Probing Cellulose Acetylation in Binary Mixtures of an Ionic Liquid with Dimethylsulfoxide and Sulfolane by Chemical Kinetics, Viscometry, Spectroscopy, and Molecular Dynamics Simulations. Issue 24 (17th November 2015)

• Record Type: Journal Article
• Authors: Nawaz, Haq; Pires, Paulo A. R.; Arêas, Elizabeth P. G.; Malek, Naved I.; El Seoud, Omar A.
• Is Part Of: Macromolecular chemistry and physics. Volume 216:Issue 24(2015:Dec.)
• Page Start: 2368
• Page End: 2376
• Publication Date: 2015-11-17
• Subjects: 1‐allyl‐3‐methylimidazolium chloride -- cellulose/solvent complex formation -- kinetics of cellulose acetylation -- molecular dynamics simulation -- molecular solvents; Polymers -- Periodicals; Polymerization -- Periodicals; Synthetic products -- Periodicals; Macromolecules -- Periodicals; 547.7
• DOI: 10.1002/macp.201500315
• Languages: English
• ISSNs: 1022-1352

Abstract

Abstract : Acetylation of microcrystalline cellulose (MCC) by ethanoic anhydride (Ac2 O) in mixtures of the ionic liquid (IL) 1‐allyl‐3‐methylimidazolium chloride and the (structurally related) mole­cular solvents (MSs), dimethylsulfoxide (DMSO) and sulfolane (Sulfn), is studied. Values of the reaction third‐order rate constants, k 3, are calculated from conductivity data; they are linearly dependent on c (IL), due to (cellulose‐solvent) complex formation, as corroborated by Fourier Transform Infrared (FTIR) spectroscopy. The observed order of reactivity (IL/DMSO > IL/Sulfn) is explained by examining differences in the following properties of the MCC‐IL/MS solutions: macroscopic (viscosity); microscopic (empirical polarity and basicity), and from the results of molecular dynamics simulations. The latter indicate faster reactant diffusion in IL/DMSO and more interaction between the biopoly­mer hydroxyl groups and the ions of the IL. Abstract : Using conductivity, the kinetics of acetylation of microcrystalline cellulose dissolved in IL/DMSO and IL/Sulfn is studied under homogeneous conditions. The order of reactivity is IL/DMSO > IL/Sulfn. Due to differences in activation parameters, solution viscosity, polarity, and basicity, MD simulations show faster reactant diffusion and stronger cellulose‐IL interactions in IL/DMSO.