Azomethine dyes

Azol Azoknen Azomethine Azomethine dyes Azomethine-H Azone [59227-89-3]... 

Two kinds of pyrazolotriazole magenta dyes are used in color photographic materials. One is the I //-pyrazolo[5,1 -r]-[l,2,4]triazole skeleton, and the other is the l//-pyrazolo[ 1,5+][ 1,2,4]triazole skeleton as shown in the representative azomethine dye 1 (Figure 1) <1994J(P2)531>. 

Triplet energy transfer measurements from porphyrin and phthalocyanine sensitizers give the triplet energies of six (Z)-A4,A4-diethyl-2-(alkyl, aryl)-A1-(3-phenyl-77/-pyrazolo[5,l-r-][l,2,4]triazol-7-ylidene)benzene-l,4-diamine azomethine dyes 154 with adsorption maxima in ethanol at 546-633 nm to lie in the range of 115-88 kJmoF1 <2003PPS563> (Figure 24). 

N1)-Fused heterocycles have been found of major application as photographic materials. Azomethine dyes are used in conventional three-color (yellow, magenta, and cyan) photographic imaging <1998JAP10264541,... 

A new class of free radical photoinitiators such as 499 (Figure 33) <1998CM3555> have been developed based on pyrazolone azomethine dyes. 

All the couplers used in colour photography contain an active centre, e.g. a methylene group, that can react with the quinone diimine to produce the azomethine dye as shown in Figure 2.31. The couplers need to remain anchored in their respective layers. The preferred method for meeting this requirement is to have medium-sized hydrophobic groups attached to the molecules. These hydrophobic couplers are introduced into the appropriate layer as oil-in-water dispersions. ... 

Yellow Couplers and Dyes. All the useful yellow couplers are based on acetanilides, especially the pivaloyl and benzoyl derivatives (2.83), which react to give the azomethine dyes (2.84) absorbing at wavelengths in the region 450 80 nm. 

Hydrazines (of type 285 R =Me, Ph, orC6H4N02-m) are similarly converted by means of jS-keto-esters into l-(l,2,4-thiadiazol-5-yl)-3-alkylpyrazol-5-ones (286), and thence by p-nitrosodialkylanilines into the azomethine dyes (287), the absorption spectra of which have been recorded.176... 

The azomethine dye (102) (76BRP1451000) and the nickel chelates (103) and (104) have also been claimed to have activity in protecting image dyes from degradation by light (79BRP2022U9, 80BRP2026518). 

Copper Complexes. The preparation of copper and nickel complexes of tridentate metallizable azo and azomethine dyes is easily carried out in aqueous media with copper and nickel salts at pH 4-7 in the presence of buffering agents such as sodium acetate or amines. Sparingly water soluble precursors can be metallized in alkaline medium at up to pH 10 by using an alkali-soluble copper tetram(m)ine solution as coppering reagent, which is available by treating copper sulfate or chloride with an excess of ammonia or alkanolamines [3],... 

Chelates in which one nitrogen atom of the azo group and that of the azomethine group form part of the coordination system can also be called medially metallized azo and azomethine dyes [24], The bond joining metal atoms to the nitrogen, sometimes referred to as a secondary valence, may be represented by an arrow or dotted line. The latter is preferred here. 

Unsymmetrical 1 2 chromium complexes based on an azo and an azomethine dye ligand can be prepared directly from a mixture of a 1 1 chromium complex and equimolar quantities of an 2-aminophenol, an anthranilic acid, or an aliphatic amino acid, and of salicylicaldehyde or a substituted salicylaldehyde [22],... 

The 5-hydrazino-l,2,4-thiadiazoles (152) are stable in acid and base and readily form hydrazone derivatives on reaction with suitable carbonyl compounds. Thus, (152 R = Me, Ph, m-02NC6H4) reacts with /3-keto esters to form 3-alkyl-l-(l,2,4-thiadiazol-5-yl)pyrazolin-5-ones (161) which undergo coupling with p-nitrosodialkylanilines to form azomethine dyes (162) (65AHC(5)119>. 

EPR was stabilized by azomethine dyes [168] by rolling them at 160 °C for 5 h under pressure. Smith et al. [169] have found that these dyes function as quenchers of O2. The azomethine derivatives may be considered as a-substituted anilines... 

