- UV photolysis of 1,4-diaminobenzene in a low-temperature argon matrix to 2,5-cyclohexadiene-1,4-diimine via 4-aminoanilino radical
-
UV photolysis of 1,4-diaminobenzene isolated in a low-temperature argon matrix has been investigated by Fourier transform infrared spectroscopy with the aid of the density-functional-theory calculation. Infrared bands of an intermediate produced from 1,4-
- Akai, Nobuyuki,Kudoh, Satoshi,Nakata, Munetaka
-
-
Read Online
- Tris(2,2′-azobispyridine) complexes of copper(II): X-ray structures, reactivities, and the radical nonradical bis(ligand) analogues
-
Tris(abpy) complexes of types mer-[CuII(abpy)3][PF6]2 (mer-12+[PF6-]2) and ctc-[CuII(abpy)2(bpy)][PF6]2 (ctc-22+[PF6-]2) were successfully isolated and characterized by spectra and single-crystal X-ray structure determinations (abpy = 2,2′-azobispyridine; bpy = 2,2′-bipyridine). Reactions of mer-12+ and ctc-22+ ions with catechol, o-aminophenol, p-phenylenediamine, and diphenylamine (Ph-NH-Ph) in 2:1 molar ratio afford [CuI(abpy)2]+ (3+) and corresponding quinone derivatives. The similar reactions of [CuII(bpy)3]2+ and [CuII(phen)3]2+ with these substrates yielding [CuI(bpy)2]+ and [CuI(phen)2]+ imply that these complexes undergo reduction-induced ligand dissociation reactions (phen = 1,10-phenanthroline). The average -N=N- lengths in mer-12+[PF6-]2 and ctc-22+[PF6-]2 are 1.248(4), while that in 3+[PF6-]·2CH2Cl2 is relatively longer, 1.275(2) ?, due to dCu → πazo back bonding. In cyclic voltammetry, mer-12+ exhibits one quasi-reversible wave at -0.42 V due to CuII/CuI and abpy/abpy?- couples and two reversible waves at -0.90 and -1.28 V due to abpy/abpy?- couple, while those of ctc-22+ ion appear at -0.44, -0.86, and -1.10 V versus Fc+/Fc couple. The anodic 32+/3+ and the cathodic 3+/3 redox waves at +0.33 and -0.40 V are reversible. The electron paramagnetic resonance spectra and density functional theory (DFT) calculations authenticated the existence of abpy anion radical (abpy?-) in 3, which is defined as a hybrid state of [CuI(abpy0.5?-)(abpy0.5?-)] and [CuII(abpy?-)(abpy?-)] states. 32+ ion is a neutral abpy complex of copper(II) of type [CuII(abpy)2]2+. 3 exhibits a near-IR absorption band at 2400-3000 nm because of the intervalence ligand-to-ligand charge transfer, elucidated by time-dependent DFT calculations in CH2Cl2.
- Maity, Suvendu,Kundu, Suman,Weyhermüller, Thomas,Ghosh, Prasanta
-
-
Read Online
- Significance of uricase in oxidase-induced oxidative coloring reaction of p-phenylenediamine
-
Uricase (urate oxidase, UOD) is found to induce the oxidative polymerization of p-phenylenediamine (PPD) effectively, which is a key reaction of color development in hair-dyeing and fur-dyeing practices. The significance of uricase is described by comparison to glucose oxidase (GOD), which also produces hydrogen peroxide as an oxidizing agent of PPD. In contrast to UOD, GOD inhibits the polymerization reaction. Spectroscopic and electrochemical study has revealed that the inhibition effect of GOD is ascribed to the glucose dehydrogenase activity, in which p-benzoquinonediimine (BQI) as the two-electron oxidized form of PPD works as an efficient electron acceptor to be reduced back to PPD, resulting in the inhibition of the subsequent polymerization of BQI. On the other hand, the UOD reaction does not compete with the polymerization of BQI owing to the lack of urate dehydrogenase activity in UOD. In addition, it has been found that UOD catalyzes the oxidation of PPD in the presence of uric acid by PPD oxidase-like and PPD peroxidase-like activities. These properties of UOD are favorable toward the oxidative generation of BQI from PPD and are responsible for the prominent ability in the oxidative coloring of PPD.
- Aoki, Masahiro,Tsujino, Yoshio,Kano, Kenji,Ikeda, Tokuji
-
-
Read Online
- Photosonoelectrochemical analysis of Lawsonia inermis (henna) and artificial dye used in tattoo and dye industry
-
Photosonoelectrochemical (PSEC) analysis of Lawsonia inermis, lawsone and ?-Phenylenediamine were investigated in ethanol to understand the degradation mechanism and harmful byproducts. To simulate the operating conditions of the tattoo ink, dye solutions
- Chandrakalavathi,Sudha,Sindhuja,Harinipriya,Jeyalakshmi
-
-
- Mechanistic Insights into Substituent Effects on Reactivity of 2-(Methoxymethyl)benzene-1,4-diamine
-
In the series of benzene-1,4-diamines (p-phenylenediamines) investigated, 2-(methoxymethyl)benzene-1,4-diamine (2-methoxymethyl-p-phenylenediamine) is the most slowly oxidized, with removal of the first electron being rate determining. This electron-withd
- Bailey, Aaron D.,Zhang, Guiru,Murphy, Bryan P.
