Browsing by Subject "Benzene"
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Item A kinetic study of the acid catalyzed benzidine rearrangement of 2,2'-hydrazonaphthalene(Texas Tech University, 1961-08) Burdick, Stanley JohnNot availableItem Parallel computation of analytic second derivatives with applications to benzene and [10]annulene(2009-05) Price, David R.; Stanton, John (John F.); Stanton, John (John F.); Rossky, Peter J.; Makarov, Dmitrii E.; Anslyn, Eric V., 1960-; Milfeld, Kent FrancisCCSD(T) has been used in the past to accurately predict compute the spectra and structures of small molecules. However, the large execution times required for these calculations has limited their use in larger molecules such as benzene and [10]annulene. The parallelization of analytic second derivatives of post Hartree-Fock methods, including CCSD(T), has enabled the VPT2+D treatment of the vibrational states of benzene. The fundamental frequencies and infrared active two quantum transitions that result are within 20 cm⁻¹ of the experimental values when treated for Fermi and Darling-Dennison resonances and empirical estimates for the harmonic frequencies and equilibrium bond lengths are determined to be within 12 cm⁻¹ and 0.004 Å of the values at the CCSD(T)/ANO2(fc) level of theory. The parallelization also facilitated the identification of two candidates for the structures of two isomers of [10]annulene. The harmonic frequencies of several conformations proposed in the literature were computed at the CCSD/DZP level of theory with five of the conformations being ground states. The NMR shifts of four of these structures were computed using CCSD(T)/tzp and conformation 6(C₂ "twist") was identified as the likeliest structure for one of the isomers isolated. The remaining compound was identified as conformation 2b(C₂ "boat") due to a low conformation barrier and the proximity of its average NMR shifts to experiment. The identification of both compounds rely on properties computed using analytic derivatives not entirely on the relative energies of optimized geometries.Item Thermodynamics of benzene sorption in polyethylene oxide(Texas Tech University, 1977-05) Chaing, Hin-ShaingThe solubility of benzene in poly(ethylene oxide) has been determined using the piezoelectric sorption method at 64.5°C, 70.6°C and 74.6°C over the concentration range 3 to 36 wt % benzene. The solubility results determined in this study are in excellent agreement with those obtained by a static method at 70°C and by gas-liquid chromatography at 75.1°C. The weight fraction activity coefficient of benzene varies directly with temperature and inversely with increasing benzene concentration. The activity data of benzene are well correlated by the corresponding-states solution theory of Prigogine and Flory. The observed negative partial molar enthalpy of benzene indicates that the poly(ethylene oxide)-benzene solution is exothermic at 67.55°C and 72.6°C. Negative partial molar entropy of benzene, observed in the poly(ethylene oxide)-benzene solution at 67.55°C and 72.6°C, indicates ordering in the solution.