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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.
A library of substituted pyrrole analogs can be quickly produced by using continuous flow chemistry (reaction times of around 8 min.). [10] The advantage of using this method, as opposed to the in-flask synthesis, is that this one does not require the work-up and purification of several intermediates, and could therefore lead to a higher ...
Primary amines are usually not used for enamine synthesis due to the preferential formation of the more thermodynamically stable imine species. [11] Methyl ketone self-condensation is a side-reaction which can be avoided through the addition of TiCl 4 [12] into the reaction mixture (to act as a water scavenger).
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 structure of the molecule can be described as molecule of pyrrole with sidechains substituted for hydrogen atoms at positions 2, 3 and 4 in the ring (1 being the nitrogen atom); respectively, an aminomethyl group −CH 2 −NH 2, an acetic acid (carboxymethyl) group −CH 2 −COOH, and a propionic acid (carboxyethyl) group −CH 2 −CH 2 ...
The formylation reaction is proposed to occur through a direct transfer reaction in which the amine group of GAR nucleophilically attacks N10-formyl-THF creating a tetrahedral intermediate. [10] As the α-amino group of GAR is relatively reactive, deprotonation of the nucleophile is proposed to occur by solvent.
Pyrrolidine is a base. Its basicity is typical of other dialkyl amines. [7] Relative to many secondary amines, pyrrolidine is distinctive because of its compactness, a consequence of its cyclic structure. Pyrrolidine is used as a building block in the synthesis of more complex organic compounds.
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]