Characterization of cellulose acetates by nuclear magnetic resonance

Goodlett, V. Wilson; Dougherty, J. T.; Patton, H. W.

doi:10.1002/pol.1971.150090114

Cited by 119 publications

(44 citation statements)

References 5 publications

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“…If we denote carbonyl carbon peaks, from lower magnetic field, as a, b, and c, then the acetyl methyl proton peaks are assigned, using these correlation peaks, to a, c, and b. These relations are in an excellent agreement with the correlation, obtained by long-range selective spin decoupling method by Kowsaka et al 6 Using these results, together with the assignment of the acetyl methyl proton peak chemically speculated by Goodlett et al, 18 carbonyl carbon peaks can 1098 be assigned, from lower magnetic field, to C 6 , C 3 , and C 2 , respectively. It is also expected that if long-range scalar coupling between the glucopyranose skeleton proton and carbonyl carbon could be observed, carbonyl carbon peaks at C 2 , C 3 , and C6 positions could be ultimately.…”

supporting

confidence: 67%

Two-Dimensional Nuclear Magnetic Resonance Spectra of Cellulose and Cellulose Triacetate

Kowsaka¹,

Okajima²,

Kamide³

1988

Polym J

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ABSTRACT:An attempt was made to give a full assignment, using only NMR information, to all peaks in 1 Hand 13 C NMR spectra for systems of cellulose in 2.5 N NaOD/D2O and of cellulose triacetate (CTA, total degree of substitution 2.92) in deuterated trichloromethane (TCM-d), and in deuterated dimethylsulfoxide (DMSO-d6). For this purpose two-dimensional (2D) homonuclear 1 H shift correlation spectroscopy (COSY), heteronuclear 1 H-13 C shift correlation spectroscopy (C-H COSY), and long-range heteronuclear 1 H-13 C shift correlation spectroscopy (long-range C-H COSY) were applied to the above systems. By COSY 1 H peaks of cellulose/aq. alkali solution were assigned, from lower magnetic field, to H,, H6 , H6 ', (H3 + H4 + H5), and H2 protons, respectively.Here, two unequivalent H6 peaks heavily overlapped in the one-dimensional spectrum were observed very separately in 2D spectrum. By C-H COSY 13 C peaks of cellulose were assigned, from lower magnetic field, to C1, (C3, C4 , C5), C2 , and C6 carbons, respectively. C3 , C4 , and C5 carbon peaks were unable to be assigned separately, due to mutual and heavy overlapping of H3 , H4 , and H5 peaks. For cellulose triacetate, through use of COSY and C-H COSY all peaks in the region of glucopyranose backbone in 1 H and 13 C NMR wre able to be successfully and completely assigned. Long-range C-H COSY confirmed definitely the existence of the close correlationships between acetyl methyl proton and carbonyl carbon at the different carbon positions of CTA, which showed again the validity of the previous assignment with respect to carbonyl carbons (i.e., C6 , C3 , and C2 carbons from lower magnetic field). KEY WORDSCellulose / Cellulose Acetate / Cellulose Triacetate / 13 C NMR / 1 H NMR / Two-Dimensional NMR / Correlation Spectroscopy/ Long-Range Heteronuclear Correlation Spectroscopy/ Recently numerous studies have been published on the high resolution NMR spectra of solutim1.s of cellulose and its derivatives. NMR spectra of cellulose were utilized widely as a method for elucidating the dissolved state of solutes in solvents (i.e., interaction between solutes and solvents) and those of cellulose derivatives were employed for analysis of the average degree of substitution for each three hydroxyl groups «:fk» (k =2, 3, 6) in the glucopyranose unit: For example, Kamide et a/. 1 showed, from 1 H NMR spectra of eellulose in dimethylformamide/chloral/pyridine mixture, that cellulose dissolved in the form of cellulose trichlorate (CTC) in the solution. Gagnaire and his coworkers 2 speculated the dissolved state of cellulose in Nmethylmorpholine-N-Oxide/dimethylsulfoxide (DMSO), methylamine/DMSO, hydrazine/ DMSO, and paraformaldehyde/DMSO by comparing the 13 C chemical shifts in these solutions. Kamide and his collaborators 3 showed that a physically treated cellulose, whose intramolecular hydrogen bondings were de-* To whom all correspondence should be addressed. 1091

