Diethyl Ether: Preparation, Reactions,Health Hazards

Diethyl ether, often known as ether, is an organic molecule composed of two ethyl groups connected by an oxygen atom as C₂H₅ – O – C₂H₅. It is a well-known anesthetic and is also known as ethyl ether. The IUPAC name for diethyl ether is ethoxyethane.

Valerius Cordus, a German physicist, botanist, and pharmacologist, developed this chemical in 1540. It was also known as the “sweet oil of vitriol” (oleum dulce vitrioli) because it is made by distilling a mixture of ethanol and sulfuric acid. August Sigmund Frobenius gave the chemical the name Ether in 1729. It is a highly flammable, colorless, volatile liquid with an ethereal odor. It’s a popular solvent for bromine, iodine, most fatty and resinous compounds, volatile oils, and pure water.

Interesting Science Videos

Structure of diethyl ether

An ether group is made up of an oxygen atom linked to two ethyl groups. They are represented by the formula C₂H₅ -O- C₂H₅. Bond angles of 104.5 degrees characterize the C-O-C connection, with C-O distances of around 140 pm. The ether’s oxygen is more electronegative than the carbons. As a result, the alpha hydrogens in the chain are more acidic than in typical hydrocarbon chains.

Preparation

By heating a mixture of ethyl alcohol and alumina

Ethyl alcohol on heating with alumina (Al₂O₃) at 250°C produces diethyl ether.

C₂H₅OH + HOC₂H₅ Al₂O₃ → C₂H₅ – O – C₂H₅ + H₂O (at250°C/ Al₂O₃)

From Williamson method

In this process, Sodium or potassium ethoxide is heated with chloro ethane, bromo ethane, or iodo ethane to produce diethyl ether.

C₂H₅ONa + C₂H₅Cl → C₂H₅OC₂H₅ + NaCl

From silver oxide

The reaction of ethyl chloride with dry silver oxide (Ag₂O), produces ether.

Ag₂O + 2 C₂H₅Cl → 2 AgCl + C₂H₅OC₂H₅

Laboratory preparation

In the laboratory and on a big scale, it is produced by heating an excess of ethyl alcohol with concentrated sulphuric acid to 140 oC. The reactions involved are:

C₂H₅OH + H₂SO₄ → C₂H₅HSO₄ + H₂O

C₂H₅HSO₄ + C₂H₅OH → C₂H₅ – O – C₂H₅ + H₂SO₄

A small amount of concentrated sulfuric acid can convert a large amount of alcohol into ether. As a result, this approach is also known as the Continuous etherification method.

Procedure

In a 250 ml distillation flask, 50 ml of conc. H2SO4 is gently mixed with 100 ml of pure alcohol with continuous shaking. The flask is then equipped with a drop funnel, a thermometer, and a water condenser that is connected to a receiver immersed in ice-cold water. The entire system is made airtight.

Fig: Laboratory preparation of diethyl ether

Image source: https://www.askmattrab.com/notes/350-Lab-Preparation-of-Ethoxyethane

The flask is now heated in a sand bath. When the temperature of the contents of the flask exceeds 140 oC, ether begins to distill over.

Impurities in the ether produced through this process include alcohol, water, and sulfuric acid. To eliminate the sulfuric acid, the resulting ether is rinsed with a sodium dioxide solution.

Ether is combined with a 50% calcium chloride solution and left to produce crystals of CaCl₂.3C₂H₅OH in order to remove the alcohol. They are filtered and separated.

Then anhydrous calcium chloride is mixed with the ether to eliminate the water. The ether is then distilled at 35 °C to produce pure ether.

Physical properties of diethyl ether

Diethyl ether is an odorless, colorless, highly volatile liquid with a sweetish-burning taste.
Its boiling point is 34.6 °C.
The melting point is -116.3 °C.
It has a density of 0.7134 g/cm3.
It is less soluble in water but more soluble in organic solvents including alcohol, benzene, and chloroform.
It burns with a light flame.
At 20 °C, the vapor pressure of Diethyl Ether is 439.8 mm Hg.
It has polar nature.

