**Author details**

*Solvents, Ionic Liquids and Solvent Effects*

nating anions are nonsolvents [44].

as well as [EMIM][Cl], [EMIM][OAc], and [EMIM][MP] have been documented to be one of the most effective ILs for cellulose dissolution, with [BMIM][Cl] able to dissolve up to 25% wt of cellulose having a DP = 1000 using a microwave heating method. During dissolution process, it has been shown by aid of various analytical techniques that the strong inter- and intramolecular hydrogen bonding of cellulose is broken up by formation of intense hydrogen bonding between ionic liquid anions and cellulose hydroxyls making cellulose to be soluble; hence, ILs with noncoordi-

**3.3 Cellulose dissolution using ionic liquids and cosolvents (organic solvents)**

The use of organic solvents in the cellulose chemistry has been vain for many decades, which lead to the use of solvents like oxide amines (NMMO), NaOH/urea, LiCl/DMI, ILs ([BMIM][Cl], [AMIM][Cl]), etc. However every solvent has its own rewards and drawbacks; so far the greenest solvents proposed are the ILs. However, the use of ILs is still not yet practical and faces a lot of industrial challenges since ILs are available in small amount, are relatively costly, and have very high viscosity compared to other common aqueous thermochemical pretreatment reagents, and it deactivates regular cellulolytic enzymes [75–77]. To overcome these challenges faced by ILs, Renaldi [67] created a solvent system, which is a bicomponent containing both ionic liquid and cosolvent (polar aprotic solvents such as DMSO, DMF DMI, etc.) that significantly lowers the IL viscosity, which increases ionic mobility, thereby promoting higher cellulose dissolving rate than net ILs [57, 67] at ambient temperature [78]. Furthermore, Renaldi [60] in his studies conducted an experiment which revealed that the use of solvent system [BMIM][Cl]/DMI dissolves more cellulose (10 wt% in few minutes) than convectional solvent LiCl/DMI (2 wt% at 150°C for 30 min). Many researches today have further carried experiments to understand the cellulose chemistry using bicomponent IL with aprotic solvent [68–71, 73–75]. The results of studied cosolvents (DMSO, DMF, DMA, and DMI) with certain ILs showed that during the dissolution of cellulose, the aprotic cosolvent does not slightly interact with the hydroxyl of the cellulose; however, it decreases the association of the IL cation with the anion making more free ions to be available for the interaction of the cellulose hydroxyls; hence, more cellulose becomes readily soluble at ambient temperatures; furthermore, as more amount of the cosolvent is added to the solution, more cellulose continues to dissolve since more IL anions become available [67–71, 73–75, 78, 79]; in addition, Xu et al. [70] further indicated that the best aprotic cosolvent are the ones which have the highest dipole moment; hence, as the dipole moment decreases, the effectiveness of the aprotic cosolvent weakens.

In this review we summarized the major solvents that are applied in the cellulose chemistry. The ILs are implemented as new solvents for the dissolution of cellulose and its derivatives having several biological and industrial applications. The cellulose can be modified such as ether, ester, sulfate, amine, hemiacetal, carbanilate, etc., and the resulting material can be used for other applications. The cellulose derivatives can be used for various purposes such as textile, medicine, agriculture, biofuels, etc. In order for ionic liquids to be applied industrially, there are major

• Development of the efficient ways to synthesis ionic liquids so that ILs can be

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**4. Conclusion**

problems still to be addressed such as:

available in high quantity.

Indra Bahadur\* and Ronewa Phadagi Department of Chemistry and Materials Science Innovation, Modelling Research Focus Area, School of Mathematical and Physical Sciences, Faculty of Agriculture, Science and Technology, North-West University, Mmabatho, South Africa

\*Address all correspondence to: bahadur.indra@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
