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[[HETLOC]] <cite>kurz91,uhrin98</cite> experiment can be used to obtain one, two, three and more -bond separated '''heteronuclear J couplings as well as their relative signs''', which depend on the conformation and stereochemical arrangement of atoms in the molecule.

HETLOC experiment has a limitation that it won't show couplings to carbon atoms (or other [[X-nucleus|X-nuclei]] to which HETLOC experiment might be tuned) not connected to a proton. That is because intrinsically HETLOC is a [[TOCSY]] experiment.

Before starting to analyze spectrum, list the couplings to be collected (chances are all observable couplings won't be needed).

Then, open HETLOC spectrum, and for a given coupling between atoms C<sub>x</sub> and H<sub>y</sub>:
*draw a horizontal line at &omega;1 (usually vertical dimension) = &delta;(H<sub>x</sub>) - i.e. chemical shift of C<sub>x</sub>-attached proton.
*draw a vertical line at &omega;2 = &delta;(H<sub>y</sub>)
*alternatively move a cursor so that cross-hairs correspond to those lines
*note the point of intersection of the two lines
*somewhere symmetric to that point along the vertical line there might be two peaks or groups of peaks (i.e. if they are observable)
*if the peaks appear to be missing - try redrawing spectrum at lower first contour level (~intensity scale in 2D plane)
*two (groups of) peaks will be offset in &omega;1 by <sup>1</sup>JC<sub>x</sub>H<sub>x</sub> and in &omega;2 -'''by the sought value of <sup>n</sup>JC<sub>x</sub>H<sub>y</sub>
*take a careful note about sign of coupling - is the doublet tilted to the left or to the right (i.e. same as main dagonal?)<br>

[[Image:Hetloc-assign.png]]

===Related documents===
[[Sensitivity- and Gradient- enhanced HETLOC]]

[[Dipsi2etgpjcsix1%2C Sensitivity and Gradient- enhanced HETLOC]]

[[Relative stereochemistry]]
===References===
<biblio>
#kurz91 bibtex=@article{kurz1991hem,
  title={HETLOC, AN EFFICIENT METHOD FOR DETERMING HETERONUCLEAR LONG-RANGE COUPLINGS WITH HETERONUCLEI IN NATURAL ABUNDANCE},
  author={KURZ, M. and SCHMIEDER, P. and KESSLER, H.},
  journal={Angewandte Chemie. International edition in English},
  volume={30},
  number={10},
  pages={1329--1331},
  year={1991},
  publisher={VCH},
  url={http://dx.doi.org/10.1002/anie.199113291}
}
#uhrin98 bibtex=@article{uhrin1998sag,
  title={Sensitivity-and Gradient-Enhanced Hetero ($\omega$1) Half-Filtered TOCSY Experiment for Measuring Long-Range Heteronuclear Coupling Constants},
  author={Uhr{\i}´n, D. and Batta, G. and Hruby, V.J. and Barlow, P.N. and K{\"o}v{\'e}r, K.E.},
  journal={Journal of Magnetic Resonance},
  volume={130},
  number={2},
  pages={155--161},
  year={1998},
  publisher={Elsevier},
  url={http://dx.doi.org/doi:10.1006/jmre.1997.1308}
}
</biblio>
[[Category:Scalar Coupling]]
[[Category:User guides]]

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