.alpha.-Butenoic acid .alpha.-Crotonic acid .beta.-Methylacrylic acid 2-Butenoic acid 3-Methylacrylic acid 3724-65-0 Acrylic acid, 3-methyl- Crotonic Acid NSC206946 Solid crotonic acid WLN: QV1U2 -T trans-2-Butenoic acid