| Definition | Heptanal, also known as enanthal or N-heptaldehyde, belongs to the class of organic compounds known as medium-chain aldehydes. These are an aldehyde with a chain length containing between 6 and 12 carbon atoms. Thus, heptanal is considered to be a fatty aldehyde lipid molecule. It is a colourless liquid with a strong fruity odor, which is used as precursor to components in perfumes and lubricants. Heptanal is a very hydrophobic molecule, practically insoluble in water, and relatively neutral. Heptanal exists in all eukaryotes, ranging from yeast to humans. Heptanal is an aldehydic, citrus, and fat tasting compound. heptanal is found, on average, in the highest concentration in a few different foods, such as corns, tea, and sweet oranges and in a lower concentration in lemons, wild carrots, and carrots. heptanal has also been detected, but not quantified, in several different foods, such as horned melons, common beets, dills, red bell peppers, and malus (crab apple). This could make heptanal a potential biomarker for the consumption of these foods. The formation of heptanal in the fractional distillation of castor oil was already described in 1878. The large-scale production is based on the pyrolytic cleavage of ricinoleic acid ester (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):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). Heptanal is a potentially toxic compound. Heptanal has been found to be associated with several diseases such as ulcerative colitis, crohn's disease, uremia, and nonalcoholic fatty liver disease; also heptanal has been linked to the inborn metabolic disorders including celiac disease. The compound has a flash point of 39.5 °C. 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. Heptanal or heptanaldehyde is an alkyl aldehyde. Full hydrogenation provides the branched primary alcohol 2-pentylnonan-1-ol, also accessible from the Guerbet reaction from heptanol. A by-product of the given reaction is the unpleasant rancid smelling (Z)-2-pentyl-2-nonenal. Heptanal forms flammable vapor-air mixtures. Heptanal is a flammable, slightly volatile colorless liquid of pervasive fruity to oily-greasy odor, which is miscible with alcohols and practically insoluble in water. 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), which is mostly used in many fragrances as a cis/trans isomer mixture. |
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