Ethyl acetate

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 is also used). Coffee beans and tea leaves are decaffeinated with this solvent. It is also used in paints as an activator or hardener. Ethyl acetate is present in confectionery, perfumes, and fruits and imparts a brief ethereal, fruity, sweet aroma. 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. Ethyl acetate is rarely selected as a reaction solvent because it is prone to hydrolysis, transesterification, and condensations.

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:

CH₃CO₂C₂H₅ + NaOH → C₂H₅OH + CH₃CO₂Na

In the Claisen condensation, anhydrous ethyl acetate and strong bases react to give 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

${\displaystyle {\log }_{10}(p)=A-\frac{B}{T+C},}$

where

${\displaystyle p}$ is the vapor pressure in bars,

${\displaystyle T}$ is the absolute temperature in kelvins, and

${\displaystyle A=4.22809}$, ${\displaystyle B=1245.702}$, ${\displaystyle C=-55.189}$ are constants.

This function is valid within the temperature range of 289 to 349 K (16–76 °C).

The enthalpy of vaporization in kJ/mol is calculated according to the empirical equation by Majer and Svoboda

${\displaystyle \mathrm{\Delta }{H}_{\text{vap}}=A\exp (-\beta T_{\text{r}})(1-T_{\text{r}}{)}^{\beta },}$

where

${\displaystyle T_{\text{r}}=T/T_{\text{c}}}$ is the reduced temperature, and ${\displaystyle T_{\text{c}}}$ = 523.2 K is the critical temperature.

${\displaystyle A}$ = 54.26 kJ/mol and ${\displaystyle \beta }$ = 0.2982 are constants.

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

Safety

The LD₅₀ 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.