Direct detection of pyridine formation by the reaction of CH (CD) with pyrrole: a ring expansion reaction

Soorkia, Satchin; Taatjes, Craig A.; Osborn, David L.; Selby, Talitha M.; Trevitt, Adam J.; Wilson, Kevin R.; Leone, Stephen R.

doi:10.1039/c002135k

Cited by 56 publications

(69 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This H elimination must be rapid as there is no evidence of H-atom scrambling in the deuterium labeling experiment. 80 The isotopomer product identifications for the CH reactions with ethene, propene and pyrrole provide strong evidence that the radical cycloaddition onto the C=C bond is a major entrance channel. This mechanism is also consistent with the CH + allene reaction products.…”

Section: Methodsmentioning

confidence: 99%

Insights into gas-phase reaction mechanisms of small carbon radicals using isomer-resolved product detection

Trevitt

Goulay

2016

Phys. Chem. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

For reactive gas-phase environments, including combustion, extraterrestrials atmospheres and our Earth's atmosphere, the availability of quality chemical data is essential for predictive chemical models. These data include reaction rate coefficients and product branching fractions. This perspective overviews recent isomerresolved production detection experiments for reactions of two of the most reactive gas phase radicals, the CN and CH radicals, with a suite of small hydrocarbons. A particular focus is given to flow-tube experiments using synchrotron photoionization mass spectrometry. Coupled with computational studies and other experiment techniques, flow tube isomer-resolved product detection have provided significant mechanistic details of these radical + neutral reactions with some general patterns emerging. Disciplines Medicine and Health Sciences | Social and Behavioral Sciences ABSTRACTFor reactive gas-phase environments, including combustion, extraterrestrials atmospheres and our Earth's atmosphere, the availability of quality chemical data is essential for predictive chemical models. These data include reaction rate coefficients and product branching fractions. This perspective overviews recent isomer-resolved production detection experiments for reactions of two of the most reactive gas phase radicals, the CN and CH radicals, with a suite of small hydrocarbons. A particular focus is given to flowtube experiments using synchrotron photoionization mass spectrometry. Coupled with computational studies and other experiment techniques, flow tube isomer-resolved product detection have provided significant mechanistic details of these radical + neutral reactions with some general patterns emerging.

show abstract

Section: Methodsmentioning

confidence: 99%

Insights into gas-phase reaction mechanisms of small carbon radicals using isomer-resolved product detection

Trevitt

Goulay

2016

Phys. Chem. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…11,17,18 The experiment comprises a reaction flow tube coupled to a photoionization mass spectrometer.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…11 Primarily, the isomer-resolved products detected in these studies can be rationalized by a reaction entrance channel characterized by CH addition to π-bond(s) of the co-reactant, although other processes, including insertion into C-H σ-bonds, could not be unequivocally ruled out.…”

Section: Introductionmentioning

confidence: 91%

Product Branching Fractions of the CH + Propene Reaction from Synchrotron Photoionization Mass Spectrometry

