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Special Issue "Gas Phase Reactions"

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A special issue of Molecules (ISSN 1420-3049).

Deadline for manuscript submissions: closed (30 June 2013)

Special Issue Editor

Guest Editor
Prof. Dr. Dietmar A. Plattner

Institute for Organic Chemistry and Biochemistry, Albert-Ludwigs-University of Freiburg, Albertstrasse 21, D-79104 Freiburg, Germany
Website | E-Mail
Interests: reactions in the gas phase; Mass spectrometry; reactions under non-standard conditions; enzyme catalysis

Special Issue Information

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).

Published Papers (4 papers)

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Research

Open AccessArticle Gas Phase Thermal Reactions of exo-8-Cyclopropyl-bicyclo[4.2.0]oct-2-ene (1-exo)
Molecules 2014, 19(2), 1527-1543; doi:10.3390/molecules19021527
Received: 19 December 2013 / Revised: 10 January 2014 / Accepted: 15 January 2014 / Published: 27 January 2014
PDF Full-text (389 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The title compound 1-exo (with minor amounts of its C8 epimer 1-endo) was prepared by Wolff-Kishner reduction of the cycloadduct of 1,3-cyclohexadiene and cyclopropylketene. The [1,3]-migration product 2-endo was synthesized by efficient selective cyclopropanation of endo-5-vinylbicyclo[2.2.2]oct-2-ene at the
[...] Read more.
The title compound 1-exo (with minor amounts of its C8 epimer 1-endo) was prepared by Wolff-Kishner reduction of the cycloadduct of 1,3-cyclohexadiene and cyclopropylketene. The [1,3]-migration product 2-endo was synthesized by efficient selective cyclopropanation of endo-5-vinylbicyclo[2.2.2]oct-2-ene at the exocyclic π-bond. Gas phase thermal reactions of 1-exo afforded C8 epimerization to 1-endo, [1,3]- migrations to 2-exo and 2-endo, direct fragmentation to cyclohexadiene and vinylcyclopropane, and CPC rearrangement in the following relative kinetic order: kep > k13 > kf > kCPC. Full article
(This article belongs to the Special Issue Gas Phase Reactions)
Open AccessArticle Pressure Dependent Product Formation in the Photochemically Initiated Allyl + Allyl Reaction
Molecules 2013, 18(11), 13608-13622; doi:10.3390/molecules181113608
Received: 27 August 2013 / Revised: 17 October 2013 / Accepted: 22 October 2013 / Published: 4 November 2013
PDF Full-text (410 KB) | HTML Full-text | XML Full-text
Abstract
Photochemically driven reactions involving unsaturated radicals produce a thick global layer of organic haze on Titan, Saturn’s largest moon. The allyl radical self-reaction is an example for this type of chemistry and was examined at room temperature from an experimental and kinetic modelling
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Photochemically driven reactions involving unsaturated radicals produce a thick global layer of organic haze on Titan, Saturn’s largest moon. The allyl radical self-reaction is an example for this type of chemistry and was examined at room temperature from an experimental and kinetic modelling perspective. The experiments were performed in a static reactor with a volume of 5 L under wall free conditions. The allyl radicals were produced from laser flash photolysis of three different precursors allyl bromide (C3H5Br), allyl chloride (C3H5Cl), and 1,5-hexadiene (CH2CH(CH2)2CHCH2) at 193 nm. Stable products were identified by their characteristic vibrational modes and quantified using FTIR spectroscopy. In addition to the (re-) combination pathway C3H5+C3H5 → C6H10 we found at low pressures around 1 mbar the highest final product yields for allene and propene for the precursor C3H5Br. A kinetic analysis indicates that the end product formation is influenced by specific reaction kinetics of photochemically activated allyl radicals. Above 10 mbar the (re-) combination pathway becomes dominant. These findings exemplify the specificities of reaction kinetics involving chemically activated species, which for certain conditions cannot be simply deduced from combustion kinetics or atmospheric chemistry on Earth. Full article
(This article belongs to the Special Issue Gas Phase Reactions)
Open AccessArticle Kinetics of Nitric Oxide and Oxygen Gases on Porous Y-Stabilized ZrO2-Based Sensors
Molecules 2013, 18(8), 9901-9918; doi:10.3390/molecules18089901
Received: 15 July 2013 / Revised: 8 August 2013 / Accepted: 13 August 2013 / Published: 16 August 2013
Cited by 3 | PDF Full-text (1926 KB) | HTML Full-text | XML Full-text
Abstract
Using impedance spectroscopy the electrical response of sensors with various porous Y-stabilized ZrO2 (YSZ) microstructures was measured for gas concentrations containing 0–100 ppm NO with 10.5%O2 at temperatures ranging from 600–700 °C. The impedance response increased substantially as the sensor porosity
[...] Read more.
