Gallic acid

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Gallic acid

General
Systematic name	3,4,5-hydroxybenzoic acid
Other names	Gallic acid
Molecular formula	C₇H₆O₅
SMILES	Oc1cc(cc(O)c1O)C(O)=O
Molar mass	170.12 g/mol
Appearance	White, yellowish-white, or pale fawn-colored crystals.
CAS number	[149-91-7] (Anhydrous) [5995-86-8] (Monohydrate)
Properties
Density and phase	1.7 g/cm³ (anhydrous)
Solubility in water	1.1g/100ml water @ 20°C (anhydrous) 1.5g/100ml water @ 20°C (monohydrate)
Melting point	250°C (523 K)
Boiling point	?°C (? K)
Acidity (pK_a)	COOH: 4.5, OH: 10.
Chiral rotation [α]_D	?°
Structure
Crystal structure	?
Dipole moment	? D
Hazards
MSDS	External MSDS]
Main hazards	Irritant
NFPA 704	0 1 0
Flash point	?°C
R/S statement	R: ? S: ?
RTECS number	?
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related phenols, carboxylic acids	?
Related compounds	Benzoic acid, Phenol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Gallic acid is an organic acid, also known as 3,4,5-trihydroxybenzoic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. The chemical formula is C₆H₂(OH)₃CO₂H. Gallic acid is found both free and as part of tannins. It is commonly used in the pharmaceutical industry. Gallic acid can also be used to synthesize the hallucinogenic alkaloid, mescaline, also known as 3,4,5-trimethoxyphenethylamine.

Salts and esters of gallic acid are termed gallates.

Gallic acid was one of the substances used by Angelo Mai among other early investigators of palimpsests to clear the top layer of text off and reveal hidden manuscripts underneath. Mai was the first to employ it, but did so "with a heavy hand," often damanging manuscripts for future study.