Proton magnetic resonance spectra of trans -(1,2 -cyclohexylenedinitrilojtetraacetic acid (CyDTA), trans -1,2 -diaminocyclohexane, dill ,2-propylenedinitrilo)tetraacetic acid (PDTA), and meso -(2,3 -butylenedinitrilo)tetraacetic acid (BDTA) at various pH values are presented andinterpreted. The functional groups in the former two compounds occupy predominantly diequatorial positions on the cyclohexane ring at pH = 5 to 14.
Bleaney's theory of dipolar shifts or "contact free" proton shifts and Golding's theory of contact shifts provide, In joint consideration, bases for separation of the contribution each makes to the experimentally observed NMR shift. This treatment makes use of shifts obtained with several selected lanthanides but does not require a prior knowledge of the structure of the ligand adduct other than effective axial symmetry around the lanthanide. The resulting G factors for the various observed nuclei (1H, 13C, etc.) may be employed to orient a known fragment of the adduct molecule with answers to subsequent structural questions being addressed from additional observed shifts for nuclei and from constraints In their relative geometric placement. The procedure is applied to two organic compounds.
columns packed with 25 weight % Apiezon L on 30-to 60-mesh Chromosorb W. Two sets of chromatograms were obtained on these columns to correspond to those on the bleeding columns. The same flow rates, temperature programs, and sample sizes were used. Under these conditions the naphthalene was eluted at 175°C. and the p-terphenyl below 320°C. where a single-column base-line would not have LITERATURE CITED
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