Résumé : This work concerns the IR study of the methylene scissoring vibrations of a large series of cyclohexanones and halogenocyclohexanones. This study permits, more particularly, an assignment of the 1433 ± 3 cm-1 band (CCl4) to the CH2 group vicinal to the axial halogen(s). This assignment makes possible the quantitative conformational analysis of 2-chloro-, 2-bromo-, trans-2-bromo-5-methyl-, cis-2,6-dichloro- and cis-2,6-dibromo-cyclohexanones by measuring the integrated intensity of this absorption and using the trans-2,6- or 2,2-dihalogenocyclohexanones as standard molecules. © 1970.