Heptanal

Heptanal or heptanaldehyde is an alkyl aldehyde. It is a colourless liquid with a strong fruity odor, which is used as precursor to components in perfumes and lubricants.[2]

Heptanal[1]
Names
IUPAC name
Heptanal
Other names
Heptanaldehyde
Aldehyde C-7
Enanthaldehyde
Heptyl aldehyde
n-Heptanal
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.545
KEGG
UNII
Properties
C7H14O
Molar mass 114.18
Appearance Clear liquid
Density 0.80902 at 30 °C
Melting point −43.3 °C (−45.9 °F; 229.8 K)
Boiling point 152.8 °C (307.0 °F; 425.9 K)
Slightly soluble
-81.02·10−6 cm3/mol
Related compounds
Related aldehydes
 Hexanal

Octanal

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Production

The formation of heptanal in the fractional distillation of castor oil[3] was already described in 1878. The large-scale production is based on the pyrolytic cleavage of ricinoleic acid ester[4] (Arkema method) and on the hydroformylation of 1-hexene with rhodium 2-ethylhexanoate as a catalyst upon addition of some 2-ethylhexanoic acid (Oxea method):[2][5]

Heptanal naturally occurs in the essential oils of ylang-ylang (Cananga odorata), clary sage (Salvia sclarea), lemon (Citrus x limon), bitter orange (Citrus x aurantium), rose (Rosa) and hyacinth (Hyacinthus).[6]

Properties

Heptanal is a flammable, slightly volatile colorless liquid of pervasive fruity to oily-greasy odor,[7] which is miscible with alcohols[6] and practically insoluble in water.[8] Because of its sensitivity to oxidation, heptanal is filled under nitrogen and stabilized with 100 ppm hydroquinone.[9]

Heptanal forms flammable vapor-air mixtures. The compound has a flash point of 39.5 °C.[8] The explosion range is between 1.1% by volume as the lower explosion limit (LEL) and 5.2% by volume as the upper explosion limit.[8] Its ignition temperature is 205 °C.[8]

Uses

Heptanal can be used for the production of 1-heptanol via hydrogenation:

The oxidation of heptanal with oxygen in the presence of a rhodium catalysts leads at 50 °C to heptanoic acid in 95% yield.[10] Heptanal reacts with benzaldehyde in a Knoevenagel reaction under basic catalysis with high yield and selectivity (> 90%) to alpha-pentylcinnamaldehyde (also called jasmine aldehyde because of the typical jasmine odor),[11][2] which is mostly used in many fragrances as a cis/trans isomer mixture.[12]

A by-product of the given reaction is the unpleasant rancid smelling (Z)-2-pentyl-2-nonenal.[13] When good reasons are given, heptanal can be converted into (Z)-2-pentyl-2-nonenal virtually quantitatively in the presence of aqueous boric acid upon azeotropic removal of water.[14]

Full hydrogenation provides the branched primary alcohol 2-pentylnonan-1-ol, also accessible from the Guerbet reaction from heptanol.[15]

References
  1. Merck Index, 11th Edition, 4578.
  2. Christian Kohlpaintner, Markus Schulte, Jürgen Falbe, Peter Lappe, Jürgen Weber. "Aldehydes, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_321.pub2.CS1 maint: multiple names: authors list (link)
  3. F. Krafft, Distillation of castor oil, under educed pressure, Analyst, 3, 329a (1878).
  4. A. Chauvel, G. Lefebvre, Petrochemical Processes: Technical and Economic Characteristics, Band 2, S. 277, Editions Technip, Paris, 1989, ISBN 2-7108-0563-4.
  5. Deutsche Patentschrift DE 102007053385, Verfahren zur Herstellung von Aldehyden, Erfinder: A. Fischbach et al., Anmelder: Oxea Deutschland GmbH, veröffentlicht am 20. Mai 2009.
  6. G. A. Burdock, Fenaroli’s Handbook of Flavor Ingredients, Fifth Edition, 2005, CRC Press, Boca Raton, Fl., ISBN 0-8493-3034-3.
  7. "Richtwerte für gesättigte azyklische aliphatische C4- bis C11-Aldehyde in der Innenraumluft" (PDF). Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz. 52 (6): 650–659. 27 June 2009. doi:10.1007/s00103-009-0860-2.
  8. Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  9. Acros Organics, Sicherheitsdatenblatt, Heptaldehyde, stabilized, überarb. am 19. November 2012.
  10. Deutsche Patentschrift DE 10010771, Verfahren zur Herstellung aliphatischer Carbonsäuren aus Aldehyden, Erfinder: H. Springer, P. Lappe, Anmelder: Celanese Chem Europe GmbH, veröffentlicht am 3. Mai 2001.
  11. Pérez-Sánchez, María; de María, Pablo Domínguez (2013). "Synthesis of natural fragrance jasminaldehyde using silica-immobilized piperazine as organocatalyst". Catalysis Science & Technology. 3 (10): 2732. doi:10.1039/C3CY00313B.
  12. Riechstofflexikon A, alpha-Amylzimtaldehyd, Letzte Änderung am 4. August 2000.
  13. J. M. Hornback, Organic Chemistry, 2nd edition, S. 886, Thomson Brooks/Cole, 2006, ISBN 0-534-49317-3.
  14. Offenhauer, Robert D.; Nelsen, Stephen F. (February 1968). "Aldehyde and ketone condensation reactions catalyzed by boric acid". The Journal of Organic Chemistry. 33 (2): 775–777. doi:10.1021/jo01266a059.
  15. G.H. Knothe: Lipid Chemistry, Guerbet Compounds Archived 2016-05-21 at the Wayback Machine, AOCS Lipid Library, 22. Dezember 2011.
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