Aromatic regions spectra

Fig. 15. Aromatic region of the H NMR spectrum for Zn(C104)2 and ethylenediamine-N,5-ethyladeninc hydrochloride, A-Et-enHf,Cl , in D20, illustrating the broadening of the H2 resonance of the adenine moiety. Reproduced with permission from Ref. (58). Copyright 2000, Wiley-VCH.

The H-NMR spectrum of 2 in CDCI3 (Figure 1) exhibits broad unresolved resonances in the aromatic region similar to those found in the monomer. Broad signals with lack of resolution are consistent with magnetic non-equivalence of the methyl group protons resulting from a mixture of triad tacticities. 

H spectra (aromatic region) upper spectrum 200 MHz, lower spectrum 600 MHz. 

The near-UV CD spectrum of carbonic anhydrase (Fig. 39) is rather strong and displays substantial fine structure at pH 7 (Wong and Hamlin, 1974). In the molten globule and the acid-denatured forms, the near-UV CD spectrum is nearly abolished, although the authors report weak residual positive CD through the aromatic region. 

Now let us consider Structure 6.21 and Spectrum 6.18 and see how the Karplus curve can be used to aid assignment of the spectrum. (This compound will be referred to from now on as the morpholine compound as we will use it to demonstrate several different techniques) Note that the aromatic region has been omitted as it contains little of interest and we wish to concentrate on the carbocyclic region of the spectrum. It was acquired in CDCI3. 

As expected, the 1H—NMR spectrum shows only one absorption in the aromatic region (r=2.7). This is shifted considerably compared with that of unsubstituted [2.2]paracyclophane (t=3.7). In the IR spectrum an intense band occurs at 718 cm-1, as is characteristic for other [2.2]paracyclophanes, e. g. methoxycarbonyl[2.2]paracyclophanes 8 and 9 35>, though it is absent in the spectrum of the linear poly-p-xylene (10). The parent hydrocarbon 2 shows this absorption, ascribed to the distorted aromatic rings, at 725 cm-1 36>. 

Fig. 13. H NMR spectra in the aromatic region for native A. variabilis PCu(II) lower spectrum), and the Ru(IlI)-modified protein [SO]...

Careful nitration of anisole (CH3OC6H5) with a new nitrating reagent gives a mixture of 4-nitroanisole and 2-nitroanisole. The section of the NMR spectrum below is from the aromatic region of the crude reaction mixture which is a mixture of the 4- and 2-nitroanisoles. Determine the relative amounts of the two products in the reaction mixture from the integrals in the spectrum. 

The appearance of a 4 proton symmetrical pattern in the aromatic region near 5 7.9 and 6.6 ppm is strongly indicative of a para disubstituted benzene ring. This is confirmed by the presence of two quaternary resonances at 5 152 and 119 ppm in the spectrum and two CH resonances at 5 131 and 113 ppm. 

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