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An efficient, one‐pot acylation of cellulose under homogeneous reaction conditions
Author(s) -
El Seoud Omar A.,
Marson Guilherme A.,
Ciacco Gabriela T.,
Frollini Elisabete
Publication year - 2000
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(20000501)201:8<882::aid-macp882>3.0.co;2-i
Subject(s) - chemistry , cellulose , microcrystalline cellulose , propionate , crystallinity , acylation , polymer chemistry , dissolution , organic chemistry , cellulose acetate , dimethylacetamide , polymer , nuclear chemistry , solvent , catalysis , crystallography
Cellulose samples from cotton linters, sisal, and sugar cane bagasse have been successively acylated (acetate, propionate, butyrate, and acetate/butyrate) under homogeneous reaction conditions, in LiCl/ N , N ‐dimethylacetamide (DMAC), by the following procedure: (i) cellulose and LiCl are heated under reduced pressure, at 110°C; (ii) cellulose is dissolved in LiCl/DMAC by heating at 155°C, followed by cooling to 40°C; (iii) the solubilized polymer is acylated at 60°C for 18 h. Attractive features of this one‐pot procedure include: easy control and high reproducibility of the degree of substitution; elimination of base catalyst; negligible degradation of the natural polymer; and recovery/recycling of high purity DMAC and acid anhydride. Reaction conditions employed for the present celluloses are different from those previously used for Avicel PH 101 microcrystalline cellulose because their fibrous nature, higher indices of crystallinity and higher molecular weights retard their dissolution and decrease their rates of acylation by acid anhydrides.