Ethyl acetate

Ethyl acetate
Names
IUPAC name
Ethyl acetate
Systematic IUPAC name
Ethyl ethanoate
Other names
Acetic ester, Acetic ether, Ethyl ester of acetic acid
Identifiers
141-78-6 YesY
ChEBI CHEBI:27750 YesY
ChEMBL ChEMBL14152 YesY
ChemSpider 8525 YesY
Jmol 3D model Interactive image
KEGG D02319 YesY
PubChem 8857
RTECS number AH5425000
UNII 76845O8NMZ YesY
Properties
C4H8O2
Molar mass 88.11 g·mol−1
Appearance Colorless liquid
Odor ether-like, fruity[1]
Density 0.902 g/cm3
Melting point −83.6 °C (−118.5 °F; 189.6 K)
Boiling point 77.1 °C (170.8 °F; 350.2 K)
Immiscible
Solubility in ethanol,
acetone, diethyl ether,
benzene		 Miscible
Vapor pressure 73 mmHg (20 °C)[1]
Acidity (pKa) 25
1.3720
Viscosity 426 μPa s (0.426 cP) at 25 °C
Structure
1.78 D
Hazards
Main hazards Flammable (F),
Irritant (Xi)
Safety data sheet See: data page
R-phrases R11, R36, R66, R67
S-phrases S16, S26, S33
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
3
1
0
Flash point −4 °C (25 °F; 269 K)
Explosive limits 2.0%-11.5%[1]
Lethal dose or concentration (LD, LC):
11.3 g/kg, rat
16000 ppm (rat, 6 hr)
12295 ppm (mouse, 2 hr)
1600 ppm (rat, 8 hr)[2]
21 ppm (guinea pig, 1 hr)
12330 ppm (mouse, 3 hr)[2]
US health exposure limits (NIOSH):
PEL (Permissible)
 TWA 400 ppm (1400 mg/m3)[1]
REL (Recommended)
 TWA 400 ppm (1400 mg/m3)[1]
IDLH (Immediate danger)
 2000 ppm[1]
Related compounds
Methyl acetate,
Propyl acetate,
Butyl acetate
Related compounds
 Acetic acid,
ethanol
Supplementary data page
Refractive index (n),
Dielectric constant (εr), etc.
Thermodynamic
data
 Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
YesY verify (what is YesYN ?)
Infobox references

Ethyl acetate (systematically, ethyl ethanoate, commonly abbreviated EtOAc or EA) is the organic compound with the formula CH3-COO-CH2-CH3, simplified to C4H8O2. This colorless liquid has a characteristic sweet smell (similar to pear drops) and is used in glues, nail polish removers, decaffeinating tea and coffee, and cigarettes (see list of additives in cigarettes). Ethyl acetate is the ester of ethanol and acetic acid; it is manufactured on a large scale for use as a solvent. The combined annual production in 1985 of Japan, North America, and Europe was about 400,000 tons.[3] In 2004, an estimated 1.3M tons were produced worldwide.[4]

Production

Ethyl acetate is synthesized in industry mainly via the classic Fischer esterification reaction of ethanol and acetic acid. This mixture converts to the ester in about 65% yield at room temperature:

CH3CH2OH + CH3COOH → CH3COOCH2CH3 + H2O

The reaction can be accelerated by acid catalysis and the equilibrium can be shifted to the right by removal of water. It is also prepared in industry using the Tishchenko reaction, by combining two equivalents of acetaldehyde in the presence of an alkoxide catalyst:

2 CH3CHO → CH3COOCH2CH3

Silicotungstic acid is used to manufacture ethyl acetate by the alkylation of acetic acid by ethylene:[5]

C2H4 + CH3CO2H → CH3CO2C2H5

By dehydrogenation of ethanol

A specialized industrial route entails the catalytic dehydrogenation of ethanol. This method is more cost effective than the esterification but is applied with surplus ethanol in a chemical plant. Typically, dehydrogenation is conducted with copper at an elevated temperature but below 250 °C. The copper may have its surface area increased by depositing it on zinc, promoting the growth of snowflake, fractal like structures (dendrites). Surface area can be again increased by deposition onto a zeolite, typically ZSM-5. Traces of rare earth and alkali metals are beneficial to the process. Byproducts of the dehydrogenation include diethyl ether, which is thought to arise primarily due to aluminum sites in the catalyst, acetaldehyde and its aldol products, higher esters, and ketones. Separations of the byproducts are complicated by the fact that ethanol forms an azeotrope with water, as does ethyl acetate with ethanol and water, and methyl ethyl ketone (MEK, which forms from 2-butanol) with both ethanol and ethyl acetate. These azeotropes are "broken" by pressure swing distillation or membrane distillation.

Uses

Ethyl acetate is used primarily as a solvent and diluent, being favored because of its low cost, low toxicity, and agreeable odor. For example, it is commonly used to clean circuit boards and in some nail varnish removers (acetone and acetonitrile are also used). Coffee beans and tea leaves are decaffeinated with this solvent.[6] It is also used in paints as an activator or hardener. Ethyl acetate is present in confectionery, perfumes, and fruits. In perfumes, it evaporates quickly, leaving only the scent of the perfume on the skin.

