Molecular Structure:

Molecular Formula: C₇H₇NO₃S
Molecular Weight: 185.2004
IUPAC Name: 1H-Thieno[3,2-d][1,3]oxazine-2,4-dione
Synonyms of 3-(Acetylamino)thiophene-2-carboxylic acid (CAS NO.50901-18-3): 3-(Acetylamino)-2-thiophenecarboxylic acid ; Buttpark 99\18-20
CAS NO: 50901-18-3
Melting point: 200 °C 
Index of Refraction: 1.657
Molar Refractivity: 45.83 cm³
Molar Volume: 124.5 cm³
Surface Tension: 67 dyne/cm
Density: 1.487 g/cm³
Flash Point: 224.4 °C
Enthalpy of Vaporization: 74.39 kJ/mol
Boiling Point: 447.5 °C at 760 mmHg
Vapour Pressure of 3-(Acetylamino)thiophene-2-carboxylic acid (CAS NO.50901-18-3): 8.59E-09 mmHg at 25°C

Hazard Codes of 3-(Acetylamino)thiophene-2-carboxylic acid (CAS NO.50901-18-3): Xi
Risk Statements: 36/37/38 
R36/37/38: Irritating to eyes, respiratory system and skin.
Safety Statements: 26-37/39 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S37/39: Wear suitable gloves and eye/face protection.
Hazard Note: Irritant