Acid derivatives CH₃COOC₂H₅, CH₃COCl, (CH₃CO)₂O, CH₃CONH₂ hydrolysis
🧪 Question:
Arrange the following compounds in the order of increasing ease of hydrolysis:
CH₃COOC₂H₅, CH₃COCl, (CH₃CO)₂O, CH₃CONH₂
✅ Correct Order (from least to most reactive):
CH₃CONH₂ < CH₃COOC₂H₅ < (CH₃CO)₂O < CH₃COCl
🔍 What Is Hydrolysis?
Hydrolysis is a chemical reaction where water helps break a compound.
It usually happens when water attacks the carbon in a carbonyl group (C=O), and Hydrolysis of CH₃COOC₂H₅, CH₃COCl, (CH₃CO)₂O, CH₃CONH₂ takes place
This reaction becomes easier or harder depending on two factors:
- First, how reactive the carbonyl carbon is
- Second, how easily the attached group (called the leaving group) can go away
In simple terms, a better leaving group means faster hydrolysis. Similarly, a more reactive carbon speeds up the process.
🧪 Explaining Each Compound
Let’s look at the compounds one by one to understand why their reactivity differs.
- CH₃CONH₂ (Acetamide) – Very slow hydrolysis
This compound has an –NH₂ group, which is a poor leaving group.
Moreover, this group donates electrons to the carbon, making it less reactive.
As a result, hydrolysis happens very slowly. - CH₃COOC₂H₅ (Ethyl acetate) – Moderate hydrolysis
This ester contains an –OC₂H₅ group.
Although it’s a better leaving group than –NH₂, it’s still not very reactive.
Therefore, its hydrolysis is moderate in speed. - (CH₃CO)₂O (Acetic anhydride) – Faster hydrolysis
This molecule has two acyl groups, and the leaving group is –COO⁻.
Compared to esters, this is a better leaving group.
So, hydrolysis occurs more easily and quickly. - CH₃COCl (Acetyl chloride) – Fastest hydrolysis
This compound has a –Cl group, which is an excellent leaving group.
In addition, the carbonyl carbon is highly reactive.
Thus, this compound undergoes hydrolysis very easily.
📊 Summary Table
| Compound | Ease of Hydrolysis | Why? |
|---|---|---|
| CH₃CONH₂ | Least | Poor leaving group and low reactivity |
| CH₃COOC₂H₅ | Moderate | Better leaving group but not very reactive |
| (CH₃CO)₂O | More | Good leaving group and decent reactivity |
| CH₃COCl | Most | Excellent leaving group and highly reactive |
📝 In Summary
To determine the ease of hydrolysis, always look at two things:
- The quality of the leaving group
- The reactivity of the carbonyl carbon
Better leaving group + more reactive carbon = faster hydrolysis