Carbon atoms generation techniques

This technique is based in the fact that when cellulose is oxidized by ceric salts such as ceric ammonium nitrate Ce(NH4)2(N03)6 free radicals capable of initiating vinyl polymerization are formed on the cellulose. However, the possibility remains that the radical formed is an oxygen radical or that the radical is formed on the C-2 or C-3 instead of the C-6 carbon atom. Another mechanism, proposed by Livshits and coworkers [13], involves the oxidation of the glycolic portion of the an-hydroglucose unit. Several workers [14,15], however, have found evidence for the formation of some homopolymer. In the ceric ion method free radicals are first generated and are then capable of initiating the grafting process [16-18]. 

Nonflame atom reservoirs have been developed for specific atomic spectrometric techniques. Electrothermal atomizers (carbon rods, carbon furnaces, or tantalum ribbons) have been developed for AAS or AFS since they require the generation of ground state atoms, whereas... 

First, various advanced multipulse techniques have been developed since the mid-1970s, and nowadays are routinely applicable on spectrometers of the latest generation. Particularly innovative and ingenious among these methods are two-dimensional NMR techniques (506-508) and double quantum transition measurements (INADEQUATE) (507-509), which allow one to determine connectivities between carbon atoms within a molecule. 

The Ireland variant of the Claisen rearrangement relies on the generation of the vinyl moiety of the double unsaturated system by enolization of an ester. The principle of this technique is given in Scheme 11.42 and it allows the transformation of allylic alcohol 177 into 180 via ester 178 and the ketene acetal 179. Application of this chemistry to the construction of the chiral quaternary carbon atom of the zaragozic acid core is shown in Scheme 11.47 [142]. Additional examples of this rearrangement are found in Section 11.5.2.2. 

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