1,4-Dibromo-2-butene 1,4-Dibromobut-2-ene 2-01-00-00177 (Beilstein Handbook Reference) 2-BUTENE, 1,4-DIBROMO- 6974-12-5 BRN 1719694 EINECS 230-219-9 NSC 23187 TL 80