Fragmentation stepwise

Five-membered ring systems are also formed on transfer of single-skeletona-tom fragments, usually in a stepwise process CR2 from diazo alkanes [28], NH from azourude (hydrazoic acid) [134], O from peroxy acids [/ii], S from phos-... 

The fragmentation can be concerted or stepwise. The concerted mechanism is restricted to molecular geometry that is appropriate for continuous overlap of the participating... 

Fig. 14 Potential energy profile for stepwise and concerted mechanisms with (solid lines) and without (dotted lines) an attractive interaction between the caged fragments in the product cluster. The case of the reduction of a neutral substrate is represented. It can be transposed for reductions of a positively charged substrate or for oxidations of neutral or negatively charged substrates.

Figure 7.8 Activation of clot formation by endotoxin. The presence of endotoxin causes stepwise, sequential activation of various clotting factors present naturally within the amoebocytes of the American horseshoe crab. The net result is the generation of the polypeptide fragment coagulin, which polymerizes, thus forming a gel or clot...

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