trans-2-Methyl-2-butenal
trans-2-Methyl-2-butenal is an organic compound with the formula CH3CH=C(CH3)CHO. This colorless liquid is a building block in organic synthesis. It is an α,β-unsaturated aldehyde related to the better known crotonaldehyde. The European rabbit, Oryctolagus cuniculus, utilizes 2-methyl-2-butenal as a pheromone.