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Containing a pyridinium ion, pyridinium chloride has a pK a of approximately 5, slightly more acidic than that of typical amines.This is due to the hybridization of the nitrogen: the nitrogen is sp 2 hybridized and more electronegative than those nitrogens in ammonium cations, which are sp 3 hybridized.
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.
Pyridine and poly(4-vinyl) pyridine have been shown to form conducting molecular wires with remarkable polyenimine structure on UV irradiation, a process which accounts for at least some of the visible light absorption by aged pyridine samples. These wires have been theoretically predicted to be both highly efficient electron donors and ...
Phase behavior Triple point: 231.48 K (–41.67 °C), ? Pa Critical point: 619 K (346 °C), 5660 Pa Std enthalpy change of fusion, Δ fus H o: 8.28 kJ/mol Std entropy change
C 5 H 5 N + HCl + CrO 3 → [C 5 H 5 NH][CrO 3 Cl] In one alternative method, formation of toxic chromyl chloride (CrO 2 Cl 2) fumes during the making of the aforementioned solution were minimized by simply changing the order of addition: a cold solution of pyridine in concentrated hydrochloric acid was added to solid chromium trioxide under ...
In organic synthesis, PPTS is used as a weakly acidic catalyst, providing an organic soluble source of pyridinium (C 5 H 5 NH +) ions.For example, PPTS is used to deprotect silyl ethers or tetrahydropyranyl ethers when a substrate is unstable to stronger acid catalysts.
Imidazo[1,2-a]pyridine—an example of imidazopyridine and a core structure of zolpidem and some compounds described below.. An imidazopyridine is a nitrogen containing heterocycle that is also a class of drugs that contain this same chemical substructure.
3-methyl pyridine is biodegradable, although it degrades more slowly and volatilize more readily from water samples than either 2-methyl- or 4-methyl-pyridine., [7] [8] 3-Methylpyridine is the main precursor to niacin , one of the B vitamins .