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The pyridine-catalysed acylation of Pine Sapwood and phenolic model compounds with carboxylic acid anhydrides. Determination of activation energies and entropy of activation

Hill, Callum and Papadopoulos, A N (2002) The pyridine-catalysed acylation of Pine Sapwood and phenolic model compounds with carboxylic acid anhydrides. Determination of activation energies and entropy of activation. Holzforschung, 56 (2). pp. 150-156. ISSN 0018-3830

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Abstract/Description

The reaction activation energies and entropies have been determined for the catalysed reaction of pyridine swollen pine sapwood samples and phenolic model compounds (in solution) with a homologous series of carboxylic acid anhydrides. With wood samples, the activation energy (Ea) was largest for the reaction of ethanoic anhydride (ca. 40 kJ mol-1), and decreased as the molecular weight of the anhydride increased (to ca. 10 kJ mol-1 with hexanoic anhydride). With the model compounds, there was no substantial evidence for such a relationship between molecular weight of anhydride and Ea. Values for the entropy of activation for reaction with wood were on the order of -300 J K-1 mol-1, whereas values for reaction with the model compounds were generally on the order of -220 to -260 J K-1 mol-1. The activation energies of diffusion (Eadiff) for the anhydride series in Corsican and Scots pine have also been determined, these varied from ca. 7 to 19 kJ mol-1. No correlation was found between Eadiff and anhydride, nor between Eadiff and wood species. The results are interpreted by considering the void space created around the reactive hydroxyl groups through swelling of the cell wall with pyridine.

Item Type: Article
Print ISSN: 0018-3830
Electronic ISSN: 1437 434X
Uncontrolled Keywords: Wood; Pine sapwood; Chemical treatment; Acylation; Catalysis; Phenols; Carboxylic acids; Activation energy; Entropy; Swelling; Molecular weight; Diffusion;
University Divisions/Research Centres: Faculty of Engineering, Computing and Creative Industries > School of Engineering and the Built Environment
Dewey Decimal Subjects: 500 Science > 540 Chemistry > 547 Organic chemistry
600 Technology > 670 Manufacturing > 674 Lumber processing, wood products & cork
Library of Congress Subjects: T Technology > TP Chemical technology
S Agriculture > SD Forestry
Item ID: 1909
Depositing User: RAE Import
Date Deposited: 28 May 2008 09:43
Last Modified: 11 Oct 2013 13:32
URI: http://researchrepository.napier.ac.uk/id/eprint/1909

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