The zwitterion isomer of orthosilicic acid and its role in neutral pH dimerization from density functional theory.

28 July 2021, Version 2
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

Using density functional theory, the plausible existence of the zwitterion isomer of orthosilicic acid is proposed to account for some of the properties of silica in water. Explicit hydration and explicit addition of salt are used in modeling the zwitterion and the dimerization reaction. Paths between orthosilicic acid, the zwitterion and the autoionization products are presented. The pK for the formation of the aqueous zwitterion species is calculated to be 7.78 in dilute silica solutions and the activation energy for the dimerization reaction ranges from 59.8 kJ/mol to 70.7 kJ/mol depending on salt concentration.

Keywords

zwitterion
orthosilicic acid
disilicic acid
density functional theory
ab initio
explicit hydration
dimerization
activation energy

Supplementary materials

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Description
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Research Data
Description
Configurations of molecules used in this study. Also, excerpts from Gaussian frequency calculations for these configurations.
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