Solutions of cellulose in N , N -dimethylacetamide/lithium chloride studied by light scattering methods

Röder, Thomas; Morgenstern, Bernd; Schelosky, N.; Glatter, Otto

doi:10.1016/s0032-3861(01)00170-7

Cited by 96 publications

(49 citation statements)

References 14 publications

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“…Although cellulose is almost insoluble in water [46] except for at very high temperatures (> 593 K) [47], solvents of cellulose have been explored to handle it as a soluble substrate and to increase the reactivity [48]. Lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) is well known to dissolve cellulose, where chloride ions cleave hydrogen bonds of cellulose [49,50].…”

Section: Pretreatment Techniques For Degrading the Rigid Structure Ofmentioning

confidence: 99%

Catalytic transformation of cellulose into platform chemicals

Yabushita

Kobayashi

Fukuoka

2014

Applied Catalysis B: Environmental

267

142

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Conversion of biomass to renewable and valuable chemicals has attracted global interest in order to build up sustainable societies. Cellulose is the most abundant and non-food biomass; however, the low reactivity of cellulose has prevented its use in chemical industry except for the paper manufacturing. The heterogeneous catalysis for the conversion of cellulose has been expected to overcome this issue, because various types of heterogeneous catalysts can be designed and applied in a wide range of reaction conditions. Furthermore, solid catalysts are easily recovered and reused. In this review article, we show the present situation and perspective of heterogeneous catalysis for the transformation of cellulose into useful platform 2 chemicals.

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Section: Pretreatment Techniques For Degrading the Rigid Structure Ofmentioning

confidence: 99%

Catalytic transformation of cellulose into platform chemicals

Yabushita

Kobayashi

Fukuoka

2014

Applied Catalysis B: Environmental

267

142

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“…Removal of hemicelluloses leads to a decrease in tendency of aggregation, as shown for sisal and its mercerized counterpart. 24 The value of RG usually depends on the form of the particle in solution and, for macromolecules, increases as a function of increasing M W , as shown in the last column of Table 1. The structure of the aggregates has been described in terms of "fringed micelles", whose dimensions are related to RG by equation (4), where (L) and ( r) refer to the length and cross section area of the micelle, respectively, with the central part approximately cylindrical, as shown schematically in Figure 2.…”

Section: Physical State Of Dissolved Cellulosesmentioning

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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“…It was not possible, however, to measure the peak areas accurately, especially at lower [W], because 'fringes' were found to be superimposed on the base line. These are identical to the interference fringes of the empty cell, and are mostly certainly due to the relatively large difference between the refractive indices of ZnS (2.4491) and that of the solution (1.4522) (Coleman 1993;Ro¨der et al 2001). Use of a different window material, with much lower refractive index (CaF 2 , 1.3942) solved this problem.…”

Section: Direct Determination Of [Water] By Ftirmentioning

confidence: 81%

Simple, expedient methods for the determination of water and electrolyte contents of cellulose solvent systems

et al. 2006

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The concentrations of water, W, and electrolytes present in solutions of LiCl in N,N-dimethylacetamide, LiCl/DMAc, and of tetrabutylammonium fluoride. x-hydrate in DMSO, TBAF.xW/DMSO can be accurately and expediently determined by three independent methods, UV -vis, FTIR and EMF measurement. The first relies on the use of solvatochromic probes whose spectra are sensitive to solution composition. It is applicable to W/LiCl/DMAc solutions but not to TBAF.xW/DMSO, because the charge-transfer complex bands of the probes are suppressed by strong interactions with the latter electrolyte. Integration of m OH band of water may be employed in order to determine [W], hence [electrolyte] by weight difference. EMF measurement uses ion-selective electrodes in order to determine [electrolyte], hence [W] by weight difference. Results of the latter method were in excellent agreement with those of FTIR. The reason for the failure of Karl Fischer titration is addressed, and the relevance of the results obtained to functionalization of cellulose under homogenous solution conditions is briefly commented on.

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Solutions of cellulose in N , N -dimethylacetamide/lithium chloride studied by light scattering methods

Cited by 96 publications

References 14 publications

Catalytic transformation of cellulose into platform chemicals

Catalytic transformation of cellulose into platform chemicals

Some aspects of acetylation of untreated and mercerized sisal cellulose

Simple, expedient methods for the determination of water and electrolyte contents of cellulose solvent systems

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