Deuteration and fluorination

Figure 1, exposures of these durations may not ensure the uptake of an equilibrium amount of the guest. Uptake data for the deuterated and fluorinated samples employed in the NMR studies are shown in Tables I and II, respectively. Uptake is reported on both a molar (millimoles/gram) and volume (cubic centimeters/gram) basis because such numbers furnish complementary information about the system. The magnitudes of uptake for the deuterated molecules are very similar to those of their protonated analogues. 

Other important hallmarks in the history of IFP include IFP systems with dopants. Ref [15] reports the first use of deuterated and fluorinated MMA derivatives to produce GRINS of lower signal loss. Additionally, Refs. [24], [25] and [50] report the use of metal-doped plastic optical fibers (POFs) to increase attenuation. In addition. Ref [26] reports the use of a two-step IFP process to... 

As the main part of the GI-POFs is composed of PMMA, the loss spectrum is nearly the same as that of SI-POF with PMMA core. The attenuation loss of GI-POF with the gel-copolymerization technique at 652 nm is 134 dB/kra Koike s group, Keio University, has used an interfacial-gel-polymerization technique where bro-mobenzene or other chemicals are used as unreactive components instead of vinyl phenyl acetate or vinyl benzoate in the interfacial-gel-copolymerization method. An attenuation loss of 90 dB/km at 572 nm was obtained. MMA-dg was also used as a monomer instead of MMA, and the deuterated polymer core GI-POF was successfully fabricated. Fluorinated acrylate monomer was also used to fabricate moisture-resistant GI-POF. Attenuation losses of 113 and 155 dB/km at 780 nm wavelength were obtained for deuterated and fluorinated POFs, respectively. These POFs are Oj pected to serve as the signal transmission medium with high information capacities in local area network systems. However, this GI-POF has not been commercially available so far because of the fabrication difficulty of the technique in a mass production level with reasonable attenuation loss and fabrication cost. 

Ultimate loss will be obtained by using a polymer with fluorine and deuterium in its structure, where the intrinsic loss of the polymer (i.e., molecular vibrational loss and Rayleigh scattering loss) will be reduced to an ideal level. Table 7.7 shows the loss factors and the loss limit estimate for deuterated and fluorinated alkyl methacrylate polymer, trideutero-hexafluorobutyl, pentadeutero-methacrylate polymer. This polymer will have a refractive index almost the same as the fluorinated methacrylate polymers. As shown in this table, the lowest loss around 6 dB/km will be attained if a POF using this polymer as a core is developed. As discussed, the value of 6 dB/km is the limit of the polymer transparency in the visible wavelengths that has been obtained to date. 

When the evolution spectra is measured during illumination for deuter-ated fluorinated amorphous silicon, the deuterium evolution rate peaks are shifted to lower temperatures compared to measurements in the dark (Weil et al., 1988). Both the low temperature and high temperature peak positions shift = 20-30°C during illumination with 100mW/cm2 heat-... 

For the formation of indoles 2 and 3 we assumed that amines 1 first reacted with fBuLi at -110°C to give N-(2-lithioallyl)amines 4, through halogen-metal exchange 23 this was confirmed by deuteration and isolation of the deuteriated amine 5 a (Scheme 2). Intermediate 4, which is stable for several hours at —110 °C, probably undergoes proton-abstraction ortho to the fluorine atom by the additional equivalents of fBuLi when the temperature is raised to — 40 °C giving the intermediate 6. The subsequent elimination of LiF produces a benzyne intermediate 7, which is efficiently... 

Shifts due to either a- or /1-deuterium substitution are also quite significant, usually leading to well-resolved fluorine signals for the deuterated and undeuterated species, which can be useful in characterization of deuterium-labeled fluorinated compounds. An example of the a-effect is shown in Figure 2.20, which depicts the fluorine NMR spectrum of F-CH2CH2CH2CH2CH2CD2-F, a molecule that has magnetically equivalent fluorines, except for the presence of the deuteriums. The observed isotope effect on the chemical shift is a 1.31 ppm upfield shift (or 0.65 ppm upheld per deuterium). This effect is an a-deuterium isotope effect, in this case a two-bond effect on fluorine. 

Samples of dried Illinois No. 6 and Wyodak coals were exposed to several deuterated or fluorinated molecular types. Exposure times for the deuterated samples were on the order of several months, while time scales of several weeks were employed for fluorinated samples. In light of the pyridine results shown in... 

Neutron and X-ray scattering techniques use shorter wavelengths and require deuterated polymers for neutron and fluorinated polymers for X-ray scattering. The information obtained with these techniques is on the molecular scale and can reveal the arrangement of side groups, crystalline structure, and conformation of molecules. 

Deuteration or fluorination will be needed even for NLO waveguides. It is necessary to fabricate channel waveguides with low loss to make NLO polymer devices such as phase modulators that can be driven with low input power. To this end, a deuterated 3RDCVXY polymer was developed for device application its chemical structure is shown in Figure 3.12(b) [48]. This polymer is composed of 3RDCVXY-attached PMMA and a transparent PMMA where all the hydrogen atoms are deuterated. 

Scheme 2.16 provides further insight regarding both a- and 3-deuterium isotope effects on fluorine chemical shifts with a series of deuterated chloro, fluoroethylenes.16... 

The second group of recently developed ionic liquids is often referred to as task specific ionic liquids in the literature [15]. These ionic liquids are designed and optimised for the best performance in high-value-added applications. Functionalised [16], fluorinated [17], deuterated [18] and chiral ionic liquids [19] are expected to play a future role as special solvents for sophisticated synthetic applications, analytical tools (stationary or mobile phases for chromatography, matrixes for MS etc.), sensors and special electrolytes. 

In recent times, the development of new ionic liquids has made great progress. Important developments include a range of new halogen-free ionic liquids (e.g., benzenesulfonates [13], toluenesulfonates, alkylsulfates [14], hydro-gensulfate [15, 16], dicyanamides [17], thiocyanates [18], etc.), as well as functionalized (task-specific) [19-23], fluorinated [24], deuterated [25] and chiral ionic liquids [26-30]. 

Triazine has D3h symmetry. The IR spectrum and assignment of the fundamental modes of 1,3,5-triazine and its fully deuterated analogue have been reported (61SA155), and the data are summarized in Table 7. Three of these frequencies persist in a variety of symmetrical 1,3,5-triazines although the band at ca. 675 cm- is often absent. Perfluoroph-enyl and some partially fluorinated alkoxy derivatives do not contain the band at 675 cm-1 either (65SA663). 

The importance of hyperconjugation in anionic fluorinated species has been questioned, 3,74 with the proposal that the effects of fluorination can be rationalized by involving polarization effects alone. A study of the relative rates of the deuteration of tris(trifluoromethyl)methane (1), l//-undecafluorobicyclo[2.2.1]heptane (2), and l//-tridecafluorobicyclo[2.2.2]octane (3) clearly illustrates that deuteration occurs much more rapidly with tris(trifluoromethyl)melhane... 

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