Radical reactions involving esters of fumaric acid—III. Chain transfer processes

Model compounds have been used in studies at 60° in connection with transfer to polymer during the copolymerization of vinyl acetate with esters of fumaric acid. Succinate esters were used to simulate the fumarate ester units and ethyl acetate the vinyl acetate units in the copolymers. The succinate esters are much more reactive than ethyl acetate in transfer reactions with polyvinyl acetate radicals. Methyl isobutyrate and methyl propionate were also examined to assess the difference in reactivity in transfer of tertiary and secondary hydrogen atoms. It is concluded that branching is a very important reaction in the preparation of high conversion copolymers of fumarate esters with vinyl acetate.     

Über den Dissoziationszustand von geschmolzenem Natriumdiwolframat (Na2W2O7)

Kordes and Nolte are of the opinion that, on melting, Na₂W₂O₇ dissociates according to the reaction whereas Gelsing et al. assume a dissociation into Na⁺ ions and a mixture of chains of WO₄ tetrahedra (WO, W₂O, W₃O, etc.). In the present paper it is demonstrated that a dissociation according to the ideas of Gelsing et al. can excellently explain the cryometric results found by Kordes and Nolte themselves. The dissociation scheme proposed by Gelsing et al., is even more likely than that proposed by Kordes and Nolte when the results of surface tension measurements reported by Gossink and Stevels are taken into account.     

Potentiometric studies of ternary complex formation Cu(II), Ni, Zn or Cd iminodiacetic acid/amino-acid complexes

The formation constants, log K(mab), for the reactions MA + B right harpoon over left harpoon MAB [where M = Cu(II), Ni, Zn or Cd, A = terdentate ligand and B = bidentate or terdentate ligand] have been determined. Potentiometric evidence is presented for the stepwise addition of the secondary ligand B to the 1:1 metal iminodiacetate (MA). The formation constants and the free energies of formation (DeltaG) have been calculated at 25 +/- 1 degrees and mu = 0.10. The order in terms of secondary ligands has been found to be ASPA > Gly > Aln and Gly > Aln > ASPA with iminodiacetic and nitrilotriacetic acid as primary ligands respectively (ASPA = aspartic acid, Gly = glycine, Aln = dl-alanine). The plot of log K(mab) against log k(mb)(2) shows a linear relationship between the formation constants of the ternary and 1:2 M(II)secondary ligand complexes.     

Force Constants and Bond Orders of Nitrogen Bonds

The force constants and the corresponding bond orders of nitrogen bonds have been calculated from the vibrational spectra (infrared and Raman spectra) of a great number of nitrogen compounds. Plotting the maximum bond order of stable nitrogen bonds against the sum of Pauling's electronegativities of the bonding partners (Σx) leads to one continuous curve for the N? X bonds where X represents elements of the first and the second short period of the periodic table. Furthermore, when the bonds formed between these elements are arranged in a coordinate system in such a way that the position of each bond is determined by the difference between the electronegativities of the bonding partners (Δx along the ordinate) and the sum of the electronegativities of the bonding partners (Σx along the abscissa), the bonding partners capable of forming multiple bonds all lie within a closed domain, where their position can be correlated with their polymerizability and other reactivities of the multiple bonds. Also discussed are the orders of bonds between nitrogen and some transition elements. In an appendix, the present methods used to calculate force constants and bond orders are surveyed.     

Ab initio MO-SCF calculation on a model of anomalous water

Ab initio calculations are carried out on the planar hexamer model of anomalous water using a variety of basis sets. The results are compared to results of similar calculations on free water and water in the ice I-like puckered ring configurations.

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Zusammenfassung Es werden ab initio-Rechnungen für das planare Hexamer-Modell von anomalem Wasser unter Verwendung mehrerer BasissÄtze durchgeführt. Die Ergebnisse werden mit Resultaten Ähnlicher Rechnungen über freies Wasser und Wasser in der I-Eis Ähnlichen Konfiguration verzerrter Ringe verglichen.

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Résumé Calculs ab initio sur le modèle hexamérique plan de l'eau anormale en utilisant différentes bases. Les résultats sont comparés à ceux de calculs similaires sur l'eau libre et sur l'eau dans une configuration cyclique compacte analogue à celle de la glace I.

     

Structure and conformational isomerism of the major dimer of 2,3-naphthoquinodimethane

The major product from 2,3-naphthoquinodimethane formed by cyclisation of $\text{o}$-dipropadienylbenzene was found to be the dimer 5 containing an eight-membered ring, for which the inversion barrier was determined by dynamic ¹H NMR spectrometry, ΔG3 = 18 kcal/mole.     

Rearrangements of organometallic compounds : XVII. Synthesis of lactones via the titanium-catalyzed hydromagnesiation of alkenols

An efficient, two-step synthesis is presented for preparing γ- and δ-lactones from aldehydes or ketones. (1) the addition of vinyl- or allyl-Grignard reagents to the appropriate carbonyl substrate; and (2) the titanium-catalyzed hydromagnesiation of the resulting alkenols with ethyl Grignard reagent and (η⁵-C₅H₅)₂TiCl₂, followed by carbonation. The selectivity of hydrometallation observed with 3-butenyl(methyl)vinylcarbinol indicates the importance of alkoxytitanium hydrides in determining the course of reaction.     

Simultaneous observation of coherent and incoherent resonant re-emission in the condensed phase

We report simultaneous observation of coherent resonance Raman scattering and incoherently broadened resonance fluorescence following excitation of cytochrome c in the α(0, 0) region. The influence of incoherent broadening processes on resonance Raman scattering experiments is considered.     

Analysis of DTA curves and calculation of kinetic data using computer technique

Principles of two computer programs useful for the evaluation of heterogeneous kinetics are described.The first program ALANTA allows to obtain the non-isothermal kinetic curve from the shape of general DTA peak using the DTA-equation derived elsewhere¹.The second program SQUEST determines the kinetic mechanism which is the most appropriate to a given non-isothermal kinetic curve and evaluates the corresponding kinetic parameters. The program decides between 19 kinetic models and uses both integral and differential methods of evaluation.     

Distribution of polymer deposition in plasma polymerization. III. Effect of discharge power

Distribution of polymer deposition in an inductively coupled rf discharge system is studied as a function of level of discharge power with acetylene and styrene as monomers. When a fixed flow rate is used, the discharge power has a relatively small effect on the pattern of distribution of polymer deposition as long as values of W/FM, where W is discharge wattage, F is flow rate, and M is molecular weight of monomer, are maintained above a critical level to maintain full glow in the reaction tube. It has been shown that plasma polymerization of two monomers which have different molecular weights can be compared in a fair manner by selecting conditions to yield similar value of W/FM.