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.[1]
Production
The formation of heptanal in the fractional distillation of castor oil[2] was already described in 1878. The large-scale production is based on the pyrolytic cleavage of ricinoleic acid[3] (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):[1][4]
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 flammable, slightly volatile colorless liquid of pervasive fruity to oily-greasy odor,[6] which is miscible with alcohols[5] and practically insoluble in water.[7] Because of its sensitivity to oxidation, heptanal is filled under nitrogen and stabilized with 100 ppm hydroquinone.[8]
Heptanal forms flammable vapor-air mixtures. 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:
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][1] which is mostly used in fragrances for its jasmine-like aroma as a cis/trans isomer mixture.[11]
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]
Full hydrogenation provides the branched primary alcohol 2-pentylnonan-1-ol, also accessible from the Guerbet reaction from heptanol.[14]
References
- ↑ a b c Template:Ullmann
- ↑ F. Krafft, Distillation of castor oil, under reduced pressure, Analyst, 3, 329a (1878).
- ↑ A. Chauvel, G. Lefebvre, Petrochemical Processes: Technical and Economic Characteristics, vol. 2, p. 277, Editions Technip, Paris, 1989, Template:ISBN.
- ↑ A. Fischbach et al on behalf of Oxea Deutschland GmbH (20 May 2009). Verfahren zur Herstellung von Aldehyden, German patent DE 102007053385.
- ↑ a b G. A. Burdock, Fenaroli's Handbook of Flavor Ingredients, Fifth Edition, 2005, CRC Press, Boca Raton, Fl., Template:ISBN.
- ↑ Script error: No such module "Citation/CS1".
- ↑ a b c d Record in the GESTIS Substance Database of the Institute for Occupational Safety and HealthScript error: No such module "TemplatePar". Script error: No such module "TemplatePar".
- ↑ Acros Organics (rev. 19 Nov 2012). Heptaldehyde, stabilized (safety data sheet).
- ↑ H. Springer and P. Lappe, on behalf of Celanese Chem Europe GmbH (3 May 2001). Verfahren zur Herstellung aliphatischer Carbonsäuren aus Aldehyden, German patent DE 10010771.
- ↑ Script error: No such module "Citation/CS1".
- ↑ alpha-Amylzimtaldehyd (rev. 4 Aug 2000) at the Riechstofflexikon [Odorant Dictionary], vol. A.
- ↑ J. M. Hornback, Organic Chemistry, 2nd edition, p. 886, Thomson Brooks/Cole, 2006, Template:ISBN.
- ↑ Script error: No such module "Citation/CS1".
- ↑ G.H. Knothe: Lipid Chemistry, Guerbet Compounds Template:Webarchive, AOCS Lipid Library, 22 December 2011.