Using impedance spectroscopy the electrical response of sensors with various porous Y-stabilized ZrO2 (YSZ) microstructures was measured for gas concentrations containing 0–100 ppm NO with 10.5%O2 at temperatures ranging from 600–700 °C. The impedance response increased substantially as the sensor porosity increased from 46%–50%. Activation energies calculated based on data from the impedance measurements increased in magnitude (97.4–104.9 kJ/mol for 100 ppm NO) with respect to increasing YSZ porosity. Analysis of the oxygen partial pressure dependence of the sensors suggested that dissociative adsorption was the dominant rate limiting. The PWC/DNP theory level was used to investigate the gas-phase energy barrier of the 2NO+O2→2NO2 reaction on a 56-atom YSZ/Au model cluster using Density Functional Theory and Linear Synchronous Transit/Quadratic Synchronous Transit calculations. The reaction path shows oxygen surface reactions that begin with NO association with adsorbed O2 on a Zr surface site, followed by O2 dissociative adsorption, atomic oxygen diffusion, and further NO2 formation. The free energy barrier was calculated to be 181.7 kJ/mol at PWC/DNP. A qualitative comparison with the extrapolated data at 62% ± 2% porosity representing the YSZ model cluster indicates that the calculated barriers are in reasonable agreement with experiments, especially when the RPBE functional is used. Full article
(This article belongs to the Special Issue Gas Phase Reactions)
Open AccessArticle Thermal Behavior of Pinan-2-ol and Linalool
Molecules 2013, 18(7), 8358-8375; doi:10.3390/molecules18078358
Received: 29 May 2013 / Revised: 26 June 2013 / Accepted: 11 July 2013 / Published: 16 July 2013
Cited by 2 | PDF Full-text (315 KB) | HTML Full-text | XML Full-text
Abstract
Linalool is an important intermediate for syntheses of isoprenoid fragrance compounds and vitamins A and E. One process option for its production is the thermal gas-phase isomerization of cis- and trans-pinan-2-ol. Investigations of this reaction were performed in a flow-type apparatus
[...] Read more.
Linalool is an important intermediate for syntheses of isoprenoid fragrance compounds and vitamins A and E. One process option for its production is the thermal gas-phase isomerization of cis- and trans-pinan-2-ol. Investigations of this reaction were performed in a flow-type apparatus in a temperature range from 350–600 °C and a residence time range of 0.6–0.8 s. Rearrangement of the bicyclic alcohol led to linalool, plinols arising from consecutive reactions of linalool and other side products. Effects of residence time, temperature, surface-to-volume-ratio, carrier gas, and the presence of additives on yield and selectivity were studied. Furthermore, the effects of such parameters on ene-cyclization of linalool affording plinols were investigated. Results indicate that manipulation of the reaction in order to affect selectivity is difficult due to the large free path length to other molecules in the gas phase. However, conditions have been identified allowing one to increase the selectivity and the yield of linalool throughout pyrolysis of pinan-2-ol. Full article
(This article belongs to the Special Issue Gas Phase Reactions)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Type of Paper: Review
Title: “Solid/gas Biocatalysis, an Efficient Tool for Fundamental Studies on Enzyme Activity and Selectivity”
Authors: M. Graber, A. Mensi, N. Fniter, B. Belkhiria and Z. Marton
Affiliations: UMR 7266 CNRS-ULR, LIENSS, LIttoral ENvironnement SociétéS, Université de La Rochelle, Pôle Sciences et Technologie, Bâtiment Marie Curie, Avenue Michel Crépeau, 17042 La Rochelle, France
Abstract:
From the middle of the 1980s, it was demonstrated that solid–gas biocatalysis was possible with enzymes usually acting on liquid substrates, with several examples of enzyme in the dry state acting on gaseous substrates. Different isolated enzymes were tested successfully such as the horse liver dehydrogenase, the Sulfolobus solfataricus dehydrogenase, the Pischia pastoris alcohol oxidase, the baker’s yeast alcohol dehydrogenase and lipolytic enzymes. This opened a new research area that led to the definition of new continuous cleaner processes for single or multi steps biotransformations, involving either enzymatic solid–gas bioreactors or microbial set-ups.
Since solid–gas bioreactors allow control and independent variation of the thermodynamic activity of substrates and other added components, they offer the possibility to modulate and to study the effect of each component present in the microenvironment of the biocatalyst. Therefore these solid–gas systems constitute an efficient tool to understand and rationalize the effects of the microenvironment of an enzyme on its activity, selectivity and stability.
In this review, some examples of the benefits of this thermodynamic approach and control of enzymatic reactions are discussed, and an overview of some applications of solid–gas technology to fundamental studies related to the influence of the microenvironment on enzymes are given.

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