Spectrophotometric study of the compounds obtained with schiff's reagent and acetaldehyde

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.     

Spectrophotometric method for the estimation of ammonium acetate with sensitized schiff's reagent

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.     

Spectrophotometric method for the determination of the relative strengths of organic acids with sensitized schiff's reagent

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.     

Metal complexes of schiff's base derived from salicoylhydrazine and biacetylmonoxime

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 (CO), azomethine nitrogen (CNl) and phenolic OH with replacement of hydrogen by metal ions but acts as a bidentate molecule coordinating through (CO) and (CNl) 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.     

Studies on nessler's reagent and nessler's precipitate part II

The composition of the precipitate formed when the Nessler's reagent is treated with ammonia, is assumed as NH_n-1Hg₂I_n, 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.     

Studies on nessler's reagent part I

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.     

Luminol as a fluorescent acid-base indicator

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.     

Phthalhydrazidylazoacetylacetone as a chemiluminescent acid-base indicator

Phthalhydrazidylazoacetylacetone, an azo derivative of luminol, has been shown to be superior to luminol as a chemiluminescent indicator for acid-base titrations.     

Application of a Schiff base derived from sulfanilamide as an acid-base indicator

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 K_a1, K_a2, K_b1 and K_b2 of weak dibasic and diacidic properties. The value of pK_a2 (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 pK_i. 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.     

4-amino-4'-chlorodiphenyl as analytical reagent for sulphate

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.     

The use of 2,6-dichlorophenolindophenol as indicator in acid-base titrations

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.     

Fluorescent dye N,N'-dioctadecylrhodamine as a new interfacial acid-base indicator

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.     

3,3'-Dihydroxybenzidine-n,n,n',n'-tetraacetic acid as a metallofluorescent indicator in edta titrations

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.     

Nicotinamidoxime as an analytical reagent

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.     

Bis-salicylaldehyde-ethylenediamine as an analytical reagent

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⁺, UO₂ ²⁺ and anions as VO₃ ^–, MoO₄ ^2–, WO₄ ^2–, CrO₄ ^2–, PO₄ ^3–, AsO₄ ^3– 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.

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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⁺, UO₂ ²⁺ sowie VO₃ ^–, MoO₄ ^2–, WO₄ ^2–, CrO₄ ^2–, PO₄ ^3– und AsO₄ ³⁺. 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.

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Part I: Singh, B. R., and S. Kumar: Z. analyt. Chem. 185, 211 (1962).     

Isonitrosoacetanilide as an analytical reagent

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.     

Nicotinamidoxime as an analytical reagent

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 p_H 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 p_N 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 p_N 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).     

Bis-salicylaldehyde-ethylenediamine as an analytical reagent

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.

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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.

     

Bismuthiol as an analytical reagent

Summary Lead can be determined from its Bismuthiol II complex volumetrically by dissolving it in an excess of EDTA at a p_H 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).