Showing papers by "Indian Association for the Cultivation of Science published in 1971"
TL;DR: In this article, metal complexes of acetylhydrazide and benzoylhydrazides are reported and the NH nitrogen atom is proved to be the coordination site, and the monodentate character and the imidol structure of the ligands in the complexes are suggested.
28 citations
19 citations
TL;DR: In this article, the preparation and properties of a series of complexes of cobalt(II) with benzoylthiocarbazide (HBTC), acetyl thiocarbazide, HATC and 2-chlorobenzoyl-thiamyl-nothioccharbazides (Cl-HBTC) are reported and the electronic spectra of the solids are used to assign their structures.
17 citations
TL;DR: In this article, the polymerization of acrylonitrile was studied in aqueous solution with ceric ammonium sulfate in the presence of triethylamine as initiator at 30, 40, and 50°C.
Abstract: The polymerization of acrylonitrile was studied in aqueous solution with ceric ammonium sulfate in the presence of triethylamine as initiator at 30, 40, and 50°C. The rate of polymerization was found to be linear with the concentration of the amine and independent of ceric ion concentration. A reaction scheme involving initial complex formation between ceric ion and the amine and subsequent disproportionation of the conplex to produce free radicals is proposed for the initiation reaction. The termination step is postulated as involving oxidation of the polymer chains by ceric ions. The results have been explained in the light of the proposed reaction scheme.
17 citations
TL;DR: In this paper, the EPR and polarized optical spectra of copper calcium acetate hexahydrate and isomorphous cadmium calcium acyclic hexahedrate were investigated in the range of temperature 300-77 K.
Abstract: The EPR and polarized optical spectra of copper calcium acetate hexahydrate and ${\mathrm{Cu}}^{2+}$ doped in isomorphous cadmium calcium acetate hexahydrate have been investigated in the range of temperature 300-77 \ifmmode^\circ\else\textdegree\fi{}K. $g$ values in both concentrated and doped crystals are found to be the same, indicating the identical ligand fields. The spin-Hamiltonian parameters remain un-changed throughout the temperature range. The parameters are ${g}_{\ensuremath{\parallel}}=2.360\ifmmode\pm\else\textpm\fi{}0.005$, ${g}_{\ensuremath{\perp}}=2.060\ifmmode\pm\else\textpm\fi{}0.005$, $|{A}_{\ensuremath{\parallel}}|=0.0119\ifmmode\pm\else\textpm\fi{}0.0002$ ${\mathrm{cm}}^{\ensuremath{-}1}$, $|{A}_{\ensuremath{\perp}}|=0.0013\ifmmode\pm\else\textpm\fi{}0.0002$ ${\mathrm{cm}}^{\ensuremath{-}1}$. Detailed study of the line-width has established the important contributions of the exchange, hyperfine, and crystal fields. The observed optical bands at 12 800 and 14 000 ${\mathrm{cm}}^{\ensuremath{-}1}$ exhibit polarization and have intensities characteristic of ligand field bands. With the knowledge of relative magnitudes of $g ({g}_{\ensuremath{\parallel}}g{g}_{\ensuremath{\perp}})$, assignments of the bands have been made, consistent with the ${D}_{2d}$ symmetry of the ligand field. The analysis has revealed that the $3{d}^{9}\ensuremath{-}3{d}^{8}4p$ configuration interaction is rather small (at most 2%) in these noncentrosymmetric complexes, and the covalent metal-ligand interaction is more pronounced in the ground state than in the excited states.
16 citations
TL;DR: In this article, the quantum defect data have been deduced from experimental spectroscopic eigenvalues of singly-ionized Ca, Sr and Ba, and the presence of an extra electron in each atomic cell has been taken into account by assuming a uniform charge density which produces a potential -2Z/r -Zr2/r3s, rs being the radius of the Wigner-Seitz cell and Z being the valency of the metal.
