Five different compounds have been identified spectrophotometrically in the reaction between acetaldehyde and Schiff's reagent.It has been found that, with a small amount of acetaldehyde, a complex with only one molecule of acetaldehyde for every molecule of the reagent is formed. This shows the peak at 545 mμ.With excess of acetaldehyde, the complex contains two molecules of aldehyde per molecule of Schiffs reagent, corresponding to the peak at 555 mμ. After standing for some time, the solution containing this compound, gradually shows the presence of three new compounds, having peaks at 525 mμ, 575 mμ and 615 mμ. The former results from the interaction of two molecules of acetaldehyde and a molecule of fuchsin derived from Schiff's reagent itself. The other two are formed when the former loses one and two water molecules, respectively. 相似文献
A spectrophotometric method has been described for the estimation of ammonium acetate with the help of sensitized Schiff's reagent. 1) Ammonium acetate restores the colour of fuchsin from the Schiff's reagent as shown by the same absorption maxima at 535 mμ of the coloured compound and fuchsin. 2) Standard curves of optical density versus concentration of ammonium acetate with different sets of sensitized Schiff's reagent having varying SO2 contents have been presented. 3) There is a limit of ammonium acetate concentration beyond which the sensitivity considerably decreases. 4) Appropriate amounts of acetone along with a particular set of sensitized Schiff's reagent make the latter useful for different sensitive ranges of concentrations of ammonium acetate. 5) The method may be extended in its scope for the estimation of ammonium salts of other organic acids which are weaker than H2SO2. 相似文献
1. Ammonium salts of the weak acids, oxalic, citric, taitaric, formic, lactic, succinic. acetic, n-butyric and propionic bring colour to sensitized Schiffs reagent. The intensity of the colour thus produced stands in inverse relationship with the dissociation constants of these acids and hence of their strengths. The intensity of colour is dependent on the concentration of the ammonium salts and hence the concent ration of the latter was adjusted to a suitable value, keeping in mind the range of the sensitivity of the reagent itself. 2. The colour produced by the different salts is the same as that of the solution. The probable mechanism appears to be that the ammonium salts react with SO2 which displaces the acids from the salts. The greater the displacement the greater the intensity of colour and the weaker the acid. 相似文献
Biacetylmonoxime-salicoylhydrazone (BMSH) complexes of the types [Hg(BMSH)Cl2] and [M(BMSH-H)2], where M = Cu(II), Co(II), Ni(III), Mn(II), Zn(II), Cd(II) and UO2(VI), have been prepared and characterized by conventional chemical and physical measurements. The IR spectra show that the ligand usually coordinates via carbonyl oxygen (CO), azomethine nitrogen (CNl) and phenolic OH with replacement of hydrogen by metal ions but acts as a bidentate molecule coordinating through (CO) and (CNl) in the Hg(II) complex. The magnetic and spectral data of the Co(II) and Ni(II) complexes support octahedral stereochemistry, whilst tetragonally distorted octahedral geometry is suggested for the Cu(II) complex. 相似文献
The composition of the precipitate formed when the Nessler's reagent is treated with ammonia, is assumed as NHn-1Hg2In, aq. and has been studied potentiometrically from iodine-hypoiodite-system. It has been observed that the value of n depends on the concentrations of [HgI4]-2 and OH- ions as well as on the amount of ammonia added and it may vary from 1 to 3. The colour of the precipitate deepens from brown to chocolate as the value of n increases. 相似文献
The nature of the reaction between [HgI4]-2 and OH- ions, which are the components of the Nessler's reagent, has been. studied and established as , by determining the concentration of iodide ions formed in the solution, potentiometrically from the concentration cells of iodide-hypoiodite system. The equilibrium constant has also been calculated and found to be lo-3.26. 相似文献
The acid and base dissociation constants of luminol are determined at various ionic strengths. The transition interval occurs at pH 7.7-9.0, therefore luminol is a fluorescent indicator for the titration of strong and weak acids and strong bases. Its value as an indicator is established by titrating milk, red wine and cherry juice. 相似文献
Phthalhydrazidylazoacetylacetone, an azo derivative of luminol, has been shown to be superior to luminol as a chemiluminescent indicator for acid-base titrations. 相似文献
