Dynamic-mechanical properties and melting points of some aliphatic and partially aromatic polyamides

Some aliphatic and partially aromatic polyamides have been prepared from hexamethylene diamine and the following dicarboxylic acids: deca-, octa-, hexa-methylenedicarboxylic, p-carboxymethylphenoxyacetic, p-carboxyethylphenoxyacetic, p-phenylenedipropionic, p-phenylenediacetic, p-carboxymethoxyphenoxyacetic, β(p-carboxymethyl)phenylpropionic.The dynamic-mechanical properties at 110 Hz have been measured between ?140° and about 200. Three relaxation processes α β and γ have been found: only the main transition α appreciably depends on chemical structure.The influences of the length of repeating unit and of in-chain substitution on melting points, crystallinity and the dynamic-mechanical α transition have been investigated. The results have been discussed in terms of chain flexibility, chain packing and intermolecular forces.     

Synthesis and free-radical polymerization of water-soluble acrylamide monomers

Water-soluble acrylamide monomers N-(hydroxymethyl)acrylamide, N-(hydroxymethyl)methacrylamide, N,N-diethanolacrylamide, N,N-diethanolmethacrylamide, N,N-methylethanolacrylamide, and N,N-methylethanolmethacrylamide have been synthesized and characterized. The kinetics and thermodynamics of the free-radical polymerization of these monomers and of the model compounds N-isopropylacrylamide and acrylamide have been studied by the methods of isothermal and scanning calorimetry. The structure and the solubility of the said polymers in water and organic solvents have been investigated and their molecular-mass characteristics and temperatures of glass transition (T _g) and melting (T _m) have been examined by DSC, liquid chromatography, ¹H NMR and IR spectroscopy, and chemical analysis of functional groups. Hydrogels and amphiphilic network polymers based on acrylamide monomers have been prepared and characterized.     

Ab initio studies of the structures and force fields of ketenimine and related molecules

Theoretical equilibrium geometries for ketenimine, aminoacetylene and ethynol have been obtained using the MP3/6-31G** ab initio method. Empirical scaling factors have been introduced to estimate the rotational constants A_o, B_o and C_o. In addition the complete harmonic force fields for ketenimine, ketene and diazomethane have been computed, normal coordinate analyses have been performed and the quartic centrifugal distortion constants estimated.     

Volumetric studies and thermodynamics of viscous flow of hydroxamic acids in acetone + water solvent at temperatures 303.15 and 313.15 K

Densities ρ and viscosities η of two hydroxamic acids, N-phenyl-2-chlorobenzo- and N-o-tolyl-4-chlorobenzo-, have been determined as a function of their concentration in aqueous acetone solution at temperatures 303.15 and 313.15 K. Apparent molar volumes, standard-state partial molar volumes and relative viscosities have been calculated. The viscosity data have been analyzed using Jones-Dole equation. The activation thermodynamic parameters of viscous flow have been evaluated using Feakins equation. These were obtained to throw light on the mechanism of viscous flow. Thermodynamic interactions in solutions have been studied in terms of a number of excess functions calculated from the experimental data. The effect of hydroxamic acid concentration and temperature on these parameters has been discussed. The results were interpreted in the light of solute-solvent interactions in aquo-organic media.     

Viscosities of Binary Liquid Mixtures of 2-Methylpropane Nitrile and Some Aromatic Hydrocarbons at 303.15 K and 308.15 K

Viscosities, ??, of five binary mixtures of 2-methylpropane nitrile with aromatic hydrocarbons, viz. benzene, methylbenzene, 1,4-dimethylbenzene, chlorobenzene and 1,2-dichlorobenzene, have been measured at temperatures 303.15 and 308.15?K. Deviations in viscosities, ????, from the linear mixing rule have been determined for all of the binary mixtures studied at both experimental temperatures. The ???? values are negative for all the five systems at both experimental temperatures. Parameters of the Redlich?CKister and Myers and Scott equations have been fitted to the ???? values and standard deviations, ??(????), have also been evaluated. The correlating performances of several viscosity models have been evaluated. The Hind?CMcLaughlin?CUbbelohde viscosity model gives fairly constant interaction parameters with composition. Results are discussed in terms of unlike molecular interactions between the components of the binary mixtures.     

Chiral ferrocenyl diphosphines for asymmetric transfer hydrogenation of acetophenone

The synthesis of new optically pure ferrocenyl diphosphines have been realized from (R)-(+)-N,N-dimethylaminoethylferrocene. Particularly, dissymmetric ferrocenyl diphosphines have been synthesized. The diphosphines have been used as ligands in asymmetric transfer hydrogenation of acetophenone in the presence of Ru catalysts.     

