Phenolphthalein

Phenolphthalein (or benzylphenol) is an indicator that turns crimson in an alkaline environment. It is used in chemistry to determine the acidity of a solution and also as an indicator to measure pH. Phenolphthalein is a condensation product of phthalate anhydride (C6H4(CO)2O) and phenol (C6H5OH).

Phenolphthalein has high solubility in water and alcohol, and low solubility in ethers and oils. It is insoluble in chloroform, benzene and other organic solvents.

Phenolphthalein is used as an indicator dye in various laboratory tests such as pH determination, hydrogen ion concentration determination, and carbonate concentration determination. It is also used as a laxative, but its use should be limited due to its toxicity to humans.

It is important to note that phenolphthalein can only be used to determine pH if it is in solution. If it is on a surface or in solid form, it will not turn crimson.

Phenolphthalene

**Phenolcarboxylic acid** - “phenel”. Phenols, dihydroxybenzene, hydroxyphenylalkyl ester 1,2-Dihydroxy-3,5-benzenedioic acid. The structure of the phenol molecule. Formula: C6H5OH. Molar mass: 74.08 g/mol. Melting point: 40 - 42 °C Boiling point: 182 - 190 °C (decomposes). Density: 1.109 g/cm³ at 20 °C. Enthalpy of formation ΔH: -315 kJ/mol Solubility in water at room temperature: 28 mg/100 ml Reacts with sodium hydroxide to form a complex compound: [C6H6OH](OH)2 - white powdery bright crimson crystalline. It is highly soluble in acetone and alcohol solvent. It is a diatomic molecule and promotes the coagulation of proteins. Leads to the formation of comedones on the skin. The neutral solution has negative surface activity and has a positive effect on the optical properties of synthetic fibers. Oxidation involves the carboxyl group of phenylacetalene: Compatible with toluene-perchlorate delipidation in an alkaline benzene solution. Forms salts and complexes. The solution is yellow. Distinguish between oxidizing products.

Synthesis In liquid state. Obtained from phenol and potassium perchlorate KClO4 conc. Dissolution in the presence of sodium sulfide Na2S. The resulting compound (xanthoronic acid) is hydrolyzed by alkali solutions (dissolves meat before the eyes). Acetone displaces