Consider the structure of 2,4-dimethyl-3-pentanone and its proton NMR spectrum, which used TMS as reference. HC CHE CHE Proton NMR Proton NMR 8ppm) As expected, the proton NMR shows that there are different proton environments. The downfield septet signal indicates that one type of hydrogen has equivalent neighboring hydrogens. The downfield signal corresponds to hydrogens, The upfield signal corresponds to hydrogens that each have one neighbor, so it appears as a Choose The upfield signal corresponds to - hydrogens.