Phthalein Dyes

Abstract

Color change has fascinated individuals for a long time. Phthaleins dyes traditionally are used for color change, and they constitute the major class of pH indicators. This review presents systematic and up‐to‐date compiled data on commonly used phthalein dyes with references to the introduction, history, chemical structures, synthesis, color‐change mechanism, color and constitution, spectral data, applications, and health/safety factors. Phthalein dyes exhibit multiple applications, which are grouped into eight major categories such as electronics, security, coatings, industrial, agriculture, food, personal‐care products, and medical. The toxicity of phenolphthein is discussed with references to bacterial toxicity, carcinogenicity, lung cancer, ovarian cancer, chromosome aberrations, cytotoxicity, DNA damage, environmental toxicity, estrogen activity, genotoxicity, mutagenicity, renal toxicity, and reproductive toxicity.

NbCl5 Promoted the Efficient Synthesis of Phthalein Derivatives: Optical Characterization and Solvatochromic Effect

“…It is possible to observe interesting results in the study carried out, because all the solutions showed significant changes in their coloration when they go from an acid medium to an alkaline medium . This effect is known as halochromism .…”

Removal of Azo Dyes from Aqueous Effluent Using Bio-Based Activated Carbons: Toxicity Aspects and Environmental Impact

“…The recalcitrant and xenobiotic natures of azo dyes can be shown to impact human and animal health in the form of severe pathologies. Indeed, azo dyes are considered carcinogenic and mutagenic organic chemicals [17][18][19][20][21][22][23][24][25][26][27]. Short-term exposure to azo dyes does not significantly impact human and animal health [18].…”

Developments in the chemistry and applications of phthalein dyes. Part 1: industrial applications

“…The most widely used condensing agents are concentrated sulphuric acid and anhydrous zinc chloride. Table summarises a comprehensive list of various condensing agents reported in the literature for synthesising phthalein dyes along with the corresponding references . Recrystallisation to purify phthalein dyes on a large scale is also reported .…”

“…Although phthalein dyes have been extensively used in various fields, no review emphasising the developments in the chemistry of phthalein dyes has so far appeared. One book on acid–base indicators covers some of the phthalein dyes, and another reports on the most commonly used phthalein dyes , namely phenolphthalein, o‐ cresolphthalein and thymolphthalein.…”