Thermal Decompositions of the Lignin Model Compounds [electronic resource] : Salicylaldehyde and Catechol

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Tác giả:

Ngôn ngữ: eng

Ký hiệu phân loại: 621.48 Nuclear engineering

Thông tin xuất bản: Washington, D.C. : Oak Ridge, Tenn. : United States. Dept. of Energy. Office of Energy Efficiency and Renewable Energy ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2018

Mô tả vật lý: Size: p. 5911-5924 : , digital, PDF file.

Bộ sưu tập: Metadata

ID: 262979

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The nascent steps in the pyrolysis of the lignin components, salicylaldehyde (o-HOC
6
H
4
CHO) and catechol (
o
-HOC
6
H
4
OH), 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 ?sec. 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, photoelectron photoion concidence mass spectroscopy, and matrix isolation infrared spectroscopy. The main pathway by which salicylaldehyde decomposes is a concerted fragmentation: 
o
-HOC
6
H
4
CHO (+ M) ? H
2
+ CO + C
5
H
4
═
C═
O (fulveneketene). At temperatures above 1300 K, fulveneketene loses CO to yield a mixture of (HC☰
C?C☰
C?CH
3
, HC☰
C?CH
2
?C☰
CH, and HC☰
C?CH═
C═
CH
2
). These alkynes decompose to a mixture of radicals (HC☰
C?C☰
C?CH
2
and HC☰
C?CH?C☰
CH) and H-atoms. H-atom chain reactions convert salicylaldehyde to phenol: 
o
-HOC
6
H
4
CHO + H ? C
6
H
5
OH + CO + H. Catechol has similar chemistry to salicylaldehyde. Electrocyclic fragmentation produces water and fulveneketene: 
o
-HOC
6
H
4
OH (+ M) ? H
2
O + C
5
H
4
═
C═
O. These findings have implications for the pyrolysis of lignin itself.

1. 09 biomass fuels
2. Infrared spectroscopy
3. Lignin
4. Mass spectrometry
5. Mixtures

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