1.3- Diazaazulenes

Diazaazulene (cycloheptimidazole) [275-94-5] M 130.1, m 120. Recrystd repeatedly from deaerated cyclohexane in the daik. 

In 2,6-disubstituted 1,3-diazaazulenes, such as 14a-c (Scheme 5 62BCJ1188), nucleophilic substitution occurs preferentially at C-6, rather than at C-2. Attack at C-2, if possible at all, demands harsher conditions. In 2,8-dichloro-l-azaazulenes only chlorine atoms at position 8 are susceptible to hydrolysis (61YZ1799 62YZ418 77BCJ1184), and in 2-ethoxy-l,3-diazaazulenes 17 and 18 only the substituents at C-6 are attacked (68CPB1308). The reason is that the electron densities at the seven-membered-ring positions 6 and 8 are lower than at C-2. 

Diazaazulene (cycloheptimidazole) [275-94-5] M 130.1, m 110-112 , 120 . It is reciystallised repeatedly from de-aerated cyclohexane in the dark or from petroleum ether/ C6H5 and forms yellow needles. It is soluble in H2O, EtOH and C6H6, and forms a monohydrate which loses H2O at 60 . The picrate has m 207 (dec). [Nozoe et al. JAm Chem Soc 76 3352 1954, Nukai et al. Bull Chem SocJpn 40 1967 1967, Beilstein 23 111/lV 1216.]... 

NaNg added at room temp, with stirring in small portions to a soln. of 2 g. 2-amino-5-(a-ethylenedioxy) ethyl-1,3-diazaazulene in coned. H2SO4, and stirring continued for 2 hrs. 1.4 g. 2,5-diamino-l,3-diazaazulene. F. e. s. I. Murata, Bull. Chem. Soc. Japan 54, 580 (1961). 

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