Non-enzymic Epimerisation and Elimination

1 Non-enzymic Epimerisation and Elimination. The non-enzymic removal of a carbon-bound proton a to an ionised carboxylate of a uronic acid 

Analysis of these rate and data show that the C5-H5 bond of a uronate is a kinetically normal acid site, like OH and NH sites. There is essentially no barrier to proton transfer between such sites, thermodynamically favoured deprotonation occurring at the diffusion rate (10 M s at 25 °C), thermodynamically disfavoured deprotonation occurring at a rate of Therefore, the rate of deprotonation of a normal acid of pK 32 by OH (pAia 

Analysis of reprecipitated xylan on fibres from kraft pulping of hardwoods by modern methods indicated that the model system of 20 years earlier had been very perceptive both hexeneuronic acid residues and p-L-iduronyl residues were found (The finding caused a stir in the pulp industry, since a KMn04 titre ( kappa number ) had been used traditionally as measure of the residual lignin in the pulp, but in hardwood pulps these titres were too high, by factors of 2, because of the reaction of permanganate with the hexeneuronic acids ). 

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