Electron impact studies. Part LVII. Negative-ion mass spectrometry of functional groups. Simple esters
The molecular anions of esters of the general type R1–CO2–R2 are strongly stabilised when R1 or R2 is a quinone residue. The resultant spectra are reproducible and extremely intense. The basic fragmentations of esters are discussed, with simple cleavage, cleavage with hydrogen rearrangement, and proximity effects being noted in the spectra. In many cases, the negative-ion spectra are more informative for structure elucidation than are the corresponding positive-ion spectra.