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In alkaline solution, pyrogallol undergoes deprotonation. Such solutions absorb oxygen from the air, turning brown. This conversion can be used to determine the amount of oxygen in a gas sample, notably by the use of the Orsat apparatus. Alkaline solutions of pyrogallol have been used for oxygen absorption in gas analysis.
Any left-over gas is assumed to be nitrogen, though other absorbents or vessels can be used to isolate additional gases. Platinum on asbestos for example can be used to determine the hydrogen content of a sample, and the Fischer-type Orsat gas analyser for example uses a platinum electrode to explode the remaining gases with hydrogen.
This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O 2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The oxygen incorporated need not be derived from O 2. The systematic name of this enzyme class is 1,2,3-trihydroxybenzene:oxygen 1,2-oxidoreductase ...
By reacting the bromopyrogallol red with niobium(V) in a tartrate medium at pH 6.0, an intense blue coloured 3:1 reagent was formed. The sensitivity and conditional selectivity of bromopyrogallol red was also studied and results show that trace amounts of silver can be detected from the formation of a ternary complex between 1,10-phenanthroline, bromopyrogallol red and silver ion.
Thus, the two substrates of this enzyme are 1,2,3,5-tetrahydroxybenzene and 1,2,3-trihydroxybenzene (pyrogallol), whereas its two products are 1,3,5-trihydroxybenzene (phloroglucinol) and 1,2,3,5-tetrahydroxybenzene. This enzyme participates in benzoic acid degradation via CoA ligation.
The pyrogallolarene macrocycle is typically prepared by condensation of pyrogallol and an aldehyde in concentrated acid solution in the presence of an alcohol solvent, usually methanol or ethanol. The reaction conditions can usually be carefully adjusted to precipitate the pure product or the product may be purified by recrystallization.
The Dakin oxidation can occur in mild acidic conditions as well, with a mechanism analogous to the base-catalyzed mechanism. In methanol, hydrogen peroxide, and catalytic sulfuric acid, the carbonyl oxygen is protonated (14), after which hydrogen peroxide adds as a nucleophile to the carbonyl carbon, forming a tetrahedral intermediate (15).
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