Chalcones as inorganic analytical reagents

1·0–6·0 p.p.m. of germanium could be estimated spectrophoto-metrically with 2′, 3′, 4′-trihydroxy chalcone as reagent at pH 5·8–6·0. The complex was shown to contain three gram-moles of the reagent to one gram-atom of germanium both by Job’s method of continuous variations and the slope ratio method of Harvey and Manning. The instability constant was determined by the method of Edmonds and Birnbaum and found to be 1·670×10^?11 at 28° C. It is concluded that complex formation involved only the two ortho hydroxyls in each molecule of the reagent and the carbonyl group played no part.     

Spectrophotometric studies of 6-methyl pyridine-2-aldoxime-iron (II) complex

6-Methyl pyridine-2-aldoxime produces with iron (II) solution a deep red complex soluble in 50% (by volume) aqueous acetone. The complex is stable at 10–45°C. and its colour intensity does not vary between pH 7·3 and 10·0. The complex obeys Lambert-Beer’s law at 520 mµ in the concentration range of 1·12 to 28·0 p.p.m. of iron.     

Complex formation between cadmium and thiosalicylic acid

Polarographic measurements on the system Cd-thiosalicylic acid (TSA) reveal the formation of a complex, 1:2:: metal: ligand (ammonia buffer pH 9·1,µ=0·2 M, 50% alcoholic medium), dissociation constant of the complex being 6·3 × 10^?8 at 30° C. Potentiometric titrations confirmed this stoichiometry, stepwise stability constants, logk ₁ and logk ₂ being 7·85 and 8·10 respectively. The complex has also been isolated and studied in solid state.     

A polarographic study of methionine complexes of cadmium and indium

The stability constants of methionine complexes of cadmium were determined polarographically by ths method of DeFord and Hume as β₁ =6·5 × 10³, β₂ = 1·7 × 10⁶ and β₃ = 2·1 · 10⁸. The indium complexes were studied by the modified method of Momoki and Ogawa and two complexes, with β₁ = 1·7 × 10⁸ and β₂ = 8·4 × 10¹³, were identified in the concentration range studied. The haf-wave potential of uncomplexed indium ion which cannot be measured directly owing to the irreversible nature of the reduction was calculated as — 0·503 Vvs. SCE.     

A polarographic study of methionine complexes of cadmium in mixed solvents

Methionine complexes of cadmium in 25 and 50 per cent aqueous mixtures of ethyl and methyl alcohol and dioxan have been studied. The half-wave potentials measured in both the alcohols were the same and the reduction was reversible. Three complex species withβ ₁=1·0×10⁴,β ₂=1·1×10⁷ andβ ₃=1·2×10⁹ were found in 25 per cent alcohol while four complexes withβ ₁=3·0×10⁴,β ₂=4·3×10⁷,β ₃=4·0×10⁹ andβ ₄=1·6×10¹¹ were observed in 50 per cent solutions. In the case of dioxan, the reduction was quasi-reversible (k _s=1·0×10^?3 cm sec^?1) in 25 per cent and irreversible (k _s=2·0×10^?4 cm sec^?1) in 50 per cent solutions. The stability constants, evaluated using the formal potentials, wereβ ₁=7·0×10³,β ₂-3·9×10⁵;β ₂=3·9×10⁸ andβ ₄=3·4×10¹⁰ in 25 per cent dioxan andβ ₁=1·5×10⁴,β ₂=3·4×10⁷.β ₃=7·5×10⁹ andβ ₄=9·0×10¹¹ in 50 per cent solutions.     

Thermal expansion of ferroelectrics

Using the interference method the thermal expansion of lithium hydrazinium sulphate [Li(N₂H₅)SO₄] has been investigated in the temperature range ?170° C. to +220° C. The principal expansion coefficients along the crystallographic axes have been determined and at room temperature (25° C.) the values ofa _a,a _b anda _c are respectively 17·7, 13·5, and 43·0, ×10^?6 (°C.)^?1. The expansion coefficients are found to vary nonlinearly, and, in particular, along thec-axis the thermal expansion shows an anomalous behaviour between ?160°C. and ?60°C. and also in the neighbourhood of +130°C. These anomalies are explained as due to homomorphous transitions in which there is a reorientation of the ?NH ₊ ³ group about the N-N axis or a re-alignment of the ?NH₂ group.     

