HVZ Reaction Mechanism (Propanoic Acid → 2-Chloropropanoic Acid)
Step 1: Red P + Cl2 → PCl3 (in situ)
Step 2: PCl3 + CH3CH2COOH (CCC(=O)O) → CH3CH2COCl (propanoyl chloride, CCC(=O)Cl) + H3PO3
Step 3: CH3CH2COCl tautomerizes to enol: CC(=C(Cl)O) (alpha-enol intermediate)
Step 4: Cl2 attacks enol at alpha-carbon: CH3CHClCOCl (2-chloro intermediate)
Step 5: Hydrolysis of acyl chloride: CH3CHClCOCl + H2O → CH3CHClCOOH (CC(Cl)C(=O)O) + HCl
Final product SMILES: CC(Cl)C(=O)O = 2-chloropropanoic acid
Fischer Esterification Mechanism (Acetic Acid + Ethanol)
Reaction: CC(=O)O + CCO --[H2SO4]--> CCOC(=O)C + H2O
| Step | Description | Key Feature |
|---|---|---|
| 1 | H+ protonates C=O oxygen of CH3COOH | Makes carbonyl C more electrophilic |
| 2 | Ethanol O attacks protonated carbonyl C | New C–O bond forms; tetrahedral intermediate |
| 3 | Proton transfers within intermediate | Internal proton migration |
| 4 | Water loss from tetrahedral intermediate | Forms oxocarbenium ion |
| 5 | Deprotonation gives ester product | H+ regenerated (catalyst) |
Key SMILES Labels:
| Compound | SMILES |
|---|---|
| Acetic acid | CC(=O)O |
| Ethanol | CCO |
| Ethyl acetate | CCOC(=O)C |
| Propanoic acid | CCC(=O)O |
| 2-Chloropropanoic acid | CC(Cl)C(=O)O |
| Benzoic acid | OC(=O)c1ccccc1 |
| Trichloroacetic acid | OC(=O)C(Cl)(Cl)Cl |
| Formic acid | OC=O |