Benzaldehyde

Last updated
Benzaldehyde
Skeletal (structural) formula Benzaldehyde.png
Skeletal (structural) formula
Ball-and-stick model Benzaldehyde-3D-balls-B.png
Ball-and-stick model
Names
IUPAC name
Benzenecarbaldehyde
Preferred IUPAC name
Benzaldehyde [1]
Other names
Benzenecarboxaldehyde
Phenylmethanal
Benzoic aldehyde
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.601 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 202-860-4
KEGG
PubChem CID
RTECS number
  • CU437500
UNII
UN number 1990
  • InChI=1S/C7H6O/c8-6-7-4-2-1-3-5-7/h1-6H Yes check.svgY
    Key: HUMNYLRZRPPJDN-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C6H5CHO/c8-6-7-4-2-1-3-5-7/h1-6H
    Key: HUMNYLRZRPPJDN-UHFFFAOYAE
  • O=Cc1ccccc1
  • c1ccc(cc1)C=O
Properties
C7H6O
Molar mass 106.124 g·mol−1
Appearancecolorless liquid
strongly refractive
Odor almond-like
Density 1.044 g/mL, liquid
Melting point −57.12 [2]  °C (−70.82 °F; 216.03 K)
Boiling point 178.1 °C (352.6 °F; 451.2 K)
6.95 g/L (25 °C) [3]
log P 1.64 [4]
-60.78·10−6 cm3/mol
1.5456
Viscosity 1.321 cP (25 °C)
Thermochemistry
−36.8 kJ/mol
−3525.1 kJ/mol
Hazards
GHS labelling:
GHS-pictogram-exclam.svg
Warning
H302
P264, P270, P301+P312, P330, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
2
0
Flash point 64 °C (147 °F; 337 K)
192 °C (378 °F; 465 K)
Explosive limits 1.4–8.5%
Lethal dose or concentration (LD, LC):
1300 mg/kg (rat, oral)
Safety data sheet (SDS) J. T. Baker
Related compounds
Related compounds
 Benzyl alcohol
Benzoic acid
Benzaldehyde oxime
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Benzaldehyde (C6H5CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is among the simplest aromatic aldehydes and one of the most industrially useful.

Contents

It is a colorless liquid with a characteristic almond-like odor, and is commonly used in cherry-flavored sodas. [5] A component of bitter almond oil, benzaldehyde can be extracted from a number of other natural sources. [6] Synthetic benzaldehyde is the flavoring agent in imitation almond extract, which is used to flavor cakes and other baked goods. [7]

History

Benzaldehyde was first extracted in 1803 by the French pharmacist Martrès. His experiments focused on elucidating the nature of amygdalin, the poisonous compound found in bitter almonds, the fruit of Prunus dulcis . [8] Further work on the oil by Pierre Robiquet and Antoine Boutron Charlard, two French chemists, produced benzaldehyde. [9] In 1832, Friedrich Wöhler and Justus von Liebig first synthesized benzaldehyde. [10]

Production

As of 1999, 7000 tonnes of synthetic and 100 tonnes of natural benzaldehyde were produced annually. [11] Liquid phase chlorination and oxidation of toluene are the main routes. Numerous other methods have been developed, such as the partial oxidation of benzyl alcohol, alkali hydrolysis of benzal chloride, and the carbonylation of benzene (the Gatterman-Koch reaction). [6]

A significant quantity of natural benzaldehyde is produced from cinnamaldehyde obtained from cassia oil by the retro-aldol reaction: [11] the cinnamaldehyde is heated in an aqueous/alcoholic solution between 90 °C and 150 °C with a base (most commonly sodium carbonate or bicarbonate) for 5 to 80 hours, [12] followed by distillation of the formed benzaldehyde. This reaction also yields acetaldehyde. The natural status of benzaldehyde obtained in this way is controversial. [11]

Occurrence

Benzaldehyde and similar chemicals occur naturally in many foods. Most of the benzaldehyde that people eat is from natural plant foods, such as almonds. [13]

Almonds, apricots, apples, and cherry seed contain significant amounts of amygdalin. This glycoside breaks up under enzyme catalysis into benzaldehyde, hydrogen cyanide and two equivalents of glucose.

