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Color reaction

About: Color reaction is a research topic. Over the lifetime, 1194 publications have been published within this topic receiving 19579 citations.


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Journal ArticleDOI
TL;DR: In this article, a new method for the spectrophotometric determination of titanium has been described, based on the fact that almost no color reaction occurs when titanium is treated with a solution of xylenol orange at pH below 2, the addition of hydrogen peroxide as a third reactant yields a new, red complex with an absorption maximum at about 535 mμ.
Abstract: Although almost no color reaction occurs when titanium is treated with a solution of xylenol orange at pH below 2, the addition of hydrogen peroxide as a third reactant yields a new, red complex with an absorption maximum at about 535 mμ. On the basis of the above reaction, a new method for the spectrophotometric determination of titanium has been described. The color stability is affected by the amount of hydrogen peroxide and xylenol orange. When, however, 0.2 to 5 ml. of a 0.3% solution of hydrogen peroxide and 3.5 to 6 ml. of a 1×10−3M solution of xylenol orange are used for less than 70 μg. of titanium and a total volume of 25 ml., the color obtained is stable for at least 30 min. Beer’s law is obeyed over the 7 to 70 μg. range of titanium. The mole ratio method and the two spectrophotometric methods have been employed to determine the composition of the complex. It has been concluded that a 1:1:1 complex is formed under the conditions investigated.

12 citations

Patent
28 Mar 1990
TL;DR: In this paper, a 2,2-bis(4-substd- sulfonyl oxyphenyl)propane is incorporated in a thermal recording material using a color reaction of a color forming dye with a color developer.
Abstract: PURPOSE:To improve a color forming density, a color forming sensitivity, a heat response, and a shelf stability and to eliminate a fogging by incorporating a specific 2,2-bispropane in a sensitizer contained in a thermal recording material using a color reaction of a color forming dye with a color developer CONSTITUTION:In a thermal recording material using a color reaction of a color forming dye with a color developer, as a sensitizer a 2,2-bis(4-substd- sulfonyl oxyphenyl)propane shown by a formula (where, two Rs independently represent phenyl or tolyl) is incorporated In this manner, a color forming density, a color forming sensitivity, and a heat response are enhanced, a fog is eliminated, and a shelf stability is also improved As a dye for the thermal recording material, normally a leuco compound is preferably used, but any dye having no possibility of adversely affecting the thermal recording material may be used On the other hand, a color developer for use is not particularly limited, but normally a phenol compound, a thiophenol compound, a thiourea compound, an organic acid, its metallic salt, and others may be used

12 citations

Journal ArticleDOI
TL;DR: In this paper, the reaction behavior of 4-(2-quinolylazo)phenol (p-QAP) is established with three noble metals, i.e. palladium(II), osmium(VIII), and gold(III), under various conditions.
Abstract: Reaction behavior of 4-(2-quinolylazo)phenol (p-QAP) is established with three noble metals, i.e. palladium(II), osmium(VIII), and gold(III), under various conditions. Palladium(II) forms a 1:1 greenish violet complex at pH 8–10 (absorption maximum at 580 nm), while osmium(VIII) forms a 1:1 violet compex at pH 8–9.5 (absorption maximum at 550 nm) with the ethanolic solution of p-QAP. Color reaction with gold(III) with ethanolic solution of p-QAP is instantaneous, but fades away with time. However, a 4:4:2 mixture of water, ethanol, and cyclohexanol stabilizes this color for 45 min. Thus a 1:1 red gold(III) complex formed at pH 8–9.5 absorbs maximum at 550 nm. The Sandell’s sensitivities (ng cm−2) of the color reactions are 2.7, 3.9, and 9.8 with palladium(II), osmium(VIII), and gold(III) respectively. Other physicochemical characteristics of the complexes are established. A number of foreign ions tested for their interferences and use of masking agents wherever necessaty it tabulated. Synthetic solutions ...

11 citations

Journal ArticleDOI
TL;DR: In this article, the Gibbs reaction was used for the determination of the optimum conditions for the photometric procedure and the optimum pH range is 8.0-10.0, obtained with a suitable buffer.
Abstract: Indophenols and indophenolates resulting from the Gibbs reaction were prepared in the pure state and their properties studied under the conditions used in the photometric reactions. The results obtained and previous investigations allowed determination of the optimum conditions for the photometric procedure. Reproducible results are obtained when 2×10−6–2×10−5 M phenol reacts with a 30–50∶1 ratio of the reagent. The optimum pH range is 8.0–10.0, obtained with a suitable buffer. It is not possible to use a glycocoll buffer (quantitative reaction with the reagent) and ammoniacal buffers cannot be used for quantitative purposes. If extraction into an organic solvent is necessary, 1-butanol should be used without previous acidification of the reaction mixture. The first step of the colour reaction is the formation of the corresponding quinoneimine. Two molecules of this reactive species react immediately with one molecule of phenol.

11 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20227
20214
20206
20198
20186
20175