A-Phenylglycine was used as the electron donor in photopolymerizations initiated by azomethine dyes [176], The primary light absorber, ChAD (Figure 36 and Table 10), is based on the quinoxalin-2-one residue [177, 178]. Kinetic traces recorded for... 

A large number of 5-oxo-2-pyrazolin-3- and 4-carboxylic acids and their derivatives have been prepared. These are listed in Tables XXIII, XXXII and XXXIII. These compounds have been of considerable commercial interest because they are the basis for many azo and azomethine dyes. 

The chemistry involved in the formation of these azomethine dyes has been extensively investigated by Vittum and others.244,1538,1539a The present interpretation of the reactions involved is that the primary amino group of the developer is oxidized to give a quinonediimine cation which then reacts with the anion of the coupler to form a leuco dye. Subsequent oxidation converts the leuco dye to a colored form (LIII). This may be done by silver ion or by the oxidized form of the developer. The over-all reaction requires the reduction of four silver ions. 

Although by far the majority of 2-pyrazolin-5-ones used as color couplers have no substituent at C-4, this is not a necessary condition. 4,4 -Bis(2-pyrazolin-5-ones) can be used for this purpose since the 4-substituents can be eliminated and an azomethine dye formed. Such couplers may offer certain advantages. It is claimed that they are more stable and also they make it possible to form two azomethine dyes if the two portions of the molecule are different. Weissberger, Vittum and Porter1540,1603 have patented a number of 4,4 -arylidenebis(2-pyra-zolin-5-ones) for use as color couplers. Gluck580 has suggested 4,4 -bis-(2-pyrazolin-5-ones) linked by sulfur which he prepared. 

In many photographic processes it has been found advantageous to use a colored coupler. In these processes a 4-arylazo-2-pyrazolin-5-one is the coupler and it reacts with a developer as shown in eq. 272 (p. 138).1539 This results in the formation of an azomethine dye which counteracts the overlapping absorption of the negative image dyes present and leads to improved color reproduction. These compounds usually have a negative substituent at N-l 1058,1305 as this enhances the... 

The rapid decay of absorption of excited states on the ps time scale has been measured for pyrazolotriazole azomethine dyes. The molecular orientation dynamics of polar dye probes in t-butanol-water mixtures have been determined by ps fluorescence depolarization spectroscopy. Dyes studied in this investigation were the monocations nile blue and thionine, resorufin a monoanion, and nile red a polar but neutral molecule. A very detailed ps study of rotational diffusion of excited states of merocyanine-540 in polar solvents, has also been reported . 

Inner salts 157, obtained by N-alkylation of the isothiazole, are azomethine dye-based fluorescent nucleotides. They were used as the labels for nucleic acid (03JP2003034696, Scheme 53). 

Pyrazol-3-one 62 is also known to attack C4 of 4-aryliminopyrazol-3-one 585. Compounds such as 585 known as azomethine dyes react with pyrazol-3-one 62 and lose 4-dimethylaminoaniline to give the proposed intermediate 586. Addition of a second molecule of 62 yields the 4.4 -bis( 5-hydroxy-17/-pyrazol-4-yl)pyrazol-3-onc 587. The reaction takes place in refluxing methanol but upon heating 587 at 140 °C, loss of a pyrazole molecule and tautomerism leads to compound 588 (88JPR435) (Scheme 174). 

Full details have appeared of the quenching of 2 by transition-metal chelates,118 and a comparison of their quenching properties towards 102 and triplet carbonyl compounds has been published.117 The azomethine dyes, of general formula (55), form a class of x02 quenchers which, unusually, do not... 

The developing agents used for chromogenic development are generally members of the p-phenylenediamine class. Quinonediimines formed by oxidation of the developer react with the couplers, which are often precursors of indophenol or azomethine dyes. Although removal of the oxidation products of the developer by sulfite is not desired in chromogenic development, a little sulfite is usually still added to protect the developer from oxidation by air. As in b/w development, alkali and antifoggant materials are also present. 

Some of the keto esters, obtained from condensation reactions with pyridinecarboxylic esters as listed in Table Xl-11, have been hydrolyzed and decarboxylated," condensed with aldehydes in Aldol condensa-tions, and converted to barbiturates, azomethine dyes, aryl-hydrazones, and acylpyridines. ... 

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