Nuclear magnetic resonance reference spectra

The nuclear magnetic resonance (NMR) spectrum (Fig. 2) was obtained by preparing a saturated solution of meperidine hydrochloride, U.S.P. (Wyeth Lot No. F-665901) in deutero chloroform containing tetramethylsilane as internal reference. The only exchangeable proton is the hydrogen associated with HC1. The NMR proton spectral assignments are given in Table II. 

Fig. 4. [ H, C] Multiple-bond coherence (HMBC) nuclear magnetic resonance (NMR) spectrum of compound [27c]. The numbers in the proton and carbon spectra refer to the corresponding proton and carbon atoms of the assigned stmctures. Cross-peaks resulting from single- and multiple-bond coherences are indicated with two numbers, the first referring to the proton and the second to the carbon atoms involved in the coherence. For example, 12/1 indicates a coherence between H-12 and C-1 of structure [27c]. Cross-peaks of single bond coherences, indicated by identical proton and carbon numbers, are split by the large single bond proton-carbon couplings.

Problem 6.4. These questions refer to the material in Scheme 6.5. (a) At higher temperatures, all of the hydrogens in 2-methylbutane react with equal facility. What ratio of products A-D are expected under such conditions (b) Sketch the H nuclear magnetic resonance (NMR) spectrum of each of the products A-D and show how you would, therefore, know which isomer corresponded to which letter, (c) Which of the isomers A-D are, at least in principle, capable of resolution into enantiomers ... 

The nuclear magnetic resonance (NMR) spectra (300MFIz) of both the compound 10 and 11 was recorded in dimethyl sulfoxide (DMSO-r4) and CDCI3. The compound 10 in its H NMR spectrum showed a singlet signal at 5 5.32 due to the two NH protons, whereas compound 11 showed the presence of two NH protons at 6 6.80 <1989JOC3062>. For information on spectral studies of the compounds 1-5, refer to CHEC-II(1996) <1996CHEC-II(8)707>. 

Almost all the reported compounds have been characterized with the help of various nuclear magnetic resonance (NMR) techniques. For previous studies of the compounds, refer to CHEC-II(1996) <1996CHEC-II(8)713>.The H NMR spectrum (300MHz) of 2,3,7-trirnethyl-3a,9a-dihydro-1,8-dithiaMa,5,9-triazacyclopenta[3]naphthalene-4,6-dione 47 <2000JHC1161> showed the presence of one quartet at 8 4.23 corresponding to the CH. Another broad singlet corresponds to the presence of the N-H proton. 

Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy ( ll NMR) have become standards for verifying the chemistry of polyanhydrides. The reader is referred to the synthesis literature in the previous section for spectra of specific polymers. The FTIR spectrum for PSA is shown in Fig. 2. In FTIR the absorption... 

Nuclear magnetic resonance spectrum (deuteriochloroform-solvent, internal tetramethylsilane reference) multiplet at... 

The H nuclear magnetic resonance spectrum of chlorpromazine hydrochloride in CDCI3 is shown in Figure 5 [13]. The data were recorded on a Varian XL 200 MHz spectrometer using tetramethylsilane as the internal reference. Assignments for the observed resonance bands are presented in Table 3. 

The C-NMR spectrum ofindinavir sulfate, shown in Figure 13, was obtained using a Bruker Instruments model AMX-400 nuclear magnetic resonance spectrometer operating at a frequency of 100.55 MHz as an approximate 4.16 % w/v solution in deuterium oxide. The 67.4 ppm resonance of dioxane was used as an external reference standard. Peak assignments are found in Table 8, and make use of the numbered structural formula given previously [11]. 

A single measurement of a calibration sample can give the concentration of the test solution by a simple ratio. This is often done in techniques where a calibration internal standard can be measured simultaneously (within one spectrum or chromatogram) with the analyte and the system is sufficiently well behaved for the proportionality to be maintained. Examples are in quantitative nuclear magnetic resonance with an internal proton standard added to the test solution, or in isotope dilution mass spectrometry where an isotope standard gives the reference signal. For instrument responses As and /sample for internal standard and sample, respectively, and if the concentration of the internal standard is Cjs, then... 

Nuclear Magnetic Resonance (NMR) spectroscopy is one of the most powerful analytical techniques in organic chemistry for elucidating the molecular structures of chemicals (1,2). Moreover, an NMR spectrum may be used like a fingerprint to identify a chemical by comparing it with its reference spectrum recorded from the authentic chemical under comparable conditions. The spectrum also reveals information on molecular conformation, isomerism, molecular dynamics, and diastereomers (3 6). 

Obtain infrared and nuclear magnetic resonance spectra following the procedures of Chapters 19 and 20. If these spectra indicate the presence of conjugated double bonds, aromatic rings, or conjugated carbonyl compounds obtain the ultraviolet spectrum following the procedures of Chapter 21. Interpret the spectra as fully as possible by reference to the sources cited at the end of the various spectroscopy chapters. 

Fig. 2. Nuclear magnetic resonance spectrum of halothane in carbon tetrachloride, tetramethylsilane reference (courtesy of Dr. J. M. Pryce).

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