Sulfuric Acid → 3H-Indole, 2,3,3-trimethyl-

HRID 1646408Notes

Reaction equation

HRID 1646408 reaction equation
[NH2:1][C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.S(=O)(=O)(O)O.[CH:13]([C:16]([CH3:18])=O)([CH3:15])[CH3:14]>>[CH3:18][C:16]1[C:13]([CH3:15])([CH3:14])[C:7]2[C:2](=[CH:3][CH:4]=[CH:5][CH:6]=2)[N:1]=1

Participants

4

Reactant 3

HCID 1118Sulfuric AcidHCID 6115AnilineHCID 112513-Methyl-2-butanone

Product 1

HCID 154273H-Indole, 2,3,3-trimethyl-Yield 98.2%

Procedure

This diazonium salt solution was reacted, likewise continuously, with 2.55 mol of sodium sulphite/sodium bisulphite mixture per mole of aniline to form a phenylhydrazodisulphonate solution. A portion of this mixture, corresponding to 1.91 mol of aniline, was added dropwise at 80° C. to 200 ml of a 48% strength sulphuric acid (1.35 mol). After a reaction time of 2 h at 80° C., 225 ml (2.1 mol) of methyl isopropyl ketone were metered in in the course of 30 min. After a reaction time of 3 hours at 95° to 100° C., the mixture was cooled. The batch was neutralised and the organic phase was separated off and distilled. 273.8 g of 98.2% pure 2,3,3-trimethylindolenine were obtained. Yield: 88.4% of the theoretical yield, based on aniline.

Workup

  1. customAfter a reaction time of 2 h
  2. customat 80° C.
  3. customwere metered in in the course of 30 min
  4. temperatureAfter a reaction time of 3 hours at 95° to 100° C., the mixture was cooled
  5. customthe organic phase was separated off
  6. distillationdistilled

Sources & evidence

ORD record
ord-753269347d8f4875b3fed7ddd4d5c0f4
Source dataset
uspto-grants-1993_01
Patent number
US05179211

Reaction notes

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