title: Correlations between steric/thermochemical parameters and O-/N-acylation reactions of cellulose.
abstract: N(α)-t-Butyloxycarbonyl (Boc)-amino acids (Xaa = Gly, Ala, or β-Ala) were reacted with the cellulose hydroxyl groups (O-acylation) using N,N'-carbonyl diimidazole. The degrees of substitution toward the total hydroxyl groups (DS%(/OH)s) were 38% for O-(Boc-Gly)-Cellulose, 29% for O-(Boc-Ala)-Cellulose and 53% for O-(Boc-β-Ala)-Cellulose. The one-by-one N-acylation between the O-(Xaa)-Celluloses and Boc-Ala-Gly using a water-soluble carbodiimide yielded the conjugates N-(Boc-Ala-Gly)-Xaa-Celluloses with DS%(/NH2) values of 25% (Xaa = Gly), 35% (Ala), and 48% (β-Ala), respectively. The results were well correlated with ΔG and ΔEstrain profiles, which were predicted by semi-empirical thermochemical parameter calculation coupled with conformer search (R(2)>0.90). N-acylation of the O-(β-Ala)-Cellulose using various length of oligo-peptides, Boc-(Ala-Gly)n and Boc-(Gly-Ala)n (where, n = 0.5, 1.0, 1.5, 2.0, 3.0), suggested that the DS%(/NH2) was dependent on the structural features of the symmetric anhydrides as the N-acylating agents, including conformer populations and their transition energy.
authors.affiliation: Institute of High Polymer Research, Faculty of Textile Science and Technology, Shinshu University, Tokida 3-15-1, Ueda 386-8567, Japan.
authors.forename: Kesavan
authors.initials: K
authors.lastname: Devarayan
authors.forename: Taketoshi
authors.initials: T
authors.lastname: Hayashi
authors.forename: Masakazu
authors.initials: M
authors.lastname: Hachisu
authors.forename: Jun
authors.initials: J
authors.lastname: Araki
authors.forename: Kousaku
authors.initials: K
authors.lastname: Ohkawa
mesh_terms: D000215:Acylation; D000409:Alanine / Q000031:analogs & derivatives* / Q000737:chemistry; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002482:Cellulose / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry; D004952:Esters; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D012995:Solubility; D013816:Thermodynamics
chemical_list: D004952:Esters; C543307:tert-butoxycarbonylalanine; D002482:Cellulose; D000409:Alanine; D005998:Glycine