Microwave‐Assisted Derivatization of Cellulose, 2 – The Surprising Effect of the Structure of Ionic Liquids on the Dissolution and Acylation of the Biopolymer

The relevance of the structure of ILs for the dissolution and microwave‐assisted acylation of eucalyptus cellulose is reported. The 1‐R‐3‐methylimizadolium‐X ILs with X = Cl, Ac and R = 1‐butyl, 2‐methoxyethyl, 1‐heptyl, and 3,6‐dioxa‐(1‐heptyl) are studied: C4MeImX, C3OMeImX, C7MeImX, and C5O2MeImX. The dissolution efficiencies are C3OMeImAc > C4MeImAc and C7MeImAc > C5O2MeImAc, i.e., they depend on the length of the side chain. This surprising result is corroborated by (i) cellulose acylation by ethanoic, butanoic, and hexanoic anhydride; (ii) the energy of viscous flow of the ILs; (iii) the solvatochromic properties of the ILs. Our results show that C3OMeImAc and C4MeImAc are distinct from C7MeImAc and C5O2MeImAc, due to chain‐dependent hydrogen bonding and hydrophobic interactions.