Molecular Structure of Vanillic acid (CAS NO.121-34-6):

IUPAC Name: 4-Hydroxy-3-methoxybenzoic acid
Canonical SMILES: COC1=C(C=CC(=C1)C(=O)O)O
InChI: InChI=1S/C8H8O4/c1-12-7-4-5(8(10)11)2-3-6(7)9/h2-4,9H,1H3,(H,10,11)
InChIKey: WKOLLVMJNQIZCI-UHFFFAOYSA-N
Molecular Weight: 168.14672 [g/mol]
Molecular Formula: C₈H₈O₄
XLogP3: 1.4
H-Bond Donor: 2
H-Bond Acceptor: 4 
EINECS: 204-466-8
Appearance: white odourless crystals or powder
Melting Point: 208-210 °C(lit.)
Index of Refraction: 1.585
Molar Refractivity: 41.74 cm³
Molar Volume: 124.3 cm³
Surface Tension: 56.5 dyne/cm
Density: 1.351 g/cm³
Flash Point: 149.4 °C
Enthalpy of Vaporization: 63.14 kJ/mol
Boiling Point: 353.4 °C at 760 mmHg
Vapour Pressure: 1.32E-05 mmHg at 25 °C
FEMA: 3988
Stability: Stable. Combustible. Incompatible with strong oxidizing agents.
Water Solubility: 1500 mg/L at 14 °C
Classification Code: Mutation data  
Product Categories: FINE Chemical & INTERMEDIATES; Aromatic Carboxylic Acids, Amides, Anilides, Anhydrides & Salts; BUILDING BLOCKS; BenzoicAcidDerivative; Organic acids

 Vanillic acid (CAS NO.121-34-6) is a benzoic acid derivative used as a flavoring agent. It is an oxidized form of vanillin. It is also an intermediate in the production of vanillin from ferulic acid.

Reported in EPA TSCA Inventory.

Safety Information of Vanillic acid (CAS NO.121-34-6):
Hazard Codes: Xi
Risk Statements: 36/37/38 
R36/37/38:Irritating to eyes, respiratory system and skin.
Safety Statements: 37/39-26-36 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S36:Wear suitable protective clothing. 
S37/39:Wear suitable gloves and eye/face protection.
WGK Germany: 1
RTECS: YW5300000
Hazard Note: Irritant
Mutation data reported. When heated to decomposition it emits acrid smoke and irritating fumes.

 Vanillic acid (CAS NO.121-34-6), its Synonyms are 3-Methoxy-4-hydroxybenzoic acid ; 4-Hydroxy-3-methoxybenzoic acid ; Benzoic acid, 4-hydroxy-3-methoxy- ; Acide vanillique ; Protocatechuic acid, 3-methyl ester ; VA ; m-Anisic acid, 4-hydroxy- ; p-Vanillic acid .