Coupling to Carbon

The F coupling to carbon can vary considerably for the carbon directly substituted (ipso), depending on its substitution environment, but it is always very large, 250 Hz or larger. F coupling to the ortho-position is usually about 20-26 Hz, to the raeta-position about 8-10 Hz, and to the para-position about 4 Hz. 

Energy Conservation by Substrate-Level Phosphorylation and Its Coupling to Carbon Dioxide Fixation... 

The major coupling to carbon that can be detected in any organic molecule is the coupling. The presence of this coupling can complicate the... 

The magnitude of one-bond fluorine coupling to carbon in a simple fluorohydrocarbon can vary from 151 to 280 Hz, depending again on whether one, two, or three fluorines are bound to the carbon. Scheme 2.22 demonstrates these trends in the fluoromethanes and fluoroalkanes. The scheme also includes mention of the one-bond H-C... 

The F coupling to carbon can vary considerably for the carbon directly substituted (ipso), depending on its substitution environment,... 

Laccases from different sources have been coupled to carbon material and recently also to modified gold electrodes [64,67,105,257,258]. For example, laccase was coupled with carbodiimide to a SAM of mercaptopropionic acid gold. A midpoint potential of the immobilized laccase of 410 mV vs. NHE was observed consistent with the potential for the Tl site [67]. DET is most obvious... 

Now that the analysis has been completed it can be seen what the function of various elements in the pulse sequence is. The first pulse and delay generate magnetization on proton which is anti-phase with respect to the coupling to carbon-13. The carbon-13 90° pulse turns this into multiple quantum coherence. This forms a filter through which magnetization not bound to carbon-13 cannot pass and it is the basis of discrimination between signals from protons bound and not bound to carbon-13. The second carbon-13 pulse returns the multiple quantum coherence to observable anti-phase magnetization on proton. Finally, the second delay A turns the anti-phase state into an in-phase state. The centrally placed proton 180° pulse refocuses the proton shift evolution for both the delays A and tv... 

However, in contrast to these sequences, in HETCOR the proton shift is in Fx and the carbon-13 shift is in F2. In the early days of two-dimensional NMR this was a popular sequence for shift correlation as it is less demanding of the spectrometer there are no strong signals from protons not coupled to carbon-13 to suppress. 

The above initiatives are illustrative of what may be expected in the near future where opportunities exist and the economics are right. Projects such as these are likely to be among the first major manifestations of hydrogen energy coupled to carbon dioxide sequestration. 

Other test solutions (e.g.. Solution B) are also available to represent mild environments. Test temperature is normally 77°F (25°C), since tests have shown this temperature to be in the most severe range for hydrogen embrittlement effects. Test durations of 21-30 days are consistent with the observed rapid failure of susceptible materials. In testing CRA, the test specimen is commonly coupled to carbon steel to provide a severe hydrogen absorption condition. 

Fernandez-Baldo, M.A., Messina, G.A., Sanz, M.I. and Raba, J. (2010) Microfluidic immunosensor with micromagnetic beads coupled to carbon-based screen-printed electrodes (SPCEs) for determination of Botrytis cinerea in tissue of fruits. J. Agric. Food Chem., 5S, 11201-11206. 

TABLE 6. Primary kinetic isotope effects for the oxidative methane coupling to carbon oxides and C2 hydrocarbons over a NaOH/CaO catalyst. 

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