Physical Properties of Ethers

Do you think you have read enough about ethers? Well, what do you know about this class of organic compounds? In this chapter, we will cover, not only ether definition but also the various chemical and physical properties of ethers. To start with, how many of you remember what ethers are?

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What are Ethers?

Ethers are a class of organic compounds that have an oxygen atom attached to two same or different alkyl or aryl groups. We can write down the general formula for ethers as R-O-R, R-O-Ar or Ar-O-Ar.

From our knowledge of organic nomenclature, we know that in the above formula, R represents an alkyl group and Ar represents an aryl group. We can classify these compounds into two main types or categories. This categorisation depends on the substituent groups attached to the compound. Accordingly, we can classify them into

• Symmetrical ether: It has two identical groups attached to the oxygen atom.
• Asymmetrical ether: It has two different groups attached to the oxygen atom.

Ethers exhibit a wide range of physical and chemical properties. Let us now discuss some of the physical and chemical properties of ethers.

Physical Properties of Ethers

• An ether molecule has a net dipole moment. We can attribute this to the polarity of C-O bonds.
• The boiling point of ethers is comparable to the alkanes. However, it is much lower compared to that of alcohols of comparable molecular mass. This is despite the fact of the polarity of the C-O bond.
• The miscibility of ethers with water resembles those of alcohols.
• Ether molecules are miscible in water. We can attribute this to the fact that like alcohols, the oxygen atom of ether can also form hydrogen bonds with a water molecule.

You can download Alcohols, Phenols and Ethers Cheat Sheet by clicking on the download button below

Browse more Topics under Alcohols Phenols And Ethers

• Chemical Reactions of Alcohols, Phenols & Ethers
• Chemical Reactions of Ethers
• Introduction and Classification of Alcohols, Phenols & Ethers
• Nomenclature
• Physical Properties of Alcohols, Phenols and Ethers
• Preparation of Alcohols
• Preparation of Ethers
• Preparation of Phenols
• Some Commercially Important Alcohols

Chemical Properties of Ethers

Ethers generally undergo chemical reactions in two ways. We will talk about them in the below section.

• Cleavage of C-O bond: Ethers are generally very unreactive in nature. When we add an excess of hydrogen halide to the ether, cleavage of C-O bond takes place. It leads to the formation of alkyl halides. The order of reactivity is as follows:

HI > HBr > HCl

R-O-R  +  HX  →  RX  +  R-OH

• Electrophilic substitution: The alkoxy group in ether activates the aromatic ring at ortho and para positions for electrophilic substitution. Common electrophilic substitution reactions are halogenation, Friedel Craft’s reaction etc.
• Halogenation reaction of ethers: Aromatic ethers undergo halogenation, for example, bromination, when we add a halogen in the presence or absence of a catalyst.
• Friedel Craft’s reaction of ethers: Aromatic ethers undergo Friedel Craft’s reaction for example addition of alkyl or acyl group when we introduce it to an alkyl or acyl halide in the presence of a Lewis acid as catalyst.

                                                            Let us also study about the preparation of Ethers. 

Solved Example for You

Q: What are the uses of ethers?

Ans: The common uses of ethers include:

• We use dimethyl ether as a refrigerant and as a solvent at low temperature.
• Diethyl ether is a common ingredient as an anaesthesia in surgery.
• Diethyl ether is common as a solvent for oils, gums, resins etc.
• We use phenyl ether as a heat transfer medium because of its high boiling point.