Open AccessAb Initio Computational Study of electronic structure of -O-C Bonding Formation on Chitosan Polymer-Part 1: Effects of NaOH
Author(s) -
Shella V Yuliani,
Siti Nur Milatus Salimah,
Dwi Hudiyanti,
Marlyn Dian Laksitorini,
Parsaoran Siahaan
Publication year - 2019
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1217/1/012054
Subject(s) - chemistry , ab initio , dimer , reaction mechanism , catalysis , chitosan , activation energy , polymer chemistry , polymer , computational chemistry , organic chemistry
Carboxymethyl chitosan (CMC) is a biopolymer that has water-soluble properties, high viscosity, biocompatibility, biodegradable, and low toxicity. CMC can be made by direct alkylation using monocloroacetic acid to produce chitosan derivatives under certain reaction conditions with NaOH as a catalyst. This research aims to explain one the reaction mechanism of bonding formation of O-C and to compare with the effect of the presence of NaOH as a catalyst. The reaction mechanism of O-CMC formation studied by the computational method. Chitosan polymer is very complex, so the molecule model used for calculation is chitosan dimer segment. The stable molecular structure of chitosan dimer which is involved in the reaction mechanism was optimized using ab initio computational method based on Hartree Fork theory and 6-31G(d,p) basis set. Mechanism of O-CMC synthesis reaction was modeled into S N 2 reaction (bimolecular nucleophilic substitution) which results in PO-CMC-2. The study showed that the -O-C bonding formation by S N 2 model and NaOH as a catalyst was more preferred with an activation energy of 323,321 kJ⋅mol −1 than without NaOH as a catalyst with an activation energy of 533,22 kJ⋅mol −1 . The mechanism of the synthesis reaction of O-CMC is an exothermic reaction and spontaneously.