The microwave spectrum,structure and centrifugal distortion constants of 2-chloroacrylonitrile

The microwave spectrum of 2-chloroacrylonitrile has been studied in the 26.5–40 GHz region. A total of 99 a- and b-type rotational transitions have been measured and assigned for CH₂ =C³⁵Cl(CN),yielding values for the rotational constants (in MHz): A = 6973.27, B = 3148.16, C = 2165.95. For CH₂=C³⁷Cl(CN) a total of 53 transitions have been measured and assigned and the rotational constants obtained are (in MHz): A = 6909.35, B = 3081.17, C = 2127.98. The distortion effects have also been studied and the quartic distortion constants have been evaluated. From the observed hyperfine structure, the chlorine nuclear quadrupole coupling constants have been obtained. The structure of vinyl cyanide and vinyl chloride can be transferred to account remarkably well for the observed rotational constants.     

Viscosities and activation energies of flow of mixtures containing 1,2-dibromoethane

The viscosities of the mixtures of 1,2-dibromoethane + cyclohexane, + benzene, +toluene, +o-xylene, +m-xylene, and +p-xylene have been measured at 298.15 and 308.15 K as a function of composition. The viscosity data have been analysed in the light of approaches developed by Hind and Grunberg . Using Eyring kine- matic scheme the viscosity data have been employed to calculate activation energies of flow.     

Molecular-dynamics simulation of the structural stability,energetics, and melting of Cu n(n = 13–135) clusters

Cluster properties of copper have been investigated using the Molecular-Dynamics md technique. The structural stability and energetics of spherical Cu_n (n = 13–135) clusters have been investigated at temperatures T = 1 K and T = 300 K. It has been found that the average interaction energy per atom in the cluster decreases and reaches an asymptotic value as cluster size increases. The melting behaviour of clusters n = 13 and n = 55 have been investigated. It has been found that the melting temperature decreases as cluster size increases, and for clusters with multishell structures melting starts from the outermost shell. In the simulation an emprical potential energy function (PEF) proposed by Erkoç has been used, which contains two-body atomic interactions.     

Isotope shift studies and electronic configuration assignments to the energy levels of neutral erbium

Isotope shifts ΔT (170-166) have been evaluated for 54 even and 94 odd energy levels covering almost all the known configurations of the neutral erbium. These ΔT values have been derived from the isotope shift measurements carried out in 159 lines in the region 3900–4605 A using a Fabry-Perot spectrometer and liquid-air-cooled hollow cathode source with highly enriched ¹⁷⁰Er and ¹⁶⁶Er isotopic samples. Electronic configurations assigned to energy levels of Er I by earlier workers have been mostly confirmed and in few cases revisions have been suggested on the basis of observed ΔT values. Probable configurations have been also suggested for unassigned levels of Er I, and a large number of even levels could be assigned to 4f¹¹ 5d 6s 6p configuration.     

Organometallic oxime and allied derivatives II. Synthesis and properties of some tri-n-butylgermanium oximates

Tributylgermanium oximates have been prepared by reactions (a) of tributylgermanium chloride with (i) oximes in the presence of a base, (ii) sodium oximates, and (iii) organotin oximates, as well as (b) of tributylgermanium ethoxide and oxide with oximes.The derivatives have been characterised by elemental analyses, molecular weight measurements and IR spectra. Their reactions have been studied in detail.     

Vibrational spectra,methyl torsional potential functions,internal rotational potential functions,and conformational properties of ethyl vinyl ether

The vibrational spectra of ethyl vinyl ether in both the fluid and solid states have been recorded from 20 to 3500 cm^?1. The 33 fundamental modes of vibration have been assigned. Three rotational isomers have been observed and their structures have been determined. The most stable conformer, s-cis/s-trans, is planar and of C_s symmetry. The two less stable rotamers, skew/s-trans and skew/gauche, are non-planar and of C_i molecular symmetry. The barrier to internal rotation of the methyl rotor has been determined for each conformation; these barriers are 3.43 kcal mol^?1 (s-cis/s-trans), 3.35 kcal mol^?1 (skew/s-trans) and 3.19 kcal mol^?1 (skew/gauche). A potential function for each of the two asymmetric internal rotations has been calculated and barriers to conformer interconversion have been determined. From the asymmetric potential function calculations, ΔH, the enthalpy difference between the conformers, has been determined. The s-cis/s-trans conformer is 1.87 kcal mol^?1 more stable than the skew/s-trans conformer; the skew/s-trans conformer is more stable than the skew/gauche conformer by 1.10 kcal mol^?1. The energetics of conformer interconversion and methyl internal rotation have been described in terms of molecular geometry and non-bonded interactions. These results are compared to those found in other alkyl vinyl and dialkyl ethers.     

The suitability of various calcium electrodes based on metal salts of di-(n-octylphenyl)phosphoric acid and some derivatives for the measurement of calcium in sea water

The calcium salts of di-(n-octylphenyl)-phosphoric acid, di-(p-n-octyl-o-nitrophenyl)-phosphoric acid and di-(p-n-octyl-o-bromophenyl)-phosphoric acid have been investigated as calcium sensors in membrane electrodes. The electrodes have been used for potentiometric titrations of calcium in sea water. The effect of varying the membrane solvent and the chelate metal has been studied.     