Amygdalin

Amygdalin structure.svg
2 H2O
HCN
Biochem reaction arrow forward YYNN horiz med.svg

benzaldehyde

Benzaldehyde.png

2 × glucose

2 ×  Alpha-D-glucose-2D-skeletal-hexagon.png

Benzaldehyde contributes to the scent of oyster mushrooms (Pleurotus ostreatus). [14]

Reactions

Benzaldehyde is easily oxidized to benzoic acid in air at room temperature, [15] causing a common impurity in laboratory samples. Since the boiling point of benzoic acid is much higher than that of benzaldehyde, it may be purified by distillation. Benzyl alcohol can be formed from benzaldehyde by means of hydrogenation. Reaction of benzaldehyde with anhydrous sodium acetate and acetic anhydride yields cinnamic acid, while alcoholic potassium cyanide can be used to catalyze the condensation of benzaldehyde to benzoin. Benzaldehyde undergoes disproportionation upon treatment with concentrated alkali (Cannizzaro reaction): one molecule of the aldehyde is reduced to the benzyl alcohol and another molecule is simultaneously oxidized to benzoic acid.

Benzaldehyd-chemical-Cannizzaro.png

With diols, including many sugars, benzaldehyde condenses to form benzylidene acetals.

Uses

Benzaldehyde is commonly employed to confer almond flavor to foods and scented products, including e-cigarette liquids. It is sometimes used in cosmetics products. [16]

In industrial settings, benzaldehyde is used chiefly as a precursor to other organic compounds, ranging from pharmaceuticals to plastic additives. The aniline dye malachite green is prepared from benzaldehyde and dimethylaniline. Benzaldehyde is also a precursor to certain acridine dyes. Via aldol condensations, benzaldehyde is converted into derivatives of cinnamaldehyde and styrene. The synthesis of mandelic acid starts with the addition of hydrocyanic acid to benzaldehyde:

Benzaldehyde-chemical-mandelicacid.png

The resulting cyanohydrin is hydrolysed to mandelic acid. (The scheme above depicts only one of the two formed enantiomers).

Niche uses

Benzaldehyde is used as a bee repellent. [17] A small amount of benzaldehyde solution is placed on a fume board near the honeycombs. The bees then move away from the honey combs to avoid the fumes. [18] The beekeeper can then remove the honey frames from the bee hive with less risk to both bees and beekeeper.

Benzaldehyde reacts with nitroethane in the presence of a catalyst to produce phenyl-2-nitropropene, a precursor to amphetamine and other chemicals. [19]

Safety

As used in food, cosmetics, pharmaceuticals, and soap, benzaldehyde is "generally regarded as safe" (GRAS) by the US FDA [20] and FEMA. [13] This status was reaffirmed after a review in 2005. [13] It is accepted in the European Union as a flavoring agent. [16] Toxicology studies indicate that it is safe and non-carcinogenic in the concentrations used for foods and cosmetics, [16] and may even have anti-carcinogenic (anti-cancer) properties. [16]

For a 70 kg human, the lethal dose is estimated at 50 ml. [6] An acceptable daily intake of 15 mg/day has been identified for benzaldehyde by the United States Environmental Protection Agency. [21] Benzaldehyde does not accumulate in human tissues. [16] It is metabolized and then excreted in urine. [16]

Related Research Articles

<span class="mw-page-title-main">Almond</span> Species of nut

The almond is a species of small tree from the genus Prunus, cultivated worldwide for its seed, a culinary nut. Along with the peach, it is classified in the subgenus Amygdalus, distinguished from the other subgenera by corrugations on the shell (endocarp) surrounding the seed.

<span class="mw-page-title-main">Amygdalin</span> Cyanogenic glycoside present in kernels of fruit

Amygdalin is a naturally occurring chemical compound found in many plants, most notably in the seeds (kernels) of apricots, bitter almonds, apples, peaches, cherries and plums, and in the roots of manioc.

