Homogeneous chemical modification of cellulose provides several advantages over heterogeneous reactions such as: increased reactivity, uniform product composi­tion, and efficient control over the overall degree of substitution (DS) as well as the distribution of functional groups within the anhydroglucose unit (AGU) and along the polymer chain. A variety of specific polysaccharide solvents that can be used not only for dissolution but also for the derivatization of cellulose have been reported in scientific literature [9]. They could be applied for preparing a broad variety of polysaccharide derivatives with potential applications from multi-kiloton food — and construction material industry to highly engineered materials for medical and biotechnological use. Nevertheless, none of the many cellulose solvents that could be utilized in lab-scale synthesis was found to be suitable for commercially attractive synthesis of cellulose derivatives up to now. Production of cellulose derivatives in technical scales is performed exclusively under heterogeneous con­ditions. In this context, ILs received a lot of interest because these versatile novel solvents might overcome the limitations of classical cellulose solvents; such as low dissolution power, inefficient solvent recycling, and incompatibility with derivati — zation reagents. In particular the broad structural diversity of ILs and the possibil­ities to create task-specific solvents by subtle manipulation of the molecular structure bear huge potential. Moreover, ILs have been employed with high effi­ciency in low-molecular chemistry as solvents for a vast number of advanced organic reactions that are still waiting to be transferred to cellulose derivatization [10]. Many cellulose derivatives could be prepared already by using ILs as reaction media for cellulose (Table 5.1). A comprehensive overview of the chemical deriv- atization of cellulose in ILs is provided in the following passages. Most of the synthesis described focused mainly on three particular imidazolium based ILs (Fig. 5.1) or slightly modified analogues. However, some reports on novel IL based reaction media were included as well.

aDS: degree of substitution

bIonic liquids: cations: ADMIM+: 1-allyl-2,3-dimethylimidazolium, AMIM+: 1-allyl-3- methylimidazolium, BDMIM+: 1-butyl-2,3-dimethylimidazolium, BMIM+: 1-butyl-3-methylimi — dazolium, EMIM+: 1-ethyl-3-methylimidazolium, anions: Ac-: acetate, Bz-: benzoate, Cl-: chloride, DEP-:diethylposphate, Pr-: propionate

cValues in braces represent degree of polymerization of the grafted chain