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This work demonstrates a novel synthesis route to halogen-free ionic liquids. A one-pot synthetic reaction route avoiding the use of toxic and high-energetic alkyl halides was developed to reduce the environmental impact of the synthesis process of ionic liquids. However, the elimination of halogens and alkyl halides in the preparation of ionic liquids is not just an environmental issue: the aforementioned species are also among the most common and persistent contaminants in today’s Ionic Liquids (ILs). Thus, this paper introduces a range of quaternized nitrogen based ionic liquids, including both aromatic and non-aromatic components, all prepared without alkyl halides in any step of the process. Moreover, bio-renewable precursors such as (bio-)alcohols and carboxylic acids were employed as anion sources and alkylation media, thus avoiding halogen contamination or halogen-containing anions. The IL’s prepared were designed to dissolve cellulose, some of which was included in a cellulose dissolution study using a sulphite cellulose from the company Domsjö.

It is commonly accepted that world-wide production of oil, coal and natural gas will eventually come to a halt, although we still heavily depend on these non-renewable feed stocks and their associated chemical derivatives. Therefore, new, sustainable resources for the production of industrially important chemicals are required. Biomaterials offer much promise in this regard, since they generally contain a lot of cellulose which can be transformed and potentially provide a great source of industrially important chemicals. Presently, only a small part of the annual biomass growth in the world is utilized by industry, while the rest is decaying along natural pathways. In order to effectively process cellulose, it needs to be dissolved in some liquid medium. Present state-of-the-art commercial technologies employ very toxic and hazardous processing with volatile organic solvents like CS2. However, this need not be the case. Ionic liquids (ILs) have shown great potential for the dissolution of cellulose. Some ILs also have attractive physical properties such as: low vapor pressure, high thermal stability and reusability. Thus, they are potentially viable and more environmentally friendly alternatives. Hereby, we present and discuss some of the challenges and perspectives for ILs in terms of their potential for cellulose processing. We briefly review the historical processes and current methods for cellulose processing, and look at alternative processes taking advantage of ILs.

The goal of the present study, devoted to wood fractionation, was to obtain monosaccharides, hexoses and pentoses by means of an ionic liquid (IL) based pre-treatment procedure. Softwood sawdust (maximum particle size of 2 mm) of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) were exposed to ionic liquids – 1-ethyl-3-methylimidazolium acetate (C2mimAce) and 1-ethyl-3-methylimidazolium chloride (C2mimCl) – and thermal treatment (80-150 °C), for various time intervals (0-72 h). Furthermore, cellulose of various origins (plants, wood pulps) was dissolved in C2mimAce and 1-butyl-3-methylimidazolium chloride (C4 mimCl) for the study of the dissolved fractions, stress being laid on monosaccharides and possible by-products, 5-hydroxymethylfurfural and furfural. Knowing the challenges in analysis techniques when ILs and sugars are involved, the present work focuses on the development of suitable analysis methods. To this end, a Hewlett Packard 1100 series HPLC equipped with a refractive index (RI), detector model HP1047 A and a diode array UV detector (DAD) fitted with a carbohydrate column HPX-87K was utilized. Challenges and improvements are discussed.