Chemical shifts, multiplicities and

If necessary, measure the chemical shifts from the ID C spectrum/lD "C DEPT ( C APT) spectrum. Draw up a table containing a column for chemical shifts, multiplicities and assignments. Leave enough space in the table to include the T, value for each carbon and a section for H/ C correlations. 

Predicting the Chemical Shifts, Multiplicity, and Integrals of Peaks in the H-NMR Spectrum of a Compound... 

Predict the H-NMR spectrum of 2-butanone. Include the approximate chemical shift, multiplicity, and integral for each type of hydrogen. 

Predict the approximate chemical shifts, multiplicities, and integrals for the absorptions in the H-NMR spectra of these compounds ... 

Chemical Shifts, Multiplicities, and Coupling Constants of Residual Protons in Commercially Available Deuterated Solvents... 

The H-NMR spectrum of diosgenin in CDCb recorded on a Jeol FT-NMR spectrophotometer (400 MHz) and on a Hitachi FT-NMR R-1900 spectrophotometer (90 Mhz) using TMS as the internal standard. The spectra are shown in Figure 7 and 8. The characteristics proton chemical shifts, multiplicities and assignment are given in the table 5 are identical with previously reported spectra [6,7]. 

In the previous sections, we explored the three characteristics of every signal (chemical shift, multiplicity, and integration). In this section, we will apply the concepts and skills developed in the previous sections, and we will practice drawing the expected H NMR spectrum of a compound. The following exercise illustrates the procedure. 

Analyze the chemical shift, multiplicity, and integration of each signal, and then draw a fragment consistent with each signal. 

So we expect its H NMR spectrum to exhibit only five signals, corresponding with the following highlighted protons. For each signal, its expected chemical shift, multiplicity, and integration are shown. 

The heteronuclear multiple-quantum coherence (HMQC) spectrum, H-NMR chemical shift assignments, and C-NMR data of podophyllo-toxin are shown. Determine the chemical shifts of various carbons and connected protons. The HMQC spectra provide information about the one-bond correlations of protons and attached carbons. These spectra are fairly straightforward to interpret The correlations are made by noting the position of each crossf)eak and identifying the corresponding 8h and 8c values. Based on this technique, interpret the following spectrum. 

Fig. 10.14. Gradient-enhanced HMQC pulse sequence described in 1991 by Hurd and John derived from the earlier non-gradient experiment of Bax and Subramanian. For 1H-13C heteronuclear shift correlation, the gradient ratio, G1 G2 G3 should be 2 2 1 or a comparable ratio. The pulses sequence creates heteronuclear multiple quantum of orders zero and two with the application of the 90° 13C pulse. The multiple quantum coherence evolves during the first half of ti. The 180° proton pulse midway through the evolution period decouples proton chemical shift evolution and interchanges the zero and double quantum coherence terms. Antiphase proton magnetization is created by the second 90° 13C pulse that is refocused during the interval A prior to detection and the application of broadband X-decoupling.

Sophorine was isolated from Sophora alopecuroides (26). The nature of MS decay showed that sophorine is a quinolizidine alkaloid of the lupinine type. The IR spectrum suggests the presence of a franj-quinolizidine moiety (2675-2945 cm ) and an — NH—CO— group (1605 and 1683 cm ). On the basis of chemical shift analysis and signal multiplicity of H- and C-NMR spectra as well as biosynthetic considerations, structure 59 was proposed for sophorine. 

The fatty acyl substituents were mainly of three types saturated straight-chain C,6-C,9 acids C21-C25 mycosanoic acids and C24-C28 mycolipanolic acids. Analysis of one of the major 2,3-di-O-acyltrehaloses by two-dimensional H-chemical-shift-correlated and H-detected heteronuclear multiple-bond correlation spectroscopy established that the C18 saturated straight-chain acyl group was located at the 0-2 position and that the C24 mycosanoyl substituent was at the 0-3 position of the same nonglycosylated terminus (structure 8). At least six molecular... 

THE 13C CHEMICAL SHIFTS, COUPLINGS, AND MULTIPLICITIES APPENDIX A OF COMMON NMR SOLVENTS... 

---