Methods of Preparation of Ethers

There are several types of ethers, but the most common ones feature an ether group made up of oxygen and two alkyl groups. This word comes from the Latin word for “ignite,” Ether. There is a good chance that Ether is likely to catch fire at room temperature and high pressure. R-O-R is used to represent alkyl and aryl groups in the generic formula of Ether.

Ether

An oxygen atom is connected to two alkyl and aryl groups in Ether in organic molecules. All three of these forms of the generic formula for ethers can describe ethers. R is an alkyl group, and Ar is an aryl group, as we learned in the chapter on nomenclature.

Symmetric ethers and asymmetrical ethers may be divided into two groups based on the substituent groups attached: When we have two identical groups connected to the oxygen atom, we get the former Ether. When we have two distinct groups connected to the oxygen atom, we’re dealing with an asymmetrical ether.

Methods of preparation of ethers

Williamson synthesis is a method for producing ethers in the laboratory using alkyl halides and alcohol. Williamson synthesis and dehydration of alcohol are widely used to prepare ethers in the experimental laboratory. Laboratory preparation can be accomplished in a variety of methods, including:

• Dehydration of Alcohol

Under certain circumstances, ethanol undergoes dehydration in the presence of sulphuric acid and phosphoric acid, which are protic acids, resulting in alkenes and ethers, respectively. When the reaction conditions are met, a reaction product will be produced.

For example, in the presence of sulphuric acid, ethanol is dehydrated to ethene at 443K. When ethanol is heated to 413 degrees Celsius in the presence of sulphuric acid, it produces ethoxyethane as a by-product.

It is a nucleophilic bimolecular process that occurs during alcohol dehydration to create ethers. Thus, the alcohol serves as a nucleophile, implying that the alcohol molecule attacks a protonated alcohol, as seen in the diagram above.

Alcohols are dehydrated, and this causes their etherification.

This approach is utilised to synthesise ethers containing primary alkyl groups. It is essential that the alkyl group be not inhibited throughout this process and that the temperature of the reaction is maintained low, or alkenes will be formed.

• Williamson Method

In the Williamson Method, a synthesis is created by combining two or more elements of the Williamson Method.

Asymmetrical and symmetrical ethers are produced in large quantities in laboratories using this technique. It is possible to create an alkyl halide that reacts with sodium alkoxide, resulting in the creation of Ether by the Williamson method.

When an alkoxide ion attacks an alkyl halide, it is an SN2 reaction. Because alkoxides are extremely strong bases, they react with alkyl halides in an unbroken chain, and as a result, they participate in elimination processes.

Williamson synthesis has better productivity when it comes to primary alkyl halides.

• Alkyl Halide With Dry Silver Oxide

In the presence of dry silver oxide, Ether can be generated by treating alkyl halides.

2C2H5Br + Ag2O → C2H5 – O – C2H5 + 2AgBr

• Ether Chemical Reaction

It is ethers that are the least reactive of all the functional groups. Ether bonds are relatively stable in the presence of bases, oxidising agents, and reducing agents, among other substances. Alternatively, ethers are cleaved when they come into contact with acids. The following are the most significant chemical reactions using ethers:

• Cleavage of C-O bonds

Cleavage of C-O bonds in Ether occurs when an excess of hydrogen halide (which is acidic) is present under severe circumstances such as concentrated acids (often HBr and HI), high temperatures, and concentrated acids.

The reaction of dialkyl ether, for example, initially results in the formation of an alkyl halide and ethanol. Following this reaction, the alcohol interacts with the halide to generate a second mole of alkyl halide and water, respectively.

it is well known that the oxygen atom is basic, analogous to the oxygen atom in water or an aqueous solution. The first interaction between ether and halide results in the formation of protonated Ether due to this reaction. In this case, the nucleophilic assault of the halide ion on the protonated ether results in the breakdown of the C-O bond.

Properties of Ether 

The gasses dimethyl ether and ethyl methyl ether are both present at room temperature when the temperature is maintained at that level. Other lower homologues include colourless, pleasant-smelling, and volatile liquids that have a unique ether aroma as well as Ether itself.

• Dipole Moment 

Since the C-O-C bond angle is not exactly 180 degrees, the dipole moments of the two C-O bonds do not cancel each other out, and the net dipole moment of ethers is low.

• Boiling Point

While ether molecules have a boiling point comparable to alkanes, their boiling point is much lower than that of alcohol molecules with the same molecular mass. Because alcohol has hydrogen bonds, this is the case.

• Solubility

It is analogous to the solubility of ethers in water compared to alcohols of the same molecular mass. Hydrogen atoms dissolve in water. Ether’s hydrogen bonds with water molecules have the same structure as those generated by alcohol’s hydrogen bonds with water molecules. When the amount of carbon atoms in a compound increases, solubility likewise decreases. Due to a rise in hydrocarbon content, there is a reduction in H-bond formation, which results in the observed alterations.

• Polarity

It is less polar than ester, alcohol, and amine due to an oxygen atom, which is prevented from engaging in hydrogen bonding by the presence of bulky alkyl groups on either side of the oxygen atom. On the other hand, Ethylene is more polar than alkenes in terms of charge.

• Hybridisation

A bond angle of 109.50 degrees is needed for oxygen sp3 hybridisation in ethers.

Conclusion :

Dehydration of alcohols or the Williamson synthesis is two methods for synthesising ethers using alkyl halides and sodium alkoxides. It should be noted that both reactions are substitution reactions that are controlled by the SN2 system. Aside from being exceedingly stable in the presence of acids, bases, oxidising and reducing agents, and active metals, ethers are also non-reactive with these substances.