Diethyl Ether: How Diethyl Ether is prepared | Uses | Properties

It is the dominant member of the ether class. It is also called simply ether or ethyl ether.

Methods of Preparation

By the action of Iodoethane and dry silver oxide: Diethyl ether is obtained by heating ethyl iodide with dry silver oxide.

Williamson Synthesis Method: In this method sodium or potassium ethoxide is heated with chloro ethane, bromo ethane or iodo ethane. This reaction results in Diethyl ether.

Read more about Williamson Synthesis Method…

C₂H₅ONa + C₂H₅I → C₂H₅ – O – C₂H₅ + NaI

By heating a mixture of ethyl alcohol and alumina: heating ethyl alcohol with alumina (Al₂O₃) at 250°C gives diethyl ether.

C₂H₅OH + HOC₂H₅  – Al2O3/250°C→  C₂H₅ – O – C₂H₅ + H₂O

Laboratory Method:

By heating a mixture of ethyl alcohol and sulphuric acid: Diethyl ether is obtained by heating this mixture to about 140°C by mixing a high concentration of ethyl alcohol with slightly concentrated sulfuric acid.

C₂H₅OH + H₂SO₄ → C₂H₅HSO₄ + H₂O

C₂H₅HSO₄ + C₂H₅OH → C₂H₅ – O – C₂H₅ + H₂SO₄

It is clear from the above reaction that a small amount of concentrated sulfuric acid taken initially can convert a very high amount of alcohol into ether. Hence this method is also called Continuous etherification method.

In practice this does not happen. Because some sulfuric acid gets reduced to form sulfur dioxide and the water concentrate in the reaction dilutes sulfuric acid. Therefore small amounts of acid are added from time to time.

About 100 ml of pure alcohol is taken in a 500 ml distillation flask. About 50 ml of concentrated sulfuric acid is slowly added to it. While adding sulfuric acid, shake the flask. Now heat the flask to 140°C by placing it on sand heat.

The ether is distilled and collected in the receptor. The receiver has a side-tube which is connected to a rubber drain and reaches the water sink. This does not allow the ether vapor to reach the burner and there is no fear of fire.

All cork in the equipment is air tight. The speed with which the ether collects in the receiver keeps pouring the alcohol into the flask from the point funnel accordingly.

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Rectification: Alcohol, water and sulfuric acid are present in the form of impurities in ether obtained from the above method. To remove sulfuric acid, the obtained ether is washed with a solution of sodium dioxide.

To remove alcohol, ether is mixed with 50% calcium chloride solution and left for some time, forming crystals of CaCl₂.3C₂H₅OH. They are filtered and separated.

To remove water, it is dried by adding anhydrous calcium chloride to the ether, thus distilling the obtained ether at 35°C to obtain pure ether.

Diethyl Ether Physical Properties

It is a colorless, pungent and highly volatile liquid. It burns with a light flame. Its boiling point is 34°C. It is less soluble in water but less soluble in organic solvents such as alcohol benzene chloroform etc.

It is itself used as a solvent. By correcting its vapors, there is unconsciousness. More heat is used than its evaporation. Therefore, applying on any part of the body makes that part cool. That is, it becomes numb for some time.

Diethyl Ether Chemical Properties

Ether is a relatively inert substance. They do not react with alkalis, dilute acids, reducing oxidizers and active metals at ordinary temperatures.

Following are the major chemical reactions of diethyl ether.

Combustion: Due to being more flammable it burns quickly and forms an explosive mixture with air.

C₂H₅ – O – C₂H₅ + 6O₂ → 4CO₂ + 5H₂O

Halogenation: It reacts with chlorine and bromine to form substitution products. Substitution on α-carbon atoms is facilitated i.e. hydrogen is substituted first from oxygen to carbon atom and then other hydrogen atoms are substituted depending on the amount of the agent and other conditions.

Produce oxonium salt: It reacts with cold and concentrated H₂SO₄ or HCl to form oxonium salt.

In this reaction, the H⁺ of the acid is combined with a lone pair of electron on oxygen. This reaction takes place in the same way as ammonium salts are formed by the reaction of ammonia or amino compounds and acids.

