Ethanol Factory: Synthesis Methods
Make ethanol from ethene or halides
What this lesson covers
Why it matters
Ethanol fuels cars and sanitizes hands, but how do we build its molecule from scratch? You have two distinct chemical routes to choose from.
The idea in plain words
Analyze the addition (hydration) reaction: notice how water adds across the double bond to form ethanol.
Predict first
Which method is the primary industrial route for making ethanol from petroleum products?
Industry prefers the hydration of ethene because it is continuous, fast, and uses abundant fossil fuel feedstocks.
- Hydration of ethene with steam — correct
- Hydrolysis of chloroethane with KOH
- Fermentation of glucose
What you do
Run both reactions. Observe the conditions required for the ethene route versus the alkyl halide route.
Check yourself
What specific catalyst is required for the hydration of ethene?
The reaction C₂H₄ + H₂O → C₂H₅OH requires phosphoric acid as a catalyst and heat.
In the reaction C₂H₅Cl + KOH → C₂H₅OH + KCl, what is the role of KOH?
This is a nucleophilic substitution (hydrolysis) where dilute KOH replaces Cl with OH.
Why is the ethene hydration method preferred over fermentation for industrial ethanol?
Hydration of ethene is faster, continuous, and yields pure ethanol, unlike the batch process of fermentation.
- Phosphoric acid — correct
- Sulphuric acid
- No catalyst needed
- Potassium hydroxide
- It provides hydroxide ions (OH⁻) that substitute the chlorine atom to form ethanol — correct
- It acts as an oxidizing agent
- It provides the carbon atoms
- It is a continuous process with higher purity — correct
- It uses renewable sugar cane
- It requires no energy input