Spectrophotometric studies of copper (II)—bis-2-pyridyl glycol complex

An aqueous solution ofbis-2-pyridyl glycol forms a deep blue water-soluble complex with an aqueous solution of copper (II) salts. The complex has an absorption maximum at 600–650 mµ between pH range 3·0–8·7. The complex is stable for four days and obeys Lambert-Beer’s law in the concentration range of 5·08–50·80 ppm. of copper (II) in solution. The optical density of the complex remains constant between pH 3·8–5·9. The molar composition as determined by the method of continuous variation and by the slope ratio method has been found to be 1:1. The limits of interference due to some foreign ions during the estimation of copper (II) have been determined.     

Studies on efficiencies of electrochemiluminescence of rubrene

The electrochemiluminescence efficiencies of rubrene system has been obtained by using the transient method in a variety of solvents. The efficiencies are in the range of 0·11 × 10^?3?4·1×10^?2. The mixed system efficiencies are less at least by an order of magnitude in all the solvents except in dimethylsulphoxide. The variation in efficiencies of the pure and mixed systems is explained on the basis of mechanistic differences. In the applied magnetic field, the electrochemiluminescence efficiency of the pure system increases by about 7% and of the mixed system by about 18–25%.     

Investigations on the multiply charged nuclei of the primary cosmic radiation near the geomagnetic equator using nuclear emulsion

A nuclear emulsion stack was exposed over Hyderabad, India (geomagnetic latitudeλ=7·6° N) under a mean atmospheric depth of 6·8 g./cm.², on 24 March 1960. The relative and absolute intensities of Be and B nuclei and nuclei of charge Z?6 (the S-nuclei) have been determined in this stack. The intensities were extrapolated to the top of the atmosphere using measured fragmentation parameters involved in collisions of cosmic ray nuclei in graphite. The flux values of Be, B and S nuclei at the top of the atmosphere have been determined to be 0·025±0·011, 0·101±0·023 and 1·12±0·10 particles/m.² sec. sr. respectively. The ratios of intensities B/S, Be/S and Be/B have been found to be 0·09±0·02, 0·022±0·008 and 0·25±0·11 respectively. These ratios of intensities have been used (a) to compute the amount of matter traversed by the radiation before reaching the vicinity of the earth as 2·6±0·6 g./cm.², (b) to show that the Fermi mechanism of acceleration of particles is not efficient at these energies (1–10 GeV/n.) in interstellar space and (c) to show that preferential acceleration of H₁-nuclei (Z?20) is not of overwhelming importance. The derived source composition of nuclei of energy ?7·5 GeV/n suggests that N, O, F and H₃-nuclei (Z=10–15) have similar abundances in the universe and in cosmic rays, and that C and H₁-nuclei are overabundant in cosmic rays.     

Oxidation studies—III

The oxidation of aliphatic unsymmetrical ketones-n-propyl methyl ketone and isobutyl methyl ketone and cyclic ketone-cyclohexanone by ceric perchlorate in perchloric acid (≈0·5–2·0 M) was studied in the temperature range 10°–30° C. The kinetics of the reactions were followed by measuring rate of Ce⁴⁺ disappearance effecting variations in [Ce⁴⁺], [Ketone], [HClO₄], ionic strengthμ, temperature, etc., and the reactions were found to be 2nd order—first order each with respect to [Ce⁴⁺] and [ketone]. No evidence for complex formation between Ce⁴⁺ and ketone was obtained from kinetics or by an independent absorptiometric method. Ce⁴⁺ (aq) and enol of the ketones were the active species for oxidation. Correlations between rates of enolisation of ketones and oxidation of the latter by Ce⁴⁺ were observed. The rate constants and their thermodynamic data were calculated and discussed. A mechanism based on the concept of oxidation as a process of successive hydroxylation of organic molecules is proposed.     

