will be approximately pH 5. A second inflection point, B mL, will occur at approximately pH 10.5.
If the pH is greater than 5, then potentiometrically titrate with 1 N hydrochloric acid volumetric solution to determine the tributylamine content. The inflection point, C mL, will be approximately pH 5. In the calculations, D mL is the total mL of 1 N hydrochloric acid added. Titrate the same sample with 1.0 N sodium hydroxide volumetric solution to an inflection point approximately pH 10.5 at E mL to determine the tributylamine hydrobromide content.
Polarographic Test [Part 2: Direct Electrometric Methods; Polarographic Analysis]. Cathode . . . . . . . . . . . . . . . . . . . . . . . . . Dropping Hg electrode Anode. . . . . . . . . . . . . . . . . . . . . . . . . . . Pt wire Reference . . . . . . . . . . . . . . . . . . . . . . . . Similar saturated calomel electrode: make up with 1.0 M tetrabutylammonium chloride. Prepare a 1.0 M solution (32.24 g in 100 mL of water), and add 0.2 mL of 1.0 M tetrabutylammonium hydroxide. Deoxygenate with high-purity nitrogen gas until minimum background current is achieved (approximately 5 min). By using a drop time of 1 s, scan at 0.01 V/s from –1.2 to –2.6 V vs electrode with a sensitivity of 0.5 µA full scale with modulation amplitude of 50 mV. The material is acceptable if no impurity current greater than 0.05 µA is observed.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4394 ACS Reagent Chemicals, Part 4