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supporting

confidence: 67%

Two-Dimensional Nuclear Magnetic Resonance Spectra of Cellulose and Cellulose Triacetate

Kowsaka¹,

Okajima²,

Kamide³

1988

Polym J

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“…The DS values of the cellulose-based macroinitiators were calculated from the integration ratios of the proton resonances of the acyl moieties to those of the cellulose backbone hydrogens , according to the method of Goodlett et al (1971).…”

Section: H Nmr Analysismentioning

confidence: 99%

Effect of the Molecular Structure of Acylating Agents on the Regioselectivity of Cellulosic Hydroxyl Groups in Ionic Liquid

Fu¹,

Li²,

Wang³

et al. 2016

BioResources

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Homogeneous functionalization of cellulose with chloroacetyl chloride (CAC), 2-bromoisobutyryl bromide (BrBiB), and 2-chloro-2-phenylacetyl chloride (CPAC) was performed in ionic liquid to evaluate the effect of the molecular structure of the reagents on the reactivity of the cellulosic hydroxyl groups. The results showed that the reaction was very selective for the less hindered C6-OH group, but the substitution of the secondary OH group still occurred, which indicated that the acylation of cellulose was only partly regioselective. The reaction extent and regioselectivity of the cellulosic hydroxyl groups partly depended on the molecular structure of the acylating agents. The reaction rate of the CAC was much faster than the relatively bulky BrBiB and CPAC, but the bulky acylating agents showed a higher C6-OH selectivity. Moreover, the BrBiB was less reactive than the CPAC, although they showed the same regioselectivity for the three hydroxyl groups. The acylation decreased the thermal stability of the cellulose, which decreased further as the bulk of the substituted groups increased.

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“…The DS of the cellulose-CPAC is calculated by Eq. (1) according to the method of Goodlett et al (1971),…”

Section: Ft-irmentioning

confidence: 99%

Homogeneous Acylation and Regioselectivity of Cellulose with 2-Chloro-2-Phenylacetyl Chloride in Ionic Liquid

Rong-Rong¹,

Fu²,

Qin³

et al. 2014

BioResources

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A cellulose acylate, cellulose-CPAC, was prepared homogeneously in the ionic liquid 1-butyl-3-methyl chloride imidazole ([Bmim]Cl) from cotton dissolving pulp. The pulp was first solubilized in the solvent system [Bmim]Cl/N,N-dimethyl formamide (DMF), and then reacted with 2-chloro-2-phenylacetyl chloride (CPAC) in the presence of an acid-binding agent. The effects of functional conditions including the molar ratio of CPAC/anhydroglucose unit (AGU), reaction time, reaction temperature, kind of acid-binding agent, and cellulose concentration on the degree of substitution (DS) were studied. The reactivities of the three hydroxyl groups in the homogeneous acylation of cellulose with CPAC were also investigated. The results showed that in homogeneous reaction medium, although all the C-6, C-3, and C-2 positions within the cellulose AGU could be substituted by CPAC, the reaction was quite selective for the C-6 OH. The successful synthesis of the cellulose-CPAC was confirmed by FT-IR, 1 H NMR, 13 C NMR, XRD, and STA. Furthermore, the acylation of cellulose with CPAC decreased the thermal stability of cellulose.

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Characterization of cellulose acetates by nuclear magnetic resonance

Cited by 119 publications

References 5 publications

Two-Dimensional Nuclear Magnetic Resonance Spectra of Cellulose and Cellulose Triacetate

Two-Dimensional Nuclear Magnetic Resonance Spectra of Cellulose and Cellulose Triacetate

Effect of the Molecular Structure of Acylating Agents on the Regioselectivity of Cellulosic Hydroxyl Groups in Ionic Liquid

Homogeneous Acylation and Regioselectivity of Cellulose with 2-Chloro-2-Phenylacetyl Chloride in Ionic Liquid

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