Rapid extraction of copper(II) with 2-thenoyltrifluoroacetone direct colorimetric determination in the organic phase

Summary The chelating agent, 2-thenoyltrifluoroacetone has been employed for rapid extraction and colorimetric determination of milligram amounts of copper(II) in one operation. At pH 2.4–6.0 copper(II) is extracted quantitatively from an aqueous solution by TTA-benzene in a single extraction. The green-coloured copper(II)-TTA chelate solution in benzene obeysBeer's law at 430 m over the range of 16–180g copper per millilitre. The coloured system is stable for 143 hours. It can tolerate silver, mercury(II), bismuth (<5 mg) and small amounts (<100 mg) of citrate and tartrate, whereas cobalt(II), nickel(II), iron(III), aluminium(III), cerium(IV), thorium and zirconium seriously interfere. The proposed method is reproducible to within ±1.4%.     

High frequency titrations: The mercury(ii)-thiocyanate reaction

Soluble complex-formation of mercury(II) thiocyanate has been studied oscillometrically. The titration of mercury(II) nitrate with thiocyanate gives one inflection corresponding to the formation of Hg(SCN)₂, while in the reverse titration the formation of Hg(SCN)⁺ is also indecated. The method is useful for a rapid determination of very small quantities of mercury or thiocyanate in highly dilute solutions. The titrations can be effected in presence of nitric acid provided its total acidity in the system does not exceed about $\text{1}\text{300}$N. Further Work on the mercury(II) -halide and mercury(II)-cyanide reactions is in progress.     

Photocatalysed eosin Y mediated C(sp3)-H alkylation of amine substrates via direct HAT

A visible light promoted, photoredox catalysed, green one-pot approach for the alkylation of amine substrates with sp² carbon has been developed. This eosin Y based organic transformations, can behave as an effective direct hydrogen-atom transfer catalyst for coupling reaction. The proposed strategy includes simple procedure which can make adduct product with sp² carbon. This eosin Y based photocatalytic hydrogen-atom transfer strategy may hold great potential for diverse functionalization of a wide range of native CH bonds in an economical and sustainable manner.     

Determination of 1,3-benzodioxanes in Piper mullesua by high-performance thin-layer chromatography

A new, simple, precise, and rapid high-performance thin-layer chromatographic method was developed for the determination of 6 benzodioxanes in Piper mullesua extract: 1',3'-benzodioxole-5'-(2,4,8-triene-isobutyl nonanoate), 1',3'-benzodioxole-5'-(2,4,12-triene-isobutyl tridecanoate), fargesin, sesamin, asarinin, 1',3'-benzodioxole-5'-(2,4,8-triene-methyl nonanoate). The ingredients were separated on a precoated Silica Gel 60 F254 plate with a solvent system of toluene-acetone (92 + 8). The 6 benzodioxanes were well separated and easily identified in this chromatographic system. The separated benzodioxanes were visualized by color development with a spray reagent consisting of 1 g vanillin dissolved in 100 mL H2SO4-ethanol (5 + 95, v/v). Quantitation was performed by scanning the spots and comparing the integrated areas of compounds in samples with those of standards. Recoveries from samples spiked with known amounts of the benzodioxanes were excellent. The results were comparable with those estimated by liquid chromatography.     

One-pot general synthesis of metalloporphyrins

A new general one-pot method for the synthesis of various metalloporphyrins has been developed from pyrrole and substituted aldehydes using transition metal salts. This method allows higher working concentrations than those previously reported. Along with the reported metalloporphyrins, some new metalloporphyrins were synthesized in good yield.     

All-trans-N-retinylidenetryptamine Schiff base in surfactant solubilized water pools in heptane—a fluorescence study

All-trns-N-retinylidenetryptamine Schiff base was incorporated into aerosol-OT (AOT, sodium bis(2-ethylhexyl)sulphosuccinate)/heptane reverse micelles. This micellar system was used as a model to study the retinal-tryptophan interactions in retinal proteins. The retinylidene Schiff base remains stable in the presence of reverse micelle-solubilized water pools. Partition coefficient and microviscosity measurements show that the Schiff base is located in the micellar interphase. The results are discussed in terms of the interaction between the retinylidene chromophore and the active site environment of rhodopsin and bacteriorhodopsin. In the present model, the quencher and emitting units are covalently attached, and are separated by two carbon spacer units. The fluorescence emission data obtained for the micelle-intercalated Schiff base chromophore are compared with the fluorescence of the native protein and intermediates in the photochemical cycle of bacteriofhodopsin. A comparison of the data obtained for tryptamine and the Schiff base with the results available for bacteriorhodopsin and bacterioopsin reveals that there is a large degree of quenching on intercalation of the retinylidene chromophore in the vicinity of the fluorophore. Evidence provided by this model suggests that energy transfer to retinal can occur from tryptophan residues located in the retinal pocket in the native protein. Thus the retinylidene unit can act as a quencher of the energy of tryptophan, the nature and extent of which may depend on the conformation and relative orientation of the protein-bound fluorophore.     

