Gallic acid is a trihydroxybenzoic acid found in many plants as either the free acid or in the esterified form of gallotannins and ellagitannins. It demonstrates antioxidant activity by scavenging 2,2-diphenyl-1-picrylhydrazyl and hydroxyl free radicals with IC50 values of 9.4 and 191 μM, respectively, and inhibiting microsomal lipid peroxidation with an IC50 value of 1.51 μM. Gallic acid is often used as a standard for determining the phenol content of various analytes by the Folin-Ciocalteau assay where results are reported in gallic acid equivalents.[Cayman Chemical]
antineoplastic, astringent, antibacterial
Inhalation of dust may irritate nose and throat. Contact with eyes or skin causes irritation.
Flash point data for Gallic acid are not available. Gallic acid is probably combustible.
Crystallise gallic from water. The tri-O-acetyl derivative has m 172o (from MeOH), and the anilide has m 207o(from EtOH). [Beilstein 10 H 470, 10 IV 1993.]
ChEBI: A trihydroxybenzoic acid in which the hydroxy groups are at positions 3, 4, and 5.
Phenols, such as Gallic acid, do not behave as organic alcohols, as one might guess from the presence of a hydroxyl (-OH) group in their structure. Instead, they react as weak organic acids. Phenols and cresols are much weaker as acids than common carboxylic acids (phenol has Ka = 1.3 x 10^[-10]). These materials are incompatible with strong reducing substances such as hydrides, nitrides, alkali metals, and sulfides. Flammable gas (H2) is often generated, and the heat of the reaction may ignite the gas. Heat is also generated by the acid-base reaction between phenols and bases. Such heating may initiate polymerization of the organic compound. Phenols are sulfonated very readily (for example, by concentrated sulfuric acid at room temperature). The reactions generate heat. Phenols are also nitrated very rapidly, even by dilute nitric acid.
A cyclooxygease inhibitor substance found in plants.
Colorless crystalline needles or prisms obtained from nutgall tannins,gallic acid is soluble in water and alcohol and melts at 235 to 240 °C. Also known as trihydroxybenzoic acid, it is used in photography, tanning, ink manufacture and pharmaceuticals.
Air & Water Reactions
Sparingly water soluble
Odorless white solid. Sinks in water.