- THE FIRST SUCCESSFUL DIRECT AZOCOUPLING OF NITROAROMATIC ANION-RADICAL
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o-Dinitrobenzene dianion reacts with p-N,N-dimethylaminobenzenediazonium cation, forming 2-nitro-4'-N,N-dimethylaminoazobenzene. o-Dinitrobenzene anion-radical, interacting with benzenediazonium cations that contain N,N'-dimethylamino or nitro group in para-position, yields 3-nitro-4-hydroxy-4'-N,N-dimethylaminoazobenzene and 3,4'-dinitro-4-hydroxyazobenzene, respectively.The above compounds are formed in media promoting the stability of ion pairs between o-dinitrobenzene dianions or anions-radicals and potassium cations.With the dissociation of ion pairs, only the electron-transfer reaction products are observed.
- Todres, Z. V.,Hovsepyan, G. TS.,Ionina, YE. A.
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p. 5199 - 5204
(2007/10/02)
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- A Simple Route for the Synthesis of Chlorosubstituted Arylazobenzenes, Arylazonaphtalenes, and Arylazopyrazoles
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The reaction of arylazophenoles and arylazohydroxypyrazoles (or their tautomer hydrazones) 10, 11, and 15 with POCl3 in dimethylformamide yields chlorosubstituted arylazobenzenes or arylazopyrazoles 12, 13 and 16, resp., in moderate to high yields.The substitution of the OH-group by the Cl-moiety is favoured by acceptor substituents in the aryl fragments ortho- and/or para-linked to the azo group.In case that arylazocompounds derived from resorcinol are used the substitution reaction runs in a stepwise manner giving raise to the formation of o-hydroxy-p-chlorosubstit uted azo compounds 18 primarily and then of dichlorosubstituted azo compounds 19.
- Guenther, R.,Jaehne, E.,Hartmann, H.,Schulze, M.
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p. 945 - 954
(2007/10/02)
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