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13C and 15N spin–lattice relaxation and chemical shift studies of pentane-2,4-diamine

✍ Scribed by Chin Yu; George C. Levy

Publisher
John Wiley and Sons
Year
1984
Tongue
English
Weight
459 KB
Volume
22
Category
Article
ISSN
0749-1581

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✦ Synopsis

C and "N NMR chemical shift and spin-lattice relaxation data have been measured for both mew-and racemic-pentane-2,4-diaminediamine. At high pH (lZ), relaxation is consistent with hindered rotation of the NH, group due, in part, to the formation of intramolecular hydrogen bonds. At low pH (Z), relaxation is consistent with relatively unhindered rotation of the NH3+ group. Rotational jump rates and barriers are reported, determined from the ATl ratios between "N and -C nuclei. In all cases, the ratios for the raeemic diastereomer are higher than those of the meso compounds; this is interpreted in terms of conformationally more stable intramolecular hydrogen bond formation in the meso compound. Chemical shifts for the diastereomeric amines show that "N shifts move d o d d d on protonation along with methyl and methylene carbons, while the methine carbon resonances move upfield.

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