Methyl vinyl ketone (MVK) is an important substrate for synthesis. In the context of UV/Vis spectroscopy, MVK provides a good example as to how conjugation causes a red shift in the absorption (e.g. to longer wavelengths).
Acetone: n to pi* 270 nm; pi to pi* 187 nm.
MVK: n to pi* 324 nm; pi to pi* 219 nm.