trans-1-Bromopropene590-15-8100 % similar 1,2-Dibromoethene540-49-845 % similar But-2-ene107-01-736 % similar cis-2-Butene590-18-136 % similar trans-2-Butene624-64-636 % similar Trans,trans-2,4-hexadiene5194-51-431 % similar 2,4-Hexadiene592-46-131 % similar