Empirical Formula: C₆H₁₀N₂O₄S
Molecular Weight: 206.2196 
EINECS: 240-357-1
Nominal Mass: 206 Da
Average Mass: 206.2196 Da
Monoisotopic Mass: 206.036127 Da 
Flash Point: 135.9 °C
Enthalpy of Vaporization: 50.54 kJ/mol
Boiling Point: 267.4 °C at 760 mmHg
Vapour Pressure: 0.00817 mmHg at 25 °C 
Melting point: >300 °C
Sensitive: Hygroscopic
Appearance: Grey to off-white powder
Structure of p-Phenylenediamine sulfate (CAS NO.16245-77-5):
                       
IUPAC Name: Benzene-1,4-diamine ; Sulfuric acid
Canonical SMILES: C1=CC(=CC=C1N)N.OS(=O)(=O)O
InChI: InChI=1S/C6H8N2.H2O4S/c7-5-1-2-6(8)4-3-5;1-5(2,3)4/h1-4H,7-8H2;(H2,1,2,3,4)
InChIKey: UFPKLWVNKAMAPE-UHFFFAOYSA-N
Product Category of p-Phenylenediamine sulfate (CAS NO.16245-77-5): Intermediates of Dyes and Pigments;Chemistry

  p-Phenylenediamine sulfate (CAS NO.16245-77-5) hasn't been listed as a carcinogen by NTP, IARC, ACGIH, or CA Prop 65. And the toxicological properties have not been fully investigated.

 Hazard Codes: T
Risk Statements: 23/24/25-36/37/38
 R23/24/25:Toxic by inhalation, in contact with skin and if swallowed. 
R36/37/38:Irritating to eyes, respiratory system and skin.
Safety Statements: 45-36/37/39-28A-26 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S28:After contact with skin, wash immediately with plenty of soap-suds. 
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.)

  p-Phenylenediamine sulfate , its cas register number is 16245-77-5. It also can be called 1,4-Benzenediamine sulfate (1:1) ; Benzene-1,4-diammonium sulphate ; and HSDB 6256 . It is hazardous, so the first aid measures and others should be known. Such as: When on the skin: first, should flush skin with plenty of water immediately for at least 15 minutes while removing contaminated clothing. Secondly, get medical aid. Or in the eyes: Flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids. Then get medical aid soon. While, it's inhaled: Remove from exposure and move to fresh air immediately. Give artificial respiration while not breathing. When breathing is difficult, give oxygen. And as soon as to get medical aid. Then you have the ingesting of the product: Wash mouth out with water, and get medical aid immediately. Notes to physician: Treat supportively and symptomatically.
In addition, p-Phenylenediamine sulfate (CAS NO.16245-77-5) is not compatible with strong oxidizing agents, acids, acetic anhydride, acid chlorides, chloroformates, and you must not take it with incompatible materials, exposure to moist air or water. And also prevent it to broken down into hazardous decomposition products: Nitrogen oxides, carbon monoxide, carbon dioxide, sulfur oxides (SOx), including sulfur oxide and sulfur dioxide.