Gas-phase pyrolysis of thiopheneacetic acids, thienylethanols, and related compounds — protophilicity of ring π-electrons and relative acidities of hydrogen-bond donors of hydroxyl groups

2002 ◽  
Vol 80 (5) ◽  
pp. 499-503 ◽  
Author(s):  
Ibtehal A Al-Juwaiser ◽  
Nouria A Al-Awadi ◽  
Osman ME El-Dusouqui
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Bond ◽  
Gas Phase ◽  
Kinetic Data ◽  
Reaction Pathway ◽  
Hydroxyl Groups ◽  
Pyrolysis Kinetics ◽  
Elimination Reactions ◽  
Related Compounds ◽  
Phase Elimination

Based on kinetic data of thermal gas-phase elimination reactions, the following Arrhenius log A (s–1) and Ea (kJ mol–1) values, respectively, are obtained: 10.76 and 153.5 for 3-thiopheneacetic acid (1), 10.08 and 149.4 for 2-thiopheneacetic acid (2), 12.04 and 207.1 for 2-(3-thienyl)ethanol (3), 11.55 and 203.3 for 2-(2-thienyl)ethanol (4), 10.91 and 123.4 for 2-thiopheneglyoxylic acid (5), 11.05 and 223.8 for 1-(2-thienyl)propan-1-one (6), and 10.33 and 149.8 for 3-thiophenemalonic acid (7). The products of these pyrolytic reactions were either carbon dioxide or formaldehyde in addition to methylthiophene or thiophenecarboxaldehyde. Both positional and molecular reactivities of the substrates and related compounds are compared, and the results are rationalized on the basis of a reaction pathway involving a concerted six-membered transition state.Key words: thiophenes, gas-phase, pyrolysis, kinetics, mechanism.

Molecular rearrangements in homogeneous gas-phase elimination reactions. Pyrolysis kinetics of alkyl methanesulphonates

1993 ◽  
Vol 6 (2) ◽  
pp. 85-94 ◽  
Author(s):  
Gabriel Chuchani ◽  
Ignacio Martin ◽  
Rosa M. Dominguez ◽  
Alexandra Rotinov ◽  
Sara Pekerarm ◽  
...  
Keyword(s):  
Gas Phase ◽  
Pyrolysis Kinetics ◽  
Molecular Rearrangements ◽  
Elimination Reactions ◽  
Kinetics Of ◽  
Phase Elimination

scholarly journals Gas-Phase Photocatalytic Oxidation of Dimethylamine: The Reaction Pathway and Kinetics

2007 ◽  
Vol 2007 ◽  
pp. 1-4
Author(s):  
Anna Kachina ◽  
Sergei Preis ◽  
Juha Kallas
Keyword(s):  
Carbon Dioxide ◽  
Gas Phase ◽  
Continuous Flow ◽  
Kinetic Data ◽  
Photocatalytic Oxidation ◽  
Reaction Pathway ◽  
Tubular Reactor ◽  
Order Process ◽  
First Order ◽  
Long Run

Gas-phase photocatalytic oxidation (PCO) and thermal catalytic oxidation (TCO) of dimethylamine (DMA) on titanium dioxide was studied in a continuous flow simple tubular reactor. Volatile PCO products of DMA included ammonia, formamide, carbon dioxide, and water. Ammonia was further oxidized in minor amounts to nitrous oxide and nitrogen dioxide. Effective at 573 K, TCO resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide, and water. The PCO kinetic data fit well to the monomolecular Langmuir-Hinshelwood model, whereas TCO kinetic behaviour matched the first-order process. No deactivation of the photocatalyst during the multiple long-run experiments was observed.

Artificial Photosynthesis - Use of a Ferroelectric Photocatalyst

2012 ◽  
Vol 1446 ◽  
Author(s):  
Steve Dunn ◽  
Matt Stock
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Titanium Dioxide ◽  
Lithium Niobate ◽  
Gas Phase ◽  
Remnant Polarization ◽  
Artificial Photosynthesis ◽  
Reaction Pathway ◽  
Mercury Lamp ◽  
Low Levels

ABSTRACTThe solid-gas phase photoassisted reduction of carbon dioxide (artificial photosynthesis) was performed using ferroelectric lithium niobate and titanium dioxide as photocatalysts. Illumination with a high pressure mercury lamp and visible sunlight showed lithium niobate achieved unexpectedly high conversion of CO2 to products despite the low levels of band gap light available and outperformed titanium dioxide under the conditions used. The high reaction efficiency of lithium niobate is explained due to its strong remnant polarization (70 μC/cm2) thought to allow longer lifetime of photo induced carriers as well as an alternative reaction pathway.

On the mechanism of base-induced gas-phase elimination reactions of ethers

1987 ◽  
Vol 109 (6) ◽  
pp. 1715-1722 ◽  
Author(s):  
Leo J. De Koning ◽  
Nico M. M. Nibbering
Keyword(s):  
Gas Phase ◽  
Elimination Reactions ◽  
Phase Elimination
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