Odor–Structure Relationships Using Fluorine as a Probe

Eight ethers, nine esters and one ketone were submitted to a systematic structural variation by replacing a hydrogen atom in the vicinity of the oxofunction by fluorine and methyl. As long as steric factors dominate, a fluorine substituent alters the olfactory properties of the parent compound much less than a methyl substituent does. However, if it occupies a position adjacent to a carbonyl group, the halogen may more profoundly affect the odor perception, presumably as a consequence of conformational changes.