53330-79-3Relevant articles and documents
Electrophilic Substitution in Indoles. Part 14. Azo-coupling of Indoles with p-Nitrobenzenediazonium Fluoroborate
Jackson, Anthony H.,Lynch, Patrick P.
, p. 1483 - 1488 (1987)
Indole and its 1- and 2-methyl derivatives undergo second-order azo-coupling reactions with p-nitrobenzenediazonium tetrafluoroborate to afford the corresponding indole-3-azo-(4'-nitrobenzenes).Kinetic studies with related 3-deutrioindoles showed that there is no isotope effect, thus confirming that the initial attack of the electrophile is the rate-determining step, as in the majority of electrophilic aromatic substitutions.In contrast, 3-methylindole afforded 3-methylindole-2-azo-(4'-nitrobenzene) and the reaction not only showed a small deuterium isotope effect (ca. 2) but was also affected by case catalysis by water added to the acetonitrile.The difference in behaviour of the 3-methylindole from indole and its 1- and 2-methyl derivatives could be accounted for by a mechanism involving primary attack of the diazonium salt at the 3-position followed by rearrangement; further evidence for this mechanism was provided by the straight line plot obtained in comparisons of the rates of reactions for the four indoles with acidity functions (which reflect protonation at the 3-position).
Kinetics of alkaline hydrolysis of p-substituted benzylidenemalononitriles in 50% aqueous acetonitrile: Substituent effects and quantification of the electrophilic reactivity
Dhahri, Nejeh,Taoufik, Boubaker,Goumont, Regis
, p. 484 - 489 (2014/06/09)
The rate constants of the reaction of p-X-substituted benzylidenemalononitriles 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h with hydroxide ion were measured in 50% water-50% acetonitrile at 20 C. The experimental kinetic data reveal that the points pertaining to electron donating substituted compounds (X = Me, OMe and NMe2) exhibit negative deviations from the Hammett plot. However, the Yukawa-Tsuno plot for the same rate constants resulted in a good straight line with an excellent correlation coefficient (r2 = 0.9916) and an r value of 1.15. Possible ground-state stabilization through resonance interactions has been suggested to explain the origin of the nonlinear Hammett plot. On the basis of the relationship between E and σp+, the electrophilicity parameter E of some benzylidenemalononitriles 1c and 1e, 1f, 1g, 1h has been evaluated. More importantly, the three compounds 1f (E = -7.90), 1g (E = -7.80) and 1h (E = -7.55) exhibit high electrophilicities that compare well with that of 4,6-dinitrobenzoselenadiazole (E = -7.40), a compound which has a general behaviour representative for the superelectrophilic dimension. We have shown that the second-order rate constants calculated from Mayr's approach for the reaction of 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h with hydroxide ion do not agree with the available experimental data. On the other hand, a good linear correlation between log kexp and log kcalc has been observed and discussed.
Diazo-coupling reaction on ion-exchange resin support
Das, P. J.,Khound, S.,Dutta, J.
, p. 161 - 163 (2007/10/02)
Diazonium ions have been immobilized on a cation exchange resin and brought into reaction with suitable substrate to give azo compounds as the only product.Byproducts are absent and recovery of the products is simple.These diazocoupling reactions could be carried out in organic solvents and under neutral condition.
