Pyrolytic alkylation-gas chromatography-mass spectrometry of model polymers Further insights into the mechanism and scope of the technique

Abstract

AbstraetThe mechanism of the high-temperature hydrolysis and alkylation with tetraalkylammonium hydroxides of bio-and geopolymers has been approached mainly by studying the behaviour of single standard compounds. In the present work, we have applied this technique to three polymers of known structure, i.e. suberin, polycitraconic acid (peA) and a lignin dehydrogenase polymer (DHP), related respectively to natural polyesters, fulvic acids and lignins, in order to get new insight into the reaction mechanism. As further application of the technique, the case study of the lignin signature during the coalification process has been analyzed by pyrolysis-butylation of humic acids extracted from two peat and lignite samples.

Influence of change in land use on the refractory organic macromolecular fraction of a sandy spodosol (Landes de Gascogne, France)

“…However, severe lignin alteration is indicated by the production upon pyrolysis of catechols (1,2-benzenediols) and the lack of methoxyphenols, as a result of demethoxylation and demethylation reactions affecting the guaiacyl and the syringyl phenolic moieties (Hatcher and Spiker, 1988;Gonzalez-Vila et al, 1996). In fact, catechols are not detected here, whereas relatively abundant methoxyphenols are observed.…”

“…Secondary reactions like acid decarboxylation and alcohol dehydration are also limited (e.g. del Rio et al, 1996). The trace of the thermochemolysate of the ROM shows numerous aromatic and aliphatic compounds that predominate in the first and second parts of the chromatogram, respectively (Fig.…”

“…Methyl ethers and esters of ω-hydroxy acids are typical THM products of suberins and cutins (e.g. de Leeuw and Baas, 1993;Gonzalez-Vila et al, 1996;Nierop, 2001). These biopolyesters, occurring in roots and bark, and on aerial parts of plants, respectively, are chiefly composed of interesterified ω-hydroxyalkanoic acids and α,ω-alkanedioic acids (e.g.…”

A comparative study on the chemical composition of humic acids from forest soil, agricultural soil and lignite deposit

“…Majority of studies examining lipid composition of humic acids have been concerned with soil and peat humic acids (Schnitzer and Ortiz de Serra, 1973;Saiz-Jimenez and de Leeuw, 1987;Hänninen and Niemala, 1991;Hänninen, 1992;Martin et al, 1995;del Rio et al, 1998;Grasset and Amblès, 1998a,b;Grasset et al, 2002). Similar studies about lignite humic acids are scarce (Gonzalez-Vila et al, 1996;Olivella et al, 2002;Rozenbaha et al, 2002). By contrast, little attention has been given to the analysis of hydrophilic constituents of humic acids.…”

Caracterização química do "pitch" em indústria de celulose e papel de Eucalyptus

“…Dos compostos aromáticos identificados, o 3-(4-hidroxi-3-metoxifenil)prop-2-enol (álcool coniferílico), ácido 4-hidroxi-3-metoxibenzóico (ácido vanílico) e 4-hidroxi-3,5-dimetoxibenzóico (ácido siríngico) já haviam sido identificados em E. globulus anteriormente 17 . Os demais compostos aromáticos, tais como o ácido 3,4-diidroxibenzóico e ácido 3,4,5-triidroxibenzóico (ácido gálico), foram identificados em madeira de E. globulus, após pirólise 32,33 . Os compostos aromáticos são formados a partir da lignina que, apesar de não ser considerada extrativo, pode ser pirolisada produzindo misturas de fenóis relativamente simples como esses identificados no extrato 34 .…”