Sulfuric Acid → 8-nitro-4-oxo-4H-chromene-2-carboxylic acid
Reaction equation
S(=O)(=O)(O)O.[N+:6]([C:9]1[CH:23]=[CH:22][CH:21]=[CH:20][C:10]=1[O:11]/[C:12](=[CH:16]\[C:17]([OH:19])=O)/[C:13]([OH:15])=[O:14])([O-:8])=[O:7].[N+](C1C=CC=CC=1O/C(=C/C(O)=O)/C(O)=O)([O-])=O>>[N+:6]([C:9]1[C:10]2[O:11][C:12]([C:13]([OH:15])=[O:14])=[CH:16][C:17](=[O:19])[C:20]=2[CH:21]=[CH:22][CH:23]=1)([O-:8])=[O:7]Participants
Procedure
After a reaction container equipped with a stirrer, a cooling tube and a thermometer was charged with 20 parts by weight of fuming sulfuric acid, 2 parts by weight of a mixture (content: 65.7% by weight) containing 2-(2-nitrophenoxy)fumaric acid and 2-(2-nitrophenoxy)maleic acid was added. After that, the mixture was stirred and kept at an inner temperature of 25° C. for 2 hours and then at an inner temperature of 50° C. for 2 hours to obtain a reaction solution containing 8-nitro-2-carboxy-4-oxo-4H-1-benzopyran (reaction yield: 35%). After cooled to room temperature, the reaction solution was gradually added into 40 parts by weight of water and the mixture was gradually cooled to an inner temperature of 0° C. Precipitated crystals were filtered and dried to obtain 0.28 parts by weight of 8-nitro-2-carboxy-4-oxo-4H-1-benzopyran as crystals (content: 95.2% by weight, yield: 20%).
Workup
- customAfter a reaction container equipped with a stirrer, a cooling tube
- additionwas added
- customat an inner temperature of 50° C. for 2 hours to obtain a reaction solution
Sources & evidence
- ORD record
- ord-f0e070e2ec3446a5a41e6eba8eb8baa1
- Source dataset
- uspto-grants-2006_08
- Patent number
- US07094914B2
Reaction notes
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