title: NMR characterization of cellulose acetate: chemical shift assignments, substituent effects, and chemical shift additivity.
abstract: A series of cellulose acetates (CA) with degrees of substitution (DS) ranging from 2.92-0.92 dissolved in dimethylsulfoxide (DMSO)-d6 and cellulose dissolved in tetrabutylammonium fluoride (TBAF)/DMSO-d6 were investigated by two-dimensional NMR spectroscopy. The NMR spectroscopic analysis allowed the determination of the (1)H and (13)C NMR chemical shifts of the eight anhydroglucose units (AGUs) that contain CA: 2,3,6-tri-, 2,3-di-, 2,6-di-, 3,6-di-, 2-mono-, 3-mono-, 6-mono-, and unacetylated AGUs. A comparative analysis of the chemical shift data revealed the substituent effect of acetyl groups at the 2-, 3-, and 6-positions on the (1)H and (13)C nuclei in the same AGU. In addition, chemical shift additivity could be applied to the (1)H and (13)C chemical shifts of CA because the chemical shifts of the diacetylated and triacetylated AGUs could be almost completely explained by the acetyl substituent effects at the 2-, 3-, and 6-positions.
authors.affiliation: Department of Science and Engineering for Materials, Tomakomai National College of Technology, Nishikioka 443, Tomakomai 059 1275, Hokkaido, Japan. Electronic address: kono@sem.tomakomai-ct.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kono
authors.affiliation: Department of Science and Engineering for Materials, Tomakomai National College of Technology, Nishikioka 443, Tomakomai 059 1275, Hokkaido, Japan.
authors.forename: Hisaho
authors.initials: H
authors.lastname: Hashimoto
authors.affiliation: Department of Science and Engineering for Materials, Tomakomai National College of Technology, Nishikioka 443, Tomakomai 059 1275, Hokkaido, Japan.
authors.forename: Yuuichi
authors.initials: Y
authors.lastname: Shimizu
mesh_terms: D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*
chemical_list: C005062:acetylcellulose; D002482:Cellulose; D004121:Dimethyl Sulfoxide
keywords: Cellulose acetate; Chemical shift; Substituent distribution; Substituent effect