The present paper firstly announces the possibility of using a Schiff base as an acid-base indicator. This surprising phenomenon can be considered as an interest due to the fact that Schiff bases are usually unstable in solutions and definitely undergo hydrolysis. It was found that such a specific observation depends merely upon the chemical structure and type of the substitute of amine that reacts with aldehyde to give the Schiff base. The latter reagent 4[(4-dimethylamino-benzylidene)-amino]-benzene sulfonamide was synthesized from the condensation of sulfanilamide with p-dimethylaminobenzaldehyde. The reagent solution shows a reproducible change in its color due to the addition of acid and base. A UV-Vis spectroscopic characterization and acid-base equilibrium study of the reagent for its possible use as an indicator were investigated. The results show that the reagent is an amphoteric which possesses four ionization constants Ka1, Ka2, Kb1 and Kb2 of weak dibasic and diacidic properties. The value of pKa2 (9.80) is parallel to the observed transition interval pH 9.5 (yellow) and pH 10.5 (colorless), which is considered to be the indicator exponents pKi. It was concluded that the benzyl sulfonamide group plays a key role in the stability of the reagent towards hydrolysis and also for indicator characteristics through breaking the conjugation. 相似文献
The acidic dissociation constant and the solubility of 4-amino-4'-chlorodiphenyl have been determined. The solubility of the amine sulphate has been redetermined and found to be ten times greater than reported earlier. The reason for the discrepancy is revealed, and the use of the amine as a reagent in the micro-analytical determination of sulphate is discussed in the light of the experimental results. 相似文献
2,6-Dichlorophenolindophenol shows acid-base indicator properties. Its colour is red in acidicmedia and blue in alkaline media. 'Ihe transitional pH value is 5.7 and the colour change is sharp and easy to observe. The use of the indicator in various acid-base titrations, as well as the effects of neutral salts, alcohol and temperatures, were checked. The absorption spectra of the acidic and basic forms of the indicator are presented. 相似文献
This paper reports the spectral properties and protolytic behavior of the fluorescent dye N,N'-dioctadecylrhodamine on the micelle/water and microdroplet/water interfaces as well as in Langmuir-Blodgett films soaked into aqueous media. Long hydrocarbon chains provide similar orientation of its cation and zwitterion, with the dissociating group (COOH-->COO(-)) directed toward the bulk (aqueous) phase. Both absorption and fluorescence of the dye can be used for monitoring electrical surface potentials and for determination of bulk pH. 相似文献
3,3'-Dihydroxybenzidine-N,N,N',N'-tetraacetic acid has been prepared and examined as a metallofluorescent indicator in compleximetric titrations. Copper(II) and lead(II) are determined by titration with EDTA in the presence of the indicator, the blue fluorescence of which is restored at the end-point. Manganese, zinc, cobalt and cadmium can also be determined if a dyestuff such as Rhodamine B is present along with the indicator. 相似文献
Summary Uranium (VI) has been found to give a yellow colour with nicotinamidoxime in alkaline medium which is highly satisfactory for the spectrophotometric estimation of the metal. The optimumph for development of the colour is 10.9–11.5 in presence of a large excess of the reagent, at 10–40C. The colour intensity is measured at 400 m. Sensitivity is 0.045 g uranium per cm2, with a visual identification limit of 5 g uranium per ml. Beer's law is obeyed in the range of 5–40 ppm of the metal with an optimum range of 8–40 ppm. The colour is stable for at least one hour. All the common anions are without effect, excepting however, phosphate, carbonate, and cyanide which are tolerated only in traces. Use of tartrate or EDTA helps to mask effectively all the interfering cations excepting copper, iron and vanadium. 相似文献
Summary Copper has been determined gravimetrically as its bis-salicylaldehyde-ethylenediamine complex of the composition C16H14O2N2 · Cu, dried at 100–120° C. The complex is completely precipitated in theph range of 10.5–13.5, adjusted with ammonia or caustic alkali. It is stable in presence of excess ammonia, 0.1 N alkali, ammonium salts and complexing agents as tartrate, citrate, sodium-thiosulphate, fluoride, thiourea, triethanolamine and EDTA. In presence of tartrate and ammonia the ions of alkali metals, alkaline earths, Ag+, Tl+, Tl3+, Pb2+, Cd2+, Co2+, Mn2+, Pd2+, Al3+, Cr3+, La3+, Ce3+, Au3+, Pt4+, Ti4+, Zr4+, Th4+, UO22+ and anions as VO3–, MoO42–, WO42–, CrO42–, PO43–, AsO43– do not interfere. Ni2+ and Hg2+ are masked by tartrate, EDTA and ammonia; As3+, Sb3+ and Sn2+ are separated using fluoride as the complexing agent; at an alkalinity of 0.1 N caustic alkali in presence of tartrate As3+, Sb3+, Sn2+, Bi3+, Zn2+ and Fe3+ are separated. Fe3+ can also be separated using triethanolamine as the masking agent at aph of about 13.0. Copper can be separated from almost all the ions, thus affording a highly selective method for the determination of copper.
