Definition

Noun 1. A type of organic acid: Tannic acid is a specific, complex chemical compound belonging to a larger class of substances known as tannins. It is a polyphenol derived from plants. 2. A substance with astringent properties: It has the chemical property of binding to and precipitating proteins, which is the basis for its primary uses.

Usage

Tannic acid is used as a technical and scientific term. It is typically discussed in contexts involving chemistry, manufacturing, and medicine. * The traditional process for making leather uses tannic acid from oak bark. * Tannic acid can be used as an astringent in some medicinal preparations. * The study analyzed the concentration of tannic acid in different tea samples.

Advanced Usage

• Technical/Industrial Context: The term is precise and refers to the specific compound, often distinguished from other types of tannins (e.g., gallotannins, ellagitannins). It is frequently discussed in terms of its molecular weight, solubility, and reactivity.
  • The formula for commercial tannic acid is often given as C₇₆H₅₂O₄₆.
• As a Standard: In laboratory settings, a purified form of tannic acid may be used as a standard or reagent.
  • The protocol requires a 1% tannic acid solution for the staining step.

Variants and Related Words

• Tannin (n): The broader category of astringent, polyphenolic biomolecules to which tannic acid belongs. All tannic acid is a tannin, but not all tannins are tannic acid.
  • Tea contains several types of tannins.
• Gallotannin (n): A more specific chemical classification; tannic acid is often considered a type of gallotannin.
• Astringent (n/adj): Describing the property of tannic acid that causes contraction of body tissues.

Synonyms

• Digallic acid (a technical synonym in some chemical contexts)
• Gallotannic acid (an alternative name emphasizing its chemical structure)

Related Phrases / Compounds

• Tannic acid stain: A solution used in microscopy to enhance contrast, particularly for visualizing viruses or cell structures under an electron microscope.
  • The viral capsid was clearly visible after treatment with a tannic acid stain.

Noun

1. any of various complex phenolic substances of plant origin; used in tanning and in medicine