.beta.-Isoamylene 1,1,2-Trimethylethylene 2-Butene, 2-methyl- 2-Methyl-2-butene 3-Methyl-2-butene 513-35-9 Amylene Ethylene, trimethyl- Methyl butene NSC74118 Trimethylethylene WLN: 2UY1&1 n-Amylene