et al. 2013

Self Cite

View full text Add to dashboard Cite

The CH(X2Π) + propene reaction is studied in the gas phase at 298 K and 4 Torr (533.3 Pa) using VUV synchrotron photoionization mass spectrometry. The dominant product channel is the formation of C4H6 (m/z 54) + H. By fitting experimental photoionization spectra to measured spectra of known C4H6 isomers, the following relative branching fractions are obtained: 1,3-butadiene (0.63 ± 0.13), 1,2-butadiene (0.25 ± 0.05), and 1-butyne (0.12 ± 0.03) with no detectable contribution from 2-butyne. The CD + propene reaction is also studied and two product channels are observed that correspond to C4H6 (m/z 54) + D and C4H5D (m/z 55) + H, formed at a ratio of 0.4 (m/z 54) to 1.0 (m/z 55). The D elimination channel forms almost exclusively 1,2-butadiene (0.97 ± 0.20) whereas the H elimination channel leads to the formation of deuterated 1,3-butadiene (0.89 ± 0.18) and 1-butyne (0.11 ± 0.02); photoionization spectra of undeuterated species are used in the fitting of the measured m/z 55 (C4H5D) spectrum. The results are generally consistent with a CH cycloaddition mechanism to the C═C bond of propene, forming 1-methylallyl followed by elimination of a H atom via several competing processes. The direct detection of 1,3-butadiene as a reaction product is an important validation of molecular weight growth schemes implicating the CH + propene reaction, for example, those reported recently for the formation of benzene in the interstellar medium ( Jones, B. M. Proc. Natl. Acad. Sci. U.S. A. 2011, 108, 452−457 ABSTRACTThe CH (X 2 Π) + propene reaction is studied in the gas phase at 298 K and 4 Torr (533.3 Pa) using VUV synchrotron photoionization mass spectrometry. The dominant product channel is the formation of C 4 H 6 (m/z 54) + H. By fitting experimental photoionization spectra to measured spectra of known C 4 H 6 isomers, the following relative branching fractions are obtained: 1,3-butadiene (0.63 ± 0.13), 1,2-butadiene (0.25 ± 0.05) and 1-butyne (0.12 ± 0.03) with no detectable contribution from 2-butyne. The CD + propene reaction is also studied and two product channels are observed that correspond to 2011, 108, 452-457).KEYWORDS: radical, gas-phase, photoionization, synchrotron, propene, methylidyne, mass spectrometry. 3 INTRODUCTIONThe highly reactive methylidyne (CH) radical affects the chemistry of energetic gasphase environments including combustion 1-3 , interplanetary atmospheres 4-6 and the interstellar medium. 7 In order to accurately model these systems, detailed chemical data are needed in the form of reaction rate coefficients and product branching fractions. Our purpose here is to determine total product branching fractions and provide mechanistic details for the CH (X 2 Π) + propene reaction. The present work builds on a series of previous product detection studies of the CH radical with small, unsaturated hydrocarbons: acetylene (C 2 H 2 ), ethylene (C 2 H 4 ), allene (C 3 H 4 , CH 2 CCH 2 ) and propyne (C 3 H 4 , CH 3 CCH). 8 Recent works have also investigated the CH reaction with the carbonyl-conta...

show abstract

“…Furthermore, a close relationship between CH and long carbon chains or cyclic molecules may originate in direct CH insertion into an unsaturated hydrocarbon (followed by H elimination) which is likely to proceed with a small or no barrier (e.g. Soorkia et al 2010, and references therein).…”

Section: The Chemistry Of Ch and Its Relation To Ohmentioning

confidence: 99%

CH abundance gradient in TMC-1

Suutarinen

Geppert

Harju

et al. 2011

A&A

View full text Add to dashboard Cite

Aims. The aim of this study is to examine if the well-known chemical gradient in TMC-1 is reflected in the amount of rudimentary forms of carbon available in the gas-phase. As a tracer we use the CH radical which is supposed to be well correlated with carbon atoms and simple hydrocarbon ions. Methods. We observed the 9-cm Λ-doubling lines of CH along the dense filament of TMC-1. The CH column densities were compared with the total H 2 column densities derived using the 2MASS NIR data and previously published SCUBA maps and with OH column densities derived using previous observations with Effelsberg. We also modelled the chemical evolution of TMC-1 adopting physical conditions typical of dark clouds using the UMIST Database for Astrochemistry gas-phase reaction network to aid the interpretation of the observed OH/CH abundance ratios. Results. The CH column density has a clear peak in the vicinity of the cyanopolyyne maximum of TMC-1. The fractional CH abundance relative to H 2 increases steadily from the northwestern end of the filament where it lies around 1.0 × 10 −8 , to the southeast where it reaches a value of 2.0 × 10 −8 . The OH and CH column densities are well correlated, and we obtained OH/CH abundance ratios of ∼16-20. These values are clearly larger than what has been measured recently in diffuse interstellar gas and is likely to be related to C to CO conversion at higher densities. The good correlation between CH and OH can be explained by similar production and destruction pathways. We suggest that the observed CH and OH abundance gradients are mainly due to enhanced abundances in a low-density envelope which becomes more prominent in the southeastern part and seems to continue beyond the dense filament.Conclusions. An extensive envelope probably signifies an early stage of dynamical evolution, and conforms with the detection of a large CH abundance in the southeastern part of the cloud. The implied presence of other simple forms of carbon in the gas phase provides a natural explanation for the observation of "early-type" molecules in this region.

show abstract

Direct detection of pyridine formation by the reaction of CH (CD) with pyrrole: a ring expansion reaction

Abstract: The reaction of the ground state methylidyne radical CH (X 2 Π) with pyrrole (C 4 H

Cited by 56 publications

References 66 publications

Insights into gas-phase reaction mechanisms of small carbon radicals using isomer-resolved product detection

Insights into gas-phase reaction mechanisms of small carbon radicals using isomer-resolved product detection

Product Branching Fractions of the CH + Propene Reaction from Synchrotron Photoionization Mass Spectrometry

CH abundance gradient in TMC-1

Contact Info

Product

Resources

About