title: Synthesis of Highly Polymerized Water-soluble Cellulose Acetate by the Side Reaction in Carboxylate Ionic Liquid 1-ethyl-3-methylimidazolium Acetate.
abstract: In the present study, we describe a novel one-step method to prepare water-soluble cellulose acetate (WSCA) with higher degree of polymerization values (DP = 650-680) by in situ activation of carboxyl group in ionic liquid. First of all, cellulose was dissolved in 1-ethyl-3-methylimidazolium acetate (EmimAc) and reacted with dichloroacetyl chloride (Cl2AcCl) in order to make cellulose dichloroacetate. Under various conditions, a series of water soluble products were produced. Elemental analysis and NMR results confirmed that they were cellulose acetate with DS (degree of substitution) values in the range from 0.30 to 0.63. NMR studies demonstrated that Cl2AcCl reacted with acetate anion of EmimAc producing a mixed anhydride that acetylated cellulose. Other acylating reagents such as benzoyl chloride, chloroacetyl chloride can also work similarly. 2D NMR characterization suggested that 6-mono-O-acetyl moiety, 3,6-di-O-acetylcellulose and 2,6-di-O-acetyl cellulose were all synthesized and the reactivity of hydroxyl groups in anhydro-glucose units was in the order C-6>C-3>C-2. This work provides an alternative way to make WSCA, meanwhile, also services as a reminder that the activity of EmimAc toward carbohydrate as acylating reagents could be a problem, because the expected acylated products may not be resulted and recycling of this ionic liquid could also be difficult.
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Pang
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, PR China.
authors.forename: Fachuang
authors.initials: F
authors.lastname: Lu
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Mingguo
authors.initials: M
authors.lastname: Ma
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, PR China.
authors.forename: Xueming
authors.initials: X
authors.lastname: Zhang