Novel 1,1-diphenylhydrazine derivatives of benzofurazan and their dimerization

作者：Hristea Elena N; Bem Marioara; Balaban Teodor Silviu; Eichhoefer Andreas; Caproiu Miron T; Draghici Constantin; Ionita Gabriela; Spataru Tanta; Enache Cristian; Maganu Maria; Beteringhe Adrian; Hillebrand Mihaela; Constantinescu Titus; Balaban Alexandru T^*

来源：ARKIVOC, 2011, 213-236.

• Capto-dative
• push-pull
• persistent radicals
• quinonediimines
• cyclic voltammetry
• EPR
• UV-Vis
• RP-TLC
• X-ray diffractometry

In a quest for novel persistent free radicals, two products were obtained from the reaction between 1,1-diphenylhydrazine and 4-chloro-7-nitrobenzofurazan: the expected 1-(4-nitrobenzofurazan-7-yl)-2,2-diphenyl-hydrazine 3 formed via an S(N)Ar process, and the unexpected 4,7-benzofurazandione-(bis-1,1-diphenylhydrazone) 4 formed from 3 by a further ipso substitution and dehydrogenation. Oxidation of 3 with solid PbO(2) or solid KMnO(4) at room temperature affords during the first few minutes a persistent mono-nitro-hydrazyl free radical 6, which reacts with NO(2) and forms another persistent hydrazyl free radical 7 having two nitro groups. Two blue dimeric compounds, 11 and 13, were obtained by dimerisation of 6 and 7 respectively, and loss of N(2)O(4), and their structures were determined by mass spectrometry and NMR spectra. Additionally, single crystal X-ray diffraction was used to ascertain the structures of compounds 4 and 13. Other novel derivatives were prepared either by N-alkylation of 3 with methyl iodide, which afforded compound 5, or by homolytic nitration of 3 with gaseous NO(2) which yielded the 4,7-dinitrobenzofurazan derivative 8. When gaseous (15)NO(2) was used in a similar reaction, only one (15)N-nitro group was present in the product 7. Persistent free radicals were obtained from 4, 11, or 13 with KMnO(4). Cyclic voltammograms for 3 and 8 as well as electronic absorption spectra for all new compounds 3, 4, 5, 8, 11, and 13 are discussed.

• 出版日期2011
• 单位东南大学