Distribution of Acetyl Group in Cellulose Acetate as Determined by Nuclear Magnetic Resonance Analysis

Sei, Tsuyoshi; Ishitani, Kazuki; Suzuki, Ryoshu; Ikematsu, Kiyoshi

doi:10.1295/polymj.17.1065

Cited by 38 publications

(14 citation statements)

References 8 publications

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“…-acetyl-acetonate. The 13 C NMR spectrum was recorded at 80°C; 8,000 scans were added, with pulse delay of 5 s; the inverse-gated decoupling program was employed for data acquisition (Braun and Berger 2004;Sei et al 1985). The chemical shifts employed for CH 3 COwere: 168.71-168.93 ppm (C 2 ), 169.11-169.60 ppm (C 3 ), 169.83-170.04 ppm (C 6 ) (Kowsaka et al 1988;20, Tshunashima and Hattori 2000).…”

Section: Dissolution and Acetylation Of The Cellulosesmentioning

confidence: 99%

Acetylation of cellulose in LiCl-N,N-dimethylacetamide: first report on the correlation between the reaction efficiency and the aggregation number of dissolved cellulose

et al. 2011

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The acylation of three cellulose samples by acetic anhydride, Ac 2 O, in the solvent system LiCl/ N,N-dimethylacetamide, DMAc (4 h, 110°C), has been revisited in order to investigate the dependence of the reaction efficiency on the structural characteristics of cellulose, and its aggregation in solution. The cellulose samples employed included microcrystalline, MCC; mercerized cotton linters, M-cotton, and mercerized sisal, M-sisal. The reaction efficiency expresses the relationship between the degree of substitution, DS, of the ester obtained, and the molar ratio Ac 2 O/AGU (anhydroglucose unit of the biopolymer); 100% efficiency means obtaining DS = 3 at Ac 2 O/AGU = 3. For all celluloses, the dependence of DS on Ac 2 O/AGU is described by an exponential decay equation: DS = DS o -Ae -[(Ac2O/AGU)/B] ; (A) and (B) are regression coefficients, and DS o is the calculated maximum degree of substitution, achieved under the conditions of each experiment. Values of (B) are clearly dependent on the cellulose employed: B (M-cotton) [ B (M -sisal) [ B (MCC) ; they correlate qualitatively with the degree of polymerization of cellulose, and linearly with the aggregation number, N agg , of the dissolved biopolymer, as calculated from static light scattering measurements: (B) = 1.709 ? 0.034 N agg . To our knowledge, this is the first report on the latter correlation; it shows the importance of the physical state of dissolved cellulose, and serves to explain, in part, the need to use distinct reaction conditions for MCC and fibrous celluloses, in particular Ac 2 O/AGU, time, temperature.

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Section: Dissolution and Acetylation Of The Cellulosesmentioning

confidence: 99%

Acetylation of cellulose in LiCl-N,N-dimethylacetamide: first report on the correlation between the reaction efficiency and the aggregation number of dissolved cellulose

et al. 2011

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“…Chemical shifts of the observed resonances are summarized in Table I. The resonance lines of CTA are assigned on the basis of the previous works in solution (6,7). It is noted that the chemical shifts for carbons do not have large differences between neat CTAs and CTAs coated on silica gel.…”

Section: Resultsmentioning

confidence: 99%

Effect of Coating Solvent on Chiral Recognition by Cellulose Triacetate

Sei

Matsui

Shibata

et al. 1992

Viscoelasticity of Biomaterials

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We have recently found that cellulose esters coated on chromatographic supports exhibit excellent capabilities of optical resolution as column packing materials for high performance liquid chromatography. In the study on the mechanism of chiral recognition, solid-state CP/MAS 13 C NMR analysis has been carried out to investigate the structure of cellulose triacetate (CTA) coated on support. It was revealed that the solvent from which CTA was solidified had an effect on the structure of the polymer, presumably on its conformational regularity. The hysteretic effect of the coating or precipitating solvent on the chiral recognition ability of the polymer was rationalized by the aforementioned structural difference caused by the solvent.We have reported (1,2) that cellulose triacetate (CTA) coated on macroporous silica gel showed excellent capabilities of chiral recognition as packing material for high performance liquid chromatographic resolution of various enantiomers.We have performed the study on the mechanism of chiral recognition to develop a more efficient stationary phase.Recently, we found (3) that the solvent with which CTA has been coated on a support had a considerable effect on the structure of CTA; that of phenol as a solvent was especially outstanding (Figure 1). On the other hand, there were some enantiomers which showed lower selectivity on CTA prepared with phenol as solvent. These results showed that the CTA enhanced a substrate selectivity.Solid-state CP/MAS 13 C NMR analysis has been carried out to investigate the structure of CTA coated on a support. We now wish to discuss the origins of the hysteretic effect of a coating solvent.

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“…The 13 C NMR spectrum was recorded at 80 8C; 8 000 scans were added, with pulse delay of 5 s; the inverse-gated decoupling program was employed for data acquisition. [18,19] The chemical shifts employed for CH 3 COÀ were: 168.71-168.93 ppm (C 2 ), 169.11-169.60 ppm (C 3 ), 169.83-170.04 ppm (C 6 ). [20] Density and Conductivity of the Ionic Liquid at Different Temperatures…”

Section: Infrared Spectramentioning

confidence: 99%

Application of 1‐Allyl‐3‐(1‐butyl)imidazolium Chloride in the Synthesis of Cellulose Esters: Properties of the Ionic Liquid, and Comparison with Other Solvents

Fidale

Possidonio

Seoud

2009

Macromolecular Bioscience

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The ionic liquid (IL), 1-allyl-3-(1-butyl)imidazolium chloride (AlBuImCl), has been synthesized and its properties determined. Increase in the temperature increased its conductivity and decreased its density, polarity, and viscosity. Microcrystalline cellulose (MCC), dissolves in this IL by heating at 80 degrees C; this did not affect its degree of polymerization, decreased its index of crystallinity (Ic), and changed in morphology after regeneration. Convenient acylation of MCC was achieved by using 50% excess anhydride at 80 degrees C, for 24 or 48 h for acetic and butyric anhydride, respectively. The composition of the mixed esters depended on the initial ratio of the anhydrides, and their order of addition.

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Distribution of Acetyl Group in Cellulose Acetate as Determined by Nuclear Magnetic Resonance Analysis

Cited by 38 publications

References 8 publications

Acetylation of cellulose in LiCl-N,N-dimethylacetamide: first report on the correlation between the reaction efficiency and the aggregation number of dissolved cellulose

Acetylation of cellulose in LiCl-N,N-dimethylacetamide: first report on the correlation between the reaction efficiency and the aggregation number of dissolved cellulose

Effect of Coating Solvent on Chiral Recognition by Cellulose Triacetate

Application of 1‐Allyl‐3‐(1‐butyl)imidazolium Chloride in the Synthesis of Cellulose Esters: Properties of the Ionic Liquid, and Comparison with Other Solvents

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