Nuclear magnetic resonance , alkylation-protonation

Nuclear Magnetic Resonance. The nmr spectmm of aromatic amines shows resonance attributable to the N—H protons and the protons of any A/-alkyl substituents that are present. The N—H protons usually absorb in the 5 3.6—4.7 range. The position of the resonance peak varies with the concentration of the amine and the nature of the solvent employed. In aromatic amines, the resonance associated with N—CH protons occurs near 5 3.0, somewhat further downfield than those in the aliphatic amines. 

Having introduced the correlation of Fig. 1, we may return to the stabilities of alkyl cations. Rate constants for the hydration of secondary and primary alkenes have been measured in concentrated solutions of aqueous sulfuric acid by Lucchini and Modena97 and by Tidwell and Kresge42 using proton nuclear magnetic resonance (NMR) or UV to monitor progress of the reactions. It is conceivable that the reactions involve a concerted addition of a proton and water molecule to the alkenyl double bonds. However, the very weak basicity of water under the conditions of reaction makes this unlikely, and the steep acidity dependences of the reactions (e.g., m =-1.65) is... 

Fig. 3.44 Approximate ranges of proton chemical shifts (R = H or alkyl Y = SR, — NR2 X = OR, — NHCO-R, — 0 C0 R, halogen). Data reproduced from L. M. Jackman and S. Stemhell (1969). Applications of Nuclear Magnetic Resonance in Organic Chemistry. 2nd edn. London Pergamon Press, p. 161.

F nuclear magnetic resonance data there is basically one resonance, split into a doublet Jp. = 585 c.p.s. S (from external trifluoroacetic acid reference) = — 44 p.p.m. (The checkers report 579 and —44.2, respectively.) Further splitting is due to coupling between fluorine atoms and protons of the alkyl groups. 

Nitrothiazole, 576 preparation of, 577 reduction of, 577 ring opening reaction, 577 Nitrothiazoles, chemical shift, proton, 68 coupling constants in EPR, 84 ionization potential, 5 2 reduction of, 381 ultraviolet absorption, 48 Nuclear magnetic resonance, 66 of alkyl thiazoles, 342 of aryl thiazoles, 342 correlation with theoretical calculations, 70... 

Betso, J.E., Carreon, R.E. and Miner, V.M. (1991) The use of proton nuclear magnetic resonance spectrometry ( H NMR) for monitoring the reaction of epoxides with butylamine and predictive capabilities of the relative alkylation index (RAI) for skin sensitization by epoxides. Toxicol. Appl. Pharm., 108, 483—488. 

Steinstrasser et al. reported the synthesis of a series of p-alkyl-p -alkoxy- and p-alkyl-p -acyloxyazoxybenzenes that were prepared by oxidation of the unsymmetrically substituted azo compounds. One member of this series, (2), exhibited nematic behavior in the range 16-76 C. Nuclear magnetic resonance spectroscopy revealed that these materials were not single compounds but instead consisted of mixtures of two azoxy isomers. The protons of the methoxy group in each isomer showed two different signals. 

Table 14. Nuclear magnetic resonance bands of alkyl groups in amines (Groups containing the relevant protons are indicated by ). 

Nilsson, P.-G., Wennerstrom, H., and Lindman, B. 1983 Stmctuie of micellar soln-tions of nonionic surfactants. Nuclear magnetic resonance self-diffusion and proton relaxation studies of poly (ethylene oxide) alkyl ethers, J. Phys. Chem. 87 1377-1385. 

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