The Experts below are selected from a list of 165 Experts worldwide ranked by ideXlab platform

Abhik Ghosh - One of the best experts on this subject based on the ideXlab platform.

  • Molecular Structure of a Free-Base β-Octaiodo-meso-tetraarylporphyrin. A Rational Route to cis Porphyrin Tautomers?
    Crystal Growth & Design, 2018
    Co-Authors: Ivar K. Thomassen, Laura J. Mccormick, Abhik Ghosh
    Abstract:

    Although a cis tautomer has long been invoked as an intermediate in porphyrin tautomerism, the first such species was only recently isolated and structurally characterized in the form of a β-heptakis(trifluoromethyl)-meso-tetraarylporphyrin. Reported herein is the molecular structure of a β-octaiodo-meso-tetraarylporphyrin solvate, which also exhibits a cis tautomeric structure. Both structures implicate two factors as critical to the stabilization of the cis tautomeric form—a free-base porphyrin that is naturally strongly saddled on steric grounds and a hydroxylic or Amphiprotic Solvent that can provide hydrogen-bonded N–H···X-H···N (X = O in both the above examples) straps connecting the central NH groups with the antipodal unprotonated nitrogens. The results raise the prospect that a rational strategy affording cis porphyrin tautomers in a predictable manner may be within reach.

  • Molecular Structure of a Free-Base β‑Octaiodo-meso-tetraarylporphyrin. A Rational Route to cis Porphyrin Tautomers?
    2018
    Co-Authors: Ivar K. Thomassen, Laura J. Mccormick, Abhik Ghosh
    Abstract:

    Although a cis tautomer has long been invoked as an intermediate in porphyrin tautomerism, the first such species was only recently isolated and structurally characterized in the form of a β-heptakis­(trifluoromethyl)-meso-tetraarylporphyrin. Reported herein is the molecular structure of a β-octaiodo-meso-tetraarylporphyrin solvate, which also exhibits a cis tautomeric structure. Both structures implicate two factors as critical to the stabilization of the cis tautomeric forma free-base porphyrin that is naturally strongly saddled on steric grounds and a hydroxylic or Amphiprotic Solvent that can provide hydrogen-bonded N–H···X-H···N (X = O in both the above examples) straps connecting the central NH groups with the antipodal unprotonated nitrogens. The results raise the prospect that a rational strategy affording cis porphyrin tautomers in a predictable manner may be within reach

Ivar K. Thomassen - One of the best experts on this subject based on the ideXlab platform.

  • Molecular Structure of a Free-Base β-Octaiodo-meso-tetraarylporphyrin. A Rational Route to cis Porphyrin Tautomers?
    Crystal Growth & Design, 2018
    Co-Authors: Ivar K. Thomassen, Laura J. Mccormick, Abhik Ghosh
    Abstract:

    Although a cis tautomer has long been invoked as an intermediate in porphyrin tautomerism, the first such species was only recently isolated and structurally characterized in the form of a β-heptakis(trifluoromethyl)-meso-tetraarylporphyrin. Reported herein is the molecular structure of a β-octaiodo-meso-tetraarylporphyrin solvate, which also exhibits a cis tautomeric structure. Both structures implicate two factors as critical to the stabilization of the cis tautomeric form—a free-base porphyrin that is naturally strongly saddled on steric grounds and a hydroxylic or Amphiprotic Solvent that can provide hydrogen-bonded N–H···X-H···N (X = O in both the above examples) straps connecting the central NH groups with the antipodal unprotonated nitrogens. The results raise the prospect that a rational strategy affording cis porphyrin tautomers in a predictable manner may be within reach.

  • Molecular Structure of a Free-Base β‑Octaiodo-meso-tetraarylporphyrin. A Rational Route to cis Porphyrin Tautomers?
    2018
    Co-Authors: Ivar K. Thomassen, Laura J. Mccormick, Abhik Ghosh
    Abstract:

    Although a cis tautomer has long been invoked as an intermediate in porphyrin tautomerism, the first such species was only recently isolated and structurally characterized in the form of a β-heptakis­(trifluoromethyl)-meso-tetraarylporphyrin. Reported herein is the molecular structure of a β-octaiodo-meso-tetraarylporphyrin solvate, which also exhibits a cis tautomeric structure. Both structures implicate two factors as critical to the stabilization of the cis tautomeric forma free-base porphyrin that is naturally strongly saddled on steric grounds and a hydroxylic or Amphiprotic Solvent that can provide hydrogen-bonded N–H···X-H···N (X = O in both the above examples) straps connecting the central NH groups with the antipodal unprotonated nitrogens. The results raise the prospect that a rational strategy affording cis porphyrin tautomers in a predictable manner may be within reach

Laura J. Mccormick - One of the best experts on this subject based on the ideXlab platform.

