Deut eration

Hussey et al. interpret the relative competitive rates on platinum catalysts as measures of competitive rates of alkene adsorption. They note that very little isomerization accompanies hydrogenation, which suggests that desorption of the alkene is slow. A rapid interconversion of adsorbed alkene and the alkyl intermediate of the Horiuti-Polanyi mechanism is indicated by the distribution of deuterium in the deut-erated alkane formed when D2 is used in place of H2 yet little or no deuterium appears in the recovered alkene. ... 

LC/NMR experiments require the use of deut-erated mobile phases to minimize background signals (especially from water in H spectra). 

Figure 3.2.17 Effect of deut-eration on the solid state proton spectrum of pentachloro-phenol with 4-methylpyridine. Reproduced with permission from Ref. [44],...

The simplest case conceptually is when kcat is fully rate limited by chemistry and, therefore, probes of chemistry (such as isotope effects) are revealed in kcat-This limit is realized in recombinant soybean lipoxygenase-1 (SLO) and its mutants, greatly facilitating the study of C-H cleavage in this enzyme [7-9]. The study of chemistry in this case simply requires that kcat can be faithfully measured as a function of external perturbation, such as temperature, pH, or substrate deut-eration. It is essential to show substrate saturation ([S] Km) under all conditions, however, and this requirement can present experimental limitations. The principal probe for tunneling in enzymes in this kinetic case is the magnitude and temperature dependence of noncompetitive kinetic isotope effects, kcat = kcat(H)/fecat(o)-... 

The standard detector in routine FT-IR instruments is the pyroelectric DTGS (deut-erated triglycine sulfate) detector, whose response in the MIR range is wavelength independent. The detector operates at ambient temperature and shows good linearity across the whole transmittance scale. The DTGS detector responds to signal frequencies of up to several thousand Hz, hence the time needed to scan one spectrum at a resolution of 4 cm is of the order of 1 s. 

Fig. 13.2 The forward recoiled spectrum of H and from He ions incident with energy 2.18 MeVon a thin deut-erated polyimid film (a) and with energy 2.75 MeV on D-plasma treated LiNbOj (b). 

Figure 4.8. Equilibrium interfacial widths between high-relative-molecular-mass deut-erated and normal polystyrene as a function of the temperature in a region of the phase diagram of partial miscibility. The interfacial profiles were analysed by nuclear reaction analysis and the solid line is the prediction of equation (4.2.10). After...

The complexity of natural membranes generally precludes the observation of specific bands due to well-known vibrations. In such cases the use of deut-erated lipids provides a useful means of circumventing these problems. This is exemplified by Fig. 9.10, where the temperature profiles of the CD2 symmetric stretching band in the spectra of live Acholeplasma laidlawii (grown on perdeuterated myristic acid) and... 

Solid-state NMR studies of biomembranes have been carried out with deuterium or phosphorus-31. H-NMR spectroscopy has been of great help in the study of the physical state of the hydrocarbon chain region of phospholipid bilayers (Smith, 1979 Chan et al, 1981). This requires the synthesis of specifically deut-erated phospholipids. These lipids are then dispersed... 

To favor a clean preparation of the nucleophile, we adopted a stronger base to perform the lithiation of 1,3-dithiane at a lower temperature. Accordingly, an experiment in which 1,3-dithiane was treated with i-BuLi in THF at -78°C was conducted. To ascertain the efficient deprotonation of the substrate, an aliquot of the reaction was quenched with D2O and completely deut-erated 1,3-dithiane was observed by H NMR spectroscopy after 10 min of mixing. Prepared this way, this nucleophile reacted smoothly with 7 yielding 12 much more efficiently (75%) after quenching with MeOH (Scheme 8, conditions B). Interestingly, the process appeared to exclusively follow a pattern of 1,4-addition, since 1,2-adducts were not observed by H NMR spectroscopy of the crude of the reaction. ... 

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