Hydrogen Bromide → 5-Bromophthalide

HRID 978649Notes

Reaction equation

HRID 978649 reaction equation
N[C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[C:7](=[O:8])[O:6][CH2:5]2.N([O-])=O.[Na+].N(O)=O.[BrH:19]>O>[Br:19][C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[C:7](=[O:8])[O:6][CH2:5]2

Participants

6

Reactant 4

HCID 260Hydrogen Bromide2×HCID 24529Nitrous AcidHCID 7206695-AminophthalideHCID 23668193Sodium Nitrite

Product 1

HCID 6031445-Bromophthalide

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

A mixture of 16.8 gm 5-aminophthalide in 34 ml 48% aqueous hydrobromic acid was cooled to 0° in an ice bath and a solution of 7.8 gm sodium nitrite in 15 ml water was added at less than 5°, using internal ice cooling as necessary. The nitrosation mixture was stirred for an additional 30 minutes at about 0° with an excess of nitrous acid (positive to starch-iodide test paper). After 30 minutes, the diazonium salt was added portion wise over about 35 minutes to a mixture of 28.2 gm freshly prepared cuprous bromide and 18 ml 48% aqueous hydrobromic acid at room temperature (the bulk of the diazonium salt was maintained at about 0°). The temperature of the reaction mixture rose to about 38° and considerable frothing occurred. The mixture was stirred for an hour, then the product was filtered off and washed neutral with water. After recrystallization from 100 ml isopropanol the product weighed 15.7 gm and melted at 153°-157°.

Workup

  1. temperaturewas cooled to 0° in an ice bath
  2. temperaturewas maintained at about 0°)
  3. customrose to about 38°
  4. filtrationthe product was filtered off
  5. washwashed neutral with water
  6. customAfter recrystallization from 100 ml isopropanol the product

Sources & evidence

ORD record
ord-0a2815c3a44741ca972c7c01babf3983
Source dataset
uspto-grants-1987_05
Patent number
US04665181

Reaction notes

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