Abstract: Attempts have been made to apply the `quantum defect method', in conjunction with the `composite wave variational method', to compute the band structure of divalent metals calcium, strontium and barium. The quantum defect data have been deduced from experimental spectroscopic eigenvalues of singly-ionized Ca, Sr and Ba. The presence of an extra electron in each atomic cell has been taken into account by assuming a uniform charge density which produces a potential -2Z/r - Zr2/r3s, rs being the radius of the Wigner-Seitz cell and Z being the valency of the metal. The calculation of the band has been performed for all these metals neglecting - Zr2/r3s. Then an attempt has been made to take into account the term - Zr2/r3s in the case of Ca. Both these calculations show that the Fermi surface of Ca is dismembered around the symmetry point W inside the Brillouin zone.
13 citations
TL;DR: In this article, it was shown that α-hydrogen abstraction from the substrate is effective in polymerization in the presence of alcohols and that chain transfer constants obtained from the conventional plot of 1/P against S/M is in fair agreement with the values computed from the estimation of hydroxyl end group in the polymer by dye-partition technique.
Abstract: Studies on Polymerization in the presence of alcohols has been carried out using mixed solvent system. It is observed that chain transferring capacity of the aliphatic alcohols do increase with the size of the alkyl group, the order being methyl alcohol < ethyl alcohol < n-propyl alcohol < iso-propyl alcohol. The results indicate that α-hydrogen abstraction from the substrate is effective. The chain transfer constants obtained from the conventional plot of 1/P against S/M is in fair agreement with the values computed from the estimation of hydroxyl end group in the polymer by dye-partition technique. The increasing transfer constant values in the alochol series with increase in the number of carbon atoms is explained on the basis of probability of available hydrogen atom in the alkyl group. It is also observed that the chain transfer values are affected due to precipitation of polymer. Thermodynamic parameters have been computed from the chain transfer values of alcohols at different temperatures.
Es wurden Polymerisation in Gegenwart von Alkoholen und Benzol als Polymerlosungsmittel (mixed-solvent system) untersucht. Die Kettenubertragungsfahigkeit aliphatischer Alkohole nimmt mit der Grose der Alkylkette in folgender Ordnung zu: Methylalkohol < Athylalkohol < n-Propylalkohol < Isopropanol. Nach den Ergebnissen ist eine Ablosung von α-Wasserstoff aus dem Substrat ubertragend wirksam. Die durch die ubliche Auftragung von 1/P gegen [S]/[M] erhaltenen Kettenubertragungskonstanten stimmen gut mit Werten uberein, die aus den mittels der Farbverteilungstechnik gemesse nen Hydroxylendgruppengehalten berechnet wurden. Die steigenden Werte der ubertragungskonstante mit wachsender Zahl der Kohlenstoffatome im Alkohol wird durch die Wahrscheinlichkeit zuganglicher Wasserstoffatome in der Alkylgruppe erklart. Die Kettenubertragungswerte werden durch die Fallung der Polymeren beeinflust. Es wurden aus den Kettenubertragungswerten der Alkohole fur verschiedene Temperaturen thermodynamische Parameter berechnet.
13 citations
TL;DR: In this article, the fluorescence spectra of Eu-chelates were analyzed in order to investigate the possibility of their use as laser materials, and new compounds derived from ketoesters were characterised by i.r. spectra.
8 citations
TL;DR: In this paper, an intramolecular electron transfer mechanism has been established for tris(acetylacetonato)cobalt(III) decomposition in aqueous solution.
8 citations
TL;DR: In this article, the effect of excited configurations on the crystal field levels of tetrahedral and octahedral Cu 2+ ion via crystal field interaction has been discussed and the shift of the Γ 3 and Γ 5 levels due to configuration interaction was estimated in two cases within the framework of crystal field model carrying out the perturbation calculation upto the second order.
8 citations
TL;DR: In this article, it has been concluded that the inclusion of the elastic displacement in the form proposed by Boswarva and Lidiard, together with the consideration of the effect of anharmonicity as laid down by Theimer, leads to a fair agreement with experiment when the next-nearest neighbors are also taken into account.
Abstract: The entropy of formation of vacancies in KCl has been computed using the approach of Theimer. It has been concluded that the inclusion of the elastic displacement in the form proposed by Boswarva and Lidiard, together with the consideration of the effect of anharmonicity as laid down by Theimer, leads to a fair agreement with experiment when the next-nearest neighbors are also taken into account.
