Some aspects of acylation of cellulose under homogeneous solution conditions

Regiani, Anelise Maria; Frollini, Elisabete; Marson, Guilherme Andrade; Arantes, Guilherme Menegon; Seoud, Omar A. El

doi:10.1002/(sici)1099-0518(19990501)37:9<1357::aid-pola16>3.0.co;2-y

Cited by 69 publications

(43 citation statements)

References 25 publications

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“…Synthesis and DS determination of cellulose acetates, CAs MCC-based CA samples with different DS were prepared as given elsewhere, i.e., by suspending Cellulose (2010) 17:937-951 939 cellulose in N,N-dimethylacetamide, DMAc, followed by heating; addition of LiCl; distillation of 25% of the solvent; reaction with acetic anhydride, and workup of the product (Regiani et al 1999 The distribution of the acetyl moiety among the carbon atoms of the AGU was calculated by integrating the (Lorentzian) CH 3 CO-peaks of one CA sample (DS = 2.04) in DMSO-d 6 (50 mg mL -1 ), in the presence of 20 mg mL -1 of Cr 3? -acetyl-acetonate.…”

Section: Methodsmentioning

confidence: 99%

Probing the dependence of the properties of cellulose acetates and their films on the degree of biopolymer substitution: use of solvatochromic indicators and thermal analysis

et al. 2010

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Section: Methodsmentioning

confidence: 99%

Probing the dependence of the properties of cellulose acetates and their films on the degree of biopolymer substitution: use of solvatochromic indicators and thermal analysis

et al. 2010

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“…56% of the water present in the cellulose/LiCl-DMAc solution. 32 A simple calculation based on 2 g cellulose (12.3 mmol) whose initial water content is 5% shows that 2.4 mmol of water is not removed; this can lead to hydrolysis of ca. 20% of cellulose acetate.…”

Section: Effect Of Dissolution Of Sisal In Licl/dmac On the Crystallimentioning

confidence: 99%

Some aspects of acetylation of untreated and mercerized sisal cellulose

Ciacco¹,

Morgado²,

Frollini³

et al. 2010

J. Braz. Chem. Soc.

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Este trabalho apresenta alguns aspectos da acetilação em LiCl/N,N-dimethylacetamida, DMAc de celulose de sisal nativa e mercerizada (sisal e M-sisal). A mercerização da fibra em solução de NaOH resulta nas seguintes alterações: decréscimo de 29.9 % no índice de cristalinidade; diminuição de 16.2% no grau de polimerização e aumento de 9.3% no conteúdo de a-celulose. Estudo com espalhamento de luz de soluções de sisal, M-sisal, celulose microcristalina e algodão mostrou que elas se apresentam na forma de agregados, com números médios de agregação de 5.2, 3.2, 9.8 e 35.3, respectivamente. A presença destes agregados afeta a acessibilidade à celulose durante sua funcionalização. Acompanhamento do grau de substituição, DS, de acetato de celulose em função do tempo, mostrou que o mesmo aumenta por um intervalo de tempo de 5 h, seguido por um decréscimo após 7 h. Possíveis razões para este decréscimo são discutidas. Como esperado, M-sisal apresenta um DS maior que a sisal nativa.We report here on some aspects of the acetylation in LiCl/N,N-dimethylacetamide, DMAc, of untreated and mercerized sisal cellulose, hereafter designated as sisal and M-sisal, respectively. Fiber mercerization by NaOH solution has resulted in the following changes: 29.9% decrease in the index of crystallinity; 16.2% decrease in the degree of polymerization and 9.3% increase in a-cellulose content. A light scattering study of solutions of sisal, M-sisal, microcrystalline and cotton celluloses in LiCl/DMAc has shown that they are present as aggregates, with (an apparent) average aggregation numbers of 5.2, 3.2, 9.8, and 35.3, respectively. The presence of these aggregates affects the accessibility of cellulose during its functionalization. A study of the evolution of the degree of substitution, DS, of cellulose acetate as a function of reaction time showed an increase up to 5 h, followed by a decrease at 7 h. Possible reasons for this decrease are discussed. As expected, M-sisal gave a higher DS that its untreated counterpart.

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“…The nondegradative nature, lower viscosity, as well as the higher solubility of cellulose in [amim]Cl, prompted us to carry out the synthesis in this media. The majority of publications regarding the chemistry of cellulose have quoted the use of microcrystalline cellulose (Avicel Ò PH-101), which is relatively soluble into traditional cellulose solvents, such as DMSO/TBAF (Heinze et al 2000Liu and Baumann 2002;El Seoud et al 2000;Regiani et al 1999;Hussain et al 2004). In the present study, we have used microcrystalline cellulose as a starting material and optimised tosylation in a way that the DS close to 1 could be achieved in [amim]Cl, and thus avoid the use of protection group chemistry in subsequent nucleophilic displacement reactions.…”

Section: Introductionmentioning

confidence: 99%

Tosylation and acylation of cellulose in 1-allyl-3-methylimidazolium chloride

et al. 2008

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Tosylation and acylation of cellulose were performed under mild reaction conditions using imidazolium based ionic liquids (ILs) as solvents. The non-degradative nature, lower viscosity, as well as higher solubility of cellulose in [amim]Cl encouraged us to carry out the reactions in this media. The reactions described here were optimised for this particular solvent in order to obtain different cellulose derivatives with high yields, homogeneity and degree of substitution (DS). Two reagents employed for the in situ activation of carboxylic acids were N,N 0 -carbonyldiimidazole (CDI) and 1-ethyl-3-(3 0 -dimethylaminopropyl)carbodiimide hydrochloride (EDCI). Final products were characterised by solution and solid-state NMR techniques.

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Some aspects of acylation of cellulose under homogeneous solution conditions

Cited by 69 publications

References 25 publications

Probing the dependence of the properties of cellulose acetates and their films on the degree of biopolymer substitution: use of solvatochromic indicators and thermal analysis

Probing the dependence of the properties of cellulose acetates and their films on the degree of biopolymer substitution: use of solvatochromic indicators and thermal analysis

Some aspects of acetylation of untreated and mercerized sisal cellulose

Tosylation and acylation of cellulose in 1-allyl-3-methylimidazolium chloride

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