{'fraction_non_alphanumeric': 0.02406015037593985, 'fraction_numerical': 0.010526315789473684, 'mean_word_length': 5.308056872037914, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
A quantum chemical study of LIX63 hydroxyoxime syn/anti isomerisation

ABSTRACT Quantum mechanical studies of the Z/E (syn/anti) acetoin oxime interconversion have been conducted using both density functional theory (DFT) and ab initio post-Hartree–Fock methods in order to understand the thermodynamic properties of the syn/anti isomerisation of the aliphatic α-hydroxyoxime 5,8-diethyl-7-hydroxydodecan-6-oxime. The anti isomer of this molecule is the active component in LIX63, a commercial reagent used in hydrometallurgical solvent extraction (SX). The effect of different sized alkyl (R) groups on both kinetic and thermodynamic properties of the equilibrium between syn and anti isomers of aliphatic α-hydroxyoxime has been studied. Theoretically, it has been shown that using R = C3H8 on both ends of the oxime is the minimum substituent size required to obtain good agreement for the thermodynamics in comparison to experimental data for LIX63. Further increases in the size of the R group do not have any significant effect on the final distribution between syn and anti isomers of LIX63 hydroxyoxime. Inversion was determined to be the most energetically favourable hydroxyoxime isomerisation mechanism, with the energy barrier lowered when isomerisation is considered between syn and anti isomers with larger R groups.