Molecular Formula: C₁₂H₂₈IN
Molar mass: 313.26 g/mol
Flash Point: 228.4 °C
Boiling Point: 454.1 °C at 760 mmHg
Vapour Pressure: 1.96E-08 mmHg at 25°C
Melting point: 280-285 °C (dec.)(lit.)
Water solubility: soluble
Sensitive: Hygroscopic
Structure of Tetrapropylammonium iodide(631-40-3):
                      
Synonyms of Tetrapropylammonium iodide(631-40-3): Tetra-N-propylammonium iodide;1-Propanaminium, N,N,N-tripropyl-;Ammonium, tetrapropyl-, iodide;N,N,N-Tripropyl-1-propanaminium iodide
Product Categories of Tetrapropylammonium iodide(631-40-3): quarternary ammonium salts:Catalysis;Phase Transfer Catalysts;Quaternary Ammonium Compounds;Greener Alternatives

1.

ivn-mus LD50:5600 µg/kg

CSLNX*    U.S. Army Armament Research & Development Command, Chemical Systems Laboratory, NIOSH Exchange Chemicals. (Aberdeen Proving Ground, MD 21010) NX#00822 .

2.   Carcinogenicity of Tetrapropylammonium iodide(631-40-3) hasn't been listed as a carcinogen by  NTP, IARC,ACGIH, or CA Prop 65.You can see actual entry in RTECS for complete information.

Reported in EPA TSCA Inventory.

Poison by intravenous route. An irritant. When heated to decomposition it emits very toxic fumes of NO_x, NH₃, and I⁻. See also IODIDES.
Hazard Codes: Xi
Risk Statements:
36:  Irritating to the eyes
37:  Irritating to the respiratory system
38:  Irritating to the skin
Safety Statements:
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

Tetrapropylammonium iodide(631-40-3) is hazardous,so the first aid measures and others should be known .Such as:
Skin: Get medical aid. Should flush skin with plenty of water immediatelyfor at least 15 minutes while removing contaminated clothing and shoes.
Eyes: Flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids.Then get medical aid soon. 
Inhalation: Remove from exposure and move to fresh air immediately.Give artificial respiration While not breathing. when breathing is difficult, give oxygen.
Ingestion: Do not induce vomiting. Wash mouth out with water,and get medical aid immediately.
Chemical Stability: Stable under normal temperatures and pressures.   
Incompatibilities with Other Materials: Strong oxidizing agents.
Conditions to Avoid: Light, exposure to moist air or water.
Hazardous Decomposition Products: Nitrogen oxides, hydrogen iodide, oxides of nitrogen, carbon monoxide, carbon dioxide.