The Experts below are selected from a list of 204 Experts worldwide ranked by ideXlab platform

Stephen G. Schulman - One of the best experts on this subject based on the ideXlab platform.

  • Proton Transfer of Phenanthridone in the Lowest Excited Singlet State in Moderately Concentrated Mineral Acid Solutions
    Journal of Fluorescence, 2003
    Co-Authors: Rong Yang, Stephen G. Schulman
    Abstract:

    A modified form of the steady state treatment for the determination of excited state proton transfer rate constants was successfully applied to a variety of oxygen and nitrogen center aromatic excited Acids. These compounds shared the characteristic of being more Acidic in the lowest excited singlet state (S1) than in the ground electronic state (S0) and of requiring a concentrated Mineral Acid medium for protonation. This treatment was extended to phenanthridone, the lactam of 6-hydroxyphenanthridine, which is a weak enough base in the ground and the excited states to require moderately concentrated Mineral Acids for protonation, and becomes a stronger base in the excited state than it is in the ground state. Phenanthridone exists as an α-lactam and is a weaker base in the ground and excited states than the α-lactams derived from 2-hydroxypyridine, 2-hydroxyquinoline, and 1-hydroxyisoquinoline. It is also a much weaker base than the vinylogous γ-lactams. The reasons for this are discussed here.

  • Kinetics of Proton Transfer of Extremely Weak Bases in the Lowest Excited Singlet State in Concentrated Mineral Acid Solutions
    Progress in Analytical Luminescence, 1
    Co-Authors: Richard N. Kelly, Stephen G. Schulman
    Abstract:

    Recently, a modified form of the steady state treatment for the determination of excited state proton transfer rate constants was successfully applied to a variety of oxygen-and nitrogen-center aromatic excited-state Acids. These compounds shared the characteristic of being more Acidic in the first excited state, S 1 , than in the ground state, So, and of requiring a concentrated Mineral Acid medium for protonation. The quantitation of excited-state proton transfer kinetics is presently extended to several protonated N-heterocyclic amines that are weak enough bases in the excited state to require concentrated Mineral Acids for protonation.

Johan A Martens - One of the best experts on this subject based on the ideXlab platform.

  • sol gel synthesis of micro and mesoporous silica in strong Mineral Acid
    Studies in Surface Science and Catalysis, 2010
    Co-Authors: Anouschka Depla, Christine E A Kirschhock, Johan A Martens
    Abstract:

    Abstract Acid catalyzed silica sol-gel syntheses were performed using TEOS and TMOS, the corresponding alcohol solvent, a high concentration of Mineral Acid and a low hydrolysis ratio. The molar Si:H 2 O:solvent:Acid ratios of the synthesis mixture were 1:2:3:0.35. The obtained silica materials were calcined to remove residual alkoxide groups. The nature of the Mineral Acid, the use of TEOS versus TMOS, and the temperature of the polymerization had a strong influence on the textural properties of the obtained silica. Distinct microporous and mesoporous materials were obtained.

Anouschka Depla - One of the best experts on this subject based on the ideXlab platform.

  • sol gel synthesis of micro and mesoporous silica in strong Mineral Acid
    Studies in Surface Science and Catalysis, 2010
    Co-Authors: Anouschka Depla, Christine E A Kirschhock, Johan A Martens
    Abstract:

    Abstract Acid catalyzed silica sol-gel syntheses were performed using TEOS and TMOS, the corresponding alcohol solvent, a high concentration of Mineral Acid and a low hydrolysis ratio. The molar Si:H 2 O:solvent:Acid ratios of the synthesis mixture were 1:2:3:0.35. The obtained silica materials were calcined to remove residual alkoxide groups. The nature of the Mineral Acid, the use of TEOS versus TMOS, and the temperature of the polymerization had a strong influence on the textural properties of the obtained silica. Distinct microporous and mesoporous materials were obtained.

Rong Yang - One of the best experts on this subject based on the ideXlab platform.

  • Proton Transfer of Phenanthridone in the Lowest Excited Singlet State in Moderately Concentrated Mineral Acid Solutions
    Journal of Fluorescence, 2003
    Co-Authors: Rong Yang, Stephen G. Schulman
    Abstract:

    A modified form of the steady state treatment for the determination of excited state proton transfer rate constants was successfully applied to a variety of oxygen and nitrogen center aromatic excited Acids. These compounds shared the characteristic of being more Acidic in the lowest excited singlet state (S1) than in the ground electronic state (S0) and of requiring a concentrated Mineral Acid medium for protonation. This treatment was extended to phenanthridone, the lactam of 6-hydroxyphenanthridine, which is a weak enough base in the ground and the excited states to require moderately concentrated Mineral Acids for protonation, and becomes a stronger base in the excited state than it is in the ground state. Phenanthridone exists as an α-lactam and is a weaker base in the ground and excited states than the α-lactams derived from 2-hydroxypyridine, 2-hydroxyquinoline, and 1-hydroxyisoquinoline. It is also a much weaker base than the vinylogous γ-lactams. The reasons for this are discussed here.

Bhat, Siddharth Sharad - One of the best experts on this subject based on the ideXlab platform.

  • Study of homogeneous Mineral Acid dehydration of monosaccharides in a CSTR
    SURFACE, 2015
    Co-Authors: Bhat, Siddharth Sharad
    Abstract:

    Simple sugars (Aldohexoses/pentoses), (Ketohexoses/pentose) when subjected to a dehydration reaction, produce various compounds. An example of one such compound is 5-hydroxymethyl furfural. Such chemical products may be used in subsequent processing steps (hydrolysis, aldol condensation, hydrogenation and dehydration) to produce similarly structured condensed compounds that form the basis of complex molecules used in various industries such as production of fuels, chemical reagents and fertilizers. Most studies focus on heterogeneous packed beds and batch reactors to carry out dehydration reactions. This study illustrates use of a Continuous Stirred-Tank reactor to carry out such dehydration reactions. In order to maintain the homogenous nature of the reaction, the catalyst chosen was sulfuric Acid. Use of a CSTR would allow study of kinetics and yields for varying residence times. This data could be used to design large scale operations in biomass processing. This study is aimed at investigating variables such as changing physical properties of the fluid reactant during reaction, variation in pH and consequent change in proton concentrations. By understanding the impact of these variables, more accurate rate measurements can be made. In the process of developing the right method for data acquisition, several substantial changes were made to the reactor and methods. These changes were instrumental in development of a cyclic process of data collection and changing methods and design, thus highlighting the chemical engineering heuristics approach and refinement in processes. The sequence of corrected results give us better insight into the process and help develop accurate models for the reactions in the scope of this thesis and also future studies. The presented results of rates and yields may be used to develop processes based on requirement and feasibility