Phenol → Benzimidazole

HRID 1414378Notes

Reaction equation

HRID 1414378 reaction equation
C(C1C=CC([C:16]2[NH:17][C:18]3[CH:24]=[C:23](N)[C:22](N)=[CH:21][C:19]=3[N:20]=2)=CC=1)(OC1C=CC=CC=1)=O.C1(S(C2C=CC=CC=2)(=O)=O)C=CC=CC=1.C1(O)C=CC=CC=1>CO>[N:17]1[C:18]2[CH:24]=[CH:23][CH:22]=[CH:21][C:19]=2[NH:20][CH:16]=1

Participants

5

Reactant 3

HCID 996PhenolHCID 31386Diphenyl sulfoneHCID 21487218Phenyl 4-(5,6-diamino-1H-benzimidazol-2-yl)benzoate

Product 1

HCID 5798BenzimidazoleYield 169.3%

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Conditions

Temperature
250 °C

Procedure

A polymerization flask equipped with nitrogen inlet and outlet tubes and mechanical stirrer was thoroughly flamed and purged with nitrogen. To this was added a mixture containing 5.0 g (14.5 mmole) of 2-[p-carbophenoxyphenyl]-5,6-diaminobenzimidazole and 25 g of diphenyl sulfone. The reaction flask was then slowly heated to 250° C and maintained at that temperature for 6 hours. During this time, phenol sublimed from the reaction mixture, and a precipitate formed. The flask was cooled to 125° C and the polymer suspension poured into 500 ml of methanol. The polymer thus precipitated was collected on a filter frit, washed several times with small portions of methanol, and dried. Reprecipitation from methane sulfonic acid into methanol, followed by successive washings with 5% ammonium hydroxide, methanol and benzene, yielded 2.9 g of benzimidazole polymer as a dark tan powder, exhibiting an inherent viscosity of 1.1 dl/g in methane sulfonic acid (0.35 g/dl).

Workup

  1. customA polymerization flask equipped with nitrogen inlet and outlet tubes and mechanical stirrer
  2. temperaturewas thoroughly flamed
  3. custompurged with nitrogen
  4. additionTo this was added a mixture
  5. temperaturemaintained at that temperature for 6 hours
  6. customa precipitate formed
  7. temperatureThe flask was cooled to 125° C
  8. customThe polymer thus precipitated
  9. customwas collected on a filter frit
  10. washwashed several times with small portions of methanol
  11. customdried
  12. customReprecipitation from methane sulfonic acid into methanol
  13. washfollowed by successive washings with 5% ammonium hydroxide, methanol and benzene

Sources & evidence

ORD record
ord-1e55e51907ea4b7ea1a4cbff742e7944
Source dataset
uspto-grants-1977_01
Patent number
US04001268

Reaction notes

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