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Pyridine has a conjugated system of six π electrons that are delocalized over the ring. The molecule is planar and, thus, follows the Hückel criteria for aromatic systems. In contrast to benzene, the electron density is not evenly distributed over the ring, reflecting the negative inductive effect of the nitrogen atom.
One family of Cr(VI) reagents employs the complex CrO 3 (pyridine) 2. [3] Sarett's reagent: a solution of CrO 3 (pyridine) 2 in pyridine. It was popularized for selective oxidation of primary and secondary alcohols to carbonyl compounds. Collins reagent is a solution of the same CrO 3 (pyridine) 2 but in dichloromethane. The Ratcliffe variant ...
Basic aromatic compounds get protonated and form aromatic cations (e.g. pyridinium) under acidic conditions. Typical examples of basic aromatic rings are pyridine or quinoline. Several rings contain basic as well as non-basic nitrogen atoms, e.g. imidazole and purine.
It is the conjugate acid of pyridine. Many related cations are known involving substituted pyridines, e.g. picolines, lutidines, collidines. They are prepared by treating pyridine with acids. [3] As pyridine is often used as an organic base in chemical reactions, pyridinium salts are produced in many acid-base reactions.
In the acidic extraction, the raw plant material is processed by a weak acidic solution (e.g., acetic acid in water, ethanol, or methanol). A base is then added to convert alkaloids to basic forms that are extracted with organic solvent (if the extraction was performed with alcohol, it is removed first, and the remainder is dissolved in water).
In organic chemistry, the aromatic alcohols or aryl-alcohols are a class of chemical compounds containing a hydroxyl group (−O H) bonded indirectly to an aromatic hydrocarbon group, [1] in contrast to the phenols, where the hydroxyl group is bonded directly to an aromatic carbon atom. [2] Aromatic alcohols are produced by the yeast Candida ...
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A workup step with acid is included to ensure formation of 2-aminopyridine. Reaction progress can be measured by the formation of hydrogen gas and red color from σ-adduct formation. [3] Sodium amide is a handy reagent for the Chichibabin reaction but handling it can be dangerous and caution is advised. [4] σ-adduct (Meisenheimer adduct) formation