Ionic Liquids in the Chemical Valorisation of Pulps and in their Chemical Analyses

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Title: Ionic Liquids in the Chemical Valorisation of Pulps and in their Chemical Analyses
Author: Rico del Cerro, Daniel
Contributor organization: University of Helsinki, Faculty of Science, Department of Chemistry
Doctoral Programme in Chemistry and Molecular Research
Helsingin yliopisto, matemaattis-luonnontieteellinen tiedekunta
Kemian ja molekyylitutkimuksen tohtoriohjelma
Helsingfors universitet, matematisk-naturvetenskapliga fakulteten
Doktorandprogrammet i kemi och molekylära vetenskaper
Publisher: Helsingin yliopisto
Date: 2021-08-10
Language: eng
Thesis level: Doctoral dissertation (article-based)
Abstract: The overall aim of this thesis is to understand the chemistry of different types of ionic liquids (ILs) and their application in cellulose processing, as well as in the chemical analyses of pulp. ILs are applied either on their own or as electrolytes with dimethyl sulfoxide (DMSO) or gamma valerolactone (GVL) as co-solvents. All of the ILs utilised in this work were synthesised in our laboratory via Menshutkin reaction followed by metathesis to different counter anions or via acid-base chemistry. The beginning of our work focused on the investigation of the C2 chemistry of imidazolium ionic liquids (IMILs), one of the first class of ionic liquids utilised in biomass processing, resulting in the understanding of the C2 chemistry of IMILs under neutral and acidic conditions, which complete the comprehension on the mechanistic scenario of the C2 chemistry of IMILs. In this investigation, the importance of the quality of the ILs is remarked. The studies continued to investigate the activation of the chemical reactivity of pulps using tetrabutylphosphonium acetate ([P4444][OAc]), a more thermal stable ionic liquid. The non-dissolving pre-treatment of pulps by [P4444][OAc] demonstrated a reduction in the crystallinity of the pulp to be directly related to its chemical reactivity enhancement. Additionally, [P4444][OAc]:d6-DMSO (20:80 wt.%) was also investigated in both the regioselectivity studies of acetylation reactions and the oxidised nanocellulose nuclear magnetic resonance (NMR) analyses. Quantitative heteronuclear single quantum correlation (HSQC) NMR was a suitable experiment for the quantitation of the oxidation level achieved in the nanocellulose, demonstrating the potential of this method for cellulose analyses. Finally, the research concluded with the studies on other cellulose solvent systems, such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with dimethylsulphoxide (DMSO), which resulted on the discovery of the unexpected reactivity of 1,1,3,3-tetramethylguanidinium acetate ([TMG][OAc]). Furthermore, this investigation led us to the design and synthesis of a novel task-specific ionic liquid (TSIL), so called ‘TMG2SA’. This IL was investigated with regard to cellulose chemical modification, resulting in the high yield production of nanocellulose-type materials by a low demanding energy step, with a different approach than previously reported.
Subject: chemistry
Rights: Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty.

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