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- Title
Reduktion von 1,2-bis[( Z)-(2-nitrophenyl)- NNO-azoxy]benzol: Synthese von Cyclotrisazobenzol ( = (5 E,6a Z,11 E,12a Z,17 E,18a Z)-5,6,11,12,17,18-Hexaazatribenzo[ aei][1,3,5,7,9,11]cyclododeca-hexaen).
- Authors
Hilpert, Hans; Hoesch, Lienhard; Dreiding, André S.
- Abstract
Reduction of 1,2-Bis[( Z)-(2-nitrophenyl)- NNO-azoxy]benzene1: Synthesis of Cyclotrisazobenzene ( = (5 E,6a Z,11 E,12a Z,17 E,18a Z)-5,6,11,12,17,18-Hexaazatribenzo[ aei][1,3,5,7,9,11]cyclododeca-hexaene) Na2S reduction of 1,2-bis[( Z)-(2-nitrophenyl)- NNO-azoxy]benzene ( 2) yielded 3 deoxygenated products: the (known) red 2,2′-(( E, E)-1,2-phenylenbisazo)dianiline ( 3, 23%), the orange 2-[2-(( E)-2-aminophenylazo)phenyl]-2 H-benzotriazol ( 4, 55%) and the colorless 2,2′-(1,2-phenylene)di-2 H-benzotriazol ( 5, 13%). The constitutions of 3- 5 and of 6, the N-acetyl derivative of 4, were deduced from their 1H-NMR spectra (chemical shifts, couplings, and symmetry properties), and the configurations of 3, 4, and 6 at their N,N-double bonds are assumed to be the same as in 2. Oxidation of 3 with 2 mol-equiv. of Pb(OAc)4 afforded 5 (47%) and a novel, highly symmetrical macrocycle, called cyclotrisazobenzene ( 7, 24%). The constitution of 7 as a tribenzo-hexaaza[12]annulene and its ( E)-configuration at the N,N-bonds was confirmed by X-ray analysis. The molecular symmetry expressed by the 1H-, 13C- and 15N-NMR spectra of 7 reveals a rapid torsional motion around the six N,C bonds. This implies that the N,N-double bonds in the cyclic 12π-electron system (or 24π-electron system if the benzene rings are included) of 7 are highly localized.
- Publication
Helvetica Chimica Acta, 1985, Vol 68, Issue 2, p325
- ISSN
0018-019X
- Publication type
Article
- DOI
10.1002/hlca.19850680206