Cellulose acetates with low degree of substituent(DS) were homogeneously synthesized in an ionic liquid,1-allyl-3-methyl-imidazolium chloride(AmimC1).Under mild reaction conditions,cellulose monoacetates(CMA) with the...Cellulose acetates with low degree of substituent(DS) were homogeneously synthesized in an ionic liquid,1-allyl-3-methyl-imidazolium chloride(AmimC1).Under mild reaction conditions,cellulose monoacetates(CMA) with the DS in a range from 0.34 to 1.60 were obtained.NMR analysis shows that the distribution of acetyl moieties among the three OH groups of anhydroglucose unit is C6■C3>C2 for the synthesized CMA.The water solubility measurement shows that the CMA samples with the DS ranging from 0.65 to 1.06 are readily dissolved in water.The relationship between the structure and water solubility of CMA was briefly discussed.展开更多
Homogeneous acetylation of cellulose in 1-allyl-3-methyl-imidazolium chloride(AMIMCl) was carried out. Acetic anhydride and acetyl chloride were used as acetylating agents in the absence and presence of pyridine. The ...Homogeneous acetylation of cellulose in 1-allyl-3-methyl-imidazolium chloride(AMIMCl) was carried out. Acetic anhydride and acetyl chloride were used as acetylating agents in the absence and presence of pyridine. The degree of substitution(DS) of the products and the distribution of substituents were determined by titration and {} 13C NMR techniques respectively. It was observed that acetyl chloride reacted faster than {anhydride}. Further, pyridine accelerated the reactions when anhydride was used as the acetylating agent, while it slowed down the reactions when acetyl chloride was used. An interesting distribution of DS_ C-2 DS_ C-3 for substitutes was observed in the product with acetic anhydride/pyridine system.展开更多
文摘Cellulose acetates with low degree of substituent(DS) were homogeneously synthesized in an ionic liquid,1-allyl-3-methyl-imidazolium chloride(AmimC1).Under mild reaction conditions,cellulose monoacetates(CMA) with the DS in a range from 0.34 to 1.60 were obtained.NMR analysis shows that the distribution of acetyl moieties among the three OH groups of anhydroglucose unit is C6■C3>C2 for the synthesized CMA.The water solubility measurement shows that the CMA samples with the DS ranging from 0.65 to 1.06 are readily dissolved in water.The relationship between the structure and water solubility of CMA was briefly discussed.
文摘Homogeneous acetylation of cellulose in 1-allyl-3-methyl-imidazolium chloride(AMIMCl) was carried out. Acetic anhydride and acetyl chloride were used as acetylating agents in the absence and presence of pyridine. The degree of substitution(DS) of the products and the distribution of substituents were determined by titration and {} 13C NMR techniques respectively. It was observed that acetyl chloride reacted faster than {anhydride}. Further, pyridine accelerated the reactions when anhydride was used as the acetylating agent, while it slowed down the reactions when acetyl chloride was used. An interesting distribution of DS_ C-2 DS_ C-3 for substitutes was observed in the product with acetic anhydride/pyridine system.
