Decalin Solutions Research Articles

Dielectric relaxation in benzotrihalides at microwave frequencies

Abstract The permittivity and dielectric loss of benzotrifluoride and benzotrichloride in benzene and decalin solution have been measured at four microwave frequencies viz., 30.25, 24.50, 18.26 and 9.83 GHz and also at 1 MHz and optical frequency at 35°C. The permittivity and dielectric loss at different frequencies have been plotted against concentration in wt. fraction. The slopes of these straight lines have been used for complex plane plots (a″ vs a′. The dispersion locus for the main dispersion region for both compounds in benzene and decalin are Debye semicircles. The values of relaxation times for overall rotation (τ 1) and group rotation (τ2) have been found out and reported. Whereas τ1 is found to be viscosity dependent, τ2 is practically independent of viscosity. The relaxation time for group rotation has been found to vary with the frame to which it is attached. Dipole moments of the compounds in both benzene and decalin have been reported.

Pyrolysis of Aryl Azides. IX. Azomethines as Weak Neighboring Groups

The following rates of pyrolysis (relative to azidobenzene at 120°) have been measured in decalin solution: 2-azidobenzaldehyde, 28.8; 2-azidobenzylideneaniline, 59.5; 2-azidobenzaldehyde phenylhydrazone, 8.9; 2-azidobenzaldehyde oxime O-methyl ether, 1.3;2-azidoacetophenone oxime O-methyl ether, 23.4; 2-azidobenzophenone phenylhydrazone, 9.7. It is argued that these relative rates are largely determined by the extent to which the ortho substituent is in the reactive conformation for an electrocyclic process. Indazoles substituted on N2 are isolated from pyrolysis of those azides with ortho-azomethine substituents.

Intramolecular ene reaction of the unsaturated acyloin 3-(but-3-enyl)-2-hydroxy-3-methylcyclohexanone

The ene reaction of the title compound takes place readily in decalin solution under reflux and affords the isomeric octahydroinden-4-ones (6) and (7).

Pyrolysis of Aryl Azides. VIII. Hammett Correlations of Rates of Pyrolysis of Substituted 2-Azidobenzophenones

Eight 2-azidobenzophenones with 4- or 5-substituents have been pyrolysed in decalin solution to yield 3-phenyl-2,1-benzisoxazoles. Rate values at 100° are correlated with the Hammett substituent constants, with respect to both the azido (A) and benzoyl (B) reaction centres , and yield the equation log k = -4.38 + 2.08σ-/A -1.52σB. There is a similar equation for rates measured at 120°. Although nitro and benzoyl differ considerably in their neighbouring group abilities in azide pyrolyses, it is concluded that they exert their effects through the same mechanism. The results are consistent with both published variants of an electrocyclic mechanism (Dyall; Smith, Budde and Chou).

Growth kinetics of polyethylene single crystals from dilute solution at low supercoolings

The growth rate of polyethylene single crystals is investigated in n-octane and decalin solutions for a wide range of supercoolings and concentrations. Transitions in the dependence of growth rate on supercooling and concentration are found to occur at relatively low supercooling. The transitions cannot be explained as transitions from regime II to regime I. They are discussed in terms of the effect of an impurity on the growth process: travelling steps are interrupted by an impurity on the steps. The origin of the impurity is discussed. A low molecular weight fraction segregated from the growth face or a small loop defect along the crystallizing chains will behave as an impurity. The lateral habit obtained in n-octane solution at lower supercoolings is somewhat rounded on the {100} face. The rounding of the habit is also discussed as an impurity effect.

Molecular Weight Dependence on the Morphological Properties of Polyethylene Gels

Polyethylene gels were prepared by gelation/crystallization from dilute decalin solutions using five kinds of polyethylenes with different molecular weights and degrees of branching. The decalin was allowed to evaporate from the gels under ambient condition in order to prepare dry gels. The dry gel of ultra-high molecular weight polyethylene (UHMWP) of Mw=6×106 forms a film but the other low molecular weight polyethylenes (LMWP) with molecular weight lower than 3×105 do not form a film. In order to investigate such a difference, the morphological properties of five kinds of dry gels were investigated by scanning electron microscopy, polarized microscopy, small angle light scattering, and small angle X-ray scattering. Within LMWP dry gels, observation reveals spherulitic textures whose crystal lamellae are rotated around a radial direction. In contrast, within the dry gels of UHMWP, there exists rodlike textures as assemblies of large lamellar crystals which are highly oriented with their flat faces parallel to the film surface. To assure ultradrawing up to consistently high draw ratio, a suitable number of entanglements should be formed by tie molecules which connect the crystal lamellae.

