Summary: Ionic Liquids (IL) were applied as solvent and reaction medium in the field of homogeneous cellulose chemistry. Whereas investigations on tosylation and nucleophilic displacement reactions lead to unexpected products the application of the Huisgen reaction was successful. The standard conditions for tosylation of cellulose using the IL 1‐ethyl‐3‐methylimidazolium acetate (EMImAc) as solvent lead exclusively to cellulose acetate, due to activation of the acetate ion of the IL by forming a mixed anhydride with p‐toluenesulfonyl chloride. Further investigations showed that the anions of EMImAc and 1‐ethyl‐3‐methylimidazolium chloride (EMImCl) are able to act as nucleophiles, thus substituting tosyl groups of tosylcellulose and forming unexpected products. Using EMImAc as solvent first to third generation propargyl‐polyamidoamine (PAMAM) dendrons were attached to 6‐azido‐6‐deoxy cellulose (degree of substitution, DS 0.75) utilising the copper catalysed Huisgen reaction leading to novel dendronized cellulose derivatives with DS values of up to 0.60. Detailed structure characterisation of the products, including elemental analysis, FTIR and NMR spectroscopy, indicates that the synthesis approach leads to products without impurities or remaining IL.
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Schöbitz et al. (2009) studied this question.
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