Methanol and Ethanol
Properties, Industrial Preparation, and Commercial Forms.
By chemca Team • Updated Jan 2026
Methanol ($CH_3OH$) and Ethanol ($C_2H_5OH$) are the two most industrially significant members of the alcohol family. They serve as vital solvents, fuels, and chemical intermediates.
1. Methanol ($CH_3OH$)
Wood Spirit
Originally produced by the destructive distillation of wood, hence the name "Wood Spirit".
Industrial Preparation:
Catalytic hydrogenation of carbon monoxide at high temperature and pressure.
$$ CO + 2H_2 \xrightarrow{ZnO-Cr_2O_3, \text{ 573K, 200 atm}} CH_3OH $$
Toxicity: Methanol is highly poisonous. Ingestion of even small amounts can cause blindness and death. It is metabolized in the liver to Methanal (Formaldehyde) and then to Methanoic Acid, which damages the optic nerve.
Uses: Solvent for paints/varnishes, preparation of Formaldehyde (Formalin).
2. Ethanol ($C_2H_5OH$)
Grain Alcohol
Commonly obtained commercially by fermentation of sugars (molasses, grapes, starch).
Preparation (Fermentation):
$$ \underset{\text{Sucrose}}{C_{12}H_{22}O_{11}} + H_2O \xrightarrow{\text{Invertase}} \underset{\text{Glucose}}{C_6H_{12}O_6} + \underset{\text{Fructose}}{C_6H_{12}O_6} $$
$$ C_6H_{12}O_6 \xrightarrow{\text{Zymase}} 2C_2H_5OH + 2CO_2 $$
3. Commercial Forms of Alcohol
Ethanol is sold in various grades depending on its purity and additives.
| Type | Composition & Characteristics |
|---|---|
| Rectified Spirit | Approximately 95.6% Ethanol and 4.4% Water. It is an Azeotropic mixture (constant boiling mixture) obtained by fractional distillation of fermented liquor. |
| Absolute Alcohol | 100% Pure Ethanol. Prepared from Rectified Spirit by Azeotropic Distillation with Benzene (which breaks the water-ethanol azeotrope). |
| Denatured Alcohol (Methylated Spirit) |
Rectified spirit made unfit for drinking by adding poisonous substances like Methanol, Pyridine (foul smell), and Copper Sulphate (blue color). Used widely in industries and labs. |
| Power Alcohol | A mixture of 20-25% Ethanol + Petrol (Gasoline) + Benzene (as co-solvent). Used as fuel for internal combustion engines. |
Knowledge Check
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