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Phenolphthalein is slightly soluble in water and usually is dissolved in alcohols in experiments. It is a weak acid, which can lose H + ions in solution. The nonionized phenolphthalein molecule is colorless and the double deprotonated phenolphthalein ion is fuchsia. Further proton loss in higher pH occurs slowly and leads to a colorless form.
Phenolphthalein does not directly participate in this process; instead, it acts as an external source of electrons. In its reaction with hydrogen peroxide, the heme center of hemoglobin behaves as a peroxidase, reducing the peroxide to water. This activity depletes hemoglobin of electrons that are, in turn, re-supplied by the phenolphthalein.
Phenol is readily alkylated at the ortho positions using alkenes in the presence of a Lewis acid such as aluminium phenoxide: [citation needed] CH 2 =CR 2 + C 6 H 5 OH → R 2 CHCH 2 -2-C 6 H 4 OH More than 100,000 tons of tert-butyl phenols are produced annually (year: 2000) in this way, using isobutylene (CH 2 =CMe 2 ) as the alkylating agent.
In subsequent phase II reactions, these activated metabolites are conjugated with charged species such as glutathione, sulfate, glycine or glucuronic acid. These reactions are catalysed by a large group of broad-specificity transferases. UGT1A6 is a human gene encoding a phenol UDP glucuronosyltransferase active on simple phenols. [106]
Animation of a strong acid–strong base neutralization titration (using phenolphthalein). The equivalence point is marked in red. In chemistry, neutralization or neutralisation (see spelling differences) is a chemical reaction in which acid and a base react with an equivalent quantity of each other. In a reaction in water, neutralization ...
A strong base is a basic chemical compound that can remove a proton (H +) from (or deprotonate) a molecule of even a very weak acid (such as water) in an acid–base reaction. Common examples of strong bases include hydroxides of alkali metals and alkaline earth metals, like NaOH and Ca(OH)
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A well-known application of this reactivity is the preparation of the anthraquinone dye quinizarin by reaction with para-chlorophenol followed by hydrolysis of the chloride. [7] Phenolphthalein can be synthesized by the condensation of phthalic anhydride with two equivalents of phenol under acidic conditions (hence