Chemical Synthesis Single-component

The component RNA chains may alternatively be generated by in vitro transcription, in which case the shorter helices may be replaced with short stem-loops—indeed, there is no reason why the individual species cannot be made as a single RNA transcript. The main drawback to this approach is that nonnatural nucleotides cannot be introduced, and for this chemical synthesis is essential. 

Single-stage chemical synthesis by annealing stoichiometric mixtures of individual oxides is often used for preparing ceramics. When highly volatile oxides are used (thallium- and mercury-based HTSCs), the process is carried out in hermetically sealed ampoules with an excess of the volatile component. The heating temperatures usually exceed those of the crystallization and can take up to lOh or more. 

M.M.El-Halwagi, V.Manousiothakis, Automatic Synthesis of Mass Exchange Networks with Single Component Targets, Chemical Engineering Science, No.9 (1990) 2813. 

Unfortunately, the simple picture shown in Fig. 1 is only valid for pure CO2 and the phase behavior of mixtures is much more compHcated [4]. It is not sufficient to adjust temperature and pressure above the critical values of pure CO2 to assure a single-phase reaction mixture in the presence of other components The phase behavior of mixtures is a function of composition and the actual phase diagram can vary considerably even for seemingly similar components. Reaction solutions are mixtures of at least three (substrate, product and solvent) but in most cases more components of variable composition and a full description of the phase behavior is not practical in most cases. Fortunately, most exploratory studies towards chemical synthesis are carried out under fairly dilute conditions (substrate concentrations < 10 mol %), and the problem can therefore often be simplified to getting an idea of the solubiUty of the various components in SCCO2. 

Chemical synthesis from stable components/ Single crystal in ruthenocene... 

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