<span class="mw-page-title-main">Benzoic acid</span> Organic compound (C6H5COOH)

Benzoic acid is a white solid organic compound with the formula C6H5COOH, whose structure consists of a benzene ring with a carboxyl substituent. The benzoyl group is often abbreviated "Bz", thus benzoic acid is also denoted as BzOH, since the benzoyl group has the formula –C6H5CO. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, which was for a long time its only source.

<span class="mw-page-title-main">Aldehyde</span> Organic compound containing the functional group R−CH=O

In organic chemistry, an aldehyde is an organic compound containing a functional group with the structure R−CH=O. The functional group itself can be referred to as an aldehyde but can also be classified as a formyl group. Aldehydes are a common motif in many chemicals important in technology and biology.

Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated as MeCHO. It is a colorless liquid or gas, boiling near room temperature. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale in industry. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit, and is produced by plants. It is also produced by the partial oxidation of ethanol by the liver enzyme alcohol dehydrogenase and is a contributing cause of hangover after alcohol consumption. Pathways of exposure include air, water, land, or groundwater, as well as drink and smoke. Consumption of disulfiram inhibits acetaldehyde dehydrogenase, the enzyme responsible for the metabolism of acetaldehyde, thereby causing it to build up in the body.

A glucoside is a glycoside that is chemically derived from glucose. Glucosides are common in plants, but rare in animals. Glucose is produced when a glucoside is hydrolysed by purely chemical means, or decomposed by fermentation or enzymes.

<span class="mw-page-title-main">Glycoside</span> Molecule in which a sugar is bound to another functional group

In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme hydrolysis, which causes the sugar part to be broken off, making the chemical available for use. Many such plant glycosides are used as medications. Several species of Heliconius butterfly are capable of incorporating these plant compounds as a form of chemical defense against predators. In animals and humans, poisons are often bound to sugar molecules as part of their elimination from the body.

<span class="mw-page-title-main">Cinnamaldehyde</span> Chemical compound

Cinnamaldehyde is an organic compound with the formula or C₆H₅CH=CHCHO. Occurring naturally as predominantly the trans (E) isomer, it gives cinnamon its flavor and odor. It is a phenylpropanoid that is naturally synthesized by the shikimate pathway. This pale yellow, viscous liquid occurs in the bark of cinnamon trees and other species of the genus Cinnamomum. The essential oil of cinnamon bark is about 90% cinnamaldehyde. Cinnamaldehyde decomposes to styrene because of oxidation as a result of bad storage or transport conditions. Styrene especially forms in high humidity and high temperatures. This is the reason why cinnamon contains small amounts of styrene.

Benzonitrile is the chemical compound with the formula C6H5(CN), abbreviated PhCN. This aromatic organic compound is a colorless liquid with a sweet bitter almond odour. It is mainly used as a precursor to the resin benzoguanamine.

<span class="mw-page-title-main">Benzyl alcohol</span> Aromatic alcohol

Benzyl alcohol (also known as α-cresol) is an aromatic alcohol with the formula C6H5CH2OH. The benzyl group is often abbreviated "Bn" (not to be confused with "Bz" which is used for benzoyl), thus benzyl alcohol is denoted as BnOH. Benzyl alcohol is a colorless liquid with a mild pleasant aromatic odor. It is a useful as a solvent for its polarity, low toxicity, and low vapor pressure. Benzyl alcohol has moderate solubility in water (4 g/100 mL) and is miscible in alcohols and diethyl ether. The anion produced by deprotonation of the alcohol group is known as benzylate or benzyloxide.

<span class="mw-page-title-main">Cinnamic acid</span> Chemical compound

Cinnamic acid is an organic compound with the formula C6H5-CH=CH-COOH. It is a white crystalline compound that is slightly soluble in water, and freely soluble in many organic solvents. Classified as an unsaturated carboxylic acid, it occurs naturally in a number of plants. It exists as both a cis and a trans isomer, although the latter is more common.

