Heterocyclic compounds pyridine

Modifications of this method, such as the use of the more stable diazonium trifluoroacetates and the decomposition of benzenedia-zonium zincichloride with zinc dust, have been used as sources of aryl radicals, although not in the arylation of heterocyclic compounds. Pyridine, quinoline, and thiophene can be phenylated by treatment with benzenediazonium chloride and aluminum trichloride. ... 

The analytical data obtained, particularly by the PUMA mass spectrometer on board Vega 1 during the flyby, indicate the presence of a large number of linear and cyclic carbon compounds, such as olefins, alkynes, imines, nitriles, aldehydes and carboxylic acids, but also heterocyclic compounds (pyridines, pyrroles, purines and pyrimidines) and some benzene derivatives no amino acids, alcohols or saturated hydrocarbons are, however, present (Kissel and Krueger, 1987 Krueger and Kissel, 1987). 

Heterocyclic compounds pyridine, picolines (these substances cause nitrocellulose to denitrate), dimethylpyrone. 

Halogen located at the 2- or 4-position of the aromatic heterocyclic compound pyridine (Sec. 31.6) is fairly reactive toward nucleophilic displacement. For example ... 

Firmenich R., G., R-E. and F-H. (Firmenich Cie) (1969h) Sulphur-containing derivatives of 6-membered heterocyclic compounds (pyridines and pyrazines). Br. Patent. 1156475. 

The reaction of nucleophilic radicals, under acidic conditions, with heterocycles containing an imine unit is by far the most important and synthetically useful radical substitution of heterocyclic compounds. Pyridines, quinolines, diazines, imidazoles, benzothiazoles, and purines are amongst the systems which have been shown to react with a wide range of nucleophilic radicals, selectively at positions a and 7 to the nitrogen, with replacement of hydrogen. Acidic conditions are essential because N-protonation of the heterocycle both greatly increases its reactivity and promotes regioselectivity towards a nucleophilic radical, most of which hardly react at all with... 

Abramovitch RA (1974/5) Heterocyclic compounds - pyridine and its derivatives, vol 14. Parts 1-4, WUey, New York... 

Chemical vapor deposition (CVD) of some organic compounds was examined to control the porosity and surface function of active carbon fiber (ACF). In this system, the deposition takes place only on the pore wall of the ACF, when the precursor organic compound and deposition temperature around 700 C were selected carefully. The surface of the ACF was modified by carbon derived from heterocyclic compounds (pyridine, pyrrole, furan and thiophene) through CVD. The moderately activated ACF modified by pyridine, pyrrole and thiophene showed molecular sieving activity, that modified by furan did not. Only fiiran was decomposed at this temperature. Thermal stability is a key factor to get molecular sieving performance after CVD. Pyridine produced amorphous carbon within the pore, which appears to maintain the pyridine ring structure, creates basic sites over the surface of the ACF. Thus catalytic oxidation of SOx over ACF of high surface area was accelerated. 

Cyclic compounds that contain at least one atom other than carbon within their ring are called heterocyclic compounds, and those that possess aromatic stability are called het erocyclic aromatic compounds Some representative heterocyclic aromatic compounds are pyridine pyrrole furan and thiophene The structures and the lUPAC numbering system used m naming their derivatives are shown In their stability and chemical behav lor all these compounds resemble benzene more than they resemble alkenes... 

Nonaromatic heterocyclic compounds piperidine for example are similar m basic ity to alkylamines When nitrogen is part of an aromatic ring however its basicity decreases markedly Pyridine for example resembles arylammes m being almost 1 mil lion times less basic than piperidine... 

Although acetonitrile is one of the more stable nitriles, it undergoes typical nitrile reactions and is used to produce many types of nitrogen-containing compounds, eg, amides (15), amines (16,17) higher molecular weight mono- and dinitriles (18,19) halogenated nitriles (20) ketones (21) isocyanates (22) heterocycles, eg, pyridines (23), and imidazolines (24). It can be trimerized to. f-trimethyltriazine (25) and has been telomerized with ethylene (26) and copolymerized with a-epoxides (27). 

In general, the solubility of heterocyclic compounds in water (Table 33) is enhanced by the possibility of hydrogen bonding. Pyridine-like nitrogen atoms facilitate this (compare benzene and pyridine). In the same way, oxazole is miscible with water, and isoxazole is very soluble, more so than furan. 

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