An investigation into switchable polarity ionic liquids using mixed carbamates

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Title: An investigation into switchable polarity ionic liquids using mixed carbamates
Author: Elliott, Todd
Contributor: University of Helsinki, Faculty of Science
Publisher: Helsingin yliopisto
Date: 2019
Language: eng
Thesis level: master's thesis
Degree program: Kemian ja molekyylitieteiden maisteriohjelma
Master's Programme in Chemistry and Molecular Sciences
Magisterprogrammet i kemi och molekylära vetenskaper
Specialisation: Kemian opettaja
Teacher in Chemistry
Lärare i kemi
Discipline: none
Abstract: An investigation into switchable polarity ionic liquids was carried out to find greener alternative substituents and still obtain a switchable polarity ionic liquid. First for fluorinated compounds (fluorinated alcohol and amine) with a non-fluorinated hydroxylamine to form a mixed carbamate, then replacing the superbase with a basic tertiary (or secondary) amine. The trigger molecule for switching polarity was CO2. It was found that O-hexylhydroxylamine was a suitable replacement for fluorinated ethanol and fluorinated ethylamine to work with DBU (superbase) to form a switchable polarity ionic liquid. The three amines of triethylamine (TEA), diisopropylethylamine (Hünigs base) and diisopropylamine (DIPA) were inconclusive or unsuccessful. Both TEA and DIPA require further alternative analysis for a conclusive result while Hünigs base was proven to be unsuccessful. These reaction products were characterised with 1H and 13C NMR and ReactIR spectral data. Synthesis of hydroxylamine was also approached for a greener improvement. A new synthesis method is demonstrated that is successful using water and methylamine in ethanol working on reaction equilibria. The new method proposed had a yield of 29.1%, while the patent literature method that used hydrazine monohydrate (which is highly toxic and unstable unless in solution) gave a yield of 54.3% of hydroxylamine. A secondary investigation was also undertaken in to basicity effects of caesium carbonate on the CO2 addition to aniline, with and without a superbase present. The superbase used was tertramethylguanidine (TMG). Aniline, p-nitroaniline and p-methoxyaniline were tested for CO2 addition by formation of an amide peak in ReactIR. There was formation of the amide peak with caesium carbonate, though not as much as with the already known TMG. A concentration series of caesium carbonate and TMG in aniline was also devised to observe the effect the added caesium carbonate had on the aniline-TMG system in absorbing CO2. This was also analysed using ReactIR spectra. It was seen generally that by increasing the concentration of both/either TMG/Cs2CO3 there is an increase in carbamate. However further concentration series data is required before a generalised rule can be defined.

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