HYDROLYTIC AND RADIOLYTIC DEGRADATION OF OCTYL(PHENYL)-N,N-DIISO-BUTYLCARBAMOYLMETHYLPHOSPHINE OXIDE AND RELATED COMPOUNDS

ABSTRACT The hydrolytic and radlolytic degradaton of octyl(phenyl)-N,N-dIIsobutylcarbamoylmethylphosphine oxide [0ϕD(lB)CMPO] has been investigated by measuring the distribution ratio of Am, D., between degraded organic solutions and aqueous solutions of selected HN03 concentrations and by measuring the concentration of OϕD(IB)CMPO In degraded solution using gas chromatographic analysis. Hydrolysis was performed by continuous stirring of decalin and CCH solutions of 0ϕD(lB)CMP0 with 5 M HNO3 at 50°C. Radiolysis was performed in a similar manner while irradiating the biphasic system with gamma rays from a 60Co source. From the experimental data, evidence was obtained for a degradation scheme of 0ϕD(iB)CMPO which Involves the formation of methyl(octyl)-(phenyl)-phosphine oxide (MOϕPO) and octyl(phenyl)phosphinic acid (H[0ϕP]). The proposed degradation scheme has been experimentally verified by measuring DAm from mixtures of MOϕPO and OϕD(iB)CMPO and of H[ϕP] and OϕD(iB)CMPO. Evidence was found that MOϕPO ca...

Pyrolysis of Aryl Azides. VI. Identification of Neighbouring Group Effects in Pyrolysis of Azidopyridines and Azidoquinolines

Although there are literature reports of anomalous behaviour on pyrolysis of ortho-nitroazido-pyridines and ortho-nitroazidoquinolines, we find that these compounds cyclize to the expected furazan 1-oxides in near-quantitative yields, and with a high degree of neighbouring group participation by the nitro group. Kinetic studies in decalin solution reveal the following rate enhancements by the ortho-nitro group: 3-azido-2-nitropyridine, 466 at least; 4-azido-3-nitropyridine, 5400; 4-azido-3,5-dinitropyridine, 640; 4-azido-3-nitroquinoline, 82.4; 5-azido-6-nitroquinoline, 27.6; 2-nitro-1-azidonaphthalene, 12.7. The unstable furazan oxide, [1,2,5] oxa-diazolo [3,4-c]pyridine 1-oxide, has now been characterized. [1,2,5] Oxadiazolo [3,4-b]pyridine 1-oxide decomposed in decalin at 145° to give products indicative of a nitrene intermediate.

Dielectric spectra of supercooled halogenobenzene-decalin solutions: A single particle site model for relaxation and resonant behaviors

Dielectric loss spectra for 10% V/V decalin solutions of PhBr, PhCl, and PhF have been measured using a precision, coaxial three-terminal cell at temperatures from 77 to 150 K and for a frequency range 200 Hz–5 MHz. These results which are in agreement and which extend previous measurements, are interpreted within the context of cosinal itinerant oscillation. Data for PhBr decalin are simulated using a model of a single Brownian particle rotating in the presence of a cosinal potential, which is a special case of the cosine itinerant oscillator model.

Determination of the first and second normal stress differences in the truncated-cone-and-plate apparatus

The steady state radial pressure distribution in the truncated cone-and-plate (TCP) apparatus has been measured for a highly elastic polyisobutylene solution in cis-trans decalin (MW=4300 kgmol−1 MW/Mn=2) at eight shear rates from 1 to 270 s−1 and temperatures of 3.0, 20.0, 30.0 and 46.0° C. The slope of pressure, corrected for inertia by the classical formula, versus the logarithm of radius provides a combination of normal stress differences N1+2N2 with a typical experimental scatter of 1 % at all measured temperatures and shear rates. The plots of N1+2N2 versus shear rate can be shifted, without loss of accuracy, by means of the time-temperature superposition principle, the shift factors strictly adhering to a WLF equation. Extrapolated rim pressures, when corrected for elastic hole pressure with a theoretical equation, give values of the second normal stress difference with typically less than 10 % of experimental scatter. Contrary to previous analyses of the TCP apparatus, the center-hole pressure is found to give a useful estimate of the second normal stress difference, although there are insufficient data at present to perform the differentiation of a nonlinear function required in the analysis of the data. Instrument imperfections are reviewed briefly in the Appendix.

