Electron-spin resonance study of some irradiated D-glucopyranosides

Sarkar, Ila; Arthur, Jett C.; Hinojosa, Oscar

doi:10.1016/s0008-6215(00)81455-x

Carbohydrate Research

1968

DOI: 10.1016/s0008-6215(00)81455-x

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Electron-spin resonance study of some irradiated D-glucopyranosides

Ila Sarkar

Jett C. Arthur

Oscar Hinojosa

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Cited by 8 publications

(2 citation statements)

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confidence: 99%

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Some Properties of Phenyl-Carbamylated Cotton

Sarkar

Arthur

George

1968

Textile Research Journal

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We have reported the substitution of aromatic groups and of substituted aromatic groups of glutosides [2,[9][10][11][12][13] and fibrous cellulose [2][3][4]6] to yield products which were resistant to degradation on exposure to high-energy, radiation. Phenyl-carbamylated glucosides were resistant to radiation-initiated degradation [11][12][13]. Also, solutions of phenyl-carbamylated glucosides exhibited fluorescent spectra with wavelengths slightly longer than those of their excitation spectra [12]. This indicated that most of the energy absorbed on excitation was emitted during fluorescence. These results suggested that cotton cellulose, reacted with phenyl isocyanate, would be resistant to radiation-initiated degradation.Cotton cellulose (about 4 g of purified Deltapine cotton [7] spun into 7s/3 yarn) was dried in '11 forceddraft oven for 1 hr at 110°C. A solution of dry pyridine containing 15 wt. % of phenyl isocyanate (about 100 g) was placed in a round-bottom flask fitted with a reflux condenser from which moisture was excluded by means of ~a CaCl2 tube. After the solution had been heated to reflux (about 130°C) the dried yarn was immersed in the solution under reflux conditions for the length of time required to give the desired degree of substitution (DS) on the cellulose. On completion of the reaction, the phenyl-carbamylated cotton yarns were washed three times with methanol at 50-60°C [8]. In one procedure, the yarns were left in the slack condition during the washing with methanol. In another procedure, the yarns were restretched to about 80% of their original length and then washed with methanol. Finally, the yarns were washed with distilled water and air-dried.The DS was calculated from the increase in weight of the original yarn. Textile tests were done according to ASTM methods [1], and other tests were done as previously described [5].The mechanical properties of phenyl-carbamylated cotton yarns (restretched before drying) are shown in Table I. If the substituted yarns were not restretched before drying, the values for the properties were decreased to values lower than those shown in Table I.

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“…Phenyl-carbamylated glucosides were resistant to radiation-initiated degradation [11][12][13]. Also, solutions of phenyl-carbamylated glucosides exhibited fluorescent spectra with wavelengths slightly longer than those of their excitation spectra [12].…”

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Some Properties of Phenyl-Carbamylated Cotton

Sarkar

Arthur

George

1968

Textile Research Journal

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ESR study of intramolecular energy transfer in the radiolysis of cellulose thenoates

Singh

Hinojosa

Arthur

1971

J of Applied Polymer Sci

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synopsisThe substitution of Zthenoyl, 5-methyl-Zthenoyl, Zthiopheneacryloyl, 5-bromo-2-thenoyl, and 5-bromo-Zthiopheneacryloyl groups on fibrous cotton cellulose increased the radiation resistance of cellulose, as indicated by the retention of the breaking strengths of the modified fibrous celluloses at high dosages of y-radiation, as compared with that of irradiated, unmodified fibrous cellulose. The presence of electropositive or electronegative substituents on the thiophene groups did not reduce the radioprotective effects of these groups for cellulose. Crosslinking of the cellulose thenoates in 1,3-di(4-pyridyl)-propane did not significantly reduce the radiation resistance of the thenoates. Examination of the ESR spectra of irradiated cellulose and cellulose thenoates indicated that the site of the long-lived free radicals on the irradiated cellulose molecules was not changed by the chemical modification. However, the concentration of long-lived free radicals in irradiated cellulose thenoates, at a given radiation dosage, was less than that in irradiated cellulose. The localization of energy on carbon CI or Cr of the cellulose molecule, which leads to depolymerization and loss in breaking strength of fibrous cellulose, was decreased. The radioprotective effects of thiophene groups for cellulose were similar to those of furan and benzenoid groups.

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Thermal behavior of carbohydrates

Shafizadeh¹

1971

J. polym. sci., C Polym. symp.

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Thermal analysis of a hardwood reflected the pyrolysis of its main components including xylan and cellulose. Thermal properties of these components were investigated with model compounds consisting of α‐D‐xylose, substituted phenyl β‐D‐xylopyranosides, β‐Dglucopyranosides and α‐D‐arabino‐hexopyranosides and 1,6‐anhydro‐β‐D‐glucopyranose. At the lower temperatures these molecules displayed anomerization, loss of water and phase change, which were studied with a variety of physical methods. Calorimeteric and wide line NMR measurements showed that 1,6‐anhydro‐β‐D‐glucopyranose and related anhydro sugars undergo plastic crystalline transition, involving reorientation of the molecules about their centers of gravity and self‐diffusion before melting. At more elevated temperatures the above compounds showed cleavage of the glycosidic group, polymerization of the sugar moiety, decomposition and evaporation of the pyrolysis products. This involved some heterolytic reactions, which could be catalyzed by acid or alkaline materials. Kinetics of the pyrolysis process, including the rates and energies of activation were determined by thermal analysis and ESR spectroscopy. These data indicated that cleavage of the glycosidic bond is directly influenced by variation of its electron density and constitutes the rate determining step in pyrolysis of the carbohydrate compounds.

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Electron-spin resonance study of some irradiated D-glucopyranosides

Cited by 8 publications

References 13 publications

Some Properties of Phenyl-Carbamylated Cotton

Some Properties of Phenyl-Carbamylated Cotton

ESR study of intramolecular energy transfer in the radiolysis of cellulose thenoates

Thermal behavior of carbohydrates

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