1-Cyanopropene 1-Propenyl cyanide 2-Butenenitrile 4786-20-3 AI3-28717 CROTONONITRILE Crotonic nitrile Crotonique nitrile [French] Crotonitrile Crotonnitrile EINECS 225-335-1 NSC 165574 beta-Methylacrylonitrile