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Pyrrole is an extremely weak base for an amine, with a conjugate acid pK a of −3.8. The most thermodynamically stable pyrrolium cation (C 4 H 6 N +) is formed by protonation at the 2 position. Substitution of pyrrole with alkyl substituents provides a more basic molecule—for example, tetramethylpyrrole has a conjugate acid pK a of +3.7.
Polypyrrole Pyrrole can be polymerised electrochemically. [1] Polypyrrole (PPy) is an organic polymer obtained by oxidative polymerization of pyrrole. It is a solid with the formula H(C 4 H 2 NH) n H. It is an intrinsically conducting polymer, used in electronics, optical, biological and medical fields. [2] [3]
The aldehyde and pyrrole are heated in this medium to afford modest yields of the meso tetrasubstituted porphyrins [RCC 4 H 2 N] 4 H 2. The reaction entails both condensation of the aldehydes with the 2,5-positions of the pyrrole but also oxidative dehydrogenation of the porphyrinogen [RCC 4 H 2 NH] 4.
Pyrrole-2-carboxylic acid is an organic compound with the formula HNC 4 H 3 CO 2 H. It is one of two monocarboxylic acids of pyrrole. It is a white solid. It arises in nature by dehydrogenation of the amino acid proline. [1] It also arises by carboxylation of pyrrole. [2] The ethyl ester of this acid is readily prepared from pyrrole. [3]
The Knorr pyrrole synthesis is a widely used chemical reaction that synthesizes substituted pyrroles (3). [ 1 ] [ 2 ] [ 3 ] The method involves the reaction of an α- amino - ketone (1) and a compound containing an electron-withdrawing group (e.g. an ester as shown) α to a carbonyl group (2) .
The Hantzsch Pyrrole Synthesis, named for Arthur Rudolf Hantzsch, is the chemical reaction of β-ketoesters (1) with ammonia (or primary amines) and α-haloketones (2) to give substituted pyrroles (3).
Examples of non-basic nitrogen-containing aromatic rings are pyrrole and indole. In the oxygen- and sulfur-containing aromatic rings, one of the electron pairs of the heteroatoms contributes to the aromatic system (similar to the non-basic nitrogen-containing rings), whereas the second lone pair extends in the plane of the ring (similar to the ...
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