Thermodynamics of undecanolactone,tridecanolactone, and pentadecanolactone from 0 to 340 K

The heat capacities C_p^o of undercanolactone, tridecanolactone, and pentadecanolactone have been measured between 10 and 370 K in a vacuum adiabatic calorimetric cryostat within about 0.2 per cent. The temperatures and enthalpies of physical transitions have been also estimated. The enthalpies of combustion of the compounds have been measured in an isothermal calorimeter with an accuracy of 0.05 per cent. From the results the functions {H (T) ? H (0)}, S^o(T), and {G^o(T) ? H^o(0)} have been calculated over the range 0 to 340 K, and the values of ΔH_f^o, ΔG_f^o and ΔS_f^o have been evaluated at T = 298.15 K.     

Terpenoids of the oleoresins ofPicea orientalis andAbies normanniana growing in the Caucasus

The terpenoid compositions of the oleoresins of the oriental spruce and of the Nordmann fir growing in the Caucasus have been studied. From the oleoresin ofPicea orientalis (L.) Link, which belongs to the sectionOmorica, 32 mono-, sesqui-, and diterpene compounds have been identified, and fromAbies nordmanniana Stev. 37 mono-, sesqui, and diterpene compounds. Together with other diterpenoids that are characteristic for the oleoresins of all species of fir, methyl dehydroabietate and methyl 15-hydroxy dehydroabietate have been found in the oleoresin of the Nordmann fir. Three new sesquiterpene hydrocarbons have been isolated.     

Thermodynamics of weak interactions: Excess enthalpies of some binary bromoform mixtures

Excess enthalpies of bromoform + toluene, +o-xylene +m-xylene and +p-xylene have been determined at 308.15 K. These compounds have been examined for Barker's theory in order to understand the magnitude and nature of various interactions between the components of these mixtures. It has been concluded that the H-atom and one bromine atom of bromoform interact with the π cloud of the aromatic ring. These conclusions have been supplemented by n.m.r. studies. An approximate distance of the bromoform proton from the plane of the aromatic ring has also been calculated and examined in the light of the proposed geometry of the molecular complexes. Equilibrium constants for the complexations reaction have also been determined.     

Thermodynamic behaviour of some glycol—water mixtures. Excess and partial volumes

Densities of water—glycol (mono- di-, tri- and tetraethyleneglycol) mixtures have been measured over the entire composition range at 298. 15 K. Mixtures involving monoethyleneglycol (MEG) have also been studied at different temperatures from 308.15 to 288.15 K. Deviations, V^E, from ideal volumes of mixing have been calculated: negative values are observed for all systems. They increase with the number of ether functions present in the organic molecule; a slight dependence of V^E towards temperature has been shown in the water—MEG mixtures. Partial molal volumes have also been calculated for both components of each system; they exhibit an extremum in the water-rich region.     

Thermodynamic and lfer studies for the oxidation of anilines by the periodate ion

The various thermodynamic parameters for the periodate oxidation of six anilines, viz. aniline, p-chloroaniline, p-ethoxyaniline, o- and p-methoxyanilines and p-methylaniline have been reported and discussed. The validity of the isokinetic relationship and various linear free energy relationships (LFERs) have been tested and discussed. An attempt has been made to correlate these findings with the mechanism operative in these reactions.     

Study of densities,viscosities, and speeds of sound of binary liquid mixtures of butan-1-ol with n-alkanes (C6, C8, and C10) at T = (298.15, 303.15, and 308.15) K

The densities (ρ) and speeds of sound (u) have been measured over the whole composition range for (butan-1-ol with hexane, or octane, or decane) at T = (298.15, 303.15, and 308.15) K and atmospheric pressure along with the properties of the pure components. Viscosities (η) of these binary mixtures have also been measured over the entire composition range at T = 298.15 K. Experimental values of density, viscosity and speed of sound have been used to evaluate excess properties viz. excess molar volumes (V^E), deviation in viscosity (Δη), deviation in speeds of sound (Δu), deviation in isentropic compressibility (Δκ_s) and excess Gibbs free energy of activation of viscous flow (ΔG^1E). The excess properties have been correlated using the Redlich–Kister polynomial equation. The sign and magnitude of these excess properties have been used to interpret the results in terms of intermolecular interactions and structural effects. The viscosity data have also been correlated by Grunberg and Nissan, Tamura–Kurata, and Hind correlation equations.     

Retro-Mannich reactions of 3-alkyl-3,4-dihydro-2H-1,3-benz[e]oxazines and the synthesis of axially chiral resorcinarenes

Intermediates involved in the conversion of 3-alkyl-3,4-dihydro-2H-1,3-benz[e]oxazines into 2-N,N-dialkylaminomethylphenol derivatives, using morpholine and other high boiling secondary amines, have been identified and characterised. Additional experiments have established the involvement of o-quinone methide intermediates in the retro-Mannich reactions. Axially chiral resorcinarenes have been prepared by utilising the exchange reactions.