Nonadien-3-one (unknown isomer), CAS 81967-36-4, is an unsaturated aliphatic ketone with two C=C bonds and a carbonyl at C-3; because the isomeric composition (position and/or geometry) is unspecified, it is used mainly as a research tool rather than a widely commercialized ingredient, notably in flavor and fragrance to explore, tune, and reproduce the green, leafy, fatty, fresh-cut facets typical of C9 unsaturated carbonyls (highly dependent on isomer distribution and purity) in foods, beverages, perfumery, and home care at trace levels after safety review; as a reference and method-control standard in GC, GC-MS, and GC-O for identification/quantitation of lipid-oxidation carbonyls, for retention indexing, odor-activity value calculations, and aroma fingerprinting of agricultural materials; for sensory panel training, threshold determination, and mixture-interaction studies; as a model substrate to probe mechanisms and kinetics (oxidation, isomerization, nucleophilic addition), to evaluate antioxidant efficacy, and to study sorption/release on packaging polymers and packaging-flavor interactions; to support microencapsulation, controlled-release, and formulation-compatibility work; as a reactive VOC exemplar in indoor-air and odor research for testing filters, sorbents, and ozone chemistry, and in postharvest volatilome mapping; and in computational modeling (QSAR, sensory prediction, volatility/reactivity) and QC method validation, where rigorous reporting of isomer distribution and impurities is required due to their strong impact on odor and stability.
