Tetrahydrofuran → 3,7-Dibromodibenzo[b,d]thiophene

HRID 354525

Reaction equation

HRID 354525 reaction equation
[H-].[H-].[H-].[H-].[Li+].[Al+3].O1CCCC1.[Br:12][C:13]1[CH:14]=[CH:15][C:16]2[C:20]3[CH:21]=[CH:22][C:23]([Br:25])=[CH:24][C:19]=3[S:18](=O)(=O)[C:17]=2[CH:28]=1.[OH-].[Na+]>C(O)C.O>[Br:25][C:23]1[CH:22]=[CH:21][C:20]2[C:16]3[CH:15]=[CH:14][C:13]([Br:12])=[CH:28][C:17]=3[S:18][C:19]=2[CH:24]=1

Participants

7

Reactant 4

HCID 8028TetrahydrofuranHCID 14798Sodium HydroxideHCID 40718983,7-Dibromo-dibenzothiophene 5,5-dioxideHCID 21226445Aluminium lithium hydride

Product 1

HCID 8037593,7-Dibromodibenzo[b,d]thiopheneYield 31.1%

Reagents, catalysts & solvents 2

HCID 702EthanolSolventHCID 962WaterSolvent2×

Procedure

Into a 1 L 3-necked round-bottomed flask equipted with a reflux condenser, nitrogen inlet, magnetic stirring bar and a heating mantle was place 4.63 g (0.122 mol) of LiAlH4, and 600 mL of dry tetrahydrofuran (THF) (distilled from benzophenone ketyl). To this was added 18.31 g (0.0489 mol) of 3,7-dibromodibenzothiophene-5,5-dioxide. The mixture was stirred overnight at room temperature, then refluxed for 1 hour. To the cooled mixture was added 5 mL H2O, 5 mL of 15% NaOH, followed by 15 mL of water. After stirring for 2 hours at room temperature the coagulated salts were filtered and washed with THF. The combined THF extracts were condensed to give 20 g of crude material. This was taken up into 1.5 L of hot ethanol, filtered and cooled. The yellow precipitate was suction filtered and air dried to give 5.2 g of 3,7-dibromodibenzothiophene: mp 174.5-176. Molecular ions by mass spectroscopy had molecular weights of 340, 342 and 344 (due to different isotopes of Br).

Workup

  1. customInto a 1 L 3-necked round-bottomed flask equipted with a reflux condenser, nitrogen inlet, magnetic stirring bar
  2. temperaturerefluxed for 1 hour
  3. stirringAfter stirring for 2 hours at room temperature the coagulated salts
  4. filtrationwere filtered
  5. washwashed with THF
  6. customcondensed
  7. customto give 20 g of crude material
  8. filtrationfiltered
  9. temperaturecooled
  10. filtrationfiltered
  11. customair dried

Sources & evidence

ORD record
ord-ecf0c5c4780c4c7fa16e2737469dd010
Source dataset
uspto-grants-1983_03
Patent number
US04375427

Linked notes

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