<span class="mw-page-title-main">Coumarin</span> Aromatic chemical compound

Coumarin or 2H-chromen-2-one is an aromatic organic chemical compound with formula C9H6O2. Its molecule can be described as a benzene molecule with two adjacent hydrogen atoms replaced by an unsaturated lactone ring −(CH)=(CH)−(C=O)−O−, forming a second six-membered heterocycle that shares two carbons with the benzene ring. It belongs to the benzopyrone chemical class and considered as a lactone.

<span class="mw-page-title-main">Benzoyl chloride</span> Organochlorine compound (C7H5ClO)

Benzoyl chloride, also known as benzenecarbonyl chloride, is an organochlorine compound with the formula C7H5ClO. It is a colourless, fuming liquid with an irritating odour, and consists of a benzene ring with an acyl chloride substituent. It is mainly useful for the production of peroxides but is generally useful in other areas such as in the preparation of dyes, perfumes, pharmaceuticals, and resins.

<span class="mw-page-title-main">Mandelic acid</span> Chemical compound

Mandelic acid is an aromatic alpha hydroxy acid with the molecular formula C6H5CH(OH)CO2H. It is a white crystalline solid that is soluble in water and polar organic solvents. It is a useful precursor to various drugs. The molecule is chiral. The racemic mixture is known as paramandelic acid.

<span class="mw-page-title-main">Benzyl benzoate</span> Chemical compound

Benzyl benzoate is an organic compound which is used as a medication and insect repellent. As a medication it is used to treat scabies and lice. For scabies either permethrin or malathion is typically preferred. It is applied to the skin as a lotion. Typically two to three applications are needed. It is also present in Balsam of Peru, Tolu balsam, and in a number of flowers.

Benzyl chloride, or α-chlorotoluene, is an organic compound with the formula C6H5CH2Cl. This colorless liquid is a reactive organochlorine compound that is a widely used chemical building block.

The Étard reaction is a chemical reaction that involves the direct oxidation of an aromatic or heterocyclic bound methyl group to an aldehyde using chromyl chloride. For example, toluene can be oxidized to benzaldehyde.

<span class="mw-page-title-main">Phenylacetaldehyde</span> Chemical compound

Phenylacetaldehyde is an organic compound used in the synthesis of fragrances and polymers. Phenylacetaldehyde is an aldehyde that consists of acetaldehyde bearing a phenyl substituent; the parent member of the phenylacetaldehyde class of compounds. It has a role as a human metabolite, a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite and a mouse metabolite. It is an alpha-CH2-containing aldehyde and a member of phenylacetaldehydes.

<span class="mw-page-title-main">Prunasin</span> Chemical compound

(R)-prunasin is a cyanogenic glycoside related to amygdalin. Chemically, it is the glucoside of (R)-mandelonitrile.

