Cyclic graphical method

For the structural analysis of cyclic fatty acid derivatives (polymerized drying oils, copolymerization products of fatty oils with various hydrocarbons), in principle the same graphical methods can be developed as have been described for the investigation of hydrocarbon mixtures. However, the construction of useful graphical representations is hampered by the fact that reliable data on physical constants are restricted to the normal saturated fatty acids and their methyl and ethyl esters the synthesis of pure unsaturated fatty acids is already extremely difficult, to say nothing of more complicated cyclic or branched compounds. 

Fig. 7L Commonly used graphical method of extrapolating the baseline, to measure the peak current densities in cyclic voltammetry.

It is well known how great a r6le graphical representation, e.g. of cyclic processes, has played in the development of thermodynamics. This is not accidental, but lies in the essence of the thermodynamic method of treatment. For no other assumption is here made as to the nature of the functions involved, e.g. as to the manner in which vapour pressure varies with temperature, than that the functions employed are continuous and continuously variable. Graphical representation is thus more general than, for example, development according to whole powers of absolute temperature, which is equally available in the thermodynamical treatment of such functions. We shall therefore make use of graphical representation to illustrate the above hypothesis. 

One example of methods developed to work around software limitations involved the requirement for a menu of cyclic nuclei as an aid in constructing structures. A partial solution to the slowness of the Graphics Tool Kit was to take advantage of the capacity for multiple screens (with only one visible at a time). 

Cyclic voltammetry (CV) is useful to probe the electronic effect of pterin and quinoxaline groups on the Mo reduction potential and this method was applied to a series of I MoO(dithiolene) complexes. The results are graphically summarized in Figure 2.16. Within a series of T MoO(dithio-lenes), it is clear that pterin (or quinoxaline) substitution causes a significant shift in the Mo redox potential to more positive values compared to simpler dithiolenes like benzenedithiolate (bdt) or ethanedithiolate (edt). This conclusion seems to contradict the results from EPR and MCD studies of Tp MoO(pterin-dithiolene vs. T MoO(bdt), which, as noted above, failed to reveal any differences among the dithiolene complexes. 

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