Precursors nitrogen

FIG. II. Nominal hydrogen fraction in the deposition atmosphere against the nitrogen precursor partial pressure. (Reproduced from [54].)... 

One may observe that in plasma deposition of a-C(N) H films, as the nitrogen precursor gas partial pressure is increased, the bombardment of the film surface by N2 ions will certainly occur. As this situation was shown to generate carbon erosion, and evolution of CN molecules, there is no reason to believe that CN fragments from the plasma would survive the bombardment, resting attached to the film. 

Li, D., Haneda, H., Hishita, S., and Ohashi, N. (2005) Visible-light-driven nitrogen-doped Ti02 photocatalysts effect of nitrogen precursors on their photocatalysis for decomposition of gas-phase organic pollutants. Materials Science and Engineering B, 117 (1), 67—75. 

Two mechanisms are possible for the Cu-mediated aziridination using PhI=NTs as a nitrogen source (i) aziridination via Cu-nitrenoid species (L Cu=NTs) and (ii) aziridination via a L (Cu—PhI=NTs) adduct, in which the Cu complex functions as a Lewis acid catalyst. Jacobsen et al. demonstrated that the enantioselectivity of the aziridination using (48) as the chiral auxiliary did not depend on the nitrogen precursors.1 5 This supports the intermediacy of the Cu-nitrenoid... 

The elusive diazoalkenes 6 and 14 are unlikely to react with methanol as their basicity should be comparable to that of diphenyldiazomethane. However, since the formation of diazonium ions cannot be rigorously excluded, the protonation of vinylcarbenes was to be confirmed with non-nitrogenous precursors. Vinyl-carbenes are presumedly involved in photorearrangements of cyclopropenes.21 In an attempt to trap the intermediate(s), 30 was irradiated in methanol. The ethers 32 and 35 (60 40) were obtained,22 pointing to the intervention of the al-lylic cation 34 (Scheme 10). Protonation of the vinylcarbene 31 is a likely route to 34. However, 34 could also arise from protonation of photoexcited 30, by way of the cyclopropyl cation 33. The photosolvolysis of alkenes is a well-known reaction which proceeds according to Markovnikov s rule and is, occasionally, associated with skeletal reorganizations.23 Therefore, cyclopropenes are not the substrates of choice for demonstrating the protonation of vinylcarbenes. 

Li J, Blatchley ER III (2007) Volatile disinfection byproduct formation resulting from chlorination of organic - Nitrogen precursors in swimming pools. Environ Sci Technol 41 (19) 6732-6739... 

Most carbenes are relatively easily generated by photolysis of nitrogeneous precursors such as diazo compoundsor diazirines. The reaction is clean, as nitrogen is the only byproduct and it is also very efficient as nitrogen evolution is a highly exothermic reaction. Therefore carbenes can be easily generated even under very inert conditions, such as in a noble gas matrix at very low temperatures. 

More effective nanoporous carbons have been obtained by the template technique. A nitrogenated precursor is introduced in a nanoporous scaffold and subsequently pyrolyzed then the nitrogen-enriched replica is obtained by etching the host with hydrofluoric acid. The first materials of this... 

Church et al. (8), in presenting additional information derived from WATOX research, report on the ocean s influence on precipitation from storms that leave the North American continent and transit over the western Atlantic. They pay particular attention to this oceanic influence on the sulfur and nitrogen precursors of acid rains. They further report that, although sea salt contributes over half (by weight) of the salt in precipitation at the coast and over three quarters of the salt in precipitation at Bermuda, most sulfate (90% at the coast and 50% at Bermuda) is in excess of sea salt. 

Since Galloway, Likens and Hawley ( ) have found that precipitation on Bermuda has significantly more excess SO , NO "", and H+ than more remote marine areas, Church and his colleagues ( ) have attributed these components to the long-range transport of sulfur and nitrogen precursors in the marine troposphere with the sulfuric-acid component dominating. 

For a given deposit material there usually exist several possible reactions, of which all may be thermodynamically feasible. The reaction with the most negative value should dominate because it leads to the most stable reaction products. For example, in order to co-deposit Si3N4 and TiN, two systems of gaseous species are available. The first is TiCl4-SiH4-N2-H2, where N2 is used as nitrogen precursor. The chemical reactions are expressed as... 

The major emphasis in this chapter related to excretion is on ammonia and urea, particularly on the control of the latter as the normal excretion product. There are two major nitrogenous precursors of urea ammonia and aspartate. Before delving into the mechanism and control of urea synthesis, it would be wise to look at the different ways that these precursors can arise and the important tissues concerned with urea synthesis. In people, the predominant synthesis of urea occurs in the liver, with very small amounts of urea formed from arginine in other tissues. The complete synthesis of urea, from amino acids and other nitrogen sources, occurs via a process known as the urea cycle. 

Onr diet also must contain the compounds we cannot synthesize, as well as all the basic building blocks for compounds we do synthesize in our biosynthetic pathways. For example we have dietary requirements for some amino acids, but we can synthesize other amino acids from our fuels and a dietary nitrogen precursor. The compounds required in our diet for biosynthetic pathways include certain amino acids, vitamins, and essential fatty acids. 

Proline and ornithine would also appear to be the most probable amino acid precursors of 1-hyoscyamine, and, as such, the source of the nitrogen of the tropane nucleus. The biosynthesis of the tropic acid half of the molecule has not yet received attention. Such investigations as have been made up to the present have been based upon Robinson s (113) proposed tropinone synthesis from ornithine plus acetone, and have been principally concerned with the identification of the original nitrogenous precursor. 

With the non-nitrogenous precursor 32, a linear plot of 31/30 versus [TME] was obtained. The photochemistry of 32 is simple. The photochemistry of 19 we believe involves a Rearrangement in Excited State (RIES) mechanism via biradical 33. [38]... 

After the inefficiency of nitrogenous precursors of dimethylcarbene was understood, an alternative source of this carbene was sought. Igor Likhotvorik synthesized compound 34 which forms indane and dimethylcarbene upon photolysis. [39]... 

Carbenes are conveniently generated from nitrogenous precursors such as diazo compounds [23] or diazirines [24] upon irradiation or thermolysis, which takes place very cleanly and efficiently. Therefore, it is possible to generate carbenes even at very low temperature in rigid matrix once those precursors are prepared. This makes it very easy to assign and characterize the carbenes spectroscopically, which is a very important point since we will then have to assign only triplet states of carbenes and to estimate their stability. 

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