  • Molecular Structure of a Free-Base β-Octaiodo-meso-tetraarylporphyrin. A Rational Route to cis Porphyrin Tautomers?
    Crystal Growth & Design, 2018
    Co-Authors: Ivar K. Thomassen, Laura J. Mccormick, Abhik Ghosh
    Abstract:

    Although a cis tautomer has long been invoked as an intermediate in porphyrin tautomerism, the first such species was only recently isolated and structurally characterized in the form of a β-heptakis(trifluoromethyl)-meso-tetraarylporphyrin. Reported herein is the molecular structure of a β-octaiodo-meso-tetraarylporphyrin solvate, which also exhibits a cis tautomeric structure. Both structures implicate two factors as critical to the stabilization of the cis tautomeric form—a free-base porphyrin that is naturally strongly saddled on steric grounds and a hydroxylic or Amphiprotic Solvent that can provide hydrogen-bonded N–H···X-H···N (X = O in both the above examples) straps connecting the central NH groups with the antipodal unprotonated nitrogens. The results raise the prospect that a rational strategy affording cis porphyrin tautomers in a predictable manner may be within reach.

  • Molecular Structure of a Free-Base β‑Octaiodo-meso-tetraarylporphyrin. A Rational Route to cis Porphyrin Tautomers?
    2018
    Co-Authors: Ivar K. Thomassen, Laura J. Mccormick, Abhik Ghosh
    Abstract:

    Although a cis tautomer has long been invoked as an intermediate in porphyrin tautomerism, the first such species was only recently isolated and structurally characterized in the form of a β-heptakis­(trifluoromethyl)-meso-tetraarylporphyrin. Reported herein is the molecular structure of a β-octaiodo-meso-tetraarylporphyrin solvate, which also exhibits a cis tautomeric structure. Both structures implicate two factors as critical to the stabilization of the cis tautomeric forma free-base porphyrin that is naturally strongly saddled on steric grounds and a hydroxylic or Amphiprotic Solvent that can provide hydrogen-bonded N–H···X-H···N (X = O in both the above examples) straps connecting the central NH groups with the antipodal unprotonated nitrogens. The results raise the prospect that a rational strategy affording cis porphyrin tautomers in a predictable manner may be within reach

Tunçer H. Özdamar - One of the best experts on this subject based on the ideXlab platform.

  • Nucleophile influence on the complex reaction network of 2-isopropylnaphthalene hydroperoxide decomposition
    Chemical Engineering and Processing: Process Intensification, 2005
    Co-Authors: Fatma Gül Boyacı, Serpil Takaç, Tunçer H. Özdamar
    Abstract:

    Abstract Acid-catalysed decomposition of 2-isopropylnaphthalene hydroperoxide (2-IPNHP), which is of industrial importance for the productions of 2-naphthol and acetone simultaneously, proceeds through a complex ionic reaction mechanism. Since two steps of the ionic reactions in series are nucleophilic reactions, the presence, character and concentration of nucleophile reagents in the decomposition reaction medium are important. In the present study, the effects of the neutral oxygen nucleophiles: H 2 O 2 , water, 2-IPNHP and dimethyl-2-naphthylcarbinol (DMNC) were investigated. 2-IPNHP is the reactant of the process, water is another reactant of the nucleophilic addition reaction, DMNC is the by-product of the preceding 2-IPNHP production process and H 2 O 2 is initially added into the medium to oxidise the DMNC to 2-IPNHP. Among the neutral oxygen nucleophiles, H 2 O 2 , water and DMNC decreased, but 2-IPNHP increased the production rate of 2-naphthol in accordance with the mechanism and with the following descending order of the strength of nucleophiles: DMNC > 2-IPNHP > H 2 O 2  > water. The influence of nucleophile characters of aprotic Solvents of low dielectric constant (propyl acetate and acetone), aprotic Solvents of high-dielectric constant (acetonitrile and nitrobenzene), protogenic Solvent (acetic acid) and Amphiprotic Solvent (methyl alcohol) on the 2-IPNHP decomposition were also discussed in the paper.

  • Solvent–catalyst interactions in the decomposition process of 2-isopropylnaphthalenehydroperoxide into 2-naphthol and acetone
    Applied Catalysis A: General, 1999
    Co-Authors: Fatma Gül Boyacı, Serpil Takaç, Tunçer H. Özdamar
    Abstract:

