Carbon-hydrogen bonds pyridazine

Molecular modeling of the reaction predicts attack of the CN" ion on the re face of the iV-allyl benzaldimine carbon to provide an (5)-adduct. The aromatic ring of the imine and the quinuclidine hydrogen bond stabilizes the iminium above the pyridazine, blocking the rear face of the imine bond. Nucleophilic attack by CN is... 

The association constant of pyridazine with ethanol was found to be 4.9 (from electronic absorption spectra) and 6.8 (infrared absorption spectra), and the corresponding values for the strength of the hydrogen bond are 4.2 and 4.6 kcal. The hydrogen-bonded form of P3n-idazine was considered to comprise one alcohol at one azine-nitrogen at small mole ratios of alcohol to azine and to involve the second nitrogen at high mole ratios (an additional shift in the electronic spectrum. The association constants (3.1-3.8) of pyridine, quinoline, and isoquinoline with methanol in carbon tetrachloride have been determined by infrared spectroscopy. 

In addition to hydrogen halides, water is the most studied HBD in the gas phase. The structures of the complexes with water, dinitrogen, carbon monoxide, ozone, benzene, ethane, formaldehyde, formamide, 1,4-dioxane, ethylene oxide, tetrahydropyran, difluo-romethane, pyrazine, pyrimidine, pyridazine, benzonitrile, quinuclidine, ammonia, methy-lamine, trimethylamine and so on can be found in the Mogadoc database [29]. In the water-morpholine complex [30], water is hydrogen bonded to the nitrogen and not to the oxygen, as predicted by the higher HB basicity of amines than that of ethers. 

Heterocyclic aromatic compounds contain C and H atoms other than carbon and hydrogen (Fig. 6). For the monocyclic molecules Hiickel s rule is applicable. For example both pyridine and pyrrole contain six ti electrons. Unlike the former the lone pair of the latter is delocalized. Armit and Robinson have shown a connection between the electronic sextet and the heteroaromaticity. Due to the electronegativity difference between carbon and nitrogen the bonds in pyridine are not of equal length and the delocalization is not perfect. Five membered heteroaromatics with oxygen and sulfur are furan and thiophene respectively. Pyrazole/imidazole, triazoles and tetrazoles are five membered heteroaromatics with two, three and four nitrogen atoms respectively. Three important aromatic six membered heterocyclic molecules are pyrimidine, pyrazine and pyridazine. Benzofused... 

W-Functionalization. Pyridazine can be functionalized at the nitrogen position to form N-0, N-N, and N-C bonds. The resulting products enhance the reactivity at the Cs-position and provide a handle toward the formation of more complex heterocycles. For instance, pyridazine dissolved in an aqueous mixture of hydroxyl amine sulfonic acid (HOS A), potassium iodide, and potassium hydrogen carbonate affords the corresponding aminated pyridazine (eq 2). ... 

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