Sulfuric Acid → 4-Bromo-6-chloro-2,3-dihydro-2,2-dimethylbenzofuran

HRID 726610Notes

Reaction equation

HRID 726610 reaction equation
N[C:2]1[C:10]2[O:9][C:8]([CH3:12])([CH3:11])[CH2:7][C:6]=2[C:5]([Br:13])=[CH:4][C:3]=1[Cl:14].C1(C)C=CC=CC=1.S(=O)(=O)(O)O.N([O-])=O.[Na+]>C(O)C>[Br:13][C:5]1[C:6]2[CH2:7][C:8]([CH3:11])([CH3:12])[O:9][C:10]=2[CH:2]=[C:3]([Cl:14])[CH:4]=1

Participants

6

Reactant 4

HCID 1118Sulfuric AcidHCID 1140TolueneHCID 23668193Sodium NitriteHCID 537053327-Amino-4-bromo-6-chloro-2,3-dihydro-2,2-dimethylbenzofuran

Product 1

HCID 536882944-Bromo-6-chloro-2,3-dihydro-2,2-dimethylbenzofuranYield 76.5%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Conditions

Temperature
75 °C

Procedure

A stirred solution of 5.1 grams (0.018 mole) of 7-amino-4-bromo-6-chloro-2,3-dihydro-2,2-dimethylbenzofuran and 25 mL of toluene in 100 mL of ethanol is cooled in an ice bath, and 2 mL (0.036 mole) of concentrated sulfuric acid is added slowly. Upon completion of addition, 2.0 grams (0.029 mole) of sodium nitrite is then added. The ice bath is then removed, and the reaction mixture is warmed to 75° C., where it is stirred for 30 minutes. After this time the reaction mixture is warmed to 95° C., where it stirred for one hour. The reaction mixture is then cooled and poured into 200 mL of water. The mixture is extracted with two 150 mL portions of diethyl ether. The combined extracts are dried with magnesium sulfate and filtered. The filtrate is concentrated under reduced pressure to a residue. The residue is subjected to column chromatography on silica gel. During is accomplished using petroleum ether. The product-containing fractions are combined and concentrated under reduced pressure, yielding 3.6 grams of 4-bromo-6-chloro-2,3-dihydro-2,2-dimethylbenzofuran. The NMR spectrum is consistent with the proposed structure.

Workup

  1. additionis then added
  2. customThe ice bath is then removed
  3. temperatureAfter this time the reaction mixture is warmed to 95° C.
  4. stirringwhere it stirred for one hour
  5. temperatureThe reaction mixture is then cooled
  6. additionpoured into 200 mL of water
  7. extractionThe mixture is extracted with two 150 mL portions of diethyl ether
  8. dry with materialThe combined extracts are dried with magnesium sulfate
  9. filtrationfiltered
  10. concentrationThe filtrate is concentrated under reduced pressure to a residue
  11. concentrationconcentrated under reduced pressure

Sources & evidence

ORD record
ord-e0589f77aaf842c2bb63f9c72a85d787
Source dataset
uspto-grants-1998_01
Patent number
US05710157

Reaction notes

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