Mean square torques from far infrared spectra

The moment analysis of far infrared spectra is used to estimate mean square torques for some dipolar solutes in decalin solution. These are compared with some model dependent values of Reid and Evans.

Broad Shear Range Viscometry of High Polymer Solutions: Polystyrene and Polyisobutene in Decalin

The flow behavior at 25°C for decalin solutions of polystyrenes (PS) of molecular weights up to 7×106 and polyisobutenes (PIB) of molecular weights up to 3×106 was examined over a wide range of shear rate up to about 105 sec−1 for several polymer concentrations. Measurements involved conventional glass capillary viscometers, a Rheometrics Mechanical Spectrometer, and custom‐built high‐shear concentric cylinder viscometer. Low‐shear Newtonian viscosities for the higher concentration entanglement region follow the forms η0=CM0.57 for PS and η0=CM0.68 for PIB. Gel permeation chromatography was used to determine polymer molecular weight, its distribution, and possible change on shearing. Shear degradation was observed for polymers at high values of concentration, molecular weight, and shear stress.

Pyrolysis of aryl azides. V. Characterization of phenylazo, benzoyl and formyl as neighbouring groups

The enhancements of thermolysis rate of azidobenzene produced by ortho phenylazo, benzoyl and substituents are 21180, 70.0 and 22.8 at 393.2 K (decalin solutions). The same ortho substituents produce much smaller enhancements (169, 8.56 and 10.7 respectively) in the pyrolysis rate of 1-azido-2,4-dibromobenzene. These results are interpreted as steric effects on an electro-cyclic thermolysis mechanism, and are not consistent with the alternative pathway of intramolecular 1,3-dipolar addition which continues to be advocated by Hall and Dolan.

Dynamic Viscoelastic Behavior of the Solutions of Styrene-Butadiene Block Copolymers

The behavior of block copolymer solutions may be highly different from that of homopolymer solutions, because of the microdomain structures formed in the systems.The behavior of decalin solutions of a PS-PB-PS and a PS-PB block copolymers were similar to that of homopolymer solutions corresponding to the homogeneity of the systems. However, in the decane solutions, the PS-blocks aggregated to form precipitated domains, then a quasi-network structure was formed in the former while a micelle structure in the latter. Corresponding to such structures, the former showed a behavior similar to crosslinked rubbers and the latter a plateau region in G″ in the lower frequency range.For SB/SBS blend systems dissolved in n-tetradecane, the difference between the micelle and quasi-network systems became more prominant when the nonlinearity of the systems was compared. While the quasi-network system showed the rubberlike linear viscoelasticity, the micelle system showed nonlinear behavior, in which odd harmonics appeared in shear stress, the fundamental harmonics had a plateau region, and the nonlinearity of the system decreased as the frequency increased.These characteristic behavior of the micelle system can be understood as a Bingham-type viscoelastic behavior. The difference between the micelle and the quasi-network systems seems to be caused by the restriction from the microdomain structures that the shear flow occurs in the former by slipping aggregated PS domains with each other, while it does not in the latter without breaking the PS domains.

Molecular and group relaxation studies in parasubstituted benzenes in various media

Dielectric absorption studies have been made on molecules of the type [Formula: see text][Formula: see text] where X—Y is —OCH3, —COCH3, —CH2Cl, and —CH2CN. The molecules have been dissolved in (a) a polystyrene matrix and (b) in the viscous liquid o-terphenyl. For 1,4-dimethoxybenzene the group process dominates in both media, and estimates have been made of the activation enthalpy for group relaxation. For 1,4-dimethoxybenzene in benzene, decalin, Nujol, and o-terphenyl solutions, however, there appears to be a small contribution from the molecular process. No such contribution was detected in the matrix studies on this solute molecule. For 1,4-diacetylbenzene, 1,4-bis(chloromethyl)benzene, and 1,4-bis(cyanomethyl)benzene in o-terphenyl solution it again seems that the group and molecular processes overlap. However, in polystyrene the enthalpies of activation which emerge are characteristic of the group relaxation process as determined by the nmr approach. Altogether, the work illustrates that o-terphenyl may be a useful solvent in helping to decide whether a solute has contributions from an intramolecular motion.

