Bromopyrogallol red

Bromopyrogallol red is a chemical compound frequently utilized in the field of analytical chemistry. It serves as a spectrophotometric reagent and a complexometric indicator, which is particularly useful in metal ion complexation reactions. When combined with quaternary ammonium salts, bromopyrogallol red's analytical capabilities are enhanced, leading to increased color contrast and sensitivity for various elements during analysis[1].

The compound is characterized as a green to dark brown crystalline powder. It exhibits absorption maxima at different wavelengths depending on the solvent used: 412 and 523 nm in dimethyl sulfoxide, 400 to 540 nm in ethanol, 360–530 nm in water, and 470 nm in a 1,4-dioxane and water mixture with a 4:2 ratio[1].

Bromopyrogallol red is soluble in water and should be stored at a temperature of 4 °C. It is not classified as harmful if ingested, but direct contact with the eyes may cause irritation or redness, and skin contact can lead to irritation. If it enters the bloodstream, it may cause systemic injury. It is important to avoid contaminating bromopyrogallol red with oxidizing agents such as nitrates, oxidizing acids, and chlorine bleaches[1].

This compound has been used as a complexometric indicator for the determination of various metals, including bismuth (Bi), cadmium (Cd), cobalt (Co), magnesium (Mg), manganese (Mn), and rare earth elements. In a 1 M H2SO4 solution, bromopyrogallol red is protonized and transitions to ionized forms in alkaline solutions. It is a stronger acid than Pyrogallol Red and exhibits bathochromic shifts in the presence of ammonia salts. An intense blue-colored reagent is formed when bromopyrogallol red reacts with niobium(V) in a tartrate medium at pH 6.0. The compound's sensitivity and conditional selectivity have been studied, showing its effectiveness in detecting trace amounts of silver ions due to the two adjacent phenol groups in its structure. It forms blue to violet-blue complexes with yttrium and cerium and shows an orange-yellow color in strong acid solutions[1].

The molecular formula of bromopyrogallol red is C19H10Br2O8S, and its CAS number is 16574-43-9[2][3][4][5].

Citations:

[1] https://en.wikipedia.org/wiki/Bromopyrogallol_red

[2] https://pubchem.ncbi.nlm.nih.gov/compound/Bromopyrogallol-red

[3] https://www.scbt.com/p/bromopyrogallol-red-16574-43-9

[4] https://www.chemimpex.com/bromopyrogallol-red

[5] https://www.fishersci.com/shop/products/bromopyrogallol-red-tci-america-2/D02071G

[6] https://www.himedialabs.com/us/grm491-bromopyrogallol-red.html

[7] https://discofinechem.com/products/bromopyrogallol-red-2/

[8] https://www.sciencedirect.com/science/article/abs/pii/S0003267098006254