10199-89-0Relevant articles and documents
Kinetic and equilibrium studies of the reactions of 4-nitrobenzo-furazan and some derivatives with sulfite ions in water. Evidence for the Boulton-Katritzky rearrangement in a σ-adduct
Crampton, Michael R.,Pearce, Lyndsey M.,Rabbitt, Lynsey C.
, p. 257 - 261 (2002)
The reactions with sulfite ions in water of 4-nitrobenzofurazan, 1, 4-nitrobenzofuroxan, 2, and three 4-nitro-7-substituted benzofurazans have been examined by 1H NMR spectroscopy and stopped-flow spectrophotometry. For each substrate the initial reaction occurs at the 5-position to give σ-adducts which have considerably higher thermodynamic stability than the corresponding adduct of 1,3,5-trinitrobenzene. In the cases of 1 and 2 isomerisation of the 5-adducts occurs slowly to yield adducts carrying sulfite at the 7-position. 1H NMR measurements on 2 labelled with 15N provide evidence that here the rearrangement involves an intramolecular Boulton-Katritzky mechanism.
Reactions of substituted phenylnitromethane carbanions with aromatic nitro compounds in methanol: Carbanion reactivity, kinetic, and equilibrium studies
Asghar, Basim H.
, p. 477 - 488 (2014/07/08)
The feasibility of carrying out nucleophilic addition from electron-deficient heteroaromatics has been addressed through a detailed investigation of the interaction of a two 7-substituted-nitrobenzofurazan (R = OMe 2a; R = Cl 2b) with a series of substituted-nitroaryl anions (X = 4-NO 2 1a; X = 3-NO2 1b; X = 4-CN 1c; X = 4-Br 1d), all reactions first lead to the quantitative formation of the σ-adducts 3a-d and 4a-d arising from covalent addition of the nucleophile to the C-5 carbon. The rate and equilibrium constants for the formation of σ-adducts 3a-d and 4a-d (k5, K5) together with the rate constants for their decomposition (k-5) have been determined in methanol at 25C, allowing a determination of intrinsic rate constants, k0 = 0.03, the lower k0 value reflects the very strong salvation by methanol of the negative charge on the nitro group. The discovery of a linear correlation between the E and pKaMeOH parameters allows a calibration of the electrophilicity power of 2a and 2b, E = -11.67 and -10.29, respectively. Applying the general approach to nucleophilicity/electrophilicity recently developed by Mayr et al. through the relationship log k = s(E + N), a successful ranking of our nitroaryl anions 1a-d on the general nucleophilicity scale (N) has been carried out. The N values of 1a-d are found to cover a range from 15.78 to 16.69. The results are compared with previously reported data in water and DMSO.
Agent and method for dyeing keratin fibers
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, (2008/06/13)
The present invention relates to a fiber-dyeing agent (A) prepared by mixing two components (A1) and (A2), said agent being characterized in that component (A1) contains at least one compound of formula (I) 1wherein X denotes a halogen atom, a methoxy group or an ethoxy group; Y denotes an oxygen atom, a sulfur atom or a selenium atom; R1 and R2 are equal or different and independently of each other denote hydrogen, a halogen atom, a (C1-C4)-alkyl group, a halogen-substituted (C1-C4)-alkyl group, a (C1-C4)-alkoxy group, a nitro group, an acetamido group or an NRaRb group, wherein the Ra and Rb groups are equal or different and independently of each other denote hydrogen, a (C1-C4)-alkyl group, an optionally substituted aromatic carbon ring or a (C1-C4)-alkanecarbonyl group, or Ra and Rb together with the nitrogen atom form a heterocyclic (C3-C6) group, and component (A2) contains at least one compound from the group consisting of amines, aminonitrobenzenes and phenols; to a method for dyeing hair by use of said agent, and to a multicomponent kit.