Therefore, ether is soluble in cold and concentrated H₂SO₄. With the help of this property of ethers, ethers can be differentiated into alkens. The elken is insoluble in cold and concentrated H₂SO₄.

Ether can be reclaimed by adding water to oxonium salt.

Reaction with concentrated sulfuric acid: Ethyl hydrogen sulfate is obtained by heating the diethyl ether with concentrated sulfuric acid.

C₂H₅ – O – C₂H₅ + H₂SO₄ → C₂H₅HSO₄ + C₂H₅OH

C₂H₅OH + H₂SO₄ → C₂H₅HSO₄

Over heating, 160 ethylene gas is obtained.

Water decomposition: Water decomposition of the ether occurs when heated with dilute sulfuric acid at high pressure. Water decomposition of diethyl ether yields ethyl alcohol.

C₂H₅ – O – C₂H₅ + H₂O → 2C₂H₅OH

Formation of peroxide or auto oxidation: In the presence of sunlight, reaction of diethyl ether with air, oxygen or ozone is made of peroxide.

ether’s peroxide is an extremely explosive substance. Therefore, more careful action is required in the distillation of the ether, by removing the detergent like FeSO₄ with a reducing agent to remove the peroxide present in it.

Reaction with Phosphorus Penta Chloride: Ethyl chloride is formed when the diethyl ether reacts with phosphorus penta chloride.

C₂H₅ – O – C₂H₅ + PCl₅ → 2C₂H₅Cl + POCl₃

Reaction with hydroiodic acid: diethyl ether with cold and concentrated hydroiodic acid forms ethyl iodide and ethanol.

C₂H₅ – O – C₂H₅ + HI → C₂H₅I + C₂H₅OH

It forms ethyl iodide with hot and concentrated HI.

diethyl ether is a simple ether (R – O – R). The reaction of mixed ether(R₁ – O – R₂) with cold and concentrated HI can occur in two ways.

R₁ – O – R₂ + HI → R₁OH + R₁I

R₁ – O – R₂ + HI → R₁I + R₂OH

It is known from the detailed study of the mechanism of the above reaction. That if one of the alkyl groups forms a more stable carbonium ion then its iodide is formed.

(CH₃)₃C – O – CH₃ + HI → (CH₃)₃Cl + CH₃OH

In other circumstances the small alkyl group forms iodide compounds.

CH₃ – O – C₂H₅ + HI → CH₃I + C₂H₅OH

Reduction: Diethyl ether is reacted with red phosphorus and hydroiodic acid and gets ethane.

C₂H₅ – O – C₂H₅ + 4H → 2C₂H₆ + H₂O

Oxidation: Reaction with strong oxidants such as acidic potassium dichromate makes it acetaldehyde and acetic acid.

C₂H₅ – O – C₂H₅ + 2O → 2CH₃CHO + H₂O

CH₃CHO + O → CH₃COOH

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Reaction with acetyl chloride: On heating with acetyl chloride in the presence of anhydrous zinc chloride, it forms ethyl chloride and ethyl acetate.

C₂H₅ – O – C₂H₅ + CH₃COCl → C₂H₅Cl + CH₃COOC₂H₅

Reaction with acetic anhydride: The reaction with acetic anhydride of diethyl ether is similar to that of acetyl chloride.

C₂H₅ – O – C₂H₅ + (CH₃CO)₂O → 2CH₃COOC₂H₅

Reaction with carbon mono oxide: In the presence of boron tri chloride at about 500 atmospheric pressure and about 100°C temperature it reacts with carbon mono oxide to form ethyl propanoate.

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

Effect of heated alumina: Ethylene gas is obtained when the vapors of diethyl ether flow at 360°C over the heated alumina.

C₂H₅ – O – C₂H₅ → 2C₂H₄ + H₂O

Diethyl Ether Uses

It is used as a solvent and medium in making Grignard reagents and in the Burtz reaction.

Ether has been used in surgery as an anesthetic in combination with chloroform.

By mixing ether in alcohol and used as a fuel in place of petrol like Power alcohol.

It is also used as a refrigerant.

The major use of ether is as a solvent. It easily dissolves many organic substances like oils, fats and resins.