(E)-2-Pentenal (E)-Pent-2-en-1-al 1576-87-0 2-(E)-Pentenal 2-Pentenal, (E)- 4-01-00-03459 (Beilstein Handbook Reference) BRN 1719742 CCRIS 4564 EINECS 216-414-1 trans-2-Pentenal