Azinium ions

When the coupling is across a tricoordinate carbon atom involved in a delocalized 7t-electron system, the absolute value of 2/(15N-C-H) may increase to as much as 16 Hz. (le) In the review period, the signs of such coupling constants have been determined as negative for formamide, (144) pyrrole, (146, 154, 155) pyrazole, thiazole, pyridine and pyridazine (155) as well as for some azinium ions. (151) The latter afford another example of the decrease in the absolute value of the coupling constant upon protonation of the nitrogen lone pair (Table XXXIII) [79], [80]. 

MB" " Meldola s blue (V,V-dimethyl-7-amino-1,2-benzophenox-azinium ion)... 

Heterocyclic structures analogous to the intermediate complex result from azinium derivatives and amines, hydroxide or alkoxides, or Grignard reagents from quinazoline and orgahometallics, cyanide, bisulfite, etc. from various heterocycles with amide ion, metal hydrides,or lithium alkyls from A-acylazinium compounds and cyanide ion (Reissert compounds) many other examples are known. Factors favorable to nucleophilic addition rather than substitution reactions have been discussed by Albert, who has studied examples of easy covalent hydration of heterocycles. 

A special type of ammonio group is represented by 4-( 1 -pyridinium)-pyridine and other azinium analogs. Such products often result from self-quaternization of highly reactive derivatives. A -(4-Pyridyl)-and A -(3-nitro-4-pyridyl)-pyridinium chloride hydrochlorides (121) react with aniline, chloride ion, and water to give 4-substituted pyridines plus pyridine. l-(2-Quinolyl)- and l-(4-quinolyl)-pyridinium salts undergo 2- and 4-substitution, respectively, with amines, anilines, hydroxylamine, phenols, alkoxides, mercaptans, and chloride... 

Cycl[2,2,2]azinium salts7 (5) have not been reported so far. Hiickel molecular orbital (HMO)-calculations of the isoelectronic acepentylene (6) lead to two singly occupied degenerate HOMO s.8,9 Since there is no contribution in both the HOMO s and the LUMO from atom 6b this situation does not change in going from 6 to the 5-ion,10 which can be represented as an annulenone derivative of the (4n + 1) rc-type. 

As a consequence, the properties of the ions 73 and 74 should differ much more than those of the known isoconjugates 71101 and 72.102 The cycl[4,2,2]azinium salts (73) presumably will be diatropic stable compounds. 

Hydrazotc acid, HN,. ply.. = 4.72, and most of its covalent compounds (including its heavy metal salts) are explosive. It is formed (1) in 90% yield by reaction of sodium amide with nitrous oxide, (2) by reaction of hydraztntum ion with nitrous acid, (3) by oxidation of hydrazimum salts, (4) by reactio n of hydt azinium hydrate with nitrogen trichloride tin benzene solution). Hvdrazoic acid forms metal azides with the corresponding hydroxides and carbonates. It reacts with HC1 to give ammonium chlonde and nitrogen, with H2SO4 to form hydrazinium acid solfate, with benzene to form aniline, and it enters into a number of oxidation-reduction reactions. 

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