scholarly journals Modulation of Prins Cyclization by Vibrational Strong Coupling

2019 ◽  
Author(s):  
Kenji Hirai ◽  
Rie Takeda ◽  
JAMES HUTCHISON ◽  
Hiroshi Uji-i
Keyword(s):  
Strong Coupling ◽  
Chemical Reactions ◽  
Reaction Pathway ◽  
Chemical Reactivity ◽  
Order Rate Constant ◽  
Pharmaceutical Chemistry ◽  
Prins Cyclization ◽  
Control Chemical ◽  
Aldehydes And Ketones ◽  
Enthalpy And Entropy

<div>Light-molecule strong coupling has emerged within the last decade as an entirely new method to control chemical reactions. A few years ago it was discovered that the chemical reactivity could be altered by vibrational strong coupling (VSC). While the potential of VSC in organic chemistry appears enormous, only a limited number of reactions have been investigated under VSC to date, including solvolysis and deprotection reactions. Here we investigate the effect of VSC on a series of aldehydes and ketones undergoing Prins cyclization, an important synthetic step in pharmaceutical chemistry. We observe a decrease of the second-order rate constant with VSC of the reactant carbonyl stretching groups. We measure an increased activation energy due to VSC, but proportional changes in activation enthalpy and entropy suggest no substantive change in reaction pathway. The addition of common cycloaddition reactions to the stable of VSC-modified chemical reactions is another step towards establishing VSC as a genuine tool for synthetic chemistry.</div>

scholarly journals Modulation of Prins Cyclization by Vibrational Strong Coupling

2019 ◽  
Author(s):  
Kenji Hirai ◽  
Rie Takeda ◽  
JAMES HUTCHISON ◽  
Hiroshi Uji-i
Keyword(s):  
Strong Coupling ◽  
Chemical Reactions ◽  
Reaction Pathway ◽  
Chemical Reactivity ◽  
Order Rate Constant ◽  
Pharmaceutical Chemistry ◽  
Prins Cyclization ◽  
Control Chemical ◽  
Aldehydes And Ketones ◽  
Enthalpy And Entropy

<div>Light-molecule strong coupling has emerged within the last decade as an entirely new method to control chemical reactions. A few years ago it was discovered that the chemical reactivity could be altered by vibrational strong coupling (VSC). While the potential of VSC in organic chemistry appears enormous, only a limited number of reactions have been investigated under VSC to date, including solvolysis and deprotection reactions. Here we investigate the effect of VSC on a series of aldehydes and ketones undergoing Prins cyclization, an important synthetic step in pharmaceutical chemistry. We observe a decrease of the second-order rate constant with VSC of the reactant carbonyl stretching groups. We measure an increased activation energy due to VSC, but proportional changes in activation enthalpy and entropy suggest no substantive change in reaction pathway. The addition of common cycloaddition reactions to the stable of VSC-modified chemical reactions is another step towards establishing VSC as a genuine tool for synthetic chemistry.</div>

scholarly journals Polariton chemistry: controlling molecular dynamics with optical cavities

2018 ◽  
Vol 9 (30) ◽  
pp. 6325-6339 ◽  
Author(s):  
Raphael F. Ribeiro ◽  
Luis A. Martínez-Martínez ◽  
Matthew Du ◽  
Jorge Campos-Gonzalez-Angulo ◽  
Joel Yuen-Zhou
Keyword(s):  
Molecular Dynamics ◽  
Strong Coupling ◽  
Electromagnetic Fields ◽  
Chemical Reactivity ◽  
Optical Cavities ◽  
Control Chemical

Strong coupling of molecules with confined electromagnetic fields provides novel strategies to control chemical reactivity and spectroscopy.

Catalytic Resonance Theory: Parallel Reaction Pathway Control

2019 ◽  
Author(s):  
M. Alexander Ardagh ◽  
Manish Shetty ◽  
Anatoliy Kuznetsov ◽  
Qi Zhang ◽  
Phillip Christopher ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Active Site ◽  
Active Sites ◽  
Reaction Pathway ◽  
Control Strategies ◽  
Oscillation Amplitude ◽  
Catalytic Performance ◽  
Parallel Reaction ◽  
Resonance Theory ◽  
Static Conditions

Catalytic enhancement of chemical reactions via heterogeneous materials occurs through stabilization of transition states at designed active sites, but dramatically greater rate acceleration on that same active site is achieved when the surface intermediates oscillate in binding energy. The applied oscillation amplitude and frequency can accelerate reactions orders of magnitude above the catalytic rates of static systems, provided the active site dynamics are tuned to the natural frequencies of the surface chemistry. In this work, differences in the characteristics of parallel reactions are exploited via selective application of active site dynamics (0 < ΔU < 1.0 eV amplitude, 10<sup>-6</sup> < f < 10<sup>4</sup> Hz frequency) to control the extent of competing reactions occurring on the shared catalytic surface. Simulation of multiple parallel reaction systems with broad range of variation in chemical parameters revealed that parallel chemistries are highly tunable in selectivity between either pure product, even when specific products are not selectively produced under static conditions. Two mechanisms leading to dynamic selectivity control were identified: (i) surface thermodynamic control of one product species under strong binding conditions, or (ii) catalytic resonance of the kinetics of one reaction over the other. These dynamic parallel pathway control strategies applied to a host of chemical conditions indicate significant potential for improving the catalytic performance of many important industrial chemical reactions beyond their existing static performance.

