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

Abstract

Cellulose acetate is widely used in films, filters, textiles, lacquer and cosmetic products. Herein we demonstrate the production of cellulose esters under homogeneous conditions using 1,5-diazabicyclo[4.3.0]non-5-ene acetate ([DBNH][OAc]) as solvent. The reagents have been chosen such that the system is recyclable, i.e. by-products are low boiling and easy to remove. It is demonstrated that cellulose acetate can be synthesized with different degree of substitution (DS) values, and that some commonly used acylation regents, like vinyl carboxylates react well without additional base catalyst. Low to high DS values are possible with good recovery of high purity ionic liquid (IL). A linear correlation method of two separate methods, IR and 31 P NMR, is proposed to reliably assess the DS of the products. The recyclability of the solvent is demonstrated by acetylating cellulose with isopropenyl acetate to high degree and regeneration into water. After regeneration of cellulose acetate from the IL with addition of water, the residual water was entrained using n-butanol to minimize hydrolysis of [DBNH][OAc], to allow for high recovery and high purity of the ionic liquid. Thus, an overall scheme for batch cellulose acetylation and recovery of [DBNH][OAc] from aqueous solutions is proposed.

Crystallinity reduction and enhancement in the chemical reactivity of cellulose by non-dissolving pre-treatment with tetrabutylphosphonium acetate

“…The diffracted intensity of Cu Ka radiation (k = 1.54 Å , under a condition of 45 kV and 40 mA) was measured in a 2h range between 5°and 50°. Molar mass determination was performed by GPC with an Agilent Infinity 1260, using LiCl/DMA as mobile phase, according to previous literature (Kakko et al 2017;Kakuchi et al 2015Kakuchi et al , 2017. (See Sect.…”

Critical Review on Sustainable Homogeneous Cellulose Modification: Why Renewability Is Not Enough

“…The same authors subsequently reported the acetylation of cellulose (pre-hydrolysis kraft, PHK) in a similar acid-base conjugate ionic liquid. [27] In this case, the ionic liquid was formed by a 1:1 molar combination of the organic super base 1,5- on acetylation of cellulose in ionic liquids requiring pyridine, K 2 CO 3 , [28] or NaOH [29] as catalyst. This was attributed to the excess of the base utilized in the ionic liquid which can act as a catalyst for the acetylation reaction.…”

“…Finally, the recovery of the ionic liquid was demonstrated (80% reported). [27] The authors observed the hydrolysis of DBN during the ionic liquid recovery. To minimize this hydrolysis, they proposed the use of n-butanol to trap remaining water molecules before distillation.…”

Natural Polymers from Biomass Resources as Feedstocks for Thermoplastic Materials

“…When compared to CA films, the added oleic acid acted as a self‐plasticizer for CA leading to lower T g and melting point, ductile material properties, and even reducing both the oxygen and water vapor permeability . It should additionally be noted that ILs can also be effectively used in the field of derivatization, serving as reaction media for cellulose modification . Recently, homogenous esterification was performed in an ionic liquid.…”

“…[38] It should additionally be noted that ILs can also be effectively used in the field of derivatization, serving as reaction media for cellulose modification. [39][40][41][42][43][44][45][46] Recently, homogenous esterification was performed in an ionic liquid. Hydroxyl groups were esterified both with bulky and small substituents, resulting in a relatively low T g from 80 to 160 °C.…”