References

  1. ↑ Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 908. doi:10.1039/9781849733069-FP001. ISBN   978-0-85404-182-4.
  2. ↑ Haynes, William M. (2014), CRC Handbook of Chemistry and Physics (95th ed.), CRC press, pp. 3–34, ISBN   9781482208689
  3. ↑ "GESTIS Substance database". Institute for Occupational Safety and Health of the German Social Accident Insurance. Archived from the original on 3 March 2016. Retrieved 21 August 2012.
  4. ↑ "Benzaldehyde_msds".
  5. ↑ Loch, Christine; Reusch, Helmut; Ruge, Ingrid; Godelmann, Rolf; Pflaum, Tabea; Kuballa, Thomas; Schumacher, Sandra; Lachenmeier, Dirk W. (2016). "Benzaldehyde in cherry flavour as a precursor of benzene formation in beverages". Food Chemistry. 206: 74–77. doi:10.1016/j.foodchem.2016.03.034. PMID   27041300.
  6. 1 2 3 Brühne, Friedrich and Wright, Elaine (2002) "Benzaldehyde" in Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH, Weinheim. doi : 10.1002/14356007.a03_463
  7. ↑ The Cook's Illustrated Baking Book. America's Test Kitchen. 2013. ISBN   9781936493784.
  8. ↑ In 1803 C. Martrès published a manuscript on the oil of bitter almonds: "Recherches sur la nature et le siège de l'amertume et de l'odeur des amandes amères" (Research on the nature and location of the bitterness and the smell of bitter almonds). However, the memoir was largely ignored until an extract was published in 1819: Martrès fils (1819) "Sur les amandes amères," Journal de Pharmacie, vol. 5, pages 289–296.
  9. ↑ Nouvelles expériences sur les amandes amères et sur l'huile volatile qu'elles fournissent Robiquet, Boutron-Charlard, Annales de chimie et de physique, 44 (1830), 352–382,
  10. ↑ Wöhler, Friedrich and Liebig, Justus von (1832). "Untersuchungen über das Radikal der Benzoesäure" [Investigations of the radical of benzoic acid]. Annalen der Pharmacie. 3 (3): 249–282. doi:10.1002/jlac.18320030302. hdl: 2027/hvd.hxdg3f .{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. 1 2 3 Innovation in food engineering : new techniques and products. Passos, Maria Laura., Ribeiro, Claudio P. Boca Raton, Florida: CRC Press. 2010. p. 87. ISBN   9781420086072. OCLC   500683261.{{cite book}}: CS1 maint: others (link)
  12. ↑ Wienes, Charles and Pittet, Alan O. (1985) U.S. patent 4,617,419 Process for preparing natural benzaldehyde and acetaldehyde, natural benzaldehyde and acetaldehyde compositions, products produced thereby and organoleptic utilities therefor.
  13. 1 2 3 Adams, T. B.; Cohen, S. M.; Doull, J.; Feron, V. J.; Goodman, J. I.; Marnett, L. J.; Munro, I. C.; Portoghese, P. S.; Smith, R. L. (1 August 2005). "The FEMA GRAS assessment of benzyl derivatives used as flavor ingredients". Food and Chemical Toxicology. 43 (8): 1207–1240. doi:10.1016/j.fct.2004.11.014. PMID   15950815.
  14. ↑ Beltran-Garcia, Miguel J.; Estarron-Espinosa, Mirna; Ogura, Tetsuya (1997). "Volatile Compounds Secreted by the Oyster Mushroom (Pleurotus ostreatus) and Their Antibacterial Activities". Journal of Agricultural and Food Chemistry. 45 (10): 4049. doi:10.1021/jf960876i.
  15. ↑ Sankar, Meenakshisundaram (2014). "The benzaldehyde oxidation paradox explained by the interception of peroxy radical by benzyl alcohol" (PDF). Nature Communications. 5: 3332. Bibcode:2014NatCo...5.3332S. doi: 10.1038/ncomms4332 . PMID   24567108.
  16. 1 2 3 4 5 6 Andersen, Alan (1 January 2006). "Final report on the safety assessment of benzaldehyde". International Journal of Toxicology. 25 (Suppl 1): 11–27. doi: 10.1080/10915810600716612 . PMID   16835129. S2CID   32177208.
  17. ↑ Evans, Elizabeth; Butler, Carol (9 February 2010). Why Do Bees Buzz?: Why Do Bees Buzz? Fascinating Answers to Questions about Bees. Rutgers University Press. pp. 177–178. ISBN   9780813549200.
  18. ↑ Sanford, Malcolm T.; Bonney, Richard E. (1 January 2010). Storey's Guide to Keeping Honey Bees: Honey Production, Pollination, Bee Health. Storey Publishing. p. 167. ISBN   9781603425506.
  19. ↑ "Synthesis of Phenyl-2-Nitropropene". Erowid. Retrieved 7 October 2023.
  20. ↑ Friedrich Brühne; Elaine Wright (2007), "Benzaldehyde", Ullmann's Encyclopedia of Industrial Chemistry (7th ed.), Wiley, p. 11
  21. ↑ Assessment, US EPA National Center for Environmental. "Health and Environmental Effects Profile for Benzaldehyde". cfpub.epa.gov. Retrieved 16 September 2017.

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