Epitaxy and Chemical Reactions During Thin Film Formation from Low Energy Ions New Kinetic Pathways, New Phases and New Properties

1991 ◽  
Vol 236 ◽  
Author(s):  
Nicole Herbots ◽  
O.C. Hellman ◽  
O. Vancauwenberghe
Keyword(s):  
Thin Film ◽  
Chemical Reactions ◽  
Degrees Of Freedom ◽  
Film Growth ◽  
Film Formation ◽  
Chemical Reactivity ◽  
Ion Beam ◽  
Low Energy ◽  
Low Energy Ions ◽  
Beam Deposition

AbstractThree important effects of low energy direct Ion Beam Deposition (IBD) are the athermal incorporation of material into a substrate, the enhancement of atomic mobility in the subsurface, and the modification of growth kinetics it creates. All lead to a significant lowering of the temperature necessary to induce epitaxial growth and chemical reactions. The fundamental understanding and new applications of low temperature kinetics induced by low energy ions in thin film growth and surface processing of semiconductors are reviewed. It is shown that the mechanism of IBD growth can be understood and computed quantitatively using a simple model including ion induced defect generation and sputtering, elastic recombination, thermal diffusion, chemical reactivity, and desorption The energy, temperature and dose dependence of growth rate, epitaxy, and chemical reaction during IBD is found to be controlled by the net recombination rate of interstitials at the surface in the case of epitaxy and unreacted films, and by the balance between ion beam decomposition and phase formation induced by ion beam generated defects in the case of compound thin films. Recent systematic experiments on the formation of oxides and nitrides on Si, Ge/Si(100), heteroepitaxial SixGe1−x/Si(100) and GaAs(100) illustrate applications of this mechanism using IBD in the form of Ion Beam Nitridation (IBN), Ion Beam Oxidation (IBO) and Combined Ion and Molecular beam Deposition (CIMD). It is shown that these techniques enable (1) the formation of conventional phases in conditions never used before, (2) the control and creation of properties via new degrees of freedom such as ion energy and lowered substrate temperatures, and (3) the formation of new metastable heterostructures that cannot be grown by pure thermal means.

Achieving tunable chemical reactivity through photo-initiation of energetic materials at metal oxide surfaces

2020 ◽  
Vol 22 (43) ◽  
pp. 25284-25296
Author(s):  
Maija M. Kuklja ◽  
Roman Tsyshevsky ◽  
Anton S. Zverev ◽  
Anatoly Mitrofanov ◽  
Natalya Ilyakova ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Chemical Reactions ◽  
Energetic Materials ◽  
Chemical Reactivity ◽  
Energetic Material ◽  
Oxide Surfaces ◽  
Oxide Interfaces ◽  
Metal Oxide Surfaces

Photo-stimulated chemical reactions in energetic materials can be highly controlled by selectively designing energetic material – metal oxide interfaces with tailored properties.

scholarly journals Modulation of Prins Cyclization by Vibrational Strong Coupling

2020 ◽  
Vol 132 (13) ◽  
pp. 5370-5373 ◽  
Author(s):  
Kenji Hirai ◽  
Rie Takeda ◽  
James A. Hutchison ◽  
Hiroshi Uji‐i
Keyword(s):  
Strong Coupling ◽  
Prins Cyclization

Modelling of chemical reactions in hypersonic rarefied flow with the direct simulation Monte Carlo method

1996 ◽  
Vol 312 ◽  
pp. 149-172 ◽  
Author(s):  
Michael A. Gallis ◽  
John K. Harvey
Keyword(s):  
Monte Carlo ◽  
Chemical Reactions ◽  
Energy Exchange ◽  
Chemical Reactivity ◽  
Direct Simulation Monte Carlo ◽  
Direct Simulation ◽  
Rarefied Flow ◽  
Rarefied Flows ◽  
Exchange Processes ◽  
Simulation Monte Carlo

In this paper the phenomenon of chemical reactivity in hypersonic rarefied flows is examined. A new model is developed to describe the reactions and post-collision energy exchange processes that take place under conditions of molecular non-equilibrium. The new scheme, which is applied within the framework of the direct simulation Monte Carlo (DSMC) method, draws its inspiration from the principles of maximum entropy which were developed by Levine & Bernstein. Sample hypersonic flow fields, typical of spacecraft re-entry conditions in which reactions play an important role, are presented and compared with results from experiments and other DSMC calculations. The latter use traditional methods for the modelling of chemical reactions and energy exchange. The differences are discussed and evaluated.

