Page 20 - Practical-workbook-organic-3
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4-Hydroxy-phthalazinone: Reaction Type &
Mechanism
Type of reaction: (Cyclocondensation).
1. Nucleophilic attack of nitrogen on the carbonyl group of phthalic anhydride
occurs.
nd
2. The 2 nitrogen of hydrazine moiety attacks the carbonyl group forming a
6-membered ring (cyclization).
3. Proton transfer occurs between +NH2 and OH group which is easily
eliminated as a water molecule (condensation).
4. Negative charge on oxygen is displaced forming phthalazinone (keto form).
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