Thermal decomposition of the lignin model compounds: Salicylaldehyde and catechol

Porterfield, Jessie P.

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https://hdl.handle.net/2142/100623 Copy

Description

Title

Thermal decomposition of the lignin model compounds: Salicylaldehyde and catechol

Author(s)

Porterfield, Jessie P.

Contributor(s)

• Ellison, Barney
• Daily, John W.
• Robichaud, David
• Nimlos, Mark R.
• Ahmed, Musahid
• Troy, Tyler
• Hemberger, Patrick
• Scheer, Adam M
• Baraban, Joshua H.
• Ormond, Thomas

Issue Date

2018-06-18

Keyword(s)

Radicals

Abstract

The nascent steps in the pyrolysis of the lignin components, salicylaldehyde (o-HOC6H4CHO) and catechol (oHOC6H4OH), have been studied in a set of heated micro-reactors. The micro-reactors are small (roughly 1 mm ID x 3 cm long); transit times through the reactors are about 100 µsec. Temperatures in the micro-reactors can be as high as 1600 K and pressures are typically a few hundred Torr. The products of pyrolysis are identified by a combination of photoionization mass spectrometry and matrix isolation infrared spectroscopy. The main pathway by which salicylaldehyde decomposes is a concerted fragmentation: o-HOC6H4CHO (+ M) → H2 + CO + C5H4−−C−−O. At temperatures above 1300 K, fulveneketene loses CO to yield a mixture of HC−−−C−C−−−C−CH3 , HC−−−C−CH2−C−−−CH, and HC−−−C−CH−−C−−CH2 . These alkynes decompose to a mixture of radicals (HC−−−C−C−−−C−CH2 and HC−−−C−CH−C−−−CH and H atoms. H-atom chain reactions convert salicylaldehyde to phenol: o-HOC6H4CHO + H → C6H5OH + CO + H. Catechol has similar chemistry to salicylaldehyde. Electrocyclic fragmentation produces water and fulveneketene: o-HOC6H4OH (+ M) → H2O + C5H4−−C−−O. These findings have implications for the pyrolysis of lignin itself.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100623

DOI

10.15278/isms.2018.MJ10

Copyright and License Information

Copyright 2018 Jessie P. Porterfield

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