Isoamyl acetate

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Isoamyl acetate
Isoamyl acetate
IUPAC name
3-methylbut-1-yl ethanoate
Other names
isopentyl acetate
banana oil
isopentyl ethanoate
pear essence
3-methylbutyl acetate
3-methylbutyl ethanoate
123-92-2 YesY
ChEBI CHEBI:31725 YesY
ChemSpider 29016 YesY
Jmol-3D images Image
KEGG C12296 YesY
UNII Z135787824 YesY
Molar mass 130.19 g/mol
Appearance colorless liquid
Odor banana-like[1]
Density 0.876 g/cm3
Melting point −78 °C (−108 °F; 195 K)
Boiling point 142 °C (288 °F; 415 K)
0.3% (20 °C)[1]
Vapor pressure 4 mmHg (20 °C)[1]
NFPA 704
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g., gasoline) Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 25 °C (77 °F; 298 K)
Explosive limits 1.0% (100 °C) - 7.5%[1]
Lethal dose or concentration (LD, LC):
7422 mg/kg (rabbit, oral)
16,600 ppm mg/kg (rat, oral)[2]
6470 ppm (cat)[2]
US health exposure limits (NIOSH):
TWA 100 ppm (525 mg/m3)[1]
TWA 100 ppm (525 mg/m3)[1]
1000 ppm[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 YesY verify (what isYesY/N?)
Infobox references

Isoamyl acetate, also known as isopentyl acetate, is an organic compound that is the ester formed from isoamyl alcohol and acetic acid. It is a colorless liquid that is only slightly soluble in water, but very soluble in most organic solvents. Isoamyl acetate has a strong odor which is also described as similar to both banana and pear.[3] Banana oil is a term that is applied either to pure isoamyl acetate or to flavorings that are mixtures of isoamyl acetate, amyl acetate, and other flavors.[4]


Isoamyl acetate is prepared by the acid catalyzed reaction (Fischer esterification) between isoamyl alcohol and glacial acetic acid as shown in the reaction equation below. Typically, sulfuric acid is used as the catalyst. Alternately, an acidic ion exchange resin can be used as the catalyst.

Isoamyl acetate synthesis.png


Isoamyl acetate is used to confer banana flavor in foods. Pear oil commonly refers to a solution of isoamyl acetate in ethanol that is used as an artificial flavor.

It is also used as a solvent for some varnishes and nitrocellulose lacquers, as well as being a honey bee pheromone and can be used to attract large groups of honeybees to a small area. As a solvent and carrier for materials such as nitrocellulose, it was extensively used in the aircraft industry for stiffening and wind-proofing fabric flying surfaces, where it and its derivatives were generally known as 'aircraft dope'. Now that most aircraft are all-metal, such use is now limited to model aircraft, where it is still popularly used for strengthening tissue coverings and balsa wood.

Because of its intense, pleasant odor and its low toxicity, isoamyl acetate is used to test the effectiveness of respirators or gas masks.

Occurrence in nature[edit]

Banana oil is made naturally by the banana plant;[5] it is also produced synthetically.[6]

Isoamyl acetate is released by a honey bee's sting apparatus where it serves as a pheromone beacon to attract other bees and provoke them to sting.[7]


  1. ^ a b c d e f g "NIOSH Pocket Guide to Chemical Hazards #0347". National Institute for Occupational Safety and Health (NIOSH). 
  2. ^ a b "Isoamyl acetate". Immediately Dangerous to Life and Health. National Institute for Occupational Safety and Health (NIOSH). 
  3. ^ "Iso-amyl acetate". 
  4. ^ Karl-Georg Fahlbusch, Franz-Josef Hammerschmidt, Johannes Panten, Wilhelm Pickenhagen, Dietmar Schatkowski, Kurt Bauer, Dorothea Garbe, Horst Surburg "Flavors and Fragrances" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. doi:10.1002/14356007.a11_141.
  5. ^ McGee, Harold. On Food and Cooking. 2003, Scribner, New York.
  6. ^ Isoamyl Acetate, Occupational Safety and Health Administration
  7. ^ Boch R; Shearer DA; Stone BC (September 8, 1962). "Identification of isoamyl acetate as an active component in the sting pheromone of the honey bee.". Nature (England: Nature Publishing Group) 195 (4845): 1018–20. doi:10.1038/1951018b0. PMID 13870346.