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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]

Heptanal[1]
Heptanal.png
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

Contents

ProductionEdit

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]

PropertiesEdit

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]

UsesEdit

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[clarification needed], 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]

ReferencesEdit

  1. ^ Merck Index, 11th Edition, 4578.
  2. ^ a b c 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
  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. ^ a b 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, Bundesgesundheitsbl - Gesundheitsforsch –Gesundheitsschutz, 2009, 52:650–659, doi:10.1007/s00103-009-0860-2.
  8. ^ a b c d 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. ^ M. Perez-Sanchez, P. Dominguez de Maria, Synthesis of natural fragrance jasminaldehyde using silica-immobilized piperazine as organocatalyst, Catal. Sci. Technol., 3, 2732-2736 (2013), 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. ^ R.D. Offenhauer, S.F. Nelsen, Aldehyde and ketone condensation reactions catalyzed by boric acid, J. Org. Chem., 33(2), 775-777 (1968), doi: 10.1012/jo01266a059.
  15. ^ G.H. Knothe: Lipid Chemistry, Guerbet Compounds, AOCS Lipid Library, 22. Dezember 2011.