Journal of Physical Organic Chemistry

Cover image for Vol. 26 Issue 1

January 2013

Volume 26, Issue 1

Pages i–iii, 1–76

  1. Issue Information

    1. Top of page
    2. Issue Information
    3. Early Excellence Profile
    4. Research Articles
    1. Issue Information (pages i–iii)

      Version of Record online: 9 JAN 2013 | DOI: 10.1002/poc.3079

  2. Early Excellence Profile

    1. Top of page
    2. Issue Information
    3. Early Excellence Profile
    4. Research Articles
  3. Research Articles

    1. Top of page
    2. Issue Information
    3. Early Excellence Profile
    4. Research Articles
    1. Chemical and photochemical reactivity of 6-hydroxymethyl-7,8-dihydropterin in aqueous solutions (pages 2–8)

      Andrés H. Thomas, Esther Oliveros, André M. Braun, Mariela S. Espinosa, Carolina Lorente and M. Laura Dántola

      Version of Record online: 7 JUN 2012 | DOI: 10.1002/poc.2967

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      6-Hydroxymethyl-7,8-dihydropterin (H2Hmp) is an intermediate in the biosynthesis of folate. In aqueous solution in the presence of O2, H2Hmp undergoes slow thermal oxidation to yield 7,8-dihydroxanthopterin (H2Xap). Hydrogen peroxide oxidizes H2Hmp faster than O2, but the same main product is obtained. In contrast, UV-A irradiation of H2Hmp leads to the formation of a dimer.

    2. Nucleophilic substitution reactions promoted by oligoethylene glycols: a mechanistic study of ion-pair SN2 processes facilitated by Lewis base (pages 9–14)

      Ju-Young Kim, Dong Wook Kim, Choong Eui Song, Dae Yoon Chi and Sungyul Lee

      Version of Record online: 12 AUG 2012 | DOI: 10.1002/poc.3010

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      A new type of mechanism is described for SN2 reactions promoted by multifunctional n-oligoethylene glycols using alkali metal salts as nucleophilic agents. The nucleophiles react as ion pairs, whose metal cation is coordinated by the oxygen atoms in oligoEGs acting as Lewis base. The two terminal hydroxyl (−OH) function as ‘anchors’ to collect the nucleophile and the substrate in an ideal configuration for reaction. Calculated activation barriers are in excellent agreement with all experimentally observed trends of SN2 yields.

    3. A comparative study on the gas-phase and liquid-phase thermal isomerization reaction of α-pinene (pages 15–22)

      Jindong He, Yan Gong, Wentao Zhao, Xiangyang Tang and Xin Qi

      Version of Record online: 30 AUG 2012 | DOI: 10.1002/poc.3011

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      This work reports that the selectivity of ocimene obtained from pyrolysis of α-pinene in liquid phase is higher than that in gas phase. According to the model of pyrolysis reaction of α-, the conclusion is that the reaction molecules are cooled more rapidly in the liquid environment than that in the gas environment. From a bond dissociation energy point of view, results support the hypothesis that the reaction involves biradical intermediates

    4. Substituent-induced regioselective hydroxylation of the aromatic C–H bond on naphthalene with metachloroperbenzoic acid catalyzed by F20TPPMnCl (pages 23–29)

      Chang-Di Chen, Wen-Bing Sheng, Guo-Jun Shi and Can-Cheng Guo

      Version of Record online: 30 AUG 2012 | DOI: 10.1002/poc.3012

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      The electron-donating substituent afforded aromatic C–H bond hydroxylation preferred at the 1α position, while the electron-withdrawing substituent afforded that preferred at the 4α position of β-substituted naphthalene hydroxylated with metachloroperbenzoic acid catalyzed by the tetrakis(pentafluorophenyl) porphyrin manganese(III) chloride.

    5. Theoretical studies on 2-(5-amino-3-nitro-1,2,4-triazolyl)-3,5-dinitropyridine (PRAN) and its derivatives (pages 30–36)

      Hui Liu, Fang Wang, Gui-Xiang Wang and Xue-Dong Gong

      Version of Record online: 17 AUG 2012 | DOI: 10.1002/poc.3013

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      The heats of formation, detonation performances, and sensitivity of PRAN and its derivatives were studied and found they are promising candidates of high energy compounds.

