IUPAC Name: 4-amino-3-methylbenzenesulfonic acid 
Empirical Formula: C₇H₉NO₃S
Molecular Weight: 187.2163g/mol
EINECS: 202-658-6 
Structure of 2-Aminotoluene-5-sulfonic acid (CAS NO.98-33-9):

Index of Refraction: 1.61
Molar Refractivity: 45.34 cm³
Molar Volume: 130.7 cm³
Polarizability: 17.97×10^-24cm³
Surface Tension: 61.7 dyne/cm
Density: 1.431 g/cm³ 
Melting Point: 290°C
Product Categories: Intermediates of Dyes and Pigments 
Canonical SMILES: CC1=C(C=CC(=C1)S(=O)(=O)O)N
InChI: InChI=1S/C7H9NO3S/c1-5-4-6(12(9,10)11)2-3-7(5)8/h2-4H,8H2,1H3,(H,9,10,11)
InChIKey: WQTCZINVPXJNEL-UHFFFAOYSA-N

Hazard Codes: T
Risk Statements: 45-34 
R45:May cause cancer. 
R34:Causes burns.
Safety Statements: 53-26-36/37/39-45 
S53:Avoid exposure - obtain special instructions before use. 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S36/37/39:Wear suitable protective clothing, gloves and eye/face protection. 
S45:In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.)
RIDADR: 2811
HazardClass: 8
PackingGroup: III

   2-Aminotoluene-5-sulfonic acid , its cas register number is 98-33-9. It also can be called 4-Amino-3-methylbenzenesulfonic acid ; 4-Amino-m-toluenesulfonic acid ; 4-Amino-m-toluenesulfonic acid (SO3H=1) ; 4-Amino-meta-toluenesulfonic acid (SO3H=1) ; AI3-16579 ; CCRIS 3412 ; NSC 7545 ; o-Toluidine-m-sulfonic acid .