A facile method of determination for distribution of the substituent in O-methylcelluloses using 1H-NMR spectroscopy

Sekiguchi, Yuka; Sawatari, Chie; Kondo, Tetsuo

doi:10.1007/s002890200020

Cited by 13 publications

(9 citation statements)

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“…The identification of the different peaks was performed as described in ref. 38–40. As shown, the spectrum of the pristine MC was the same as that for the plasma-treated sample.…”

Section: Resultsmentioning

confidence: 87%

Thermosensitive hydrogels to deliver reactive species generated by cold atmospheric plasma: a case study with methylcellulose

et al. 2022

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“…The identification of the different peaks was performed as described in ref. 38–40. As shown, the spectrum of the pristine MC was the same as that for the plasma-treated sample.…”

Section: Resultsmentioning

confidence: 87%

Thermosensitive hydrogels to deliver reactive species generated by cold atmospheric plasma: a case study with methylcellulose

et al. 2022

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“…Analysis of the spectra was performed after identification of the different signals according to the literature [25][26][27][28].…”

Section: Methodsmentioning

confidence: 99%

“…1 H-NMR spectroscopy may also be used to characterize methylcellulose. A 1 H-NMR spectrum of MC is shown in Figure 3 with the attribution of the main resonances [27,28]. The spectrum shows intense signals at 3.48-3.47 ppm corresponding to the overlapping of methyl protons at C-2 and C-3, and at 3.31 ppm attributed to methyl protons at C-6.…”

Section: Substitution Patternmentioning

confidence: 98%

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Methylcellulose, a Cellulose Derivative with Original Physical Properties and Extended Applications

et al. 2015

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This review covers the preparation, characterization, properties, and applications of methylcelluloses (MC). In particular, the influence of different chemical modifications of cellulose (under both heterogeneous and homogeneous conditions) is discussed in relation to the physical properties (solubility, gelation) of the methylcelluloses. The molecular weight (MW) obtained from the viscosity is presented together with the nuclear magnetic resonance (NMR) analysis required for the determination of the degree of methylation. The influence of the molecular weight on the main physical properties of methylcellulose in aqueous solution is analyzed. The interfacial properties are examined together with thermogelation. The surface tension and adsorption at interfaces are described: surface tension in aqueous solution is independent of molecular weight but the adsorption at the solid interface depends on the MW, the higher the MW the thicker the polymeric layer adsorbed. The two-step mechanism of gelation is confirmed and it is shown that the elastic moduli of high temperature gels are not dependent on the molecular weight but only on polymer concentration. Finally, the main applications of MC are listed showing the broad OPEN ACCESSPolymers 2015, 7 778 range of applications of these water soluble cellulose derivatives.

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“…A detailed 13 C chemical shift assignment of HPMCAS was recently published, 27 with the conventional cellulose C1 and C4 assignments to 104 and 84 ppm, as well as an attribution of the signal at 61 ppm to C5, an OCH moiety. Here, we demonstrate, based on quantitative 13 C NMR 28 combined with spectral editing 29,30 and empirical chemical shift predictions as well as 1D and 2D solution-NMR data for methylcellulose, [31][32][33] cellulose acetate, 34,35 and HPMC 36,37 in the literature, that the peaks of C2-C6 and C9 in HPMCAS 27 were actually misassigned. A key factor is that ether formation can raise OCH n chemical shifts by up to 10 ppm relative to the corresponding HOCH n forms.…”

Section: Introductionmentioning

confidence: 86%

Corrected solid‐state ¹³C nuclear magnetic resonance peak assignment and side‐group quantification of hydroxypropyl methylcellulose acetyl succinate pharmaceutical excipients

Zheng,

Su,

Schmidt‐Rohr

2023

Magnetic Reson in Chemistry

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Hydroxypropyl methylcellulose acetyl succinate (HPMCAS) is widely used as a pharmaceutical excipient, making a detailed understanding of its tunable structure important for formulation design. Several recently reported peak assignments in the solid‐state 13C NMR spectrum of HPMCAS have been corrected here using peak integrals in quantitative spectra, spectral editing, empirical chemical‐shift predictions based on solution NMR, and full spectrum simulation analogous to deconvolution. Unlike in cellulose, the strong peak at 84 ppm must be assigned to C2 and C3 methyl ethers, instead of regular C4 of cellulose. The proposed assignment of signals at <65 ppm to OCH sites, including C5 of cellulose, could not be confirmed. CH2 spectral editing showed two resolved OCH2 bands, a more intense one from O‐CH2 ethers of C6 at >69 ppm and a smaller one from its esters and possibly residual CH2‐OH groups, near 63 ppm. The strong intensities of resolved signals of acetyl, succinoyl, and oxypropyl substituents indicated the substitution of >85% of the OH groups in HPMCAS. The side‐group concentrations in three different grades of HPMCAS were quantified.

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A facile method of determination for distribution of the substituent in O-methylcelluloses using 1H-NMR spectroscopy

Cited by 13 publications

References 1 publication

Thermosensitive hydrogels to deliver reactive species generated by cold atmospheric plasma: a case study with methylcellulose

Thermosensitive hydrogels to deliver reactive species generated by cold atmospheric plasma: a case study with methylcellulose

Methylcellulose, a Cellulose Derivative with Original Physical Properties and Extended Applications

Corrected solid‐state ¹³C nuclear magnetic resonance peak assignment and side‐group quantification of hydroxypropyl methylcellulose acetyl succinate pharmaceutical excipients

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A facile method of determination for distribution of the substituent in O-methylcelluloses using 1H-NMR spectroscopy

Cited by 13 publications

References 1 publication

Thermosensitive hydrogels to deliver reactive species generated by cold atmospheric plasma: a case study with methylcellulose

Thermosensitive hydrogels to deliver reactive species generated by cold atmospheric plasma: a case study with methylcellulose

Methylcellulose, a Cellulose Derivative with Original Physical Properties and Extended Applications

Corrected solid‐state 13C nuclear magnetic resonance peak assignment and side‐group quantification of hydroxypropyl methylcellulose acetyl succinate pharmaceutical excipients

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Product

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About

Corrected solid‐state ¹³C nuclear magnetic resonance peak assignment and side‐group quantification of hydroxypropyl methylcellulose acetyl succinate pharmaceutical excipients