Phthalic Anhydride → 1,4-Phthalazinedione
Reaction equation
[C:1]1(=O)[C:9]2[C:4](=[CH:5][CH:6]=[CH:7][CH:8]=2)[C:3](=[O:10])[O:2]1.O.[NH2:13][NH2:14]>>[C:3]1(=[O:10])[C:4]2[C:9](=[CH:8][CH:7]=[CH:6][CH:5]=2)[C:1](=[O:2])[N:14]=[N:13]1Participants
3
Procedure
When R7 and R8 are cyclopentylene or cyclohexylene, the dichloro intermediate is conveniently prepared from a 4,5,6,7-tetrahydro-4,7-(methano or ethano)isobenzofuran-1,3-dione. Diels and Alder, Ann., 478, 149 (1930); Ann., 490, 236 (1931). The dione compound is reacted with excess hydrazine hydrate in an exothermic reaction to produce the corresponding hexahydro-5,8-(methano or ethano)phthalazine-1,4-dione. Additional heating at 100°-170° C. for 10-30 minutes may be useful to complete the reaction. The phthalazine-1,4-dione is then reacted with excess phosphorus oxychloride heated at reflux for about 2-4 hours, cooled and the product hydrolyzed by careful addition of ice and water to produce the dichloro intermediate.
Sources & evidence
- ORD record
- ord-4d5f9cfc07da4fd6aefd8ce1b41dd8f0
- Source dataset
- uspto-grants-1985_07
- Patent number
- US04526890
Reaction notes
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