Ethers

Ethers are organic compounds that are generally composed of two alkyl or aryl groups bonded by an ether group. “Aether” , the Latin word which means ‘to ignite,’ is the root of the word Ether. The main property of ether is that it is a flammable substance at room temperature or under high pressure. Ether is a compound with the general formula R-O-R, R-O-R’, R-O-Ar or Ar-O-Ar where R is for an alkyl group and Ar is for an aryl group.

Ethers, when we examine their structure, have bent C–O–C links.

Some of the Examples of Ether

– Dimethyl Ether- CH3–O–CH3 

– Diethyl ether- CH3CH2–O–CH2CH3

– Tetrahydrofuran – O(CH2)4

– Dioxane-  O(C2H4)2O

Ethers are a class of organic composites that contain an ether group. An ether group is an oxygen atom connected to two alkyl or aryl groups. They follow the general formula R-O-R’. The C-O-C relation is characterized by bond angles of104.5 degrees, with the C-O distances being about 140 pm. The oxygen of the ether is more electronegative than the imitations. Therefore, the alpha hydrogens are more acidic than in regular hydrocarbon chains.

Ethers  R-O-R ,The general structure of an ether 

An ether is characterized by an oxygen bonded to two alkyl or aryl groups, represented then by R and R’. The substituents can be, but don’t need to be, the same.

There are two ways to name ethers.

Physical Properties of Ether

• Dipolarity- Net dipole moments are found in ether molecules. This is due to the polarity of C-O bonds.
• Boiling point- Ethers have a similar boiling point to alkanes. In contrast, it is considerably lower than that of alcohols with similar molecular masses. In spite of the C-O bond’s polarity, this occurs.
• Miscibility- Ethers are miscible with water in the same way that alcohols are. This is because oxygen atoms of ether can form hydrogen bonds with water molecules just like oxygen atoms of alcohols.

Classification of ether

Depending on the substituent attached to the oxygen atom, ethers can be divided into two broad categories: 

• Symmetrical ethers  
• Asymmetrical ethers.

In symmetric ethers, the oxygen atom is attached to two identical groups

Example: CH3 – CH2 – O – CH2 – CH3  (Diethyl ether)

In asymmetrical ethers, two different groups attach to the oxygen atom.

Example: CH3 – O – CH2 – CH3 (Ethyl methyl ether)

As with alcohols, ethers have a similar structure. In an interesting coincidence, both alcohol and ether have structures similar to those of water molecules. This is because an alkyl group is substituted for one hydrogen atom of water molecule in an alcohol, and an alkyl or aryl group is substituted for both hydrogens of water molecule in an ether.

Nomenclature of Ether

Ethers are usually named after the two groups of alkyls attached to oxygen combined with the word “ether.”. Modern practices order the alkyl groups alphabetically (t-butyl ethyl ether), whereas older names typically list them in increasing order of size (methyl t-butyl ether). When the name consists of just one alkyl group, it implies two identical groups, such as in two ethyl in one ether bond will be named as diethyl ether.

Ethers are designated by their systemic (IUPAC) names using the root name of the more complex group because of the presence of single oxygen and the alkoxy group as a subscript. For example diethyl ether will be named as ethoxyethane, or methyl ethyl ether will be named as methoxyethane.  

Naming The Ether Using IUPAC Name

• Choose the longest carbon chain as a base chain and name it.
• Tackle the other hydrocarbon group which is ended by ‘yl’ and change it to ‘oxy’. 

Example-  Ethyl becomes an ethoxy group and  methyl becomes methoxy.

•  With a locator number, Alkoxy names are placed in front of base chain names.

Example:

1. CH3–O–CH2–CH2–CH2–CH3 (1 – Methoxybutane)
2. CH3–CH(CH3)–CH2–O–CH2–CH3 ( 1- Ethoxy – 2- methylpropane)

Preparation of Ether

1. Preparation of Ethers by Dehydration of Alcohol

Under different conditions this method produces alkenes and ethers when alcohols are dehydrated with protic acids. The dehydration of ethanol at 443K, in the presence of sulphuric acid, gives ethane, and at 413K, we get ethoxyethane. 

The mechanism can be either SN1 or SN2. A choice is made depending on whether the protonated alcohol loses water before or after the second alcohol molecule attacks it. The S1 mechanism is usually followed by second and third alcohols, while S2 usually follows the primary alcohols. 

2. Preparation of Ether by Williamson Synthesis

• Alkyl halides can be attacked by alkoxide ions, substituting the alkoxy (-OR) group for the halide. In order to achieve a desirable substitute, the alkyl halide must be unobstructed. 
• An SN2 reaction takes place in the Williamson Ether Synthesis with a primary alkyl halide and an alkoxide ion. Due to this chemical reaction, the structure of ethers was established. When the alkyl halide is either primary or secondary, SN2 way is necessary for the synthesis in this reaction.  

This process yields ethers containing more carbon atoms than the basic materials and they are therefore more complex. Here is how the reaction is expressed chemically: 

Na+ + C2H5O⁻ + C2H5Cl → C2H5OC2H5 + Na+ + Cl⁻ 

Uses of ether

• Low temperatures make dimethyl ether an effective refrigerant and solvent.
• Diethyl ether is commonly used in surgeries as an anesthetic
• In addition to petrol, ether is used as a motor fuel.
• Oils, gums, resins, and other substances commonly use diethyl ether as a solvent.
• Due to its high boiling point, phenyl ether may be used as an elemental heat transfer medium.

 Conclusion 

A short summary of ethers is that they are organic compounds with the general formula R-O-R′, and they are very useful in a variety of different applications. Early on in medical history, ethers were used as anesthesia. Today, they are commonly used as antiseptics as well. Various ether compounds, such as dimethyl ether, diethyl ether, etc., are used as solvents and a wide variety of other applications including perfumery for their pleasant smell, cooking flavors, adding color and flavor to medicines, paints, and many other uses. Thus, we can conclude that ethers are also very useful chemical compounds, like alcohols. We also know that chemicals can cause side effects, which is why they should be used sparingly. Ethers may be toxic and have severe effects on our health.