Chemistry informtion about 2-Pentene (CAS NO.646-04-8) is:
IUPAC Name: (E)-Pent-2-Ene
Synonyms: Sym-Methylethylethylene ; Trans-2-Amylene ; Trans-2-Pentene ; Trans-Sym-Methylethylethylene ; Trans-B-N-Amylene ; (2e)-2-Pentene ; (E)-2-Pentene ; 2-(E)-C₅H₁₀ 
Product Categories: Acyclic ; Alkenes ; Organic Building Blocks ; Alpha Sort ; P ; PA - PEN ; P-SAlphabetic ; Volatiles/ Semivolatiles 
MF: C₅H₁₀
MW: 70.13
EINECS: 203-695-0 
Density: 0.669 g/cm³
Melting Point: −140 °C(lit.)
Flash Point: °C
Boiling Point: 37.5 °C at 760 mmHg
Vapour Pressure: 485 mmHg at 25°C
Enthalpy of Vaporization: 27.06 kJ/mol
Refractive Index: n20/D 1.381
Storage temp.:  2-8°C
Merck: 14,7123
BRN: 1718795
Following is the molecular structure of 2-Pentene (CAS NO.646-04-8) is:

2-Pentene (CAS NO.646-04-8)  can be used as a solvent, in organic synthesis, and as a polymerization inhibitor.

A dangerous fire and explosion hazard when exposed to heat or flame; can react vigorously with oxidizing materials. When heated to decomposition it emits acrid smoke and irritating fumes. 
Hazard Codes:
F
Xn
Risk Statements:
R11:Highly flammable. 
R36/37/38:Irritating to eyes, respiratory system and skin. 
R65:Harmful: may cause lung damage if swallowed.
Safety Statements:
S9:Keep container in a well-ventilated place. 
S16:Keep away from sources of ignition. 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S29:Do not empty into drains. 
S33:Take precautionary measures against static discharges. 
S36:Wear suitable protective clothing. 
S62:If swallowed, do not induce vomitting; seek medical advice immediately and show this container or label.
RIDADR: UN 3295 3/PG 2
WGK Germany: 3
RTECS: SB2184500
HazardClass: 3
PackingGroup: II

2-Pentene (CAS NO.646-04-8) is a clear colourless to slightly yellowish liquid with a hydrocarbon odor. It usually in technical grade as a mixture of isomers. It is highly flammable and insoluble in water. The unsaturated aliphatic hydrocarbons, such as 2-Pentene, are generally much more reactive than the alkanes. Strong oxidizers may react vigorously with them. Reducing agents can react exothermically to release gaseous hydrogen. In the presence of various catalysts (such as acids) or initiators, compounds in this class can undergo very exothermic addition polymerization reactions.
First Aid Measures:
Eyes: Flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids. Get medical aid.
Skin: Get medical aid. Flush skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes.
Ingestion: Get medical aid. Wash mouth out with water.
Inhalation: Remove from exposure and move to fresh air immediately. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical aid.
Notes to Physician: Treat symptomatically and supportively. 
Handling and Storage:
Handling: Use spark-proof tools and explosion proof equipment. Avoid breathing dust, vapor, mist, or gas. Avoid contact with skin and eyes. Avoid ingestion and inhalation.
Storage: Keep away from sources of ignition. Store in a cool, dry place. Store in a tightly closed container. Flammables-area.