AbstractThe proton magnetic resonance spectra of ethylenoxyde, trimethylenoxyde, tetramethylenoxyde, pentamethylenoxyde, cyclobutanone, cyclopentanone and cyclohexanone have been measured in pure liquid state and in solution in carbon disulfide and cyclopentane. The spectra of these compounds with one, two and more sets of equivalent nuclei show the expected behaviour with respect to chemical shifts, with the exception of cyclopentanone. In this compound the difference in chemical shifts of the α‐ and β‐protons is abnormally small. The analysis of the spectra will be discussed in a subsequent