2-Nonenal

2-Nonenal
IUPAC name Non-2-enal
Identifiers
CAS number	18829-56-6 (trans) Y, 60784-31-8 (cis), 2463-53-8 (cis/trans mixture)
PubChem	5283335
ChemSpider	4446456 Y
ChEMBL	CHEMBL450072 N
Jmol-3D images	Image 1
SMILES O=C/C=C/CCCCCC
InChI InChI=1S/C9H16O/c1-2-3-4-5-6-7-8-9-10/h7-9H,2-6H2,1H3/b8-7+ Y Key: BSAIUMLZVGUGKX-BQYQJAHWSA-N Y InChI=1/C9H16O/c1-2-3-4-5-6-7-8-9-10/h7-9H,2-6H2,1H3/b8-7+ Key: BSAIUMLZVGUGKX-BQYQJAHWBS
Properties
Molecular formula	C9H16O
Molar mass	140.22
Appearance	Clear, colorless liquid
Boiling point	55-60 °C at 0.30 mmHg
Hazards
MSDS	External MSDS
EU classification	Irritant (XI)
R-phrases	R38
S-phrases	S24/25 S37 S45 S28
NFPA 704	2 1 0
Flash point	79 °C
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

2-Nonenal is an unsaturated aldehyde which some research has associated with human body odor alterations during aging. The substance is also an important aroma component of aged beer ^[1] and buckwheat.^[2] The odor of this substance is perceived as orris, fat and cucumber.^[3]

In the April 2001 issue of the Journal of Investigative Dermatology, Shinichiro Haze, et al. published an article entitled: "2-Nonenal, Newly Found in Human Body Odor Tends to Increase with Aging".^[4]

In this article they reported on their work which involved the analysis of body odor components collected via headspace gas chromatography/mass spectrometry, from shirts worn for three days by subjects between the ages of 26 and 75. They found that the concentration of many components of body odor were unaffected by age. They found that the concentration of 2-nonenal tended to increase with the age of the subjects, and determined that that 2-nonenal is generated by the oxidative degradation of omega-7 unsaturated fatty acids, such as palmitoleic acid and vaccenic acid, found on the skin surface.

They analyzed concentrations of various lipids on the skin surface by collecting samples in a gauze pad sewn into the shirts and then extracting the lipids with a hexane solvent. The article reported that concentrations of omega-10 fatty acids such as sapienic acid showed no change with age. Concentrations of omega-7 fatty acids do increase with age.

Because of these findings, some observers have concluded that Haze's team has identified the cause of the phenomenon commonly known as "old lady smell", "old man smell" or "old person smell", a meme found in pop culture relating to an odor that is characteristically associated with the elderly. Similarly, some consider 2-nonenal's odor to resemble that of old books and is at times casually referred to as "library aldehyde".

References

1. ^ Santos J.R.; Carneiro J.R.; Guido L.F.; Almeida P.J.; Rodrigues J.A.; Barros A.A. (2008). "Determination of E-2-nonenal by high-performance liquid chromatography with UV detection - Assay for the evaluation of beer ageing.". Journal of Chromatography A 985 (1): 395–402. doi:10.1016/S0021-9673(02)01396-1. 
2. ^ Janes D, Kantar D, Kreft S, Prosen H (2008). "Identification of buckwheat (Fagopyrum esculentum Moench) aroma compounds with GC-MS". Food Chemistry 112: 120. doi:10.1016/j.foodchem.2008.05.048. 
3. ^ 2-nonenal 60784-31-8
4. ^ S. Haze, Y. Gozu, S. Nakamura, Y. Kohno, K. Sawano, H. Ohta and K. Yamazaki (2001). "2-Nonenal Newly Found in Human Body Odor Tends to Increase with Aging". Journal of Investigative Dermatology 116 (4): 520–524. doi:10.1046/j.0022-202x.2001.01287.x. PMID 11286617. 

Further reading

• Env. Sci. Tech.. PMID 12038828.