Color reaction

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

Visual Detection of Selenium(IV) Using a Gallium(III) Complex Retained in a Support Filter

Abstract: A sensing membrane for selenium(IV) was fabricated by retaining tris(2,4-pentanedionato)gallium(III) (Ga(acac)3) in a glass-fiber filter. From a sample solution containing selenium(IV), gaseous hydrogen selenide was generated by reducing-vaporization and was passed through the membrane while turning the color to reddish pink. The color difference (ΔE*(ab)) before and after the reaction was measured by a reflection spectrometer. The ΔE*(ab) value increased with the increase of the selenium(IV) concentration. From the reflective spectra of reacted membranes; gallium(III) selenide (Ga2Se3) was suggested to be formed. Most of the coexisting cations showed no significant interference to the reaction, besides a large amount of arsenic(V) and antimony(III) suppressed the color change. Since adding iron(II) salt resulted in enhancing the color difference, 10 mg dm−3 of iron(II) was used as an accelerating additive. In order to investigate the influence of ligands in gallium(III) complexes, several gallium(III) compounds were retained in a filter, and examined as sensing materials. The complexes of β-diketones and dithiocarbamates had appropriate sensing activity, while inorganic salts, like gallium(III) sulfate or nitrate, showed no color change. This suggests that ligands having larger pKa values are effective for the reaction. The complexes of monobasic, dibasic and tribasic carboxylic acids showed decreased color differences in this order, and those of multidentate ligands, e.g., EDTA, exhibited no color change. These results showed excessively stable gallium(III) complexes have no reactivity to hydrogen selenide. Visual detection of 0.01 mg dm−3 selenium(IV) was achieved in the presence of 10 mg dm−3 iron(II) in a 50 cm3 sample solution.

Synthesis of 1-(4-Antipyrine)-3-(Sulfanilic Acid)-Triazene and Study on Determination of Zinc(II) in Water Samples by Spectrophotometry

Abstract: The synthesis of a new triazene reagent 1-(4-antipyrine)-3-(sulfanilic acid)-triazene (ASTA) and is proposed as a new sensitive reagent for the extractive spectrophotometric determination of Zinc(II) was established. The results showed that in the presence of micromulsion Tween-80, ASTA could reacted with Zn ( Ⅱ) to form a red stable complex of which the molar ratio of reagent︰metal was 2︰1 in Na2B4O7-NaOH medium. The maximum absorption peak of the complex was located at 520 nm with the apparent molar absorption of 1.7×105 L•mol-1•cm-1. Beers law was obeyed in the range of 0.3～5.0 μg/10 mL for Zn (Ⅱ) and the detection limit was 0.11 mg/L. Many ions did not interfere the colour reaction system due to the existence of ammonia. This method was applied to determination of Zn (Ⅱ) in water samples, and the results were in accordance with those obtained by AAS method. Recovery was in the range of 96.5～101.5 % and the RSD(n=6) was not more than 1.4%.

A possible mechanism of the sakaguchi reaction

Abstract: in Deitch’s barium hydroxide solvent. An intense red reaction is produced in sperm heads, Panetii cell and eosinophul leukocyte granules, keratohyaiin, tricholiyalin, liairrneduila and alkali-treated hair cortex; weaker reactions are produced in keratin, collagen, muscle and resting nuclei. Alkaline benzil, 1,2-cyclohexanedione and 9,10-phenanthrenequinone treatments prevent the reaction completely, glyoxal eloes partly and nitrous acid deamination has no effect; some acylations are partially effective and in part reversible; methvlation attenuates, reversibh; aIdehyde and SH blockades are ineffective. The reaction requires 6-10 mm for full developnient; longer exposures do not increase the density. The extreme reaction pu range is from about 12.4 to about 13.6; the reaction is optimal at 13.2-13.4 (ca. 0.20.4 N Ba(OH)2). NaOH solutions require added BaC12 or SrCl2; CaC12 and MgCI2 are less effective. Arginine gives a red color in vitro, detectable to about 2.7 mg/100 ml; alike in NaOH and Ba(OH)2, red colors appear also with guanidine and protasnine; other amino acids give green to yellow colors at pH 13. Intrusion of brown into the color reaction is retarded by exclusion of air. Dehydration and mounting proce(lures are well tolerated; stains appear stable for some months at least.

Method for the selective spectrophotometric determination of 2,6-lutidine

Abstract: A method is described for the spectrophotometric determination of 2,6-lutidine using p-dimethylaminocinnamaldehyde in acidic medium An initial attempt has been made to postulate the mechanism of this complex system