Chemical pathways, decomposition

The chemical pathways for the decomposition of H202 appear to play a minor role in the overall decay processes. Direct-sunlight photolysis is not important in natural waters (I). The effect of H202 on metal speciation, and therefore on H202 decomposition, has been demonstrated in marine systems but not in lakes. Additional studies are required to better understand these processes in lake waters. 

Tarasevich et al. [417, 420] employed the rotating disk electrode with an oxide disk electrode to study the electrochemical reactions of peroxide in conjunction with a gasometric method, by means of which the rate of the peroxide decomposition via a purely chemical pathway [eqn. (72)] could be followed independently. The authors compared the rate of gas evolution and peroxide electroreduction and oxidation, respectively, as a function of electrode potential and attributed the difference of these rates to chemical... 

The principal role of EGD and EGA is mainly as complementary techniques for other thermal analysis data. Samples are studied by TG, DTA, DSC and other thermal analysis techniques first and if the decomposition reactions are unknown, EGA is usually called on to determine the composition of the reaction products. With these known, as well as the other physicochemical data, the chemical pathway of the reaction can usually be elucidated. As mentioned earlier, the EGD-EGA data can often be obtained simultaneously with the other thermal data using multiple techniques with a substantial saving of time and effort. 

Both biochemical (i.e., in vivo) and chemical (i.e., in vitro) pathways for the decomposition of proteins (polypeptides) to amino acids and for the formation of peptides (proteins) from amino acids are known. Having shown some biosynthetic and synthetic pathways to some amino acids in Section B, this part begins with obtaining the same amino acids by the decomposition of the polypeptides (proteins) by biochemical and chemical pathways and concludes with using those amino acids to produce the peptides and polypeptides. 

Experimental data obtained from isothermal mass loss experiments, adiabatic and isothermal heat flow calorimetry can be used for kinetic modeling and the prediction of life and storage time of energetic materials under different environmental conditions. However, the models, that such predictions are based on, are often very complex and thus not a result of simple extrapolation procedures. For example, different chemical pathways and mechanisms of decomposition reactions as well as aspects of autocatalysis must be considered. ... 

Figure 21.11 The hypothetical chemical pathways for thermal decomposition of cellulose, lignin and hemicellulose. Adapted from Refs. [13,15,96,97,100].

---