Heptanal
Chemical compound (C7H14O)
From Wikipedia, the free encyclopedia
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]
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| Names | |
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| Preferred IUPAC name
Heptanal | |
| Other names
Heptanaldehyde Aldehyde C-7 Enanthaldehyde Heptyl aldehyde n-Heptanal | |
| Identifiers | |
3D model (JSmol) |
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| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.003.545 |
| KEGG | |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| 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 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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 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 jasminaldehyde,[11][2] which is mostly used in fragrances for its jasmine-like aroma 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] 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.[14]
Full hydrogenation provides the branched primary alcohol 2-pentylnonan-1-ol, also accessible from the Guerbet reaction from heptanol.[15]