Phenolphthalein, identified by its CAS number 77-09-8, is more than just a laboratory staple; it's a compound with a rich chemical profile that underpins its diverse applications. From its synthesis to its distinct pH-dependent color change, understanding its properties is key for chemists and formulators. NINGBO INNO PHARMCHEM CO.,LTD. is a premier manufacturer and supplier of high-quality Phenolphthalein, ensuring purity for various industrial and research needs.

The synthesis of Phenolphthalein typically involves the condensation of phthalic anhydride with two equivalents of phenol, catalyzed by a strong acid like sulfuric acid or zinc chloride. This process, still largely the standard method, yields a white to pale yellow crystalline powder. Its molecular structure, a triphenylmethane derivative, is responsible for its characteristic behavior. While practically insoluble in water, it readily dissolves in alcohol, making it suitable for preparing indicator solutions.

The most celebrated property of Phenolphthalein is its function as a pH indicator. In acidic and neutral solutions (pH < 8.2), the molecule exists in a closed lactone ring form, which does not absorb visible light, rendering it colorless. As the solution becomes alkaline (pH > 8.2), the lactone ring opens, leading to a structural rearrangement. This results in a quinoid structure with extended conjugation, capable of absorbing visible light and exhibiting a vibrant pink to fuchsia color. This reversible color change between pH 8.2 and 10.0 makes it invaluable for acid-base titrations.

Historically, Phenolphthalein was widely used as a laxative. However, concerns regarding its potential carcinogenicity led to its discontinuation in many medicinal products. Today, its primary applications lie in analytical chemistry, forensic science (Kastle-Meyer test), and construction (concrete carbonation testing).

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Understanding the chemical nuances of Phenolphthalein allows for its optimal application. Whether for precise laboratory analysis or industrial testing, its unique properties continue to make it a valuable compound. If you are seeking a dependable source to buy Phenolphthalein, our team is ready to assist you.