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Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects
This review discusses principal patterns that govern the processes of lignins’ catalytic oxidation into vanillin (3-methoxy-4-hydroxybenzaldehyde) and syringaldehyde (3,5-dimethoxy-4-hydroxybenzaldehyde). It examines the influence of lignin and oxidant nature, temperature, mass transfer, and of othe...
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
MDPI
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5713389/ https://www.ncbi.nlm.nih.gov/pubmed/29140301 http://dx.doi.org/10.3390/ijms18112421 |
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author | Tarabanko, Valery E. Tarabanko, Nikolay |
author_facet | Tarabanko, Valery E. Tarabanko, Nikolay |
author_sort | Tarabanko, Valery E. |
collection | PubMed |
description | This review discusses principal patterns that govern the processes of lignins’ catalytic oxidation into vanillin (3-methoxy-4-hydroxybenzaldehyde) and syringaldehyde (3,5-dimethoxy-4-hydroxybenzaldehyde). It examines the influence of lignin and oxidant nature, temperature, mass transfer, and of other factors on the yield of the aldehydes and the process selectivity. The review reveals that properly organized processes of catalytic oxidation of various lignins are only insignificantly (10–15%) inferior to oxidation by nitrobenzene in terms of yield and selectivity in vanillin and syringaldehyde. Very high consumption of oxygen (and consequentially, of alkali) in the process—over 10 mol per mol of obtained vanillin—is highlighted as an unresolved and unexplored problem: scientific literature reveals almost no studies devoted to the possibilities of decreasing the consumption of oxygen and alkali. Different hypotheses about the mechanism of lignin oxidation into the aromatic aldehydes are discussed, and the mechanism comprising the steps of single-electron oxidation of phenolate anions, and ending with retroaldol reaction of a substituted coniferyl aldehyde was pointed out as the most convincing one. The possibility and development prospects of single-stage oxidative processing of wood into the aromatic aldehydes and cellulose are analyzed. |
format | Online Article Text |
id | pubmed-5713389 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2017 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-57133892017-12-07 Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects Tarabanko, Valery E. Tarabanko, Nikolay Int J Mol Sci Review This review discusses principal patterns that govern the processes of lignins’ catalytic oxidation into vanillin (3-methoxy-4-hydroxybenzaldehyde) and syringaldehyde (3,5-dimethoxy-4-hydroxybenzaldehyde). It examines the influence of lignin and oxidant nature, temperature, mass transfer, and of other factors on the yield of the aldehydes and the process selectivity. The review reveals that properly organized processes of catalytic oxidation of various lignins are only insignificantly (10–15%) inferior to oxidation by nitrobenzene in terms of yield and selectivity in vanillin and syringaldehyde. Very high consumption of oxygen (and consequentially, of alkali) in the process—over 10 mol per mol of obtained vanillin—is highlighted as an unresolved and unexplored problem: scientific literature reveals almost no studies devoted to the possibilities of decreasing the consumption of oxygen and alkali. Different hypotheses about the mechanism of lignin oxidation into the aromatic aldehydes are discussed, and the mechanism comprising the steps of single-electron oxidation of phenolate anions, and ending with retroaldol reaction of a substituted coniferyl aldehyde was pointed out as the most convincing one. The possibility and development prospects of single-stage oxidative processing of wood into the aromatic aldehydes and cellulose are analyzed. MDPI 2017-11-15 /pmc/articles/PMC5713389/ /pubmed/29140301 http://dx.doi.org/10.3390/ijms18112421 Text en © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Review Tarabanko, Valery E. Tarabanko, Nikolay Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects |
title | Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects |
title_full | Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects |
title_fullStr | Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects |
title_full_unstemmed | Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects |
title_short | Catalytic Oxidation of Lignins into the Aromatic Aldehydes: General Process Trends and Development Prospects |
title_sort | catalytic oxidation of lignins into the aromatic aldehydes: general process trends and development prospects |
topic | Review |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5713389/ https://www.ncbi.nlm.nih.gov/pubmed/29140301 http://dx.doi.org/10.3390/ijms18112421 |
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