TL;DR: In this paper, 3-methyl ethylacetoacetate (HEEAA), 3-ethyl benzoylacetate, and 1:1 chelate as isolated has been inferred by i.r. spectra.
TL;DR: In this article, a quantitative treatment of the extraction of ionic dyes from aqueous solutions into organic solvents of low dielectric constant by surfactants or polymers with ionic groups having a charge opposite to that of the dye ion, is presented.
Abstract: A quantitative treatment of the extraction of ionic dyes from aqueous solutions into organic solvents of low dielectric constant by surfactants or polymers with ionic groups having a charge opposite to that of the dye ion, is presented. The assumption is made that the extracted species are ion-paired in the organic phase. Based on this, a graphical extrapolation method is suggested for the quantitative estimation of ionic groups in polymers. Theoretically, the method should yield quantitative results irrespective of polymer chain length and character. This method of analysis does not require any calibration data.
TL;DR: In this paper, the acid dissociation constants of 2-acetylcyclohexanone and ethyl benzoylacetate and the formation constants of the rare earth complexes were determined in a solvent mixture of acetone and water (3 : 1 by volume) containing 0·1 M sodium perchlorate at 25°C.
TL;DR: In this article, a new dye partition method, known as reverse dye partition (RDP)-technique for estimation of carboxyl and sulfoxy endgroups in water-soluble acrylamide polymers has been described.
Abstract: A new dye partition method, known as reverse dye partition(RDP)-technique for estimation of carboxyl and sulfoxy endgroups in water-soluble acrylamide polymers has been described. Detailed experimental conditions for the use of the RDP technique have been discussed and plausible theory underlying this technique has been proposed. The estimated numbers of endgroups in the polymers are in agreement with the existing free radical mechanism of initiation of polymerization. Particularly, the results support the existing idea that the termination of polymerization of acrylamide monomer occurs mainly by disproportionation.
Es wird eine neue Farbstoffverteilungsmethode beschrieben, als umgekehrte Farbstoffverteilung (RDP) bezeichnet, um Carboxyl- und Sulfoxyendgruppen in wasserloslichen Polyacrylamiden quantitativ zu bestimmen. Die einzelnen experimentellen Bedingungen und theoretischen Erklarungen zu dieser Methode werden erortert. Die ermittelten Endgruppenzahlen je Polymermolekul stimmen mit einer redikalischen Startreaktion der Polymerisation uberein. Insbesondere bestatigen die Ergebnisse die derzeitige Vorstellung, das die Abbruchsreaktion bei der Polymerisation von Acrylamid hauptsachlich in einer Disproportionierung besteht.
TL;DR: In this paper, Malondihydrazide (MDH, L) complexes of lanthanides are described and characterised by u.v. spectra and conductance data.
TL;DR: A new type of mixed tetrakis compound derived from tris acetylacetonates of La, Pr, Nd and Sm with other β-diketones, like propionylacetone, benzoylacetone and dibenzoylmethane, has been synthesized as discussed by the authors.
TL;DR: In this paper, the authors used reverse dye partition (RDP) technique developed in this laboratory to study the mode of branching in poly(vinyl acetate) molecules and found that the degree of polymerization of the polymer decreases in all cases.
Abstract: The mode of branching in poly(vinyl acetate) has been studied using reverse dye partition (RDP) technique developed in this laboratory. It has been observed that during hydrolysis of poly(vinyl acetate) the degree of polymerization of the polymer decreases in all cases. This degradation is found to be erratic. It may be caused by the separation of branches which were connected to the main chain through ester linkage. This idea has been confirmed by the detection of average one carboxyl endgroup in the resulting shorter polymer chains.
The change in the number of endgroups in the parent and the corresponding hydrolysed polymer has been used as a tool for the estimation of number of branches in poly(vinyl acetate) molecules.
Die Art der Verzweigung von Polyvinylacetat wurde mittels einer besonderen Versuchstechnik (reverse dye partition (RDP)) untersucht. Wahrend der Hydrolyse von Polyvinylacetat nahm der Polymerisationsgrad jedesmal ab. Dieser Abbau gehorcht keiner einfachen Bezichung. Vermutlich beruht er auf der Abtrennung von Zweigen, die mit der Hauptkette uber Esterbindungen verknupft waren. In Ubereinstimmung hiermit enthielten die kurzeren Polymerketten im Mittel eine Carboxylendgruppe je Kette. Der Vergleich der Endgruppenzahl vor und nach der Hydrolyse diente dazu, die Zahl der Zweige in den Polyvinylacetatmolekulen zu bestimmen.
