(Z)-But-2-ene 2-BUTENE, (Z)- 2-Butene, (2Z)- 2-Butene-cis 590-18-1 EINECS 209-673-7 HSDB 5704 High-boiling butene-2 beta-cis-Butylene cis-1,2-Dimethylethylene cis-2-Butene cis-Butene