13CNMR

Tabic 3. 13CNMR Spectra of (Benzo)Thiepins in CDC13 (Chemical Shifts in ppm)... 

The and 13CNMR spectra of various azepines have been recorded (Tables 1 and 2). 

Apparently, the 1H NMR spectra of 1 //-azepines are invariant over substantial temperature ranges.61 However, temperature dependence has been noted69 in the 13CNMR spectra of some 1 -acyl-1 //-azepines, and is attributed to hindered rotation about the N-CO bond rather than to ring-inversion phenomena AG free enthalpies of activation for hindered rotation of 62-66 kJ moP1 have been calculated. E/Z-rotamcr ratios for l-aroyl-l//-azepines have been assessed and show a slight preference for the -rotamer 22 however, an X-ray structural analysis of l-(4-bromobenzoyl)-2-methyl-3.5,7-triphenyl-l//-azepine demonstrates that in the crystal state it is exclusively in the E configuration.22... 

The H and 13CNMR spectra of various cyclopentazepines have been recorded (Tables 1 and 2), as has the HNMR spectrum of 7V,7V-dimethylcyclopent[e]azepin-l-amine.68 A detailed analysis of geminal and long-range 13C-H coupling constants for cyclopent[c]azepine is also available.87 The HNMR spectra of 9//-pyrrolo[l,2-a]azepin-9-one (8b) and its fully delocalized cation have been recorded in various solvents.7... 

Treatment of the Z-aldehyde 9 (R1 = R2 = H) with trifluoroacetic acid in dichloromethane at — 10 C, then with l,4-diazabicyclo[2.2.2]octane or /V,/V-diethylpyridin-4-amine, constitutes the first synthesis of 27/-azepine (10, R1 = R2 = H) which was isolated, with great difficulty and in very low yield (1 %), as a highly volatile, unstable oil, the structure of which was confirmed by high field H and 13CNMR spectroscopy.290 Similar treatment of the Z-alkenones 9a-d furnishes the thermally unstable (5)-2/7-azepines lOa-d in much higher yields.291... 

Nuclear Magnetic Resonance Spectra. The 13CNMR spectra of quinoxaline and a dozen 5-substituted quinoxalines have been determined for comparison with those of corresponding naphthalene derivatives.918 Aspects of the 1H, 13C, and 14N NMR spectra of quinoxaline and related heterocycles have been correlated with the Ji-electron densities of the system.419 In contrast with the... 

C Nuclear Magnetic Resonance Spectra. The solid-state 13CNMR spectra of 6,7-dimethyl-2,3-di(pyridin-2-yl)quinoxaline (130) and its salts have been used to complement X-ray information (see above) on fine structure.908 A study of the 13C spectra of mono- to tetramethylquinoxalines has made possible the analysis of mixtures of such methylated quinoxalines obtained from ambiguous primary syntheses.526... 

Figure 39 BC CPMAS NMR spectra of [3- 3C]Ala-labelled ppR (a), A149S (b) and A149V (c) reconstituted in egg PC bilayer. 13CNMR signal at 15.9 ppm corresponding to Alal49 in ppR is shown by the grey (a) and arrows (b, c, and d). The resonance peak at 14.1 ppm is ascribed to methyl carbon peak of egg PC as shown as asterisk. Difference spectrum between (a) and (c) is shown in (d). From Ref. 214 with permission.

The second termination reaction is alkyl chain end transfer from the active species to aluminium [155]. This termination becomes major one at lower temperatures in the catalyst systems activated by MAO. XH and 13CNMR analysis of the polymer obtained by the cyclopolymerization of 1,5-hexadiene, catalyzed by Cp ZrCl2/MAO, afforded signals due to methylenecyclopentane, cyclopentane, and methylcyclopentane end groups upon acidic hydrolysis, indicating that chain transfer occurs both by /Miydrogen elimination and chain transfer to aluminium in the ratio of 2 8, and the latter process is predominant when the polymerization is carried out at — 25°C [156]. The values of rate constants for Cp2ZrCl2/MAO at 70°C are reported to be kp = 168-1670 (Ms) 1, kfr = 0.021 - 0.81 s 1, and kfr = 0.28 s-1 [155]. 

Resin Reaction Time 00 Conversion (%) 13cnmr Shift (ppm)... 

Polymerization was carried out in NaOH aqueous solution. Table 4 summarizes the reaction conditions and polymer yields. The first step of the polymerization was hydrolysis and oligomerization of the silylethers at low temperatures from 90°C to 150 °C. In order to increase the polymer yield and the softening point of the polymers, the second step was carried out at higher temperatures under reduced pressure, removing alcohol and water, 1H-NMR, 13CNMR and IR spectroscopy of each polymer show that these polymers have the polysiloxane structure substituted with a phenol group. 

CNMR Spin-Lattice Relaxation and Conformational Dynamics in a 1,4-Polybutadiene Melt. 

While examining the coordination properties of new di- and triaza-crown ether ligands containing multiple ferrocene moieties (Fig. 13) we discovered using H and 13Cnmr titration that these systems form selectively 1 1 complexes with ammonium cations (Beer et al., 1993c). 

Table 15. AS Tor Three Diastereomeric Pairs of Cyclic Acetals of 3-Methylcyclohexanone (13CNMR, 100 MHz, CDC13)66...

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