Ether is a pleasant-smelling colourless volatile liquid that is highly inflammable. It is in use as an anaesthetic, as a solvent or as an intermediary in industrial processes. It is commonly known as Ethyl ether or diethyl ether. It is an organic compound that belongs to the large group of compounds called ethers. The molecular structure is made up of two ethyl groups joined through an oxygen atom as in C2H5OC2H5. In this article, we shall learn about the preparation of ether. Ethers are classified into two classes: symmetrical ethers and symmetrical ethers. We shall also learn about Ether synthesis from an alkene.
There are two methods for the preparation of ether.
In this method, in the presence of protic acids, alcohols dehydrate to produce alkenes and ethers in various conditions. In the presence of sulphuric acid, dehydration of ethanol at 443 K gives ethane, and we get ethoxyethane at 413 K. It is the best method to prepare ether with necessary alcohol. This method is a nucleophilic substitution reaction. The alcohol in use in the reactions plays two roles - one acts as a substrate and the other act as a nucleophile.
It can follow two mechanism - SN1 or SN2. The choice depends if the protonated alcohol loses water before or along with the attack of a second alcohol molecule. Usually, the second and the third alcohol follow the S1 mechanism while the primary alcohols follow the S2 mechanism.
It is the most versatile method for making ethers. The process is named after English chemist Alexander Williamson who invented this method in the 19th century. This method uses an alkoxide ion to attack an alkyl halide, substituting the alkoxy (-O-R) group for the halide. The alkyl halide must be unobstructed (primary), or else the elimination will compete with the desired substitution.
Williamson Ether Synthesis takes place as an SN2 reaction with primary alkyl halide with alkoxide ion. It is essential to note that the structure of ethers was proved due to this chemical reaction. SN2 way is necessary for the synthesis in this reaction as it is useful only when the alkyl halide is primary or secondary.
The ethers obtained through this process have more carbons atoms than either of the basic materials and thus, they are more complex structures. So, this process is an important process in organic chemistry. The basic working of this reaction is as follows:
Diethyl Ether and Sodium Chloride are formed when Sodium Ethoxide and Chloroethane react with each other. The chemical notation for the reaction is as under:
Na + C2H5O⁻ + C2H5CL = C2H5OC2H5 + Na + Cl⁻ … Ref Fig.1
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The Mechanism of this Reaction is Summed up as Under:
The nucleophile attacks the alkyl halide to form an ether passively
This response is a single step action; it is both cleavage and bond formation.
When halides are sterically stopped, alkoxides act as a base, and protons in β - place are accessed.
The products are a result of a response to elimination.
The Favourable Conditions Required for this Method are:
Using original mixture or in situ formation of alkoxide ions is done as they are very reactive.
Potassium hydroxide or carbonated base is in use for lab preparation. The phase transfer catalyst is in use in industrial synthesis.
Acetonitrile and N-dimethylformamide are in use as the solvents.
It takes approximately 1 to 8 hours to complete the reaction. It needs a temperature of around 50 to 100 degrees Celsius.
The results are between 50-95 per cent in labs because of side reactions.
One can get better results, quantity-wise, in the industrial procedure.
There is no requirement for a catalyst in lab synthesis. If the alkalising agent is non-reactive, iodide salt can add to increase the rate. It gives a reactive iodide after a halide exchange with the chloride.
Silver oxide salts are in use in rare cases – it makes the reaction simpler.
Q1. What is the Nomenclature of Ethers?
Ether can be named in two ways. One way is to identify the alkyl groups on either side of the oxygen atom in alphabetical order, followed by ‘ether’. For example, ethyl methyl ether is the ether that has an ethyl group and methyl group on either side of the oxygen atom. If two alkyl groups are the same, the ether is called di (alkyl) ether. Diethyl ether is an example of the ether with the ethyl group on each side of the oxygen atom. The second way of naming is the IUPAC method. In this form, (short alkyl chain) (oxy) (long alkyl chain). The IUPAC name for ethyl methyl ether will be methoxy ethane.
Q2. What are the Uses of Ether?
Ether has been in use for long. It is in use for illnesses such as scurvy or pulmonary inflammation. In modern times, it is in use as a surgical anaesthetic. Ether is pleasant –smelling colourless highly volatile and flammable liquid. It can be vaporised into a gas that can reduce pain in patients but keep them conscious during surgeries. Due to its anaesthetic and sedative qualities, ether is also in use as an illicit drug to induce sedation and euphoria. Ether is also in use as a solvent to create perfumes with a fragrant smell, refine other waxes or fats, and create other medicinal drugs. Williamson Ether Synthesis method prepares ethers in labs and industries.