title: Acylation of cellulose in a novel solvent system: solution of dibenzyldimethylammonium fluoride in DMSO.
abstract: A novel electrolyte, dibenzyldimethylammonium fluoride has been obtained essentially anhydrous (BMAF-0.1H2O) by a simple route. Its thermal stability, relative to tetra(1-butyl)ammonium fluoride trihydrate (TBAF3H2O) has been demonstrated by thermogravimetric analysis. DMSO solution of (BMAF-0.1H2O) dissolves microcrystalline- and fibrous celluloses; the dissolved biopolymers have been acylated by ethanoic-, butanoic-, and hexanoic anhydride. The degrees of substitution of the esters are higher than with TBAF3H2O/DMSO. The reasons are discussed in terms of differences in electrolyte structure and contents of water of hydration, whose presence leads to side reactions and decreases of the basicity of (F(-)). This conclusion is corroborated by molecular dynamics simulations of the interactions of glucose dodecamer/R4NF-hydrate/DMSO. These show that the interactions oligomer-F(-)-water is operative only for TBAF3H2O/DMSO. The efficiency of BMAF-0.1H2O/DMSO is explained based on better accessibility of the biopolymer due to efficient hydrogen-bonding between its hydroxyl groups and the essentially desolvated (F(-)).
authors.affiliation: Institute of Chemistry, University of São Paulo, P.O.B. 26077, 05513-970 São Paulo, Brazil.
authors.forename: Romeu
authors.initials: R
authors.lastname: Casarano
authors.forename: Paulo A R
authors.initials: PA
authors.lastname: Pires
authors.forename: Omar A
authors.initials: OA
authors.lastname: El Seoud
mesh_terms: D000215:Acylation; D002482:Cellulose / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D004355:Drug Stability; D008958:Models, Molecular; D008968:Molecular Conformation; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012996:Solutions; D012997:Solvents / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D000644:Quaternary Ammonium Compounds; D012996:Solutions; D012997:Solvents; D014867:Water; C007316:dibenzyldimethylammonium; D002482:Cellulose; D004121:Dimethyl Sulfoxide
keywords: Cellulose acylation; Dibenzyldimethylammonium fluoride-hydrate; Molecular dynamics; Tetra(1-butyl)ammonium fluoride-hydrate