The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:
The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:
Introduction
Alcohols, Phenols and Ethers are common chemical compounds that are used to manufacture several products. You will find these compounds both in the industrial sector as well as domestic households. The perfumes, medicines, and detergents that are used at your home are made of alcohol. It is also used to produce chemicals. Phenols are used in our homes as disinfectants and as an antiseptic for medical use. Ether is used primarily as a coolant in refrigerators.
As you will see, the structure of alcohols and phenols are quite similar. In both these compounds, the carbon atoms are attached to the hydroxyl group (OH). In the ether compounds, the hydrogen atom connected to alkyl or aryl groups is replaced by the oxygen atom.
In alcohol, the hydroxyl group is attached to the carbon atom of the aliphatic system. It means that the atoms are connected in straight chains or branches. For example, CH3-OH.
Alcohol structures can be classified as monohydric alcohols that comprise one hydroxyl group (OH), dihydric alcohols that comprise two hydroxyl groups, trihydric containing three hydroxyl groups, and polyhydric alcohol containing more than three hydroxyl groups. They are further divided into primary, secondary and tertiary alcohol based on whether the hydroxyl atoms are placed on the primary, secondary or the tertiary carbon atom.
1. Monohydric Alcohol Structure
Only one (OH) group is attached to the carbon atom.
For example, Ethyl alcohol, i.e., C2H5OH
CH3–CH2-OH.
2. Dihydric Alcohol Structure
It has two hydroxyl groups that are attached to carbon atoms.
For example, Ethanediol, i.e., C2H6O2.
CH2OH
I
CH2OH
3. Trihydric Alcohol Structure
It has three hydroxyl groups. For example, i.e. propanediol, i.e., C3H8O3.
CH2OH
I
CH2OH
I
CH2OH
Alcohols are further classified into primary, secondary and tertiary alcohols. You can see the structures of Benzylic alcohols below.
1. Primary Alcohol
In primary alcohols, the hydroxyl groups are attached to the primary carbon.
For example, Methanol
2. Secondary Alcohol
In secondary alcohols, two carbon atoms are attached to each other. The hydroxyl group is attached to the secondary carbon atom.
3. Tertiary Alcohol
In tertiary alcohols, three carbon atoms are attached to each other. The hydroxyl group is attached to the tertiary or the third carbon atom.
In phenols, the hydroxyl group is attached to an aromatic system. It means that phenol structures are made in the form of rings.
Just like alcohols, phenol structures can also be classified into three types known as mono, di, and trihydric phenols depending on the number of hydroxyl groups attached to the compound. Let’s have a look at the phenol structure in a bit more detail.
1. Monohydric phenols:
As the name suggests, mono stands for one and hydric stands for hydroxyl (-OH) group. Hence the phenols that contain one -OH group are called Monohydric phenols.
Example: Phenol
2. Dihydric phenols: Similar to the above logic, phenols containing two -OH groups are called dihydric phenols.
Since Phenols are the simple hydroxy derivatives of Benzene, their structure contains benzene rings, and are often termed as ortho (1,2- disubstituted), meta (1,3-disubstituted) and para (1,4-disubstituted).
Example: Benzene 1,2- diol
3. Trihydric phenols:
The phenols that contain three hydroxyl (-OH) groups in their structure are called Trihydric phenols.
Example: Trihydroxybenzene
Three hydroxyl groups are attached to the benzene ring.
If the phenol contains more than three hydroxyl groups in their structure, they would be referred to as Polyhydric phenols.
Ether compounds are divided into two kinds, the simple or symmetrical ether structure and the mixed or unsymmetrical ether structure. This classification depends on the type of alkyl or aryl groups attached to the atom. Let’s look at how the placement of alkyl or aryl groups to oxygen atom classifies them differently:
1. Simple Ether or Symmetrical ether structure: The ether structure where the alkyl or aryl group attached to either side of the oxygen atoms in the compound are the same is called symmetrical ether, also known as simple ether.
For example, CH3-O-CH3, here as you can see on either side of the oxygen atoms the same group CH3 is attached. Another example is C2H5-O-C2H5, where again you can see the same group C2H5 attached to either side of the oxygen atom. Hence, the name symmetrical ether.
2. Mixed Ether or Unsymmetrical ether structure: As the name suggests, the ether structure where the alkyl or aryl groups attached to either side of the oxygen atoms are not the same, they are referred to as unsymmetrical ether, also known as the mixed either.
Let’s say, in CH3-O-C2H5, the group on the left (CH3) of the oxygen atom is not the same as the one on the right (C2H5). Similarly, in C2H5-O-C6H5, the C2H5 on the left is not the same as C6H5, which is on the right.
Alcohols, Phenols and Ethers form a major component of organic chemistry. You should be familiar with the structures and alcohol hydroxyl groups and formulas of these compounds. Instead of learning only the formulas, it would be best to try to understand the concepts. However, understanding the concepts can be quite difficult at times. It is why you should download the MSVgo learning app where you can learn the concepts through videos or animations. It will provide you with a better explanation so that your basics are cleared. To get a clear understanding of the concepts, check out the videos on MSVgo.
