6-Nonenal

6-Nonenal
	; cis-6-Nonenal
	; trans-6-Nonenal
Names
	IUPAC names (Z)-Non-6-enal; (E)-Non-6-enal
	Other names 6-Nonenal
Identifiers
CAS Number	6728-35-4 ; 2277-20-5 (E) ; 2277-19-2 (Z) ;
3D model (JSmol)	Interactive image; (E): Interactive image; (Z): Interactive image;
ChemSpider	15903; 4446459 (E); 4515200 (Z);
PubChem CID	16778; 5283338 (E); 5362720 (Z);
CompTox Dashboard (EPA)	DTXSID60859713 ;
	InChI InChI=1/C9H16O/c1-2-3-4-5-6-7-8-9-10/h3-4,9H,2,5-8H2,1H3 Key: RTNPCOBSXBGDMO-UHFFFAOYAV; (E): InChI=1/C9H16O/c1-2-3-4-5-6-7-8-9-10/h3-4,9H,2,5-8H2,1H3/b4-3+ Key: RTNPCOBSXBGDMO-ONEGZZNKBC; (Z): InChI=1/C9H16O/c1-2-3-4-5-6-7-8-9-10/h3-4,9H,2,5-8H2,1H3/b4-3- Key: RTNPCOBSXBGDMO-ARJAWSKDBN;
	SMILES O=CCCCCC=CCC; (E): O=CCCCC/C=C/CC; (Z): O=CCCCC/C=C\CC;
Properties
Chemical formula	C9H16O
Molar mass	140.226 g·mol−1
Appearance	Colorless liquid
Density	0.841 g/cm3
Boiling point	62 to 63 °C (144 to 145 °F; 335 to 336 K) at 2 mmHg
Solubility in water	0.63 g/L
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	Irritant
Flash point	113 °C (235 °F; 386 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

6-Nonenal is an organic compound with the formula C₂H₅CH=CH(CH₂)₄CHO. Other isomeric nonenal compounds are also known to exist naturally, e.g. 2-nonenal. The cis-isomer of 6-nonenal is often listed as the principal component in the aromas of muskmelon fruits.^[1] The trans-isomer is listed as an off-flavor aroma of milk foams,^[2] and thought to be a possible polypropylene odorant.^[3]

Biosynthesis

6-Nonenal is thought to be biosynthesized from γ-lineolenic acid catalyzed by a lipoxygenase. The lipoxygenase converts alkene groups into hydroperoxides, which cleave by hydroperoxide lyase into the corresponding cis-aldehydes.^[4] Consistent with this mechanism, the odor of muskmelons requires exposure to air. In the ripe, unmodified muskmelon, cis-6-nonenal exists in only low concentration. A steep increase in the concentration of 6-nonenal is noticed when the cells are lysed and exposed to air. This increase is attributed to rapid formation of hydroperoxides. Trans,cis-2,6-nonadienal is a related fragrance that arises via a similar pathway.

Laboratory synthesis

Either geometric isomer of this compound may be prepared by preparing by brominating 5-octene-1-ol, then preparing the appropriate Grignard reagent. Triethyl orthoformate is treated with this Grignard reagent, then hydrolyzed to give 6-nonenal.^[5]

References

^ Hong, S.J.; Lee, S.K.; Oh, S.H. (2011). "Aroma Volatile Changes of Netted Muskmelon (Cucumis melo L.) Fruit during Developmental Stages". J. Hort. Environ. Biotechnol. 52 (6): 590–595. doi:10.1007/s13580-011-0090-z. S2CID 44969740.
^ Allen, C.A.; Parks, O.W.; Schwartz, D.P.; Wong, N.P. (1969). "6-trans-Nonenal: an off-flavor component of foam spray-dried milks". Journal of Dairy Science. 52 (7): 953–956. doi:10.3168/jds.S0022-0302(69)86673-7.
^ Haar, N.; Hopfer, H.; Leitner, E.; Sauer, C.; Stockreiter, W. (2012). "Combining different analytical approaches to identify odor formation mechanisms in polyethylene and polypropylene". J. Anal. Bioanal. Chem. 402 (2): 903–919. doi:10.1007/s00216-011-5463-8. PMID 22048233. S2CID 23691565.
^ Harada, T.; Hatanaka, A.; Kajiwara, T. (1975). "Biosynthetic Pathway of Cucumber Alcohol: trans-2,cis-6-nonadienol via cis-3,cis-6-nonadienal". Phytochemistry. 14 (12): 2589–2592. Bibcode:1975PChem..14.2589H. doi:10.1016/0031-9422(75)85230-7.
^ Seifert, R.M. (1981). "Synthesis, Spectra, Odor Properties, and Structural Relationship of (Z)-6-Nonenal and (Z)-5-Octen-l-ol to Fruit Fly Attractants". J. Agric. Food Chem. 29 (3): 647–649. doi:10.1021/jf00105a053.

[1] Hong, S.J.; Lee, S.K.; Oh, S.H. (2011). "Aroma Volatile Changes of Netted Muskmelon (Cucumis melo L.) Fruit during Developmental Stages". J. Hort. Environ. Biotechnol. 52 (6): 590–595. doi:10.1007/s13580-011-0090-z. S2CID 44969740.

[2] Allen, C.A.; Parks, O.W.; Schwartz, D.P.; Wong, N.P. (1969). "6-trans-Nonenal: an off-flavor component of foam spray-dried milks". Journal of Dairy Science. 52 (7): 953–956. doi:10.3168/jds.S0022-0302(69)86673-7.

[3] Haar, N.; Hopfer, H.; Leitner, E.; Sauer, C.; Stockreiter, W. (2012). "Combining different analytical approaches to identify odor formation mechanisms in polyethylene and polypropylene". J. Anal. Bioanal. Chem. 402 (2): 903–919. doi:10.1007/s00216-011-5463-8. PMID 22048233. S2CID 23691565.

[4] Harada, T.; Hatanaka, A.; Kajiwara, T. (1975). "Biosynthetic Pathway of Cucumber Alcohol: trans-2,cis-6-nonadienol via cis-3,cis-6-nonadienal". Phytochemistry. 14 (12): 2589–2592. Bibcode:1975PChem..14.2589H. doi:10.1016/0031-9422(75)85230-7.

[5] Seifert, R.M. (1981). "Synthesis, Spectra, Odor Properties, and Structural Relationship of (Z)-6-Nonenal and (Z)-5-Octen-l-ol to Fruit Fly Attractants". J. Agric. Food Chem. 29 (3): 647–649. doi:10.1021/jf00105a053.

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