Activating cellulose via its reversible reaction with CO₂ in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene for the efficient synthesis of cellulose acetate

Abstract

The reversible reaction of cellulose pulp with CO 2 in the presence of 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) resulted in a rapid and effective derivative dissolution of cellulose in DMSO, which could be applied for subsequent 10 derivatization of cellulose into cellulose acetate by using acetic anhydride as an acylation reagent under mild conditions. A serials of cellulose acetates with degree of substitution from 1.78 to 2.89 had been successfully synthesized without adding external catalysts, and the structure and thermal properties 15 of the products were characterized by various analytic technologies, such as NMR, FT-IR, TGA.

Organocatalytic Cellulose Dissolution and In Situ Grafting of ϵ‐Caprolactone via ROP in a Reversible DBU/DMSO/CO2System

“…Peaks at 2θ=14.9°, 16.3°, 22.6° and 34.6° in the diffraction pattern of the raw cellulose are characteristic for the crystalline structure of cellulose I. For the cellulose‐g‐PCL copolymers, the absence of the above peaks and the appearance of dispersive broad peaks around 2θ=19.6° indicate amorphous structures, confirming the introduction of PCL chains onto cellulose chains during the ROP, which are in good agreement with previous studies ,…”

“…The different dissolution behaviours are observed through the crystal structure changes as evidenced by Wide‐angle X‐ray diffraction (WXRD) spectra in Figure S1. The WXRD spectrum of raw cellulose shows well‐defined characteristic diffraction peaks of cellulose I at 2θ=14.9 , 16.3, 22.6 and 34.6° . The WXRD spectra of the regenerated celluloses from TMG, TBD and DBU‐based solvent systems show disperse broad peaks around 2θ= 19.6°, which indicates the transformation of cellulose I to cellulose II during the dissolution and regeneration process.…”

Chemisorption of air CO2 on cellulose: an overlooked feature of the cellulose/NaOH(aq) dissolution system

“…The presence and action of CO 2 in NaOH(aq) during the dissolution of cellulose could be of considerable importance when considering the numerous studies reporting on CO 2 as a solvent component or a derivatising agent for cellulose. These include a CO 2 -mediated synthesis of cellulose carbonate in different solvents as an intermediate step towards improved dissolution in NaOH(aq) (Oh et al 2002(Oh et al , 2005; dissolution of cellulose in switchable ionic liquids based on interactions between CO 2 and strong organic bases (Zhang et al 2013;Xie et al 2014) and activation of cellulose by CO 2 for a subsequent acetylation (Yang et al 2015). Moreover, in terms of NaOH(aq), the presence of dissolved CO 2 is likely to affect the properties of the solvent system itself by consuming the hydroxide ions in well-known conversions to HCO 3 -and CO 3 2- (Yoo et al 2013) and should as such be taken into account.…”

Inedible saccharides: a platform for CO2 capturing

“…Another example of a reaction between cellulose and CO 2 in the presence of a SB (namely 1,8-diazabicyclo-[5.4.0]-undec-7-ene, DBU), yielding [DBUH] + [cellulose-OCO 2 ] – , was reported by Yang et al 61 The reaction allowed a successful dissolution of the cellulose pulp, and subsequently allowed its modification into cellulose acetate using acetic anhydride ( Scheme 4A ). Mu and co-workers 62 monitored the formation of the aforementioned adduct via in situ infrared spectroscopy.…”