-
supporting information
p. 729 - 742
(2017/09/02)
-
- Conformational landscape, photochemistry, and infrared spectra of sulfanilamide
-
A combined matrix isolation FTIR and theoretical DFT(B3LYP)/6-311++G(3df, 3pd) study of sulfanilamide (SA) was performed. The full conformational search on the potential energy surface of the compound allowed the identification of four different minima, all of them bearing the sulfamide nitrogen atom placed in the perpendicular orientation relatively to the aromatic ring and differing from each other in the orientation of the hydrogen atoms connected to the two nitrogen atoms of the molecule. All conformers were predicted to be significantly populated in the gas phase (at 100 C, their relative populations were estimated as being 1:0.9:0.3:0.2). However, in agreement with the theoretically calculated low-energy barriers for conformational isomerization, in the low-temperature matrices, only the most stable conformer could be observed, with the remaining forms being converted into this form during matrix deposition (conformational cooling). The unimolecular photochemistry of matrix-isolated SA (in both argon and xenon) was also investigated. Upon broadband UV irradiation (λ > 215 nm), two photofragmentation pathways were observed: the prevalent pathway (A), leading to extrusion of sulfur dioxide and simultaneous formation of benzene-1,4-diamine, which then converts to 2,5-cyclohexadiene-1,4-diimine, and the minor pathway (B), conducting an γ-cleavage plus [1,3] H-atom migration from the sulfamide group to the aromatic ring, which leads to formation of iminosulfane dioxide and aniline, the latter undergoing subsequent phototransformation into cyclohexa-2,5-dien-1- imine. Finally, the crystalline polymorph of SA resulting from warming (265 K) the amorphous solid obtained from fast cooling of the vapor of the compound onto the cold (13 K) substrate of the cryostat was identified spectroscopically, and found to be the γ-crystalline phase, the one exhibiting in average longer H-bonds and an infrared spectrum resembling more that of the low temperature SA glass. Full assignment of the infrared spectra of this crystalline variety as well as of those of the β-polymorph room temperature crystalline sample and low temperature amorphous state was undertaken with help of theoretical results obtained for the crystallographically relevant dimer of SA.
- Borba, Ana,Gómez-Zavaglia, Andrea,Fausto, Rui
-
p. 704 - 717
(2013/04/10)
-
- Preparation of quinonediimines from phenylenediamines using oxygen and a metal or metal salt catalyst
-
A phenylenediamine compound can be converted, with high selectivity, into its corresponding quinonediimine by reacting the phenylenediamine with oxygen and a metal catalyst or a salt thereof.
- -
-
-
- ELECTROCHEMICAL AZIDATION OF ANILINES
-
It was found possible to effect the direct electrochemical introduction of the azido group into the aromatic nucleus of anilines and so obtain p-azidoanilines in high yields.
- Koshechko, V. G.,Shpil'nyi, S. A.,Pokhodenko, V. D.
-
p. 328 - 331
(2007/10/02)
-
- GIBBS REACTION. PART 1. REDUCTION OF BENZOQUINONE N-CHLOROIMINES TO BENZOQUINONE IMINES
-
The behaviour of benzoquinone N-chloroimines under neutral, acidic, and basic conditions has been studied.Although these compounds are stable under neutral conditions they are hydrolysed in acidic solution to the corresponding benzoquinone derivatives.In the presence of base and alcohols, they are reduced to benzoquinone imines.Kinetic investigation of the reaction suggested an ionic mechanism, in which cleavage of the Cα-H bond of the alcohol is the rate-determining step.
- Pallagi, Istvan,Dvortsak, Peter
-
p. 105 - 110
(2007/10/02)
-
- REAKTIONEN AN KOMPLEXGEBUNDENEN LIGANDED. XXXVI. SYNTHESE UND OXIDATIONSVERHALTEN VON M(CO)5-KOMPLEXEN (M = Cr, Mo, W) MIT AMIN- UND BENZOCHINONDIIMIN-LIGANDEN
-
The oxidation of yellow Cr(CO)5NH2R complexes (NH2R = aniline, m-toluidine, 3,5-xylidine, m-anisidine) with Pbac4 gives deep blue to deep purple coloured compounds, which have been identified as the respective complexes.Oxidation of the p-phenylenediamine complex yields , which is also deep blue.The binuclear blue complex 2HN=C6H4=NC6H5> is obtained by treating Cr(CO)5THF with the free ligand in THF/hexane; it dissociates rapidly in acetone to form and Cr(CO)5.Analogous Mo(CO)5 and W(CO)5 complexes could not be obtained.The oxidation of W(CO)5(m-anisidine)> by I2 yields 2.All the compounds were characterized by spectroscopic methods as well as by elemental analysis.
- Sellmann, Dieter,Mueller, Juergen
-
p. 379 - 394
(2007/10/02)
-
- Spectroscopic and Thermochemical Characteristics of the Solid-phase Complexes of p-Phenylenediamine
-
The electronic and infrared spectra of complexes of p-phenylenediamine (D) with p-benzoquinone (Q) and chloro-p-benzoquinone (Q1) heve been investigated.In the crystal the complex Q.D exists as two structures ("compact" and "loose") differing in the state of the hydrogen bond.The complex Q1.A has only the "loose" structure.The charge-transfer bands in the spectra of the crystalline substance are displaced towards lower frequencies by ca. 5000 cm-1 relative to the spectrum of the solution owing to the formation of a hydrogen bond.The oxidation-reduction reactions of the complexes Q.D and Q1.D take place with activation energies of 134 and 117 kJ mol-1, which are consistent with the activation energies for charge transfer in the corresponding complexes (136 and 115 kJ mol-1).
- Kalnin'sh, K. K.
-
p. 685 - 687
(2007/10/02)
-