Empirical Formula: C₆H₁₂
Molecular Weight: 84.1595 g/mol
EINECS: 212-078-5 
Index of Refraction: 1.395
Density: 0.687 g/cm³
Enthalpy of Vaporization: 29.17 kJ/mol
Boiling Point: 62 °C at 760 mmHg
Vapour Pressure: 194 mmHg at 25 °C 
Structure of 2-Ethyl-1-butene (CAS NO.760-21-4):
             
IUPAC Name: 3-Methylidenepentane
Product Categories of 2-Ethyl-1-butene (CAS NO.760-21-4): Acyclic;Alkenes;Organic Building Blocks
 

Reported in EPA TSCA Inventory.

A human eye irritant. A very dangerous fire hazard when exposed to heat, flames, or oxidizers. To fight fire, use dry chemical, CO₂, foam, spray. When heated to decomposition it emits acrid smoke and irritating fumes.
Hazard Codes of 2-Ethyl-1-butene (CAS NO.760-21-4): F,Xi,N
Risk Statements: 11-43-51/53 
R11:Highly flammable. 
R43:May cause sensitization by skin contact. 
R51/53:Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.
Safety Statements: 36/37-61 
S36/37:Wear suitable protective clothing and gloves. 
S61:Avoid release to the environment. Refer to special instructions / safety data sheets.

 2-Ethyl-1-butene ,its cas register number is 760-21-4. It also can be called Pentane, 3-methylene- ; 3-Methylenepentane ; and 1-Butene, 2-ethyl- .