Helium compounds synthesis

Pare compound 179 can be i solated by gas chromatography (100 °C, phenyl silicon oil type 0 S 26.14 (PE) on Sterchamol, 6 m column, 1 atm helium). By a study of the nmr, i.r. and mass spectra, compound 179 is identified, and compared with that produced by a different synthesis S4 The yield was 30%. As the following possibilities for a hydrosilylation exist, this low yield is not surprising ... 

The mechanism of spontaneous fullerene formation has been the subject of much debate and speculation [90]. One of the major advances in this area comes from gas-phase ion chromatography, which allows to separate charged carbon clusters of specific mass into families of isomers based on their mobilities through helium-filled drift tubes [91-93]. These families (e.g., monocyclic rings, bi- and tricyclic compounds, fullerenes) are identified by comparing the observed mobilities with those calculated from optimized semiempirical equilibrium geometries [92], which are aceurate enough for this purpose. Such studies lead to product distributions of the cations C as a function of n [90-93] and allow the tentative formulation of a detailed mechanism for fullerene synthesis [93]. 

In the inerts-containing loop, the synthesis gas will normally contain certain concentrations of inerts , i.e. compounds that are not consumed by the ammonia synthesis reaction and that do not interfere with the catalyst performance. The inerts are typically CH4, Ar, and traces of other rare gases. In special cases, significant amounts of helium may be present originating from He-containing natural gas. In all inerts-containing loops, it is necessary to purge a gas stream from the synthesis loop in order to prevent excessive build-up of the inerts. 

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