Cooperative Activation of Cellulose with Natural Calcium

05 October 2020, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Naturally occurring metals such as calcium catalytically activate the inter-monomer β-glycosidic bonds in long chains of cellulose initiating reactions to volatile oxygenates for renewable applications. In this work, the millisecond kinetics of calcium catalyzed reactions were measured via the method of pulse-heated analysis of solid/surface reactions (PHASR) at high temperature (370-430 °C) to reveal accelerated glycosidic ether scission with a second order rate dependence on Ca2+ ions. First principles density functional theory (DFT) calculations were used to identify stable binding configurations for two Ca2+ ions that demonstrated accelerated transglycosylation kinetics with an apparent activation barrier of 50 kcal mol-1 for a cooperative calcium catalyzed cycle. The agreement of mechanism with calcium cooperativity to the experimental barrier (48.7 ± 2.8 kcal mol-1) suggests that calcium enhances reactivity through a dual role of disrupting native H-bonding and stabilizing charged transition states.

Keywords

Activation
Cellulose
Calcium
Hydrogen Bond
Glycosidic Bond
Cyclodextrin

Supplementary materials

Title
Description
Actions
Title
Supporting Information
Description
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.