IUPAC Name: 3,5-Dihydroxybenzoic acid 
Following is the structure of Benzoic acid,3,5-dihydroxy- (CAS NO.99-10-5):
             
Molecular Formula: C₇H₆O₄
Molecular Weight: 154.12 g/mol
EINECS: 202-730-7
Density: 1.559 g/cm³
Melting Point: 235 - 237 °C
Flash Point: 216.8 °C
Freely Rotating Bonds: 3  
Index of Refraction: 1.67
Molar Volume: 98.8 cm³ 
Molar Refractivity: 36.94 cm³
Polarizability: 14.64 10^-24 cm³
Surface Tension: 84.2 dyne/cm
Water Solubility: 84 g/L (20 °C)
Boiling Point: 411.5 °C at 760 mmHg 
Enthalpy of Vaporization: 70.01 kJ/mol 
Vapour Pressure: 1.64E-07 mmHg at 25 °C
Solubility: slightly soluble (soluble in hot alcohol, ether)
Appearance of Benzoic acid,3,5-dihydroxy- (CAS NO.99-10-5): white to off-white crystalline powder
Product Categories: Aromatic Carboxylic Acids, Amides, Anilides, Anhydrides & Salts; Benzoic acid; Organic acids; Building Blocks for Dendrimers; Functional Materials
Canonical SMILES: C1=C(C=C(C=C1O)O)C(=O)O
InChI: InChI=1S/C7H6O4/c8-5-1-4(7(10)11)2-6(9)3-5/h1-3,8-9H,(H,10,11)
InChIKey: UYEMGAFJOZZIFP-UHFFFAOYSA-N

α-resorcylic acid(99-10-5) is used in organic synthesis and as intermediate  for the pharmaceutical.

 Benzoic acid,3,5-dihydroxy- (CAS NO.99-10-5) hasn't been listed as a carcinogen by ACGIH, IARC, NTP, or CA Prop 65. And the toxicological properties have not been fully investigated. You can see actual entry in RTECS for complete information.

Reported in EPA TSCA Inventory.

Moderately toxic by intravenous route. When heated to decomposition it emits acrid smoke and irritating vapors.
Hazard Codes:  Xi.
Xi:  Irritant.
Risk Statements:  36/37/38.
36/37/38:  Irritating to eyes, respiratory system and skin.
Safety Statements:  26-36-37/39.
26:  In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.
36:  Wear suitable protective clothing.  
37/39:  Wear suitable gloves and eye/face protection.
WGK Germany: 1
RTECS: VH3708000
Hazard Note: Irritant
HS Code: 29182990

 Benzoic acid,3,5-dihydroxy- , its cas register number 99-10-5. It also can be called 3,5-Dihydroxybenzoic acid ; Acide 3,5-dihydroxybenzoïque ; and 5-Carboxyresorcinol . Benzoic acid,3,5-dihydroxy- (CAS NO.99-10-5) should avoid the condition like incompatible materials, excess heat, exposure to moist air or water. It is not compatible with strong oxidizing agents, strong bases. And also prevent it to broken down into hazardous decomposition products: carbon monoxide, carbon dioxide. However, its hazardous polymerization has not been reported.