Support Curvature and Conformational Freedom Control Chemical Reactivity of Immobilized Species

2013 ◽  
Vol 136 (7) ◽  
pp. 2711-2714 ◽  
Author(s):  
Tino Zdobinsky ◽  
Pradipta Sankar Maiti ◽  
Rafal Klajn
Keyword(s):  
Chemical Reactivity ◽  
Control Chemical ◽  
Conformational Freedom

scholarly journals Chloroacetone as an active-site-directed inhibitor of the aliphatic amidase from Pseudomonas aeruginosa

1980 ◽  
Vol 191 (3) ◽  
pp. 811-826 ◽  
Author(s):  
M R Hollaway ◽  
P H Clarke ◽  
T Ticho
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Active Site ◽  
Chemical Reactivity ◽  
Covalent Bond ◽  
Order Rate Constant ◽  
Reaction Scheme ◽  
Enzymic Activity ◽  
Adsorption Complex ◽  
Apparent Dissociation Constant ◽  
Kinetic Experiment

1. Chloroacetone (I) was shown to be an active-site-directed inhibitor of the aliphatic amidase (EC 3.5.1.4) from Pseudomonas aeruginosa strain PAC142.2. This inhibitor reacted with the enzyme in two stages: the first involving the reversible formation of an enzymically inactive species, EI, and the second the formation of a species, EX, from which enzymic activity could not be recovered. 3. Different types of kinetic experiment were conducted to test conformity of the reaction to the scheme: E + I k+1 Equilibrium k-1 EI Leads to K+2 EX A computer-based analysis of the results was carried out and values of the individual rate constants were determined. 4. No direct evidence for a binding step before the formation of EI could be obtained, as with [E]0 Less Than [I]0 the observed first-order rate constant for the formation of EI was directly proportional to the concentration of chloroacetone up to 1.2 mM (above this concentration the reaction became too rapid to follow even by the stopped-flow method developed to investigate fast inhibition). 5. The value of k+1 exhibited a bell-shaped pH-dependency with a maximum value of about 3 × 10(3) M-1. S-1 at pH6 and apparent pKa values of 7.8 and about 4.8.6. The values of k-1 and K+2 were similar and changed with the time of reaction from values of about 3 × 10(-3) S-1 (pH8.6) at short times to about one-sixth this value for longer periods of incubation. In this respect the simple reaction scheme is insufficient to describe the inhibition process. 7. The overall inhibition reaction is rapid, whether it is considered in relation to the expected chemical reactivity of chloroacetone, the rate of reaction of other enzymes with substrate analogues containing the chloromethyl group, or the rate of the amidase-catalysed hydrolysis of N-methylacetamide, a substrate that is nearly isosteric with chloroacetone. 8. Acetamide protected the amidase from inhibition by chloroacetone, and the concentration-dependence of the protection gave a value of an apparent dissociation constant similar to the Km value for this substrate. 9. Addition of acetamide to solutions of the species EI led to a slow recovery of activity. Recovery of active enzyme was also observed after dilution of a solution of EI in the absence of substrate. 10. The species EI is considered not to be a simple adsorption complex, and the possibilities are discussed that it may be a tetrahedral carbonyl adduct, a Schiff base (azomethine) or a complex in which the enzyme has undergone a structural change. The species EX is probably a derivative in which there is a covalent bond between a group in the enzyme and the C-1 atom of the inhibitor.

2003 Alfred Bader Award LecturePredicting the rates of chemical reactions

2005 ◽  
Vol 83 (1) ◽  
pp. 1-8 ◽  
Author(s):  
J Peter Guthrie
Keyword(s):  
Computational Chemistry ◽  
Chemical Reactions ◽  
Chemical Reaction ◽  
Chemical Reactivity ◽  
Equilibrium Thermodynamics ◽  
Detailed Mechanism ◽  
Quantitative Tool

The dream of being able to predict the rate of a chemical reaction corresponding to a detailed mechanism is now almost within our grasp. No barrier theory (NBT), which makes the calculations relatively facile, is described, as are various applications of the approach to date. Illustrations are given of the use of NBT not just as a quantitative tool for predicting rates, but as a qualitative tool for thinking about which of a pair of reactions will have the higher intrinsic barrier, and thus be slower for similar thermodynamic driving force.Key words: rate, equilibrium, thermodynamics, kinetics, no barrier theory, computational chemistry, chemical reactivity.

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