Figure 9.45
Basic COSY spectrum of geraniol, in CDCl 3 at 500 MHz. The H-5, H- 6
coupling is shown.(ii) Heteronuclear chemical shift correlation (HETCOR) or heteronuclear correlated spectroscopy
(HETEROCOSY) identifies the specific protons attached to each carbon-13 (^1 H–^13 C connectivities).
The contour plot is related to the 1-D proton spectrum along the F 1 axis at the side and to the broadband
decoupled^13 C spectrum along the F 2 axis at the top. The cross-peaks, which confirm specific^1 H–^13 C
attachments, are located at the intersections of horizontal lines drawn from proton peaks or multiplets
and vertical lines drawn from^13 C peaks. Compared to DEPT, more specific information on^1 H–^13 C
connectivities is obtained as illustrated by the HETCOR spectrum of geraniol (Figure 9.46).
(iii) Incredible natural abundance double quantum transfer experiment (2-D INADEQUATE) identifies
directly bonded^13 C nuclei (^13 C–^13 C connectivities) which allows the carbon skeleton of a compound to
be elucidated. Because the natural abundance of^13 C is 1.1%, only about 1 in 10 000 molecules will
have adjacent^13 C nuclei. The sensitivity of this technique is therefore correspondingly low, and it is
very time consuming to collect the data. The contour plot shows a series of widely separated pairs of