Colorimetric estimation of rapox by ferric chloride solution

A method has been developed for estimating even one part per million RAPOX in aqueous medium using Lumetron photoelectric colorimeter 402-E and 620-M filter. The colour of RAPOX ferric complex has been found to obey Beer’s law in the range 10^?5?2·2×10^?4 mole per litre of the aqueous solution. The method depends on the development of colour on mixing aqueous RAPOX with ferric chloride solution in water.     

Photometric study of iron-resacetophenone-oxime complex

A detailed study of iron-resacetophenone-oxime complex was made photometrically. It was found that the complex obeys Beer’s Law in the concentration range of 1 to 10 p.p.m. at 475 mµ and 550 mµ, both at pH 7·0 and 4·5. Iron (III) and the reagent combine in the molar ratio of 1:1 to form the complex. The sensitivity was found to be 0·01γ of iron per ml. The interfering ions are the same as with salicylaldoxime.     

Gallacetophenone as an analytical reagent for tantalum

Gallacetophenone is proposed as a new specific reagent for the determination of tantalum in the presence of niobium. It gave an yellow colour with tantalum (pH 1.2–3.0) and orange-yellow to orange-red colour with niobium (pH 5.0–8.0). The limits of identification (and dilution) were 10 γ (1:10⁴) and 0.5 γ (1:10⁵) for tantalum and niobium pentoxides respectively. The reagent is specific for tantalum at pH 1.5. The absorption maxima for gallacetophenone were 215 and 280 nm. The maximum absorption for the tantalum and niobium complexes were 395 and 385 nm respectively. The effects of pH, time, ammonium oxalate and reagent on the absorbancy of tantalum complex were studied. The tolerance limits for other ions were determined. Beer’s law was obeyed in the range of 0.5–8.0 mg of tantalum pentoxide per 25 ml. Tantalum pentoxide could be determined colorimetrically in presence of ten times its weight of niobium pentoxide. Gallacetophenone formed 1:1 complex with tantalum (pH 1.5) and 1:2 complex with niobium (pH 6.4). The probable structures have been suggested.     

Isotropic background cosmic X-rays in the energy range 50–290 KeV

The observations of omnidirectional X-ray flux at the top of the atmosphere have been extended upto 200 KeV using a balloon-borne NaI (Tl) scintillator detector at Hyderabad, India. The omnidirectional flux at 60 KeV is found to be 0·0066±0·0014 photons/cm.² sec. ster. KeV. The X-ray flux in the energy range 50–290 KeV can be adequately represented by the spectrum Ke^?2.2±0.4. New upper limits to the hard X-ray flux from the quiet sun have also been obtained from the same measurement.     

Spins of the first two excited states in27Mg by an angular correlation technique in the reaction26Mg (d,pγ)27Mg

Proton-gamma-ray angular correlation measurements, employing the ‘method II’ of Litherland and Ferguson, have been made in the reaction²⁶Mg (d, pγ)²⁷Mg, using 1·80 MeV deuteron beam and detecting the outgoing protons at 0° with respect to the beam. Analysis of these measurements leads to spin assignments of 3/2 and 5/2 for the 0·98 and 1·69 MeV excited states of²⁷Mg. The 1·69 MeV second excited state is found to decay almost completely to the ground state.     

He3 nuclei in the low energy primary cosmic radiation

The flux of He³ nuclei and the ratio He³/(He³+He⁴) in the low energy primary cosmic radiation have been determined using a stack of nuclear emulsions exposed at 3·1 g. cm.^?2 of atmospheric depth from Fort Churchill, Canada, in June 1963. The grain-densityversus residual range method was used to determine the masses of the helium nuclei. Using a sample of 146 helium nuclei whose masses could be identified, the ratio He³/(He³+He⁴) is obtained as 0·14±0·04 for the kinetic energy interval 115–210 MeV per nucleon and 0·43±0·11 for the rigidity interval 0·85–1·05 BV. The differential fluxes of He³ nuclei are determined as 0·017±0·006, 0·045±0·015, and 0·054±0·017 particles/M². Sr. Sec. MeV/nucleon, in the kinetic energy intervals of 117–183, 183–217, and 217–250 MeV/nucleon respectively. These results are compared with those of other investigators. From the results of the present work the amount of matter traversed in space by the primary cosmic ray helium nuclei of energy 115–210 MeV/nucleon is obtained as 4·7±1·8 gm. cm.^?2 of hydrogen.     

