Ethers Definition
Derived from the Latin word ‘aether’, ethers refer to a class of organic compounds containing an oxygen atom between two alkyl groups. From the general ether definition, it’s clear that they have the formula as R-O-R, R-O-Ar, R-O-R’, Ar-O-Ar, where R’s being alkyl groups and Ar’s being aryl groups. The oxygen atom is bonded to two alike or different aryl/ alkyl groups. These groups are inflammable at room temperature and high-pressure.
Ethers Nomenclature
According to ethers meaning, it’s clear that ethers are named by the names of two alkyl or aryl groups attached to one oxygen atom. Moreover, two alkyl/ aryl groups are written according to alphabetical order.
Example: CH3 – O – C2H5 is an ethyl methyl ether
In the name of ether, if only one alkyl/ aryl group is shown, then it implies two similar groups are bonded to oxygen.
Example: CH3 – O – CH3 is diethyl ether
IUPAC Nomenclature for Naming Ethers
According to IUPAC Nomenclature, the more complex group is named as root or the alkane base name with the smaller group named as an alkoxy substituent. Thus, to define ether names according to IUPAC systems, consider ethers as alkoxy alkanes.
Example: CH3 – O – CH3 is ethoxy ethane
Rules for IUPAC Naming of Ethers
The longest carbon chain must be selected and name it as root.
Change the name of the smaller hydrocarbon group ending with ‘yl’ to ‘oxy’.
Place the alkoxy group with a locator number before the root or base chain name.
Example:
CH3 – CH2 – O – CH2 – CH2 – CH3 is 1- Ethoxybutane
Ethers- General Classification
Based on the substituent group attached to its oxygen atom, ethers can be classified into two major categories:
Symmetrical Ethers: To define ether as symmetrical ethers, two identical groups are attached to one oxygen atom as R-O-R or Ar-O-Ar.
Example: CH3 – CH2 – O – CH2 – CH3
Asymmetrical Ethers: From the ether meaning, it’s clear that two groups attached with one oxygen atom can be identical or dissimilar. If two different groups are attached to one oxygen atom-like R-O-R’ or R-O-Ar, then it refers to asymmetrical ether.
Example: CH3 – CH2 – O – CH2 – CH2 – CH2 – CH3
How Are Ethers Prepared?
From the ether definition, it’s found that there are different ways to prepare ethers. Some of the common industrial methods to synthesise ethers include:
Dehydration of Alcohols:
In the presence of protic acids like phosphoric acids or sulphuric acid, alcohol undergoes dehydration. It gives ethers and alkenes as reaction products under diverse conditions. For example:
2CH3CH2−OH+H2SO4 ----> CH3CH2−O−CH2CH3 + H2O
Ethanol gets dehydrated to ethene when reacted with sulphuric acid at 443K temperature. On the contrary, ethanol gets dehydrated to form ethoxyethane when treated with sulphuric acid at 413K.
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The reaction is a nucleophilic bimolecular reaction.
Williamson Synthesis:
According to ether definition, there are two types of ethers, and this reaction is highly used to prepare them in laboratories. An alkyl halide of the type R-X reacts with R-ONa to form an ether.
For example:
Na+C2H5O− + C2H5Cl → C2H5OC2H5 + Na+Cl−
The reaction follows the SN2 attack of ONa- ion on C2H5Cl.
Other Reactions:
When alkyl halide (R-X) reacts with dry silver oxide (Ag2O), it produces ether. For example:
Ag23O + 2CH3Cl → 2AgCl + CH3OCH3
Physical Properties of Ethers
Appearance: All ethers are colourless, volatile liquids with a pleasant smell at room temperature except dimethyl ether and ethyl methyl ether that are gases.
Boiling Point: Ether molecules have low boiling points as compared to alcohols, but are comparable with alkanes.
Polarity: Oxygen atom surrounded by two alkyl/ aryl groups is incapable of participating in hydrogen bonding and hence, ethers possess less polarity.
Solubility: According to the Ether definition, these molecules are soluble in water. Because oxygen atoms present tend to form hydrogen bonds with the H2O molecule, however, the solubility decreases with the relative increase in the hydrocarbon chain.
Hybridisation: In the ether, the oxygen atom is sp3 hybridised and possess a bond angle of 109.5-degrees.
Chemical Reactions:
Formation of Peroxides: When ether gets exposed to air in the presence of sunlight, it forms peroxide linkage.
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The above reaction shows two reactions of peroxide formation from ether in the presence of oxygen.
Electrophilic Reactions: Ethers undergo different types of electrophilic reactions such as halogenation, Friedel- Crafts Reaction, Nitration, and more.
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The above diagram shows ether undergoing electrophilic substitution reaction.
Ether- Significant Uses
At small temperatures, dimethyl ether is used as a solvent.
Diethyl ether acts as a common ingredient in anaesthesia, and solvent for gums, oils, resins, and more.
Phenyl ether has a high boiling point and thus can be used as a heat transfer.
FAQs on Ethers
1. How Can You Identify Ethers?
Ethers are known with different names as some call them as diethyl ethers. It is basically an organic compound in which an oxygen atom combines two different ethyl groups. These compounds are highly volatile, are colourless, and flammable liquids. These possess high odour, are powerful, and have a sweet taste. These are highly used in medicines and other medical purposes. Usually, ethers are identified with their alkyl or aryl groups, and another way is through the alphabetical listing of atoms at one side of the Oxygen atom.
2. How Do I Get Ethers?
In the fair, ethers are unreactive in nature. But still, they react in three different forms. For producing ethers, Williamson ether synthesis is the most common way. When SN2 reacts with some metal oxides, it will produce halide ions. Thus it produces alkyl halide. Further alkoxide ion is formed with the reaction of a strong base and alcohol. This ion will displace the halide ion and thus finally form an ether.
