Check sibling questions

Alcohols

When a hydrogen of an alkane is replaced by Hydroxyl (-OH)  group , we get Alcohol

  • Alkane - (Hydrogen Atom) + Hydroxyl (-OH) Atom = Alcohol 
  • For alcohol, we use the suffix ‘ol’.

Eg. Methanol , ethanol etc.

Example:

  • We know that Methane (CH 4 ) is an alkane.
  • It has 1 Carbon atom and 4 Hydrogen Atoms.
  • If we replace 1 of Hydrogen Atom with Hydroxyl (-OH) ,
  • We get CH 3 OH (Methanol).
  • This Methanol is an alcohol.

CH 4 - H + H 2 O = CH 3 OH + H 2

 

Similarly, 

  • If we replace 1 of Hydrogen Atom with Hydroxyl (-OH) in Ethane,
  • We get C 2 H 5 OH (Ethanol)

Ethanol is an alcohol.

Structure of Ethanol - Teachoo.jpg

Naming of Alcohols:

Step 1

We take Parent alkane by seeing number of carbon atoms in the longest chain.

(If 1 Carbon Atom, we use Methane, if 2 carbon atoms ,we use ethane)

Step 2

We use the suffix ‘ol’ for Alcohols, added to the parent chain name.

Example:

  CH 3 OH is called Methanol for its 1 Carbon Atom , and 1 Hydroxyl ion in the structure.

General Formula for Alkanes and Alcohols:

Alkane 

Alcohol 

C n H 2n+2

C n H 2n+1 OH

 

 

Different Alkanes and their Alcohols of Hydroxyl (-OH)

 

Number of Carbon Atoms

Alkane Name

HaloAlkane Name ( IUPAC)

General Name

1

Methane

Methanol

Methyl Alcohol

 

CH 4

CH 3 OH

 

2

Ethane

Ethanol

Ethyl Alcohol

 

C 2 H 6

C 2 H 5 OH

 

3

Propane

Propanol

Propyl Alcohol

 

C 3 H 8

C 3 H 7 OH

 

4

Butane

Butanol

Butyl Alcohol

 

C 4 H 10

C 4 H 9 OH

 

 

Note :

  • Methanol, Ethanol and Butanol all have same functional group OH
  • Hence all these have the same chemical properties.
  • The presence of a functional group such as alcohol decides the properties of the carbon compound, regardless of the length of the carbon chain .

VARIOUS ALCOHOLS HAVING SIMILAR CHEMICAL PROPERTIES - Teachoo.jpg

Maths Crash Course - Live lectures + all videos + Real time Doubt solving!

Ask a doubt (live)
Maninder Singh's photo - Co-founder, Teachoo

Made by

Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 12 years and a teacher from the past 16 years. He teaches Science, Economics, Accounting and English at Teachoo