Types of Alcohols: Overview, Questions, Preparation

Alcohols are organic compounds formed by a covalent bond of one or more hydroxyl (-OH) functional groups with the carbon atom. They get connected in an alkyl group.

Example – ethyl alcohol, butyl alcohol, methyl alcohol, etc. When there are two carbons, alcohol is called Ethanol. The general formula for alcohol is CnH2n+1OH.

Alcohols are commonly occurring organic compounds containing carbon. Most of the alcohols are colourless liquids or solid at room temperature.

Alcohols are characterized by the number of carbon atoms that bond with the atom containing the hydroxyl functional group. Alcohols fall under three types, namely- Primary, Secondary, and Tertiary alcohols-

Primary Alcohol

When the carbon atoms of Hydroxyl (OH) groups are attached to only one single alkyl group, they are called Primary alcohols. Example – 1-butanol, 2-methyl-1-propanol, etc. 

Primary alcohol doesn't give any turbidity when it reacts with the agent. Any alcohol considered as primary is unrelated to the complex classification of this alkyl chain. Therefore, only a single link between the -OH group and an alkyl group is the qualification of the alcohol falling the category of primary alcohols.

Secondary Alcohol

When the carbon atoms of Hydroxyl (OH) groups are attached to two alkyl groups, they are called Secondary alcohols. The alkyl groups that are attached may be both structurally identical or even different. 

Secondary alcohol reacts slower than tertiary alcohols. They take approximately 3 – 5 mins to show the rigidity after being reacted with a reagent. Some examples of secondary alcohols are – propane-2-ol, butan-2-ol, pen-3-ol, etc.

Tertiary Alcohol

When the carbon atoms of Hydroxyl (OH) groups are attached to three alkyl groups (same or different), they are called Tertiary alcohols. Unlike the primary and secondary alcohols. The physical properties of these alcohols are dependent on their formation structure. 

They have a high boiling point as the compound formed is weak. They also react rapidly with the reagents and form alkyl halides insoluble in nature and further form an oily layer. Examples of tertiary alcohols are – 2-methylpropan-2-ol, 2-methylbutan-2-ol, etc. 

Conclusion

The formation of alcohol occurs by replacing one of the hydrogen atoms with an alkyl group represented by R in the alcohol's organic structure. They have a low molecular weight, which makes them highly soluble in water. 

As their molecular weight increases, they become less soluble in water. Methanol and Ethanol are the most common alcohols used and formed.

Q. What type of alcohol is methanol?

A. Methanol also called methyl alcohol, wood alcohol, or wood spirit is the simplest form of alcohol. It is a colourless liquid, highly flammable with air, and completely miscible in water.

Procedure to name alcohols is –

Find the longest and most continuous sequence of hydroxyl carbon atoms

Start numbering from the end of the chain and assign the lowest possible number to the -OH group attached to the carbon

Replace the ending -e with the suffix -ol

Suffixes such as -dilo and -trilo are put if there is the presence of multiple alcohols

A. Some of the uses are –

People consume it in the form of beverages because of the presence of 30-40% of Ethanol in it

When alcohol gets heated in the air, it can be used as a transportation fuel or blended with petrol

It behaves as a solvent when dissolved in liquids

Its use as an antiseptic agent is also becoming popular with time

A. Few properties of alcohol are –

Since they are hydrogen, carbon compounds are strongly polar

They have a high boiling point and are highly soluble in water too

They absorb many radiations

They are colourless at room temperature

Some highly branched and complex alcohols are solid at room temperature

A. Ethanol, when mixed with other ingredients, is called Denatured alcohol. It kills germs and is highly flammable. The usage of this type of alcohol is mostly in hand sanitisers and cleaning products. Similar to Ethanol, even Denatured alcohol is unsafe.