Is indole a pyrrole?
Is indole a pyrrole?
Indole is an aromatic heterocyclic organic compound with formula C8H7N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indole is widely distributed in the natural environment and can be produced by a variety of bacteria.
Does chemically indole resemble pyrrole?
Like pyrrole, indole has both weakly basic and also weakly acidic properties and gives positive Ehrlich and “pine-splinter” tests. Its general reactivity is closely analogous to that of pyrrole being dominated by the presence of the reactive heterocyclic ring system.
Why does indole undergoes electrophilic substitution at 3 position?
➢ Indole is markedly less reactive than corresponding monocyclic heterocycles. ➢ The preferred site of electrophilic substitution is C-3, because the cation formed by the C-3 attack of electrophile is more stable than that of the C-2 attack.
Which is more basic pyrrole or indole?
Indole (pKa = -2) and imidazole (pKa = 7.0), see above, also have similar heterocyclic aromatic rings. Imidazole is over a million times more basic than pyrrole because the sp2 nitrogen that is part of one double bond is structurally similar to pyridine, and has a comparable basicity.
Which is more basic indole or pyrrole?
Why is pyrrole amphoteric?
Compounds that can behave as both acids and bases are said to be amphoteric. (a) Acidic Character: Pyrrole changes to the anion by losing proton which accounts for its acidic character. Pyrrole is weakly acidic compound (pKa = 17.5) due to the presence of imino hydrogen atom whereas Pyrrolyl anion is a strong base.
Why is pyrrole more basic?
The greater stability of the pyrrole is due to its ability to form a conjugated system of pi electrons. This is because the lone pair present in the nitrogen atom contributes with two C=C bonds in the five membered ring.
Why is pyrrole less basic?
Pyrrole is a much weaker base than pyridine (see above). This is because the lone pair on the N atom is already involved in the aromatic array of p electrons. Protonation results in loss of aromaticity and is therefore unfavourable.
Is pyrrole basic or acidic?
In pyrrole, the electron pair is part of the aromatic system. As a result, pyrrole is a very weak base.
Why pyrrole behaves as a weak base?
(i) Lone pair of electrons on the N atom is not readily available for protonation and hence pyrrole behaves as a weak base. (ii) Much weaker base than pyridine because lone pair of electrons involved in forming aromatic sextet.