Homogeneous vinyl ester-based synthesis of different cellulose derivatives in 1-ethyl-3-methyl-imidazolium acetate

Abstract

A homogeneous process for the formation of various cellulose esters using the ionic liquid [EMIM]OAc and vinyl esters is described.

Homogenous esterification of cellulose pulp in [DBNH][OAc]

“…Acetic acid is a side product, which can be difficult to remove from the IL solution and may also lead to partial hydrolysis (degradation) of the cellulose polymer, if some water is present. Barthel and Heinze (2006) and Hinner et al (2016) have studied esterification of cellulose with longer fatty acid chlorides in ionic liquids, e.g., [Bmim]Cl and [Emim]Cl. Isopropenyl acetate (IpeAc) has been used in 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) to form cellulose acetates (Kakuchi et al 2015).…”

Propylene Carbonate Based‐Organic Electrolytes for Cellulose Dissolution Processing and Derivatization

“…The structure was confirmed by the 1 H NMR (Figure S8‐9). However, partial acetation of cellulose also observed, which was consisted with the results when pure [Emim]OAc ionic liquids were used as solvents . On top of these, it is reasonable to conclude that the obtained cellulose PC/[Emim]OAc solution are ready for cellulose processing and derivatisation, but further study is still needed to demonstrate the full potential.…”

“…Secondly, after the successful dissolution of cellulose in PC/[Emim]OAc (X ILs =0.3), its potential for cellulose derivatization was primary investigated by transesterification of cellulose with vinyl pivalate and vinyl benzoate, a promising way to synthesize cellulose carboxylic acidic ester avoiding the use of reactive and corrosive carboxylic acid chlorides or anhydrides . To our delight, the efficiency of the transesterification in the PC/[Emim]OAc (X ILs =0.3) is comparative to that in pure [Emim]OAc ionic liquids, and much better than those in other homogeneous and heterogeneous systems although the molar fraction of [Emim]OAc ionic liquids was set to 0.4 . Cellulosic pivalate and benzoate with degrees of substitution of 1.29 and 0.45 respectively was prepared under un‐optimized conditions.…”

Effect of anion in carboxylate-based ionic liquids on catalytic activity of transesterification with vinyl esters and the solubility of cellulose

“…9 This system enables us to obtain the desired cellulose esters easily using mild acyl agents without the need for strong acids and bases (e.g., 1,8-diazabicyclo [5.4.0]undec-7-ene, 10 1,5,7-triazabicyclo [4.4.0]dec-5-ene), or metal catalysts. 11 However, as others have reported, 12 in the case of acylation except for acetylation, this EmimOAc system has side reactions and undesired peaks corresponding to the introduced acetyl group derived from anion of EmimOAc appeared around 2.0 ppm in 1 H NMR measurement (Scheme 1a). Clarication and control of selectivity are required in the case that mixture products were obtained.…”

“…In the proposed side reaction via the mixed acid anhydride, the nucleophilic attack of the hydroxyl group on the carbonyl carbon derived from the anion of the employed IL decreased among the two carbonyl groups of the mixed anhydride due to the steric hinderance of the anion. 12,15,17 In other words, the steric effects of the anion can improve the selectivity of the desired reaction. Furthermore, the DS main value changed due to the difference in the basicity.…”