Isomerization and fragmentation of cyclohexanone in a heated micro-reactor

Ellison, Barney

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https://hdl.handle.net/2142/91258 Copy

Description

Title

Isomerization and fragmentation of cyclohexanone in a heated micro-reactor

Author(s)

Ellison, Barney

Contributor(s)

• Daily, John W.
• Stanton, John F.
• Ahmed, Musahid
• Kostko, Oleg
• Troy, Tyler
• Buckingham, Grant
• Baraban, Joshua H.
• Nguyen, Thanh Lam
• Porterfield, Jessica P.

Issue Date

2016-06-20

Keyword(s)

Conformers, isomers, chirality, stereochemistry

Abstract

\begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.185]{TableofContents.eps} \end{wrapfigure} The thermal decomposition of cyclohexanone (\chem{C_6H_{10}}=O) has been studied in a set of flash-pyrolysis micro-reactors. Samples of \chem{C_6H_{10}}=O were first observed to decompose at 1200 K. Short residence times of 100 $\mu$sec and dilution of samples ($<$0.1\%) isolate unimolecular decomposition. Products were identified by tunable VUV photoionization mass spectroscopy, photoionization appearance thresholds, and complementary matrix infrared absorption spectroscopy. Thermal cracking of cyclohexanone appeared to result from a variety of competing pathways pictured to the right. Isomerization of cyclohexanone to the enol, cyclohexen-1-ol (\chem{C_6H_9OH}), is followed by retro-Diels-Alder cleavage to \chem{CH_2}=\chem{CH_2} and \chem{CH_2}=\chem{C(OH)}-CH=\chem{CH_2}. Further isomerization of \chem{CH_2}=C(OH)CH=\chem{CH_2} to methyl vinyl ketone (\chem{CH_3CO}CH=\chem{CH_2}, MVK) was also observed. Photoionization spectra identified both enols, \chem{C_6H_9OH} and CH=C(OH)CH=\chem{CH_2}, and the ionization threshold of \chem{C_6H_9OH} was measured to be 8.2 $\pm$ 0.1 eV. At 1200 K, the products of cyclohexanone pyrolysis were found to be: \chem{C_6H_9OH}, \chem{CH_2}=C(OH)CH=\chem{CH_2}, MVK, \chem{CH_2CHCH_2}, CO, \chem{CH_2}=C=O, \chem{CH_3}, \chem{CH_2}=C=\chem{CH_2}, \chem{CH_2}=CH-CH=\chem{CH_2}, \chem{CH_2}=\chem{CHCH_2CH_3}, \chem{CH_2}=\chem{CH_2}, and HCCH.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

En

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http://hdl.handle.net/2142/91258

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Copyright 2016 by the authors

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