Heptanal

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Heptanal[1]
Names
Preferred 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
  • InChI=1S/C7H14O/c1-2-3-4-5-6-7-8/h7H,2-6H2,1H3 checkY
    Key: FXHGMKSSBGDXIY-UHFFFAOYSA-N checkY
  • InChI=1/C7H14O/c1-2-3-4-5-6-7-8/h7H,2-6H2,1H3
    Key: FXHGMKSSBGDXIY-UHFFFAOYAJ
  • O=CCCCCCC
Properties
C7H14O
Molar mass 114.188 g·mol−1
Appearance Clear liquid
Density 0.80902 g/cm3 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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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]

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[4] (Arkema method) and on the hydroformylation of 1-hexene:[2]

Hydroformylation of 1-Hexene

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).[5]

Properties

Heptanal is a slightly volatile colorless liquid. It has a pervasive fruity to oily-greasy odor,[6] It is miscible with alcohols[5] but practically insoluble in water.[7] Because of its sensitivity to oxidation, heptanal is stored under nitrogen and stabilized with 100 ppm hydroquinone.[8]

Heptanal is flammable. The compound has a flash point of 39.5 °C.[7] 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.[7] Its ignition temperature is 205 °C.[7]

Uses

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

Synthese von 1-Heptanol

The oxidation of heptanal with oxygen in the presence of a rhodium catalysts leads at 50 °C to heptanoic acid in 95% yield.[9] Heptanal reacts with benzaldehyde in a Knoevenagel reaction under basic catalysis with high yield and selectivity (> 90%) to jasminaldehyde,[10][2] which is mostly used in fragrances for its jasmine-like aroma as a cis/trans isomer mixture.[11]

α-pentylcinnamal (jasminal) by aldol condensation of benzaldehyde with heptanal

A by-product of the given reaction is the unpleasant rancid smelling (Z)-2-pentyl-2-nonenal.[12] Nevertheless, heptanal can be converted into (Z)-2-pentyl-2-nonenal virtually quantitatively in the presence of aqueous boric acid upon azeotropic removal of water.[13]

2-Pentyl-2-nonenal by self-condensation of heptanal

Full hydrogenation provides the branched primary alcohol 2-pentylnonan-1-ol, also accessible from the Guerbet reaction from heptanol.[14]

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. ISBN 978-3-527-30673-2.{{cite encyclopedia}}: CS1 maint: multiple names: authors list (link)
  3. F. Krafft, Distillation of castor oil, under reduced pressure, Analyst, 3, 329a (1878).
  4. A. Chauvel, G. Lefebvre, Petrochemical Processes: Technical and Economic Characteristics, vol. 2, p. 277, Editions Technip, Paris, 1989, ISBN 2-7108-0563-4.
  5. G. A. Burdock, Fenaroli's Handbook of Flavor Ingredients, Fifth Edition, 2005, CRC Press, Boca Raton, Fl., ISBN 0-8493-3034-3.
  6. "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. PMID 19557457.
  7. Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  8. Acros Organics (rev. 19 Nov 2012). Heptaldehyde, stabilized (safety data sheet).
  9. H. Springer and P. Lappe, on behalf of Celanese Chem Europe GmbH (3 May 2001). Verfahren zur Herstellung aliphatischer Carbonsäuren aus Aldehyden Archived 2016-03-04 at the Wayback Machine, German patent DE 10010771.
  10. 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.
  11. alpha-Amylzimtaldehyd (rev. 4 Aug 2000) at the Riechstofflexikon [Odorant Dictionary], vol. A.
  12. J. M. Hornback, Organic Chemistry, 2nd edition, p. 886, Thomson Brooks/Cole, 2006, ISBN 0-534-49317-3.
  13. 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.
  14. G.H. Knothe: Lipid Chemistry, Guerbet Compounds Archived 2016-05-21 at the Wayback Machine, AOCS Lipid Library, 22 December 2011.