Molecular Structure of Gallic acid (CAS NO.149-91-7):

IUPAC Name: 3,4,5-trihydroxybenzoic acid 
Empirical Formula: C₇H₆O₅
Molecular Weight: 170.1195
H bond acceptors: 5
H bond donors: 4
Freely Rotating Bonds: 4
Polar Surface Area: 53.99 ?2
Index of Refraction: 1.73
Molar Refractivity: 38.82 cm³
Molar Volume: 97.2 cm³
Surface Tension: 109.2 dyne/cm
Density: 1.749 g/cm³
Flash Point: 271 °C
Enthalpy of Vaporization: 81.07 kJ/mol
Boiling Point: 501.1 °C at 760 mmHg
Vapour Pressure: 7.32E-11 mmHg at 25°C
EINECS: 205-749-9
Melting point: 252 °C (dec.)(lit.)
Water Solubility: 12 g/L cold water
Merck: 14,4345
BRN: 2050274
Stability: Stability Stable, but may discolour upon exposure to light. Hygroscopic. Incompatible with strong oxidizing agents, strong bases, acid chlorides, acid anhydrides.
Product Categories: Pharmaceutical Intermediates; Aromatic Carboxylic Acids, Amides, Anilides, Anhydrides & Salts
InChI
InChI=1/C7H6O5/c8-4-1-3(7(11)12)2-5(9)6(4)10/h1-2,8-10H,(H,11,12)
Smiles
c1(cc(c(O)c(c1)O)O)C(O)=O

Reported in EPA TSCA Inventory. EPA Genetic Toxicology Program.

Poison by intravenous route. Moderately toxic by intraperitoneal route. Mildly toxic by ingestion. Experimental reproductive effects. Mutation data reported. When heated to decomposition it emits acrid smoke and irritating fumes.
Hazard Codes: Xi
Risk Statements: 36/37/38
R36/37/38:Irritating to eyes, respiratory system and skin.
Safety Statements: 26-36-24/25
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S36:Wear suitable protective clothing. 
S24/25:Avoid contact with skin and eyes.
WGK Germany: 2
RTECS: LW7525000
F: 8-9-23

  Gallic acid , with CAS number of 149-91-7, can be called 3,4,5-Trihydroxybenzoesäure ; 3,4,5-trihydroxy-Benzoic acid ; Acid, Gallic ; Acide 3,4,5-trihydroxybenzoïque ; benzoic acid, 3,4,5-trihydroxy- . It is a white powder, 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. 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.