Reactions of diethyl ether

Combustion

As it is more flammable, it burns more rapidly and generates an explosive combination with air.

C₂H₅ – O – C₂H₅ + 6O₂ → 4CO₂ + 5H₂O

Halogenation

It produces a substituted product when it reacts with chlorine and bromine. Substitution on alpha-carbon atoms is facilitated, which means that hydrogen is substituted first from carbon next to an oxygen atom, and then other hydrogen atoms are substituted depending on the amount of the agent and other variables.

Peroxide formation

In the presence of sunlight, diethyl ether reacts with atmospheric oxygen to produce ether peroxide due to the presence of a lone pair of electrons on the ethereal oxygen.

Reaction with conc. Sulphuric acid

The diethyl ether on heating with concentrated sulfuric acid produces ethyl hydrogen sulfate.

C₂H₅ – O – C₂H₅ + H₂SO₄ → C₂H₅HSO₄ + C₂H₅OH

C₂H₅OH + H₂SO₄ → C₂H₅HSO₄

Reaction with water

Ethyl alcohol is produced when diethyl ether is decomposed in water.

C₂H₅ – O – C₂H₅ + H₂O → 2 C₂H₅OH

Reaction with HI

Ethyl iodide and ethanol are formed when diethyl ether reacts with cold and concentrated hydroiodic acid.

C₂H₅ – O – C₂H₅ + HI → C₂H₅I + C₂H₅OH

Reduction

In the presence of red phosphorous diethyl ether reacts with hydroiodic acid to give ethane.

C₂H₅ – O – C₂H₅ + 4H → 2C₂H₆ + H₂O

Oxidation

It reacts with strong oxidizing agents like acidic potassium dichromate, to give acetaldehyde and acetic acid.

C₂H₅ – O – C₂H₅ + 2 (O) → 2 CH₃CHO + H₂O

CH₃CHO + (O) → CH₃COOH

Reaction with carbon monoxide

In the presence of boron trichloride, diethyl ether reacts with carbon mono oxide to give ethyl propanoate. This reaction is usually carried out at about 500 atmospheric pressure and about 100°C temperature.

C₂H₅ – O – C₂H₅ + CO → C₂H₅ – CO – O – C₂H₅

Reaction with acetyl chloride

It produces ethyl chloride and ethyl acetate when heated with acetyl chloride in the presence of anhydrous zinc chloride.

C₂H₅ – O C₂H₅ + CH₃COCl → C₂H₅Cl + CH₃COOC₂H₅

Uses of diethyl ether

Diethyl ether is a common aprotic solvent used in laboratories.
As diethyl ether has high volatility and low flash point, it is used as a starting fluid in gasoline and diesel engines.
By combining ether with alcohol, Power alcohol can be used as a fuel in place of gasoline.
It is employed as a solvent and medium in the production of Grignard reagents as well as in the Burtz reaction.
It is used to cure hiccups by instilling it into the nasal cavity.
It works well as a solvent for alkaloids, colors, fats, oils, resins, and waxes.
It is used in the cellulose acetate and plastic industries to extract acetic acid from aqueous solutions.
Diethyl ether usually superseded chloroform as a general anesthetic due to ether’s superior therapeutic index, or a larger gap between an effective dose and a potentially toxic dose.

Health hazards of diethyl ether

Many diseases or health problems can result from inhaling diethyl ether, including nausea, vomiting, headache, cough, sore throat, labored breathing, and loss of consciousness.
When it comes into contact with the eyes or skin, it produces irritation, which leads to skin dryness or cracking.
High levels of Diethyl Ether exposure may also harm the kidneys.
It is a highly flammable liquid and vapor that can also produce explosive peroxides.

References

Morrison, R. T., & Boyd, R. N. (1983). Organic chemistry. Boston: Allyn and Bacon.
Arun Bahl, and B.S. Bahl (2006). A textbook of organic chemistry Chemistry. New delhi: S. CHAND.
https://www.vedantu.com/chemistry/diethyl-ether
https://byjus.com/chemistry/diethyl-ether/.
https://www.britannica.com/science/ethyl-ether

Diethyl Ether: Structure, Preparation, Properties, Reactions, Uses, Health Hazards