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| Titel: |
Solar State 1H and 13C NMR Studies of Melanoidins Synthesized from D-Xylose and Glycine |
| Auteur: |
Benzing-purdie, L. M. Ratcliffe, C. I. Ripmeester, J. A. |
| Verschenen in: |
Journal of carbohydrate chemistry |
| Paginering: | Jaargang 5 (1986) nr. 4 pagina's 571-584 |
| Jaar: |
1986-12-01 |
| Inhoud: |
Parameters affecting 13C CP/MAS NMR spectra of solid melanoidins (in particular 1H T1, T10 and the cross polarization time tcp) have been obtained with the aim of determining the optimum conditions necessary for quantitative studies. Melanoidins were synthesized at 22d`, 68d` and 100 d`C, from molar solutions of D-xylose and glycine. The 1H T10 values for all melanoidins were similar. Single exponential 1H T1 and 1H T10 relaxation curves were observed for all three polymers, suggesting that the mace-rials were relatively homogenenous. An increase in T1's with an increase in unsaturation was also observed. The optimum conditions for quantifying the different types of C were found to be tcp = 2 msec., recycling time 2 sec. and for these conditions, the melanoidins synthesized at 22d`C showed 18% unsaturation, 18% carboxyl and amide C, while the melanoidin synthesized at 100 d`C showed 28 and 11% respectively. Solid state 1H NMR lineshapes were obtained and these consisted in all three melanoidins of a broad and a narrow component attributed to the protons of the polymer core and the protons of the mobile side chains or methyl groups respectively. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 115 van 178 gevonden artikelen
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