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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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Patent
13 Sep 2002
TL;DR: In this article, a temperature-sensitive metachromatic and color-memorizing microcapsule pigment exhibits a hysteresis breadth of 20-60°C in relation to a color density-temperature curve to cause a color change.
Abstract: PROBLEM TO BE SOLVED: To find out a new reaction medium and to extend the degree of freedom of selection in a thermochromic material exhibiting color-memorizing effects by selecting a specific compound as the reaction medium for a color reaction according to a transfer reaction of electrons. SOLUTION: A temperature-sensitive metachromatic and color-memorizing microcapsule pigment exhibits a hysteresis breadth (ΔH) of 20-60°C in relation to a color density-temperature curve to cause a color change. The pigment is obtained by encapsulating a temperature-sensitive metachromatic and color-memorizing composition composed of (a) an electron-donating coloring organic compound, (b) an electron-accepting compound and (c) a homogeneous compatibilized substance of diesters composed of a ≥12C saturated straight-chain dibasic acid and a monohydric alcohol having an aromatic ring in the molecule as the reaction medium for controlling the color reaction of (a) and (b) in a microcapsule. COPYRIGHT: (C)2004,JPO

9 citations

Journal ArticleDOI
31 Dec 1987
TL;DR: In this article, the color reaction between o-hydroxyhydroquinonephthalein (Qnph) and aluminum (III) was examined in the presence of various surfactants alone or in combination (cationic, anionic, nonionic and amphoteric) in weakly acidic media.
Abstract: The color reaction between o-hydroxyhydroquinonephthalein (Qnph) and aluminum (III) was examined in the presence of various surfactants alone or in combination (cationic, anionic, nonionic and amphoteric surfactants) in weakly acidic media. A simple, rapid and sensitive spectrophotometric determination of aluminum (III) (0-2.0 μg of aluminum (III) in a final volume of 10 ml, at 555 nm) was developed by using the Qnph-aluminum (III) complex in a mixed micelle system of zephiramine (tetradecyldimethylbenzylammonium chloride) as a cationic surfactant and Brij 35 (poly (oxyethylene) dodecylether) as a nonionic surfactant. This proposed method (apparent molar absorptivity of 2.1×105 l·mol-1·cm-1) showed good reproducibility, and the influence of foreign ions was reduced to 1/4-1/10 of that in the previous method with Qnph alone in weakly basic media. The method was used for the determination of aluminum (III) in pharmaceutical preparations (aspirin aluminum). Further, since aluminum may leach out of aluminum packaging of the kind widely used for instant foods, this proposed method was applied to the assay of aluminum (III) in biological specimens (calf serum and human urine), and in leaching solution used on aluminum foil. The recovery was good, and it was found that the leaching solution contained significant amounts of aluminum (III).

9 citations

Journal ArticleDOI
TL;DR: The optimal conditions - pH on extraction of organic bases, shaking time, concentration of dye, percentage extraction of the bases and the linear ranges of calibration curves are investigated for the determinations of methamphetamine, ephedrine and methylephedrine.
Abstract: A new procedure for sensitive and selective determination of stimulant drugs in urine is described. The method consists of extracting the organic base in alkaline media and performing the color reaction with tetrabromophenolphthalein ethyl ester molecule. Colored products have maximum absorption at 570nm for methamphetamine, 555nm for ephedrine and 550nm for methylephedrine, respectively. The optimal conditions - pH on extraction of organic bases, shaking time, concentration of dye, percentage extraction of the bases and the linear ranges of calibration curves are investigated for the determinations of methamphetamine, ephedrine and methylephedrine. The extracting solvent used is 1, 2-dichloroethane. This new method allows the sensitive and selective determination of methamphetamine, ephedrine and/or methylephedrine in urine.

9 citations

Journal ArticleDOI
TL;DR: In this article, the spectral behavior of two coloring matters (I and II) were investigated, which were formed in the color reaction of acetone with TNB, and an equilibrium reaction system related with I and II was proposed as shown in Chart 4.
Abstract: The spectral behaviors of two coloring matters (I and II) were investigated, which were formed in the color reaction of acetone with TNB. An equilibrium reaction system related with I and II was proposed as shown in Chart 4. We had found that the colorations of acetone with TNB in sodium hydroxide solutions were intensified by neutralizing the reaction mixtures with sodium dihydrogen phosphate. Now, the phenomenon was successfully explained by the scheme. On the other hand, another coloring matter (III) was isolated from the reaction mixture, which clarified the cause why the final absorption intensity at 480 mμ much increased when the conversion of I to II was carried out in the presence of excessive TNB. The structure of III, a tetracyclic compound, was determined as III' as shown in Chart 5. The correlations among the three coloring matters and their roles in the color reaction were discussed.

8 citations


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