Laboratory uses

In the laboratory, mixtures containing ethyl acetate are commonly used in column chromatography and extractions. Ethyl acetate is rarely selected as a reaction solvent because it is prone to hydrolysis and transesterification.

Ethyl acetate is fairly volatile at room temperature and has a boiling point of 77 °C. Due to these properties, it can be removed from a sample by heating in a hot water bath and providing ventilation with compressed air.

Occurrence in wines

Ethyl acetate is the most common ester in wine, being the product of the most common volatile organic acid — acetic acid, and the ethyl alcohol generated during the fermentation. The aroma of ethyl acetate is most vivid in younger wines and contributes towards the general perception of "fruitiness" in the wine. Sensitivity varies, with most people having a perception threshold around 120 mg/L. Excessive amounts of ethyl acetate are considered a wine fault. Exposure to oxygen can exacerbate the fault due to the oxidation of ethanol to acetaldehyde, which leaves the wine with a sharp vinegar-like taste.[7]

Entomological killing agent

In the field of entomology, ethyl acetate is an effective asphyxiant for use in insect collecting and study. In a killing jar charged with ethyl acetate, the vapors will kill the collected insect quickly without destroying it. Because it is not hygroscopic, ethyl acetate also keeps the insect soft enough to allow proper mounting suitable for a collection.

Reactions

Ethyl acetate can be hydrolyzed in acidic or basic conditions to regain acetic acid and ethanol. The use of an acid catalyst accelerates the hydrolysis, which is subject to the Fischer equilibrium mentioned above. In the laboratory, and usually for illustrative purposes only, ethyl esters are typically hydrolyzed in a two step process starting with a stoichiometric amount of strong base, such as sodium hydroxide. This reaction gives ethanol and sodium acetate, which is unreactive toward ethanol:

CH3CO2C2H5 + NaOH → C2H5OH + CH3CO2Na

The rate constant is 0.111 dm3/mol.sec at 25 °C.

Safety

The LD50 for rats is 5620 mg/kg,[8] indicating low toxicity. Given that the chemical is naturally present in many organisms, there is little risk of toxicity.

Overexposure to ethyl acetate may cause irritation of the eyes, nose, & throat. Severe overexposure may cause weakness, drowsiness, & unconsciousness. [9] Humans exposed to a concentration of 400 ppm in 1.4 mg/l ethyl acetate for a short time were affected by nose and throat irritation. [10] Ethyl acetate is an irritant of the conjunctiva and mucous membrane of the respiratory tract. Animal experiments have shown that, at very high concentrations, the ester has /CNS depressant/ and lethal effects; at concentrations of 20000 to 43000 ppm, there may be pulmonary edema with hemorrhages, symptoms of central nervous system depression, secondary anemia and damage of the liver. In humans, concentrations of 400 ppm cause irritation of the nose and pharynx; cases have also been known of irritation of the conjunctiva with temporary opacity of the cornea. In rare cases exposure may cause sensitization of the mucous membrane and eruptions of the skin. The irritant effect of ethyl acetate is less strong than that of propyl acetate or butyl acetate. International Labour Office. Encyclopedia of Occupational Health and Safety. Vols. I&II. Geneva, Switzerland: International Labour Office, 1983., p. 782

References

  1. 1 2 3 4 5 6 "NIOSH Pocket Guide to Chemical Hazards #0260". National Institute for Occupational Safety and Health (NIOSH).
  2. 1 2 "Ethyl acetate". Immediately Dangerous to Life and Health. National Institute for Occupational Safety and Health (NIOSH).
  3. ↑ Wilhelm Riemenschneider, Hermann M. Bolt "Esters, Organic" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a09_565.pub2. Article Online Posting Date: April 30, 2005
  4. ↑ Dutia, Pankaj (August 10, 2004). "Ethyl Acetate: A Techno-Commercial Profile" (PDF). Chemical Weekly: 184. Retrieved 2009-03-21.
  5. ↑ Misono, Makoto (2009). "Recent progress in the practical applications of heteropolyacid and perovskite catalysts: Catalytic technology for the sustainable society". Catalysis Today 144 (3-4): 285–291. doi:10.1016/j.cattod.2008.10.054.
  6. ↑ ico.org
  7. ↑ J. Robinson (ed) "The Oxford Companion to Wine" Third Edition pg 259 Oxford University Press 2006 ISBN 0-19-860990-6
  8. ↑ http://hazard.com/msds/mf/baker/baker/files/e2850.htm. Missing or empty |title= (help)
  9. ↑ Mackison, F. W., R. S. Stricoff, and L. J. Partridge, Jr. (eds.). NIOSH/OSHA - Occupational Health Guidelines for Chemical Hazards. DHHS(NIOSH) Publication No. 81-123 (3 VOLS). Washington, DC: U.S. Government Printing Office, Jan. 1981. from HSDB
  10. ↑ /From table/ Clayton, G.D., F.E. Clayton (eds.) Patty's Industrial Hygiene and Toxicology. Volumes 2A, 2B, 2C, 2D, 2E, 2F: Toxicology. 4th ed. New York, NY: John Wiley & Sons Inc., 1993-1994., p. 2981 from HSDB

External links

http://pubchem.ncbi.nlm.nih.gov/compound/ethyl_acetate#section=Toxicity

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