Ethyl acetate

Production and synthesis

Ethyl acetate was first synthesized by the Count de Lauraguais in 1759 by distilling a mixture of ethanol and acetic acid.

In 2004, an estimated 1.3 million tonnes were produced worldwide. The combined annual production in 1985 of Japan, North America, and Europe was about 400,000 tonnes. The global ethyl acetate market was valued at $3.3 billion in 2018.

Ethyl acetate is produced 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: : The reaction can be accelerated by acid catalysts 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: :

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

:

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-like fractal 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. 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 the scent of the perfume on the skin.

Ethyl acetate is an 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. However, ethyl acetate is regarded as potentially doing damage to insect DNA, making specimens processed this way less than ideal for subsequent DNA sequencing.

Laboratory uses

In the laboratory, mixtures containing ethyl acetate are commonly used in column chromatography and extractions.{{OrgSynth|prep=v95p0001

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.

Reactions

Ethyl acetate is only weakly Lewis basic, like a typical carboxylic acid ester.

Ethyl acetate hydrolyses to give acetic acid and ethanol. Bases accelerate 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 a strong base, such as sodium hydroxide. This reaction gives ethanol and sodium acetate, which is unreactive toward ethanol: :

In the Claisen condensation, anhydrous ethyl acetate and strong bases react to give ethyl acetoacetate: :[[Image:Claisen ethyl acetate.png|400px|left|Preparation of ethyl acetoacetate.]]

Properties

Physical properties

Its melting point is −83 °C, with a melting enthalpy of 10.48 kJ/mol. At atmospheric pressure, the compound boils at 77 °C. The vaporization enthalpy at the boiling point is 31.94 kJ/mol. The vapor pressure function follows the Antoine equation : \log_{10}(p) = A - \frac{B}{T + C}, where : p is the vapor pressure in bars, : T is the absolute temperature in kelvins, and : A = 4.22809, B = 1245.702, C = -55.189 are constants.

This function is valid within the temperature range of 289 to(-).

The enthalpy of vaporization in kJ/mol is calculated according to the empirical equation by Majer and Svoboda : \Delta H_\text{vap} = A\exp(-\beta,T_\text{r}),(1 - T_\text{r})^\beta, where : T_\text{r} = T/T_\text{c} is the reduced temperature, and T_\text{c} = 523.2 K is the critical temperature. : A = 54.26 kJ/mol and \beta = 0.2982 are constants.

The following table summarizes the most important thermodynamic properties of ethyl acetate under various conditions.

Safety

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

World Health Organization (WHO) has assessed the Acceptable Daily Intake (ADI) of ethyl acetate at 25 mg per kg of body weight. This is similar to the ADI of other artificial sweeteners that are friendly and have been commonly used for a long time. According to European Food Safety Authority (EFSA), ethyl acetate taken orally is rapidly metabolized and broken down. The half-life in blood after ingestion exposure is known to be approximately 35 seconds.

Overexposure to ethyl acetate may cause irritation of the eyes, nose, and throat. Severe overexposure may cause weakness, drowsiness, and unconsciousness. 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. 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 central nervous system depressant and lethal effects; at concentrations of 20,000 to 43,000 ppm (2.0–4.3%), there may be pulmonary edema with hemorrhages, symptoms of central nervous system depression, secondary anemia and liver damage. 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 weaker than that of propyl acetate or butyl acetate.

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