Quinoneimine

Quinone dyes Quinoneimine Quinoneimine dye Quinone methides Quinonemonoimine Quinones... 

Polysulfide Melt. Cl Sulfur Black 1 [1326-82-5] (Cl 53185), derived from 2,4-dinitrophenol, is the most important dye in this group which also includes the indophenol-type intermediates. The latter are appHed in the stable leuco form. The derived dyes are usually confined to violet, blue, and green shades. Other members of this group are intermediates capable of forming quinoneimine (10) or phenazone stmctures (11) that produce red-brown or Bordeaux shades ... 

Several studies characterizing the reactions of alkenyl radicals with quinone dumines and quino-neimines were published in the late 1970s. Quinone dumines react with allylic radicals yielding both the reduced PPD and the alkylated product. In these experiments 2-methyl-2-pentene served as a model olefin (model for NR). Samples of the olefin and quinoneimines or quinone diimine were heated to 140°C. Isolation and analysis of products demonstrated that 40%-70% of the imine or diimine was reduced to the corresponding PPD, while 20%-50% was isolated as the alkylated product. This alkylation reaction (via an allylic radical) represents the pathway to the formation of rubber-bound antidegradant. ... 

The leuco quinoneimine dyes are unstable to isolate but the substitution of an electron-withdrawing group such as acyl,13 carbamoyl,13 carboxy,13 or arylsulfonyl 12 group at the amino nitrogen atom stabilizes the... 

Polyhydroxybenzenes or aminophenol derivatives can be considered as leuco quinones or leuco quinoneimines. They are easily oxidized and couple... 

Quinoneimines can also be used, but in this case iminolactams 9-93 are the final products because the aromatization process cannot take place [59]. A completely different mechanism is proposed when methylene active compounds such as 4-hy-... 

Anodic oxidation of JV,iV-disubstituted trifluoroethanimidamide 45 in dry and in aqueous acetonitrile gave the imidazole 46 and quinoneimine 47 as the reaction products (Scheme 24). The constant current electrolysis on a glassy carbon anode and a platinum cathode was performed in an undivided cell [74]. 

Anodic oxidation of 45 in dry acetonitrile at 60 °C and at low current density provided a quantitative yield of 46, while oxidation of 45 in aqueous acetonitrile at 0 °C provided a high yield of 47. It has been shown that quinoneimine 47 can be transformed to 46 in 93% yield, through BF3Et20 catalyzed cyclization [75]. The reaction pathways leading to the formation of 46 or 47 are summarized in Scheme 25. Two-electron oxidation of 45 leads to the cation 45a through an ECE or e-p-e mechanism. It seems that the cyclization of 45a is the ratedetermining step in the overall intramolecular cyclization of 45 to 46. The high... 

Jurva, U., Holmen, A., Grdnberg, G., Masimirembwa, C. and Weidolf, L. (2008) Electrochemical generation of electrophilic drug metabolites characterization of amodiaquine quinoneimine and cysteinyl conjugates by MS, IR, and NMR. Chemical Research in Toxicology, 21 (4), 928-935. 

Glucose (65) kits Commercial kits are based on the enzymatic process shown in equation 16, followed by a chromogenic oxidation process catalyzed by peroxidase, similar to equation 27, involving 4- aminoantipyrine (81) and a phenol or aniUne derivative, leading to a quinoneimine dye. Among the latter aromatic substrates in use are A -ethyl-Al-(2-hydroxy-3-sulfopropyl)-3, 5- dimethoxyaniline (92) , phenol , p-hydroxybenzoic acid and p-hydroxybenzenesidfonate other chromogenic reactions are peroxidase-catalyzed oxidation of iV,iV,iV, iV -tetramethyl-p-phenylenediamine (89) and D-ditoluidine (93) . d... 

The reduction of hydroperoxides may be coupled with the oxidation of phenol in the presence of 4-aminoantipyrine (81) to yield a quinoneimine dye (186), determined... 

Chloromethane, vibrational spectra, 692 /fteto-Chloroperbenzoic add (m-CPBA) diastereoselectivity, 1144 transition metal peroxides, 1090, 1091 p-Chlorophenol, quinoneimine dyes, 630 Chlorophyll, UV-visible spectrophotometry, 664... 

Dilauroyl peroxide, determination, 701 Dimesityldioxirane, 26, 1133-4 3-(Dimethylamino)benzoic acid hydrogen peroxide determination, 635 oxalate determination, 633 DimethylaniUne, quinoneimine dyes, 630... 

Methylphenol, quinoneimine dyes, 630 N -Methyl-2-phenyUndole, malondialdehyde... 

Oxidation of 5//-dibenz[6,/]azepines by Fremy s salt has been examined closely. At pH 7.5 the quinonoid dibenz[6,/]azepin-2-one is produced together with acridine-9-aldehyde (74CRV101). 3-Chloro-10,11 -dihydro-5//-dibenz[6,/]azepine yields a mixture of the quinoneimines (174 R=C1) and (175) which with sodium dithionite reduce to the corresponding chlorohydroxydihydrodibenzazepines (76JHC269). 

Calculations by the Pariser-Parr-Pople method on the quinoneimine obtained by Fremy s salt oxidation of dibenz[6,/]azepine indicate that the carbon adjacent to the carbonyl group is the most nucleophilic center. This is confirmed by nitration [Cu(N03)2-Ac0H] and bromination [NBS-(PhC0)202] studies, in which the 1-substituted derivatives are obtained. However, acylation by Vilsmeier or Friedel-Crafts reaction fails, extensive decomposition of the ring system taking place. 

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