Alcohol and its types.

Alcohol.

Alcohols are hydroxyl derivative of alkanes containing –OH as a functional group. These compounds are obtained from alkanes replacing hydrogen atom by a hydroxyl group.

$$\underbrace{R-H}_{Alkane}\xrightarrow{-H\,,+OH}\underbrace{R-OH}_{Alcohol}$$

$$Where\,R\,is\,an\,alkyl\,group$$

In homologous series, alcohols are represented by molecular formula CnH_2n+2.

Example of alcohol are as follows.

$$\underbrace{CH_3OH}_{Methanol}$$

$$\underbrace{C_2H_5OH}_{Ethanol}$$

$$\underbrace{C_3H_7OH}_{Propanol}$$

Classification of alcohols.

Alcohols are classified on the basis of

1. On the basis of number of –OH group:-
2. On the basis of nature of C-atoms containing –OH group.

1. On the basis of number of –OH group: On the basis , alcohols are classified as

• Monohydric alcohol.
• Dihydric alcohol.
• Trihydric alcohol
• Polyhydric alcohol.

Monohydric alcohol.

An alcohol heaving only one -OH group are called monohydric alcohol. Example.

$$\underbrace{CH_3OH}_{Methanol}$$

$$\underbrace{C_2H_5OH}_{Ethanol}$$

$$\underbrace{C_3H_7OH}_{Propanol}$$

Dihydric alcohol.

An alcohol containing two -OH group is called dihydric alcohol.

Trihydric alcohol.

An alcohol containing 3-OH group are called Trihydric alcohol.

Polyhydric alcohol.

2. On the basis of nature of C-atom containing monohydric alcohol are classified into three types.

• Primary alcohol.
• Secondary alcohol.
• tertiary alcohol.

Primary alcohol. 1^0.

If carbon containing -OH group is bonded to non or one carbon atom,it is called primary alcohol or called 1^0.

$$\underbrace{CH_3OH}_{Methanol}$$

$$\underbrace{C_2H_5OH}_{Ethanol}$$

Secondary alcohol. 2⁰

If the carbon containing -OH group is bonded with two C-atom it is called secondary alcohols.

Example

Tertiary alcohol.3⁰.

If the carbon containing -OH group is bonded to two C atoms it is called tertiary alcohol.

Important question.

Write a structural formula of secondary alcohol of C₃H₈O and give a method of its preparation using Grignard reagent.

The structural formula of secondary alcohol from the molecular formulaC₃H₈O is given below.

IUPAC name=Propan-2-ol

Reference.

Bahl, B S, Bahl, and Arun. Advanced Organic chemistry. S. Chand and company Ltd., n.d.

Sthapit, M K, R R Pradhananga, and K B Bajracharya. Foundations of chemistry. Taleju Prakashan, n.d.

Tewari, K S, S N Mehrotra, and N K Vishnoi. A textbook of organic chemistry. Vikash publishing House Pvt. ltd., n.d.

Verma, N K and S K Khanna. Compressive chemistry. 8th edition. Laxmi publications P. Ltd., 1999.