Zusammenfassung Es wird eine gravimetrische Methode zur Bestimmung von Kupfer beschrieben, die auf der Bildung des Bis-salicylaldehyd-äthylendiaminkomplexes beruht. Dieser hat die Zusammensetzung C16H14O2N2 · Cu. Die Fällung wird imph-Bereich 10,5–13,5 (mit Ammoniak oder Alkalilauge eingestellt) vorgenommen und der Niederschlag bei 100°–120° C getrocknet. Der Komplex ist beständig in Gegenwart von überschüssigem Ammoniak, 0,1 n Alkali, Ammoniumsalzen sowie Tartrat, Citrat, Natriumthiosulfat, Fluorid, Thioharnstoff, Triäthanolamin und ÄDTA. In Gegenwart von Tartrat und Ammoniak stören nicht: Alkalien, Erdalkalien, Ag+, Tl+, Tl3+, Pb2+, Cd2+, Co2+, Mn2+, Pd2+, Al3+, Cr3+, La3+, Ce3+, Au3+, Pt4+, Ti4+, Zr4+, Th4+, UO22+ sowie VO3–, MoO42–, WO42–, CrO42–, PO43– und AsO43+. Ni2+ und Hg2+ können mit Tartrat, ÄDTA und Ammoniak maskiert werden, As3+, Sb3+ und Sn2+ mit Fluorid. In 0,1 n ätzalkalischer Lösung in Gegenwart von Tartrat können As3+, Sb3+, Sn2+, Bi3+, Zn2+ und Fe3+ abgetrennt werden. Fe3+ kann ebenfalls mit Triäthanolamin beiph 13,0 maskiert werden. Das beschriebene Verfahren erlaubt somit eine Abtrennung des Kupfers von fast allen anderen Ionen.
Part I: Singh, B. R., and S. Kumar: Z. analyt. Chem. 185, 211 (1962). 相似文献
In a continuation of earlier work on the reactivity of various isonitrosoacetarylides, the simplest of the series, isonitrosoacetanilide was examined. In acidic medium, this reagent gives a specific reaction with palladium (dilution limit 1:400,000), and in ammoniacal medium a very sensitive reaction with cobalt (dilution limit 1:1,000,000). The composition of the complexes involved was established as R2Pd and R3Co2. The effect of substitution on the reactivity is discussed. 相似文献
Summary Cobalt(II) gives a deep blue colour with nicotinamidoxime in alkaline aqueous-ethylalcoholic medium which has been used with advantage for the spectrophotometric determination of this metal. The optimum pH for the development of colour is 9.8–11.3 in aqueous-alcoholic (40% v./v.) medium in presence of a large excess of the reagent, at 15–40°C. The colour intensity is measured at 580 m,. Sensitivity is 0.01 g cobalt per cm2, while visual identification limit is 0.5 g cobalt per ml (12·106). Beer's law is obeyed in the range of 0.2–20 ppm of the metal, with an optimum range of 2–16 ppm. The colour is stable for about half an hour in the pN range of 9.8–11.3 and at least one hour in the range of 10.5 to 11.0. On account of the high pN and alcoholic medium used, most of the cations and anions interfere and, hence, must be removed.Part I: See Z. anal. Chem. 168, 326 (1959). 相似文献
Summary The compound bis-salicylaldehyde-ethylenediamine was prepared by the condensation of salicylaldehyde with ethylenediamine. It was crystalline and quite stable. The solution of the compound in caustic alkali was used for the analytical reactions of various ions. Ions of Cu2+, Ni2+, Bi3+, Zn2+, Hg2+, Sb3+, Sn2+ and Ce4+ formed precipitates, while those of As3+ and Pd2+ gave slight turbidity and Fe2+, Pe3+, Co2+ gave colour reactions. Rest of the ions did not respond towards the reagent. The sensitivity of the reactions for Cu2+, Ni2+, Fe2+, Fe3+, Ce4+, Co2+ and Sb3+ was high and their quantitative determinations are possible.
Zusammenfassung Die Verbindung Bis-salicylaldehyd-äthylendiamin wurde durch Kondensation von Salicylaldehyd mit Äthylendiamin dargestellt. Sie ist kristallin und durchaus stabil. Die ätzalkalische Läsung dieser Verbindung wird zu analytischen Reaktionen mit verschiedenen Ionen benutzt. Die Ionen Cu2+, Ni2+, Bi3+, Zn2+, Hg2+, Sb3+, Sn2+ und Ce4+ ergeben Niederschläge, As3+ und Pd2+ geben eine geringe Trübung und Fe2+, Fe3+ sowie Co2+ liefern Farbreaktionen. Die übrigen Ionen sprechen auf das Reagens nicht an. Die Empfindlichkeit der Reaktionen mit Cu2+, Ni2+, Fe2+, Fe3+, Ce4+, Co2+ und Sb3+ ist groß und eine quantitative Bestimmung dieser Ionen ist möglich.
Summary Lead can be determined from its Bismuthiol II complex volumetrically by dissolving it in an excess of EDTA at a pH of about 10 and titrating the excess of the EDTA against a magnesium or lead solution. In the same way silver can be determined by dissolving the complex in an excess of cyanide and back titrating the excess against a standard silver nitrate with iodide as the indicator. The results of the former are fairly accurate while those due to latter are highly satisfactory with silver less than 20 mg. With higher amounts of silver, however, the results are within +2%.Part VIII see Z. analyt. Chem. 156, 103 (1957). 相似文献