1.2- Dinitroso

Substituted benzofurazan oxides 9 and 11 have been studied by NMR at low temperature and were observed as a mixture of tautomers, presumably interconverting via the ortho-dinitroso intermediate 10. When R = Cl, MeO, or AcO, tautomer 9 is the more stable... 

There is some debate in the literature as to the actual mechanism of the Beirut reaction. It is not clear which of the electrophilic nitrogens of BFO is the site of nucleophilic attack or if the reactive species is the dinitroso compound 10. In the case of the unsubstituted benzofurazan oxide (R = H), the product is the same regardless of which nitrogen undergoes the initial condensation step. When R 7 H, the nucleophilic addition step determines the structure of the product and, in fact, isomeric mixtures of quinoxaline-1,4-dioxides are often observed. One report suggests that N-3 of the more stable tautomer is the site of nucleophilic attack in accord with observed reaction products. However, a later study concludes that the product distribution can be best rationalized by invoking the ortho-dinitrosobenzene form 10 as the reactive intermediate. 

Electronic spectral considerations were invoked by Boyer et in favor of the i/i-o-dinitroso- structure and by Mallory and Wood against an oxaziridine formulation for the jV-oxide structure. The spectra of some nitrobenzofuroxans have been reported. 

PNDA = p-dinitroso diphenyl amine PETA-penta erythritol triacrylate DHBP-peroxy hexane values in parentheses are after aging at 100°C, 72 h. 

Aus 2,2 -Dinitro-biphenyl erhalt man mit Natriumboranat in Dimethylsulfoxid 79% d.Th. 2,2 -Dinitroso-bi-pkenyP. 

Dinitroso-benzol wird durch Tributyl- oder Triphenyl-phosphan zu Benzofurazan, 1,2-Dinitroso-naphthalin (2 Stdn. Kochen unter N2) zu Naphtho-[l,2-c]-furazan (65% d.Th. F 77-78°) und 4,5-Dinitroso-3,6-diphenyl-pyridazin zu4,7-Diphenyl- furazano-[.3,4-d]-pyridaZin) (36% d.Th. F 193-195°) reduziert4 ... 

Dinitroso-benzol (analog verhalt sich 1,2-Benzochinon-bis-oxim, S. 614) wird in 1 n athanolischer Schwefelsaure bei 0 V (vs. SCE) iiberwiegend zu 1,2-Diamino-benzol (51% d.Th.) reduziert, daneben fallt hauptsachlich 2,3-Diamino-phenazin (39% d.Th.) (s.S. 700)3 an. 

Dinitroso-piperazin laBt sich in Essigsaure (25 A/60°) zu 1,4-Diamino-piperazin (bis 95°/0 d.Th.) reduzieren1. 

Dimethylamino-methyl)-2-hydroxymethyl-aus 2 -Carboxy-2-(dimethylaminocarbonyl)-biphenyl und Lithiumalanat 165 2,2 -Dinitro- 474, 476, 695 6,6 -Dinitro-2,2 -bis-[chlorcarbonyl]- 188 2,2 -Dinitro-4,4 -bis-[diathylamino]- 695 4,4 -Dinitro-2,2 -bis-rhydroxymethyl]- 213 6,6 -Dinitro-2,2 -bis-[hydroxymethyl]- 188 2,2 -Dinitro-4,4 -diamino- 695 6,6 -Dinitro-2,2 -diformyl- 694 4,4 -Dinitro-2,2 -dimethoxycarbonyl- 213 2,2 -Dinitro-4,4 -dimethyl- 695 6,6 -Dinitro-2 -formyl-2-carboxy- 694 2,2 -Dinitroso- 476 -4-hydroxamsaure-chlorid 537 4-(a-Hydroxy-benzyl)- 542 Methoxy- 678 2-Methyl- 556 Nitro- 672, 678 4-Nitro- 687... 

Ring nitrosation with nitrous acid is normally carried out only with active substrates such as amines and phenols. However, primary aromatic amines give diazonium ions (12-47) when treated with nitrous acid, " and secondary amines tend to give N-nitroso rather than C-nitroso compounds (12-49) hence this reaction is normally limited to phenols and tertiary aromatic amines. Nevertheless secondary aromatic amines can be C-nitrosated in two ways. The N-nitroso compound first obtained can be isomerized to a C-nitroso compound (11-32), or it can be treated with another mole of nitrous acid to give an N,C-dinitroso compound. Also, a successful nitrosation of anisole has been reported, where the solvent was CF3COOH—CH2CI2. " ... 

Diels-Alder reactivity of 4-aza-6-nitrobenzofuroxan 235 has been studied via reactions with cyclopentadiene, cyclohexadiene, and 2,3-dimethylbutadiene this has led to three types of Diels-Alder adducts, namely the normal Diels-Alder adducts 234, 236, a Diels-Alder hetero-adduct 238, and the di-adducts 237, 239 arising from a minor dinitroso tautomer of compound 235 (Scheme 59) <1999CC1009, 2000JOC7391>. 

N-Nitroso compounds occur in many operations in the rubber industry. Some nitrosamines (nitrosodiphenylamine, N-N-dinitrosopentamethylenetetramine, polymerized N-nitroso 2,2,4-trimethyl-l,2-dihydroquinoline and N-methyl-N-4-dinitroso aniline) are used as organic accelerators and antioxidants in the production of rubber and often the products are found to be contaminated with such compounds [19]. 

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