1H NMR spectra

How many absorptions would you expect (S)-malate, an intermediate in carbohydrate metabolism, to have in its 1H NMR spectrum Explain. 

Figure 13.12 The 1H NMR spectrum of methyl 2,2-dimethylpropanoate. Integrating the peaks in a "stair-step" manner shows that they have a 1 3 ratio, corresponding to the ratio of the numbers of protons (3.91 responsible for each peak.

Figure 13.15 The 1H NMR spectrum of 2-bromopropane. The -CH3 proton signal at 1.71 <5 is split into a doublet, and the -CHBr- proton signal at 4.28 8 is split into a septet. Note that the distance between peaks—the coupling constant—is the same in both multiplets. Note also that the outer two peaks of the septet are so small as to be nearly lost.

Figure 13.18 The 1H NMR spectrum of toluene, showing the accidental overlap of the five nonequivaient aromatic ring protons.

To understand the 1H NMR spectrum of trans-cinnamaldehyde, we have to isolate the different parts and look at the signal of each proton individually. 

Active Figure 13.19 The 1H NMR spectrum of frans-cinnamaldehyde. The signal of the proton at C2 (blue) is split into four peaks—a doublet of doublets—-by the two nonequivalent neighboring protons. Sign in arwww.thomsonedu.com to see a simulation based on this figure and to take a short quiz. 

Figure 13.21 (a) The 1H NMR spectrum of cyclohexylmethanol, the product from hydroboration/oxidation of methylenecyclohexane, and (b) the 1H NMR spectrum of 1-methylcyclohexanol, the possible alternative reaction product. 

The compound whose 1H NMR spectrum is shown has the molecular formula C4H7O2CI and has an infrared absorption peak at 1740 cm-1. Propose a structure. 

Compound A, CgHjo, yields three substitution products, C H9Br, on reaction with Bt 2- Propose two possible structures for A. The 1H NMR spectrum of A shows a complex four-proton multiplet at 7.0 8 and a six-proton singlet at 2.30 8. What is the structure of A ... 

The 1H NMR spectrum shown is that of 3-methyl-3-buten-l-ol. Assign all the observed resonance peaks to specific protons, and account for the splitting... 

Figure 18.4 The 1H NMR spectrum of dipropyl ether. Protons on carbon next to oxygen are shifted downfield to 3.4 S.

Figure 19.18 1H NMR spectrum of acetaldehyde. The absorption of the aldehyde proton appears at 9.8 8 and is split into a quartet.

In the 1H NMR spectrum, the acidic -C02H proton normally absorbs as a singlet near 12 5. As with alcohols (Section 17.11), the -C02H proton can be replaced by deuterium when D20 is added to the sample tube, causing the absorption to disappear horn the NMR spectrum. Figure 20.6 shows the H NMR spectrum of phenylacetic acid. Note that the carboxyl proton absorption occurs at 12.0 8. 

Aromaticity (Chapter 15 introduction) The special characteristics of cyclic conjugated molecules. These characteristics include unusual stability, the presence of a ring current in the 1H NMR spectrum, and a tendency to undergo substitution reactions rather than addition reactions on treatment with electrophiles. Aromatic molecules are planar, cyclic, conjugated species that have An + 2 7T electrons. 

N-Methylcyclohexylamine, 13C NMR spectrum of, 954 1H NMR spectrum of, 953 Methylene group, 178 N-Methylguanine, electrostatic potential map of, 1121 6-Methyl-5-hepten-2-ol, DRPT-NMR spectra of. 451... 

When a methanolic solution of luciferin was left at -20° C in the presence of air, most of the luciferin was oxidized in three days, based on its 1H-NMR spectrum. The air oxidation product was purified by HPLC on a TSK DEAE-5PW column using 35% acetonitrile containing 85mM NaCl and 3mM NaHCC>3. The purified product in the HPLC eluent showed absorption maxima at 237nm... 

Figure 2.86 The 1H NMR spectrum in the hydride region of the isomers of [IrH3(PEt2Ph)j] top, /ac-isomer bottom, mer-isomer. (Reproduced with permission from E.L. Muetterties (ed.), Transition Metal Hydrides, published by Marcel Dekker, 1971, p. 80.)...

Recently, a photoisomerization reaction of azoferrocene was found to proceed in polar solvents such as benzonitrile and DMSO through both a 7t it transition of the azo-group with a UV light (365 nm) and the MLCT transition with a green light (546 nm) (Fig. 6) (Scheme 1) (153). The quantum yields of the photo-isomerization reaction at 365 nm and 546 nm were estimated to be 0.002 and 0.03, respectively. The transformation into the cis form causes the higher field shift of Cp protons in the 1H-NMR spectrum and an appearance of u(N = N) at 1552 cm-1. The cis form is greatly stabilized in polar media, and dilution of the polar solution of cis-25 with less polar solvents resulted in a prompt recovery of the trans form. 

The methyl ester gives rise to a fairly sharp singlet at 3.59 ppm, and the ester carbonyl exhibits an infrared band at 1730 cm"1. The MM content of the copolymer is easily ascertained by integration of the 1H NMR spectrum and may be corroborated by elemental analysis. 

The anionic polymerization of the MM block was initiated with fluorenyllithium (14) in THF at -78°C. After several hours, t-butyl methacrylate was introduced, and the polymerization was allowed to slowly rise to room temperature. The reaction was quenched with a few drops of methanol and precipitated from ligroin. The dried polymer was analyzed by NMR, IR, and GPC. The 1H NMR spectrum displays signals at 0.85, 1.02, and 1.13 (shoulder) ppm for the... 

The result of a typical diffusion measurement is shown in Figure 2. In the 1H-NMR spectrum of a cubic phase of monoolein and 2H20 with 10% Desmopressin, the signals from the aromatic residues (Tyr and Phe) in Desmopressin, appear in a spectral region which does not contain any signals from the lipid. Therefore, the peptide and lipid diffusion coefficients could be determined separately (Table II), and in Figure 2 the spectra from such an experiment are shown. The lipid diffusion coefficient was also determined in a cubic phase in the absence of Desmopressin. 

Copolymerization reactions with p-methoxy-a-methylstyrene were also attempted at 0°C, and a methanol-insoluble product having an Mjj of 1600 was obtained over a period of 36 h. From the 250-MHz 1h-NMR spectrum, it was found that p-methoxy-a-methylstyrene was present in the polymer to the extent of 14%. 

Spectroscopic data and subsequent isolation by crystallization point to the formation of 12 in 98% yield. The 1H NMR spectrum of 12 shows a slightly... 

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