10 Questions
What is the major product of the reaction of indole with benzoyl nitrate in acetonitrile?
3-nitroindole
What is the product of the nitrosation of 2-methylindole with sodium nitrite in the presence of acetic acid?
3-oximino-2 methylindole
What is the product of the chlorination of indole with an excess of sulfuryl chloride?
2,3-dichloroindole
What is the product of the bromination of indole when the position-3 is already substituted?
2-bromoindole
What is the product of the sulfonation of indole with pyridine-sulfur trioxide complex?
indole-3-sulfonic acid
What is the product of the Vilsmeier-Haack formylation of indole?
3-formylindole
What is the effect of the presence of sodium ethoxide on the nitration of indole?
It increases the yield of 3-nitroindole
What is the product of the reaction of 3-methylindole with sodium nitrite in the presence of acetic acid?
N-nitroso-3 methylindole
What is the intermediate in the chlorination of indole with an excess of sulfuryl chloride?
3,3-dichloro-3H-indole
What is the effect of the acid sensitivity of indole on its reactions with electrophiles?
It affects the reaction conditions
Study Notes
Nitration of Indole
- Nitration of indole with benzoyl nitrate in acetonitrile or with ethyl nitrate in the presence of sodium ethoxide at low temperature yields 3-nitroindole.
- Reaction conditions affect the products of nitration of indoles with different nitrating agents.
Nitrosation of Indole
- Nitrosation of 2-methylindole with sodium nitrite in the presence of acetic acid occurs at position-3, forming 3-oximino-2-methylindole (or 3-nitroso-2-methylindole).
- Nitrosation of 3-methylindole yields N-nitroso-3-methylindole.
Halogenation of Indole
Chlorination
- Chlorination of indole with sulfuryl chloride produces 3-chloroindole.
- Excess sulfuryl chloride leads to the formation of 2,3-dichloroindole via 3,3-dichloro-3H-indole.
Bromination
- Bromination of indole occurs at position-3, forming 3-bromoindole.
- If position-3 is already substituted, bromination takes place at position-2.
Sulfonation of Indole
- Indole is sulfonated with pyridine-sulfur trioxide complex, yielding indole-3-sulfonic acid.
- If position-3 is already occupied, sulfonation occurs at position-2 via an initial reversible sulfonation at position-3.
Vilsmeier-Haack Formylation
- Indole undergoes Vilsmeier-Haack formylation with N,N-dimethylformamide (DMF) in the presence of phosphorus oxychloride, forming 3-formylindole.
This quiz covers the reactions of indoles with electrophiles, specifically nitration and nitrosation reactions, including the effects of different reaction conditions and agents.
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