Spectrophotometric studies of uranium (VI)-pongamol complex

The spectrophotometric studies of uranium (VI)-pongamol complex have been carried out in 50% aqueous ethanolic solutions. Pongamol produces a yellow complex with an aqueous uranyl salt solution, the complex is soluble in 50% aqueous ethanol. The complex is quite stable for 24 hours, the optical density remaining constant at pH 5·6–7·1. The complex obeys Beer-Lambert’s law at 390 mµ in the concentration range of 1 to 5 p.p.m. of uranium in solution. The molar composition of the pongamol uranium (VI) complex has been found to be 2:1, and its tentative structure has been suggested. The cations and anions which interfere in the estimation of uranium using pongamol have been indicated.     

Oxidation of aldehydes by aqueous Ce (IV) in nitric acid

The kinetics of oxidation of acetaldehyde (at 20°, 31° and 40° C.), propionaldehyde (at 15°, 25° and 35° C.) and chloral hydrate (40°, 50° and 60° C.) by ceric nitrate in nitric acid medium [(H⁺) ≈ 0 · 5?1 · 5 M] were studied. The reactions were followed by determining rates of ceric disappearance for variations in [Ce⁴⁺], [RCHO], [H⁺], μ, temperature, etc. The stoichiometry, ΔCe⁴⁺ / Δ CH₃CHO ≈ 2 was established. The reactions were found to be 2nd Order—first order each with respect to [Ce⁴⁺] and [RCHO]. No complex formation between Ce⁴⁺ and aldehydes was observed. Neutral Ce (NO₃)₄ (H₂O)₂ and diol of the aldehyde were assumed the active species. The rate and thermodynamic data were calculated and discussed. The rates of oxidation were correlated with the structures of the aldehydes.     

Equilibrium constants of UO 2 2+ , Cu2+ with dicarboxylic acids in dioxane-water mixtures

The interactions of uranyl and copper ions with dicarboxylic acids such as succinic, itaconic, adipic and malonic acids have been investigated in 20, 40, 60 and 80% (v/v) dioxane-water mixtures at 30°C and 0·06 ionic strength by Calvin-Bjerrum titration technique. UO ₂ ²⁺ , Cu²⁺ form only 1:1 complexes with succinic, itaconic and adipic acids and both 1:1 and 1:2 with malonic acid in the pH range 2·5–5. The plots of pK/log K vs mole fraction gave linear while those with 1/D gave non-linear. The complexation equilibria: are proposed. The radius of anionic ligand is calculated from Born equation and attempts are made to understand the medium effect on the pK values.     

Nuclear disintegrations produced in nuclear emulsions by α-particles of great energy

A study of nuclear disintegrations caused by α-particles of primary cosmic radiation with energies > 5 BeV per nucleon, has been carried out. In a systematic survey in nuclear emulsions using ‘along the track’ scanning method, 479 α-particles with a total track length of 40·84 metres and 242 interactions were obtained. From the angular distribution of shower particles associated with these interactions, a procedure has been found for distinguishing protons, which originally formed part of the incident α-particle and which have not taken part in the interaction, from other charged particles. The mean free path for nuclear interaction in G-5 emulsion is found to be 17·5±1·1 cm. (68·9±4·3 gm./cm.²). Assigning both to the incident α-particle and to the target nuclei a radius R=r _oA^1/2, one obtains an effective nuclear radiusr _o=1·13±0·04 ×10^?13 cm. Using the number of protons emerging from disintegrations of heavy nuclei (Silver and Bromine) without having participated in the interaction (as can be deduced from the angular distribution) and assuming spherical nuclei of uniform density, the mean free path of nucleons in nuclear matter is calculated to be less than 3·2×10^?13 cm.