Kinematic and electrodynamic interpretations of molecular motion in glasses

Abstract The development of a Smoluchowski equation for the evolution of the probability density of angular molecular motion in the condensed phase is considered in terms of kinematic and electrodynamic models. These are equivalent in some cases (i.e. two or more different interpretations may be assigned to the same equations of motion) so that wide ranges of environment and frequency are needed to distinguish between the different models. Therefore data over about ten or more decades of frequency have been used in the glassy and liquid environments of decalin solutions in order to illuminate the paths along which development of the basic formalism (due to Budo) should proceed. The overall features of the experimental loss profile may be reproduced even in the glassy state but only by imposing severe constraints on the model parameters as they stand at present. These are more acceptable in a kinematic rather than electrodynamic interpretation of the Smoluchowski equation.

Model predictions of mean librational frequencies for rigid molecules in dilute decalin solution

The product of the reduced inertia J r of a dipolar molecule and the square of the far infrared absorption maximum wave-number ν max that it displays in dilute solution is shown, using a three-parameter Mori/itinerant oscillator model, to be related to the mean-square action on the molecule and hence by a simple argument to the solute volume of rotation V. Estimates of V have been made for seventeen rigid molecules (mainly substituted phenyls) and their ν max values have been measured in decalin solution at 293 and 110 K. Provided allowance is made for translation—rotation coupling in four cases, the derived relation I r ν 2 max = (8a a 2 c 2 kT) −1 V 2 P(0) is found to be approximately obeyed at both temperatures with P(0) (the solute-independent mean-square torque acting on a molecule of unit V) having a value of 4.0 × 10 17 (N m −2) 2 at both temperatures. It should now be possible to predict μ max for other solutes in decalin if their structures are known.

Viscoelastic properties of linear chain macromolecular gels. Growth of stress at the onset of steady shear flow

AbstractThe growth of stress (shear stress and normal stress) at the onset of steady shear flow was investigated for linear chain macromolecular fluids to determine nonlinear viscoelasticity. The polyacrylamides (PAAm) were dissolved in H2O, formamide and ethyleneglycol. The polymers were prepared in this laboratory. They were unbranched and free of initiator. The polystyrene (PS) samples from Pressure Chemical Company were studied in decalin solutions. PAAm shows increasingly typical gel character—in all 3 solvents—with increasing molecular weight and polymer concentration. For homogeneous systems gel fracture and undershoot were observed. Further for the first time overshoot due to entangled molecules and overshoot due to energetically associated chains have been distinguished. This behaviour is a strong contrast to the PS/decalin system and demonstrates the strength of the second valence bondings in the PAAm‐systems.

Intramolecular Rotation in Some Trihalogenated Esters at Microwave Frequencies

The permittivity and dielectric loss of methyl, ethyl and n-propyl trichloroacetate in decalin solution have been measured at four microwave frequencies viz., 30.20, 24.50, 18.26 and 9.83 GHz and also at 1 MHz and optical frequency at 35 °C. The permittivity and dielectric loss at different frequencies have been plotted against concentration (wt. fraction). The slopes of these straight lines have been used for complex plane plots (a″ vs a′). The dispersion curves which could not be resolved in benzene could be resolved in decalin due to the increase in viscosity of the solvent. Data have been analysed in terms of two relaxation processes i.e., overall rotation and group rotation.

Relationship of temperature to composition of copolymers of α-methylstyrene and maleic anhydride

Alternating copolymers of α-methylstyrene and maleic anhydride were prepared in good yields in a decalin solution at temperatures below 80°C. Random copolymers with large percentages of α-methylstyrene were obtained in good yields at higher temperatures. These results were in accord with the charge transfer complex which was characterized by n.m.r. and u.v. spectrophotometry and shown to exist below 80°C. The copolymers were characterized by pyrolysis/gas chromatography and differential scanning calorimetry. The glass transition temperature of poly(α-methylstyrene) and the random copolymer of this monomer and maleic anhydride were approximately 450 and 458 K respectively.