NMR characterization of cellulose acetate: Chemical shift assignments, substituent effects, and chemical shift additivity

Kono, Hiroyuki; Hashimoto, Hisaho; Shimizu, Yuuichi

doi:10.1016/j.carbpol.2014.11.004

Cited by 97 publications

(50 citation statements)

References 32 publications

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“…4 shows that there were two clusters of hydrogen atom signals. The first was proton resonance signals of the glucose ring (ı = 3.53-5.06 ppm), and the second was methyl protons resonance signals of the acetate group (ı = 1.93-2.11 ppm) (Kono, Hashimoto, & Shimizu, 2015). The DS of cotton cellulose acetates can be calculated by 1 H NMR spectroscopy according to the following equation (Cao et al, 2007):…”

Section: H Nmr Analysismentioning

confidence: 99%

Synthesis of cellulose triacetate from cotton cellulose by using NIS as a catalyst under mild reaction conditions

Nemr

Ragab

El-Sikaily

et al. 2015

Carbohydrate Polymers

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Section: H Nmr Analysismentioning

confidence: 99%

Synthesis of cellulose triacetate from cotton cellulose by using NIS as a catalyst under mild reaction conditions

Nemr

Ragab

El-Sikaily

et al. 2015

Carbohydrate Polymers

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“…The quantitative 13 C NMR spectra were obtained by the inverse-gated 1 H decoupling method [31] with a flip angle for 13 C excitation pulse of 30 • and a pulse repetition time of 45 s [32]. The 13 C chemical shifts were calibrated by setting the methyl peak of DSS to 0 ppm.…”

Section: C Nmr Spectroscopymentioning

confidence: 99%

Removal of anionic dyes in aqueous solution by flocculation with cellulose ampholytes

Kono

Kusumoto

2015

Journal of Water Process Engineering

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a b s t r a c tCellulose ampholytes (CAms) prepared from biocompatible and biodegradable carboxymethyl cellulose (CMC) could represent an environmentally friendly alternative for the efficient removal of anionic dyes from water effluents. In order to evaluate their potential for this application, a series of CAms with a degree of cationic substitution (DS C ) between 0.26 and 1.08 were prepared from sodium CMC, by cationization with 2,3-epoxypropyltrimethylammonium chloride. The flocculation ability of the CAms against the anionic dye Acid Red 13 (AR13) was found to strongly depend on the DS C as well as on the pH of the solution. The highest flocculation ability was observed at lower pH and higher DS C : a color removal as high as 99% was achieved at pH 3 using a CAm with the highest DS C . The kinetic analysis revealed that the flocculation of AR13 can be accurately fitted by a pseudo-second order kinetic model, which thus allows to predict the flocculation behavior of CAms under these conditions. Besides AR13, the ampholytes also showed high flocculation ability against Acid Red 9 and Acid Blue 13. The flocculation behavior of these anionic dyes followed the Langmuir adsorption isotherm model, which revealed the maximum flocculation capacity of a CAm for these dyes. Moreover, the analysis of the flocculation isotherm data and the SEM observation of the formed flocs allowed to determine the flocculation mechanism.

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“…2) and CA (Fig. 5 (Kono et al 2015) in decreased spectral resolution and 13 C T 2 values, as observed in the 13 C-enriched CMC spectra. Therefore, the TOCSY spin-lock time required to obtain longranged 13 C-13 C coupled spins with high S/N ratios, thereby allowing determination of the structures of cellulose derivatives, including CMC and CA, is an important factor; a short spin-lock time of about 24 ms yielded correlations between all carbons in each AGU of the cellulose derivatives, while longer spin-lock times ([48 ms) caused dramatic decreases in the S/N ratio.…”

Section: Resultsmentioning

confidence: 74%

“…If the 13 C chemical shifts of an anhydroglucose unit are affected by the species on the adjacent monomer units, a variation in the chemical shifts will be observed. Recently, we investigated the 13 C and 1 H chemical shifts of the AGUs comprising CA by NMR analysis of CA samples with DS AC in the range of 2.92-0.92 and revealed that the chemical shift could be explained by the substituent effects of acetyl groups in the 2-, 3-, and 6-positions and that the effects of the neighboring AGUs are negligible (Kono et al 2015). In contrast, for CMC, the effects of the neighboring AGUs have not been clarified, and the chemical shifts of the di-and tri-substituted anhydroglucose units have not been assigned in this study.…”

Section: Resultsmentioning

confidence: 98%

“…4. The 13 C chemical shifts of AGUs in CA (Table 1) were recently assigned by 1 H-detection 2D NMR experiments utilizing 1 H-1 H COSY, 1 H-1 H TOCSY, and 1 H-13 C HSQC with a series of unlabeled CA samples having DS AC ranging from 0.92 to 2.92 (Kono et al 2015). The four correlation networks in this study could be assigned to 2,3,6-tri-, 2,3-di-, 2,6-di-, and 3,6-di-substituted AGUs, according to the previous assignments.…”

Section: Resultsmentioning

confidence: 99%

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13C-detection two-dimensional NMR approaches for cellulose derivatives

et al. 2015

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To demonstrate the effectiveness of 13 Cdetection two-dimensional NMR methods used for the characterization protein structures for the characterization of cellulose derivatives, 13 C-13 C COSY, 13 C-13 C INADEQUATE, and 13 C-13 C TOCSY experiments were applied to 13 C-enriched sodium carboxymethyl cellulose and cellulose acetate. These samples were prepared from bacterial cellulose biosynthesized by Gluconacetobacter xylinus ATCC 53582 in medium containing 20 % uniformly 13 Clabelled glucose in unlabeled glucose. The combination of 13 C-13 C COSY (or 13 C-13 C INADEQUATE) and 13 C-13 C TOCSY spectra of the cellulose derivatives facilitated the direct and precise assignment of all ring carbons of each anhydroglucose unit comprising the cellulose chain during the short experimental time. In addition, a short spin-lock time (*24 ms) in the 13 C-13 C TOCSY experiments was revealed to be preferable for achieving improved sensitivity and obtaining correlation signals between all carbons in the anhydroglucose units of the cellulose derivatives.

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NMR characterization of cellulose acetate: Chemical shift assignments, substituent effects, and chemical shift additivity

Cited by 97 publications

References 32 publications

Synthesis of cellulose triacetate from cotton cellulose by using NIS as a catalyst under mild reaction conditions

Synthesis of cellulose triacetate from cotton cellulose by using NIS as a catalyst under mild reaction conditions

Removal of anionic dyes in aqueous solution by flocculation with cellulose ampholytes

13C-detection two-dimensional NMR approaches for cellulose derivatives

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