    Abstract Decomposition of 2-isopropylnaphthalenehydroperoxide (2-IPNHP) proceeds through either ionic or radical reaction mechanism. 2-Naphthol and acetone are produced by ionic reactions, however, dimethyl-2-naphthylcarbinol and 2-acetonaphthone productions through radical reactions cannot be avoided because of induced decomposition effects. In this work, we performed the acid-catalysed decomposition of 2-IPNHP for 2-naphthol and acetone production in the presence of eight different Solvents and three different acid catalysts. The results were discussed in combination with the ionic reaction mechanism to evaluate the Solvent–catalyst interactions. Dodecane, isopropylnaphthalene, propyl acetate, acetone (aprotic Solvents of low dielectric constant); acetonitrile, nitrobenzene (NB) (aprotic Solvents of high dielectric constant), acetic acid (AcOH) (protogenic Solvent) and methyl alcohol (MeOH) (Amphiprotic Solvent) were used separately with oxyacids HClO 4 and H 2 SO 4 , and hydroacid HCl. 2-IPNHP decomposition and 2-naphthol production rates increased with increasing dipole moment of aprotic Solvents. The highest reaction rates were obtained in the protogenic Solvent AcOH and in the aprotic Solvent NB where the reactions in the Amphiprotic Solvent MeOH resulted in the lowest reaction rates. In addition to characters of the Solvent and catalyst of the decomposition medium, the composition of the reactant mixture also affected the reaction mechanism and decomposition yield. According to the experimental results, AcOH and HClO 4 are the favourable Solvent and catalyst for 2-naphthol production, respectively. 61% yield of 2-naphthol was achieved in the presence of AcOH by 0.114 mol dm −3 HClO 4 with the medium concentrations of 1.078 mol dm −3 2-IPNHP, 0.222 mol dm −3 DMNC, 8.680×10 −3  mol dm −3 AN and 0.255 mol dm −3 H 2 O 2 .

Fatma Gül Boyacı - One of the best experts on this subject based on the ideXlab platform.

  • Nucleophile influence on the complex reaction network of 2-isopropylnaphthalene hydroperoxide decomposition
    Chemical Engineering and Processing: Process Intensification, 2005
    Co-Authors: Fatma Gül Boyacı, Serpil Takaç, Tunçer H. Özdamar
    Abstract:

    Abstract Acid-catalysed decomposition of 2-isopropylnaphthalene hydroperoxide (2-IPNHP), which is of industrial importance for the productions of 2-naphthol and acetone simultaneously, proceeds through a complex ionic reaction mechanism. Since two steps of the ionic reactions in series are nucleophilic reactions, the presence, character and concentration of nucleophile reagents in the decomposition reaction medium are important. In the present study, the effects of the neutral oxygen nucleophiles: H 2 O 2 , water, 2-IPNHP and dimethyl-2-naphthylcarbinol (DMNC) were investigated. 2-IPNHP is the reactant of the process, water is another reactant of the nucleophilic addition reaction, DMNC is the by-product of the preceding 2-IPNHP production process and H 2 O 2 is initially added into the medium to oxidise the DMNC to 2-IPNHP. Among the neutral oxygen nucleophiles, H 2 O 2 , water and DMNC decreased, but 2-IPNHP increased the production rate of 2-naphthol in accordance with the mechanism and with the following descending order of the strength of nucleophiles: DMNC > 2-IPNHP > H 2 O 2  > water. The influence of nucleophile characters of aprotic Solvents of low dielectric constant (propyl acetate and acetone), aprotic Solvents of high-dielectric constant (acetonitrile and nitrobenzene), protogenic Solvent (acetic acid) and Amphiprotic Solvent (methyl alcohol) on the 2-IPNHP decomposition were also discussed in the paper.

  • Solvent–catalyst interactions in the decomposition process of 2-isopropylnaphthalenehydroperoxide into 2-naphthol and acetone
    Applied Catalysis A: General, 1999
    Co-Authors: Fatma Gül Boyacı, Serpil Takaç, Tunçer H. Özdamar
    Abstract:

    Abstract Decomposition of 2-isopropylnaphthalenehydroperoxide (2-IPNHP) proceeds through either ionic or radical reaction mechanism. 2-Naphthol and acetone are produced by ionic reactions, however, dimethyl-2-naphthylcarbinol and 2-acetonaphthone productions through radical reactions cannot be avoided because of induced decomposition effects. In this work, we performed the acid-catalysed decomposition of 2-IPNHP for 2-naphthol and acetone production in the presence of eight different Solvents and three different acid catalysts. The results were discussed in combination with the ionic reaction mechanism to evaluate the Solvent–catalyst interactions. Dodecane, isopropylnaphthalene, propyl acetate, acetone (aprotic Solvents of low dielectric constant); acetonitrile, nitrobenzene (NB) (aprotic Solvents of high dielectric constant), acetic acid (AcOH) (protogenic Solvent) and methyl alcohol (MeOH) (Amphiprotic Solvent) were used separately with oxyacids HClO 4 and H 2 SO 4 , and hydroacid HCl. 2-IPNHP decomposition and 2-naphthol production rates increased with increasing dipole moment of aprotic Solvents. The highest reaction rates were obtained in the protogenic Solvent AcOH and in the aprotic Solvent NB where the reactions in the Amphiprotic Solvent MeOH resulted in the lowest reaction rates. In addition to characters of the Solvent and catalyst of the decomposition medium, the composition of the reactant mixture also affected the reaction mechanism and decomposition yield. According to the experimental results, AcOH and HClO 4 are the favourable Solvent and catalyst for 2-naphthol production, respectively. 61% yield of 2-naphthol was achieved in the presence of AcOH by 0.114 mol dm −3 HClO 4 with the medium concentrations of 1.078 mol dm −3 2-IPNHP, 0.222 mol dm −3 DMNC, 8.680×10 −3  mol dm −3 AN and 0.255 mol dm −3 H 2 O 2 .