Unimolecular thermal decomposition of dimethoxybenzenes.

doi:10.1063/1.4879615

Paper

Unimolecular thermal decomposition of dimethoxybenzenes.

Published Jun 21, 2014 · D. Robichaud, A. Scheer, C. Mukarakate

The Journal of chemical physics

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35

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Abstract

The unimolecular thermal decomposition mechanisms of o-, m-, and p-dimethoxybenzene (CH3O-C6H4-OCH3) have been studied using a high temperature, microtubular (μtubular) SiC reactor with a residence time of 100 μs. Product detection was carried out using single photon ionization (SPI, 10.487 eV) and resonance enhanced multiphoton ionization (REMPI) time-of-flight mass spectrometry and matrix infrared absorption spectroscopy from 400 K to 1600 K. The initial pyrolytic step for each isomer is methoxy bond homolysis to eliminate methyl radical. Subsequent thermolysis is unique for each isomer. In the case of o-CH3O-C6H4-OCH3, intramolecular H-transfer dominates leading to the formation of o-hydroxybenzaldehyde (o-HO-C6H4-CHO) and phenol (C6H5OH). Para-CH3O-C6H4-OCH3 immediately breaks the second methoxy bond to form p-benzoquinone, which decomposes further to cyclopentadienone (C5H4=O). Finally, the m-CH3O-C6H4-OCH3 isomer will predominantly follow a ring-reduction/CO-elimination mechanism to form C5H4=O. Electronic structure calculations and transition state theory are used to confirm mechanisms and comment on kinetics. Implications for lignin pyrolysis are discussed.

Study Snapshot

The unique thermolysis mechanisms of o-, m-, and p-dimethoxybenzenes can be used to optimize lignin pyrolysis processes.

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

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Unimolecular thermal decomposition of dimethoxybenzenes.

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Citations

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Computational Study on Ring Saturation of 2-Hydroxybenzaldehyde Using Density Functional Theory

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