C5H9NO

The molecular formula C5H9NO may refer to:


 * 3-Dimethylaminoacrolein
 * 2-Ethyl-2-oxazoline
 * N-Methyl-2-pyrrolidone
 * N-Methyl-4-pyrrolidone
 * 4-Piperidinone
 * 2-Piperidinone