Phenylacetaldehyde

Phenylacetaldehyde

Names
IUPAC name 2-Phenylacetaldehyde
Other names Hyacinthin Phenylethanal
Identifiers
CAS Number	122-78-1 Y
3D model (Jmol)	Interactive image
Beilstein Reference	385791
ChemSpider	13876539 N
ECHA InfoCard	100.004.159
PubChem	998
UNII	U8J5PLW9MR Y
InChI InChI=1S/C8H8O/c9-7-6-8-4-2-1-3-5-8/h1-5,7H,6H2 N Key: DTUQWGWMVIHBKE-UHFFFAOYSA-N N InChI=1/C8H8O/c9-7-6-8-4-2-1-3-5-8/h1-5,7H,6H2 Key: DTUQWGWMVIHBKE-UHFFFAOYAO
SMILES O=CCc1ccccc1
Properties
Chemical formula	C8H8O
Molar mass	120.15 g/mol
Appearance	Colorless liquid
Density	1.079 g/mL
Melting point	−10 °C (14 °F; 263 K)
Boiling point	195 °C (383 °F; 468 K)
Solubility in water	2.210 g/L
Refractive index (nD)	1.526
Hazards
Main hazards	Harmful, Flammable
R-phrases	R22 R36 R37 R38
S-phrases	S26 S36
Flash point	87 °C (189 °F; 360 K)
Related compounds
Related 2-phenyl aldehydes	3,4-Dihydroxyphenylacetaldehyde Phenylglyoxal
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Phenylacetaldehyde is an organic compound used in the synthesis of fragrances and polymers.^[1]

Natural Occurrence

Phenylacetaldehyde occurs extensively in nature because it can be biosynthetically derived from the amino acid phenylalanine. Natural sources of the compound include chocolate,^[2] buckwheat,^[3] flowers, and communication pheromones from various insect orders.^[4]

Uses

Fragrances and flavors

The aroma of pure substance can be described as honey-like, sweet, rose, green, grassy and is added to fragrances to impart hyacinth, narcissi, or rose nuances.^[1] For similar reasons the compound can sometimes be found in flavored cigarettes and beverages.

Historically, before biotechnology approaches were developed, phenylacetaldehyde was also used to produce phenylalanine via the Strecker reaction as a step in the production of aspartame sweetener.^[1]

Polymers

Phenylacetaldehyde is used in the synthesis of polyesters where it serves as a rate-controlling additive during polymerization.^[1]

Natural Medicine

Phenylacetaldehyde is responsible for the antibiotic activity of maggot therapy.^[5]

Preparation

Phenylacetaldehyde can be obtained via various synthetic routes and precursors. Notable examples include:

• Isomerization of styrene oxide.^[1]
• Dehydrogenation of 2-Phenylethanol over silver or gold catalysts.
• Darzens reaction between benzaldehyde and chloroacetate esters.
• Wacker oxidation of styrene.
• Hofmann rearrangement of Cinnamamide (aka (2E)-3-Phenylacrylamide).^[6][7]
• Oxidation of Cyclooctatetraene with aqueous Mercury(II) sulfate.^[8][9]
• Strecker degradation of phenylalanine.^[10]

Reactivity

Phenylacetaldehyde is often contaminated with polystyrene oxide polymer because of the especial lability of the benzylic alpha proton and the reactivity of the aldehyde. Aldol condensation of the initial dimer gives rise to a range of Michael acceptors and donors.

References

1. 1 2 3 4 5 Kohlpaintner, Christian; Schulte, Markus; Jürgen, Falbe; Lappe, Peter; Jürgen, Weber; Frey, Guido (2014). "Aldehydes, Araliphatic". Ullmann's Encyclopedia of Industrial Chemistry. 1. doi:10.1002/14356007.m01_m03.pub2. ISBN 9783527334773. 
2. ↑ Schnermann, Petra; Schieberle, Peter (1997). "Evaluation of Key Odorants in Milk Chocolate and Cocoa Mass by Aroma Extract Dilution Analyses". Journal of Agricultural and Food Chemistry. 45 (3): 867–872. doi:10.1021/jf960670h. 
3. ↑ Janes D, Kantar D, Kreft S, Prosen H (2009). "Identification of buckwheat (Fagopyrum esculentum Moench) aroma compounds with GC-MS". Food Chemistry. 112 (1): 120–124. doi:10.1016/j.foodchem.2008.05.048. 
4. ↑ El-Sayed, Ashraf. "Semiochemical-2-phenylacetaldehyde". The Pherobase: Database of Insect Pheromones and Semiochemicals. Extensive Database of Insect Pheromones and Semiochemicals. Retrieved 26 November 2014. 
5. ↑ Pavillard, E.R.; Wright, E. A. (1957). "An Antibiotic from Maggots". Nature. 180: 916–917. doi:10.1038/180916b0. PMID 13483556. 
6. ↑ Weerman, R.A. (1913). "Einwirkung von Natriumhypochlorit auf Amide ungesättigter Säuren". Justus Liebigs Annalen der Chemie. 401 (1): 1–20. doi:10.1002/jlac.19134010102. 
7. ↑ Adams, Rodger (1946). Organic Reactions Volume III (PDF). Newyork: John Wiley and Sons Inc. pp. 275, 276, & 285. ISBN 9780471005285. Retrieved 15 June 2014. 
8. ↑ Reppe, Walter; Schlichting, Otto; Klager, Karl; Toepel, Tim (1948). "Cyclisierende Polymerisation von Acetylen I Über Cyclooctatetraen". Justus Liebigs Annalen der Chemie. 560 (1): 1–92. doi:10.1002/jlac.19485600102. 
9. ↑ Kunichika, Sango (1953). "Cyclopolyolefins Derived from Acetylene". Bulletin of the Institute for Chemical Research, Kyoto University. 31 (5): 323–335. 
10. ↑ Schonberg, Alexander; Radwan, Moubacher (1952). "The Strecker Degradation of α-Amino Acids". Chemical Reviews. 52 (2): 261–277. doi:10.1021/cr60156a002.