Reactions of powdered silicon with some pyrotechnic oxidants

Thermogravimetry (TG) and differential scanning calorimetry (DSC) have been used to examine the thermal behaviour, in N₂ and in air, of the Si/Sb₂O₃, Si/KNO₃, Si/Fe₂O₃ and Si/SnO₂ pyrotechnic systems, in relation to the behaviour of the individual constituents.TG curves for Si powder, heated alone in air, showed that limited oxidation of Si occurred above 700°. In N₂, Sb₂O₃ sublimed completely between 500 and 900° and, in air, sublimation was accompanied by oxidation to Sb₂O₄. The Sb₂O₄ decomposed at higher temperatures. DSC curves for KNO₃ heated in N₂ showed the usual crystalline transition and melting endotherms followed by endothermic decomposition between 400 and 950°. DSC and TG curves of SnO₂and Fe₂O₃ revealed no thermal events when samples were heated to 1000° in either N₂ or air.For the Si/Sb₂O₃ system, the oxidation of Si by Sb₂O₃ between 590 and 700°, was complicated by sublimation of Sb₂O₃ in N₂ and also by the oxidation of Sb₂O₃ in air. No thermal events were observed for the Si/SnO₂and Si/Fe₂O₃ systems when heated under a variety of conditions in either N2 or in air, although these systems do sustain combustion on suitable ignition. In the Si/KNO₃ system, oxidation of Si occurs in a KNO₃ melt at temperatures above 560° in nitrogen and in air.

---

Zusammenfassung Mittels TG und DSC wurde das thermische Verhalten der pyrotechnischen Systeme Si/Sb₂O₃, Si/KNO₃, Si/Fe₂O₃ und Si/SnO₂in N₂ und in Luft im Vergleich zum Verhalten der einzelnen Komponenten untersucht.TG-Aufnahmen über das Erhitzen von Si-Pulver in Luft zeigten eine begrenzte Oxidation von Silizium oberhalb 700°C. Sb₂O₃ sublimiert in Stickstoff vollständig zwischen 500 und 900°C, in Luft wird die Sublimation durch Oxidation zu Sb₂O₄ begleitet. Sb₂O₄ zersetzt sich bei höheren Temperaturen. DSC-Aufnahmen für KNO₃ in N₂ zeigen die gewohnten Umwandlungs- und Schmelzendothermen, gefolgt von einer endothermen Zersetzung zwischen 400 und 950°C. Die DSC- und TG-Kurven für SnO₂und Fe₂O₃ zeigen bei Erhitzen bis 1000°C weder in N₂ noch in Luft den Verlauf thermische Prozesse an.Bei dem System Si/Sb₂O₃ spielt sich neben der Oxidation von Si durch Sb₂O₃ zwischen 590 und 700°C auch eine Sublimation von Sb₂O₃ in N₂ sowie eine Oxidation von Sb₂O₃ in Luft ab. Für die Systeme Si/SnO₂und Si/Fe₂O₃ konnten durch Erhitzen unter einer Reihe von Bedingungen weder in Luft noch in N₂ Thermoprozesse nachgewiesen werden, obwohl diese Systeme nach geeigneter Zündung den Brennvorgang aufrechterhalten. Im System Si/KNO₃ erfolgt sowohl in N₂ als auch in Luft oberhalb 560°C die Oxidation von Si in der KNO₃-Schmelze.

---

---

Dedicated to Professor Dr. H. J. Seifert on the occasion of his 60^th birthday     

Differential thermal and thermogravimetric analyses of bound water content in cellulosic substrates and its significance during cellulose hydrolysis by alkaline active fungal cellulases

Various cellulosic substrates were examined for bound water content by differential thermal analysis (DTA) and thermogravimetry (TG). Samples were heated in the range of 30-100 degrees C at a rate of 3 degrees C/min. DTA vaporization curves for different cellulose samples indicated that the bound water (Wf) was vaporized at higher temperature than free water (Wf) at the surface. Weight loss was observed in two stages, corresponding to Wf and Wb in TG curves. The bound water content was dependent on the degree of crystallinity of cellulose. Among different cellulosic substrates, Walseth cellulose showed the highest bound water content, and it also was found to be the least crystalline. The alkaline-active, alkali-stable cellulase was obtained from the alkalotolerant Fusarium sp. The substrate specificity and viscometric characteristics confirmed the enzyme to be an endoglucanase. The Wb content of Walseth cellulose was lowered during the enzymatic hydrolysis. The possible application of bound water analysis in understanding the hydrolysis of cellulosic substrates of different crystallinity is discussed.     

Analytical aspects of some organic acids Part III

Summary m-Phenylenedioxydiacetic acid gives a white precipitate with thorium even in the absence of an electrolyte which is quantitative up toph 4. Be²⁺, Mg²⁺, Ca²⁺, Zn²⁺, Pb²⁺ and Mn²⁺ ions are removed by single precipitation and Al³⁺, UO₂ ²⁺ and trivalent cerite earth ions are removed by double precipitation. Sn²⁺, Sn⁴⁺ and Cr³⁺ ions interfere.Part II: See. Z. analyt. Chem.165, 343 (1959).