TL;DR: In this article, the authors studied the composition and temperature dependence of the thermal diffusion factor α T of the argon-methane system and showed that α T vs. composition curves show a dip for both the temperatures at which measurements have been made.
Abstract: The composition and temperature dependence of thermal diffusion factor α T of the system argon-methane have been studied by the swing separator and two-bulb methods. This system has the special feature that the heavier component has a smaller collision diameter than the other one. The α T vs. composition curves show a dip for both the temperatures at which measurements have been made. This apparently anomalous behaviour which has also been observed for the hydrogen-helium system cannot be explained either by the elastic or the available inelastic theories for thermal diffusion.
TL;DR: In this article, the thermodynamic stability constants at 25°C of the 1 : 1 complexes of some bivalent transition metal ions of 4-methyl and 4-nitro phthalic acids were determined by a potentiometric method using a glass electrode employing Monk's technique.
TL;DR: Cross-reactions of the gum and its derivatives in several antipneumococcal sera are described, measured quantitatively, and interpreted insofar as possible.
01 Jan 1971
TL;DR: In this paper, the results have been interpreted in terms of the solvation of extracted dye carboxylate ion pairs with the solvent through dipole-dipole interaction, and the success of the dye partition method of analysis of polymer end groups depends greatly on the organic solvent and not on the polarity of the polymer.
Abstract: Physico-chemical aspects of the extraction of pinacyanol dye from basic solution by carboxyl-ended polymers of varying chain lengths into low dielectric constant organic solvents are discussed. Dye extraction is greater the higher the pH, the higher the aqueous phase dye concentration, the higher the chain length of the carboxylic acid and the greater the polarity of the organic solvent. The effect of chain length of the carboxylic acid on dye extraction is considerably reduced in dipolar organic solvents. The results have been interpreted in terms of the solvation of extracted dye carboxylate ion pairs with the solvent through dipole-dipole interaction. It has been pointed out that the success of the dye partition method of analysis of polymer end groups depends greatly on the organic solvent and not on the polarity of the polymer. Use of detergents as model carboxylate compounds leads to overestimation. The danger in using mixed-bed resins for cleaning polymer latices to process polymers for end group study by the dye partition method has been pointed out.
TL;DR: In this paper, the enthalpies of formation of complexes of bivalent manganese, nickel and cupric ions with phthalate ion were determined by direct calorimetry and the results were compared with those derived earlier from temperature coefficient of K values.
TL;DR: In this article, the theoretical expressions for magnetic susceptibility of Fe2+ ion in a tetrahedral environment have been derived on the basis of the more general molecular orbital method of Van Vleck, Stevens and Bose et al., considering quantum-mechanical tunneling which links the equivalent vibronic states of the Jahn-Teller ions.
TL;DR: In this paper, the preparation and properties of nitrato complexes of nickel(II) with substituted aryl(acyl-)thiocarbazides are described.
TL;DR: In this paper, the S-wave potential in momentum space, corresponding to a local two-body central short-range potential may be expanded in separable form with the help of suitable quadrature formulae.
TL;DR: In this paper, the trace of the product of an arbitrary number of Pauli matrices is determined for the case where terms of the type σi1σi2...σin occur in both traces.
Abstract: Several methods for the determination of the trace of the product of an arbitrary number of Pauli matrices are established. Formulae are derived for the evaluation of various types of products of two traces when terms of the type σi1σi2...σin occur in both of them. Expressions are found for the product of two different traces and the square of the trace of an arbitrary number of Pauli matrices. Similar formulae are obtained when Dirac matrices occurring as\(\sum\limits_{i = 1}^5 {\gamma _i A_i } \) are considered instead of Pauli matrices. From this all previous results in which γ5 has been considered separately are recovered. A useful identity for traces involving either Pauli or Dirac matrices is given.