Molecular Formula: C₁₀H₁₈Cl₂N₂
Molar mass: 237.1693 g/mol
EINECS: 211-274-8
Flash Point: 104.9 °C
Boiling Point: 260.6 °C at 760 mmHg
Vapour Pressure: 0.0121 mmHg at 25°C
Melting point: 222-224 °C(lit.)
Storage temp: Store at RT.
Sensitive: Air Sensitive/Heat Sensitive
Appearance: Off white to gray powder
Form: powder
Color: off-white to gray
Product categories: Benzoquinones;Charge Transfer Complexes for Organic Metals;Functional Materials
Structure of N,N,N',N'-Tetramethyl-p-phenylenediamine dihydrochloride (637-01-4):

XLogP3-AA: 1.7
H-Bond Donor: 2
H-Bond Acceptor: 2
IUPAC Name: 1-N,1-N,4-N,4-N-Tetramethylbenzene-1,4-diamine dihydrochloride
Canonical SMILES: CN(C)C1=CC=C(C=C1)N(C)C.Cl.Cl
InChI: InChI=1S/C10H16N2.2ClH/c1-11(2)9-5-7-10(8-6-9)12(3)4;;/h5-8H,1-4H3;2*1H 
InChIKey: FBHKTSXMTASXFJ-UHFFFAOYSA-N

Carcinogenicity of N,N,N',N'-Tetramethyl-p-phenylenediamine dihydrochloride (637-01-4) hasn't been listed as a carcinogen by NTP, IARC,ACGIH, or CA Prop 65. And its toxicological properties have not been fully investigated.

Reported in EPA TSCA Inventory.

Poison by subcutaneous route. When heated to decomposition it emits very toxic fumes of NO_x and HCl.
 

Hazard Codes: Xi,Xn
Risk Statements:
20:  Harmful by inhalation
21:  Harmful in contact with skin
22:  Harmful if swallowed 
36:  Irritating to the eyes
37:  Irritating to the respiratory system
38:  Irritating to the skin
40:  Limited evidence of a carcinogenic effect
Safety Statements:
22:  Do not breathe dust
26:  In case of contact with eyes, rinse immediately with plenty of water and seek medical advice
36:  Wear suitable protective clothing 
37:  Wear suitable gloves
39:  Wear eye/face protection

 N,N,N',N'-Tetramethyl-p-phenylenediamine dihydrochloride (637-01-4) also can be called Wurster's reagent dihydrochloride ; N,N,N',N'-Tetramethylbenzene-1,4-diamine dihydrochloride ; N,N,N',N'-Tetramethylbenzol-1,4-diamindihydrochlorid ; 1,4-benzenediamine, N~1~,N~1~,N~4~,N~4~-tetramethyl-, hydrochloride (1:2) ; N,N,N',N'-Tetramethyl-1,4-benzenediamine dihydrochloride ; 1,4-Benzenediamine, N,N,N',N'-tetramethyl-, dihydrochloride .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 immediatelyfor at least 15 minutes while removing contaminated clothing. Secondly,Get shoesmedical 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.
In addition, N,N,N',N'-Tetramethyl-p-phenylenediamine dihydrochloride (637-01-4) can be stable under normal temperature and pressure conditions.It is not compatible with strong oxidizing agents, strong bases, and you must not take it with incompatible materials. And also prevent it to broken down into hazardous decomposition products: oxides of nitrogen, carbon dioxide, carbon monoxide, hydrogen chloride.