Isoamyl acetate
Names Preferred IUPAC name Systematic IUPAC name Other names Identifiers 1744750 ChEBI ChEMBL ChemSpider ECHA InfoCard 100.004.240 EC Number 101452 KEGG RTECS number UNII UN number 1104 1993 Properties C7H14O2 Molar mass 130.187 g·mol−1 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 or 0.533 kPa (20 °C)[1] −89.4·10−6 cm3/mol 1.4020 at 20° Hazards GHS labelling: Danger H226, H315, H319, H335, H336, H372 P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P280, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P312, P314, P321, P332+P313, P337+P313, P362, P370+P378, P403+P233, P403+P235, P405, P501 NFPA 704 (fire 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 mg/kg (rat, oral)[2] 6470 ppm (cat)[2] NIOSH (US health exposure limits): TWA 100 ppm (525 mg/m3)[1] TWA 100 ppm (525 mg/m3)[1] 1000 ppm[1] Related compounds Isoamyl formate
Isoamyl acetate, also known as isopentyl acetate, is an ester formed from isoamyl alcohol and acetic acid, with the molecular formula C7H14O2. 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 described as similar to both banana and pear.[3] Pure isoamyl acetate, or mixtures of isoamyl acetate, amyl acetate, and other flavors in ethanol may be referred to as banana oil[4] or pear oil.[5]
Isoamyl acetate occurs naturally in many plants, including apple, banana, coffee, grape, guava, lychee, papaya, peach, pomegranate, and tomato.[6][7] It is also released by fermentation processes, including those used for making beer, sake, cognac, and whisky.[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.[8]
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. Alternatively, p-toluenesulfonic acid or an acidic ion exchange resin can be used as the catalyst.
It is also produced synthetically by the rectification of amyl acetate.[9]
Isoamyl acetate is used to confer banana or pear flavor in foods such as circus peanuts, Juicy Fruit and pear drops.[10] Banana oil and pear oil commonly refer 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, oil paints, and nitrocellulose lacquers. 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 wings are made of metal, such use is mostly limited to historically accurate reproductions and scale models.
Because of its intense, pleasant odor and its low toxicity, isoamyl acetate is used to test the effectiveness of respirators or gas masks.[11]