    6. DFT studies of squarylium and core-substituted squarylium dye derivatives: understanding the causes of the additional shorter wavelength absorption in the latter (pages 37–46)

      Avinash L. Puyad, G. Krishna Chaitanya, Anup Thomas, Mahalingavelar Paramasivam and K. Bhanuprakash

      Version of Record online: 19 SEP 2012 | DOI: 10.1002/poc.3023

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      Core-substituted SQ (CSQ) dyes are functionalized dyes of Squarylium (SQ) dyes by any electron withdrawing/π-donor group/atom (–X). These CSQ dyes showing bathochromic shift in their NIR absorption along with additional shorter wavelength absorption. This DFT study facilitates the understanding of these dyes.

    7. Homo-Diels–Alder reaction of a very inactive diene, bicyclo[2,2,1]hepta-2,5-diene, with the most active dienophile, 4-phenyl-1,2,4-triazolin-3,5-dione. Solvent, temperature, and high pressure influence on the reaction rate (pages 47–53)

      Vladimir D. Kiselev, Ilzida I. Shakirova, Dmitry A. Kornilov, Helen A. Kashaeva, Lubov N. Potapova and Alexander I. Konovalov

      Version of Record online: 24 SEP 2012 | DOI: 10.1002/poc.3054

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      The rate constants change on about seven orders of magnitude: from 3.95 10−3 L mol−1 s−1 in reaction (1+2) to 12200 L mol−1 s−1 in reaction of (1+4e) in toluene solution at 298 K. The heat of reaction (1+2) is −218±2 kJ mol−1, (1+4e) is −117.8±0.7 kJ mol−1, and (1+4f) is −91.6 ±0.2 kJ mol−1. Since the energy of the N=N bond is considerably lower (418 kJ/bond) than that of the C=C bond (611 kJ/bond), it was proposed that this difference in the energy of breaking bonds can be the main reason of unusual high reactivity of 1 in the Diels–Alder cycloaddition reaction.

    8. Solvation thermodynamics of xylitol in water and in aqueous amino acids at 298.15 K (pages 54–58)

      Anwar Ali and Priyanka Bidhuri

      Version of Record online: 5 NOV 2012 | DOI: 10.1002/poc.3061

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      Calculated the solvation energy, enthalpy and entropy of xylitol in aqueous amino acids at 298.15 K and explained in terms of cavity formation and solute–solvent interactions.

    9. Solvent nucleophilicities of hexafluoroisopropanol/water mixtures (pages 59–63)

      Johannes Ammer and Herbert Mayr

      Version of Record online: 26 NOV 2012 | DOI: 10.1002/poc.3064

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      First-order rate constants k1 for the trapping of substituted benzhydrylium ions in mixtures of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and water ranging from 50 to 99% HFIP were determined by laser flash photolytic generation of benzhydrylium ions in these solvents. From these rate constants, we derived the solvent-specific reactivity parameters N1 and sN for HFIP/water mixtures as defined by the linear free energy relationship shown in the figure.

    10. Thermal reaction of electron deficient 4-oxo-4H-pyrazole 1,2-dioxide with cycloheptatriene: the first examples of the formation of an endo-[4π + 6π]-cycloadduct and an intramolecular 1,3-dipolar reaction leading to a heterocage (pages 64–69)

      Koki Yamaguchi, Masashi Eto, Yasuyuki Yoshitake and Kazunobu Harano

      Version of Record online: 6 NOV 2012 | DOI: 10.1002/poc.3066

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      The reaction of 3,5-bis(methoxycarbonyl)-4-oxo-4H-pyrazole 1,2-dioxide with 1,3,5-cycloheptatriene gave a mixture of the novel endo-[4+6]-cycloadduct, anti-exo-[4+2]-cycloadduct and the heterocage derived from the intramolecular 1,3-dipolar cycloaddition reaction of the syn-endo-[4+2]-cycloadduct. The cycloaddition behaviour is discussed on the basis of transition-state structures optimized at the B3LYP/6-31G(d) level of theory, from which predictions of the peri-, regio-, and stereoselectivities agreed well with the experimental results.

    11. Differences between insertions of ethylene into metallocene and non-metallocene ethylene polymerization catalysts (pages 70–76)

      Cheng-Gen Zhang, Liaoyun Zhang, Huayi Li, Shu-Yuan Yu and Zhi-Xiang Wang

      Version of Record online: 26 NOV 2012 | DOI: 10.1002/poc.3069

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      Density functional theory mechanistc study shows the insertions of ethylene into octahedral group 4 catalysts have the energy profiles distinguished from the insertions into group 4 metallocene catalysts.