2-Diazo-l-oxide

Vaughan and Phillips [16] studied the decomposition of 4-diazo-l-oxide (III) and nitro derivatives of this compound (IV, V) and of the nitro derivatives of 2-diazo-l-oxide (VI, VII, VIII). 

Nitro-4-diazophenol. See 2-Nitrobenzene-4-diazo-l-oxide under Mononitrobenzenediazo-dxide, Vol 2, p B58-R... 

Diphenyl-1,2,4-triazine-3-diazonium tetralluoroborate 2-oxide, 3677 Ethyl 4-diazo-l,2,3-triazole-5-carboxylate, 1853 l-Ethyl-l,l,3,3-tetramethyltetrazenium tetralluoroborate, 2586 Formylhydrazine, 0473... 

Diazo-l,2,3-triazole reacted with triphenyl phosphine in ether to give the ylide 248, which is so unstable it rapidly hydrolizes during filtration to triphenylphosphine oxide and triazole [83DIS(B)(43)2557]. 

Diazodinitrophenol (DDNP or Dinol) [Structure (2.11)] or 4,6-dinitrobenzene-2-diazo-l-oxide was first prepared by Griess [9] in 1858 but was developed commercially as a detonating agent 70 years later. It is prepared by the diazotization of... 

The introduction of a nitro group at the orl/jo-position to the oxygen atom in 4-diazo-1-oxide (IV) increases the stability. Great stability is also demonstrated by the 0- and p-substituted nitro derivatives of 2-diazo-l-oxide (VI and VII). On the other hand, the m-substituted compound (VIII) has a lower stability than compounds (VI) and (VII). Dinitro substituted derivatives, ortho-ortho (V) and orthopara (Ila), are distinguished by a higher stability than the mononitro derivatives of the same oxides (IV) or (VI) and (VII). 

Dinitro-2-diazopbenol. See Dinitrobenzenediazooxide or Diazodinitrophenol, Vol 2, p B 59-L.. This compd is also known as Diazol 2t6-Dinitro-4-diazopbenol. See 2,6-Dinitro-benzene-4-diazo-1-oxide, Vol 2, p B59-R... 

Trinitro-4-diazophenol. See 2,3,6-rTri-nitrobenzene-4-diazo-1-oxide, Vol 2, p B60-L... 

Djnitrobenzene-2 diazo-l oxide 4,6-Dinitr o-2-diazopbenot Diazodinitrophenol or Dinol. See Vol 2, p B59-L... 

DADN Ph see 4,6-Dinitrobenzene-2-diazo-l-, oxide 2 B59 5 D1160-D1163... 

Refs l)Beil 16,520 2)Beil 27,567 Mononitrobenzenediozooxide, C H3N303, mw 165.11, N 25.45%. The following isomers are reported by Morgan Porter(Ref 6) 2-Nitroben-zene-4-diazo-1 -oxide, -----------O... 

The thermal decompn of these nitrobenzene-diazooxides, in a vacuum, has been studied betw 50 and 120° by Vaughan Phillips(Ref 7). Under these conditions, mononitrobenzene-2-diazo-l-ox-ides appear to be less stable than the corresponding 4-diazo-1-oxides... 

Diazodinitrophenol (DDNP, Dinol) 4,6-Dinitrobenzene-2-diazo-l-oxide, or diazodinitrophenol as it is more commonly called, occupies a place of some importance in the history of chemistry, for its discovery by Griess56 led him to undertake his classic researches on the diazonium compounds and the diazo reaction. He prepared it by passing nitrous gas into an alcoholic solution of picramic acid, but it is more conveniently prepared by carrying out the diazotization in aqueous solution with sodium nitrite and hydrochloric acid. 

Nitro-4 diazo-l naphthol (called 2-Nitro-4-dia2otiaphthalene l-oxide by Hodgson Sc Smith), pale-yel ndls (from ale), mp 163°... 

On heating of 3,4,5,6-tetrachlorophenyl-2-diazo-l-oxide 409 in the presence of phenyl isocyanate nitrogen is evolved and the benzoxazolone 410 is obtained44°. 

The treatment of 3-amino-1,2,4-triazine 2-oxides 1 or 3-amino-1,2,4-benzotri-azine 1-oxides 29 with nitrous acid proceeds as a diazotization reaction, but the diazo compounds have never been isolated owing to the easy displacement of the di-azo group with nucleophiles. Thus the reaction of 3-amino-1,2,4-triazine 2-oxides 1 with sodium nitrite in hydrochloric or hydrobromic acids leads to the corresponding 3-halogen-1,2,4-tiiazine 2-oxides 119 or 3-bromo-l,2,4-benzotriazine 1-oxides 120 (77JOC546, 82JOC3886). 

Methyl-1,2,4-benzotriazm-3(4//)-one 1-oxide 122 can be obtained in good yield by the diazotization of 121 to give 3-diazo-7-methyl-l,2,4-benzotriazine 1-oxide followed by the substitution of the diazo group with water (82JHC497). 

The most important results are given in Figure 4-1. The oxygen atom lies 244 pm from the N(l) atom of the diazonio group, well within the sum of the van der Waals radii. The diazonio group deviates by 10.4° from linearity. It seems that the 0(1) N(l) interaction is attractive, as indicated by the angle of 169.6° (instead of 180°) at N(l), but the 0(1) N(2) interaction is not. The NN distance (109.9 pm) is, however, not different from normal values found in diazonium ions. The same authors demonstrated later (Wallis et al., 1993) that this result is not unique for the quino-line-8-diazonium-l-oxide salt, as it was found also for two 1-naphthalenediazonium tetrafluoroborates substituted in the 8-position with the electron donors -SCH3 and -N(CH3)2 and - perhaps unexpectedly - for 8-nitronaphthalene-l-diazo-... 

The structure of 1,2,3-benzoxadiazole (4.16) bears some resemblance to Wallis and Dunitz s structure (4.14, Fig. 4-1) for quinoline-8-diazonium-l-oxide, as the latter structure has a tendency towards forming a five-membered heteroaromatic ring. The two compounds are, however, different with respect to the involvement of an N(2) and an N(l) diazo atom. The 1,2,3-benzoxadiazole structure is consistent with the bands observed in the 9.45 to 12.37 eV range in the photoelectron spectrum,... 

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