Diazo compounds mechanistic studies using

Acid solutions, strong, spectroscopic observation of alkylcarbonium ions in, 4, 305 Acids, reactions of aliphatic diazo compounds with, 5, 331 Activation, entropies of, and mechanisms of reactions in solution, 1, 1 Activation, heat capacities of, and their uses in mechanistic studies, 5, 121 Activation, volumes of, use for determining reaction mechanisms, 2, 93 Aliphatic diazo compounds, reactions with acids, 5, 331... 

A study of this reaction is an appropriate example of the usefulness of spectroscopic method in mechanistic studies. H NMR studies on the reaction between the catalyst and the diazo compound show complexes 2.1 and 2.2 of Fig. 2.11 to be present in the reaction mixture. Complex 2.1 is stable at -40°C, and on warming to 0°C it undergoes conversion to 2.2. This reaction i.e., conversion of 2.1 to 2.2 is one of the several pieces of evidence for the intermediacy of the carbene complex 2.3. In other words, in situ NMR data, in conjunction with other evidences, indicate the involvement of 2.3 as a catalytic intermediate. 

Azido compounds are versatile molecules. They are used extensively in both organic reactions and chemical biology. All azides are potentially explosive and must be handled with care. Azides, which have been known for over 100 years, are the most widely used precursors of nitrenes. like diazo compounds, they possess a linear 1,3-dipolar stracture and are easily prepared, often by introduction of the azide (Nj ) ion from inorganic salts such as sodium azide. The thermal stability of azides is critically dependent on the substituent on nitrogen. Most azides decompose thermally in the range 100-200 °C to give nitrenes. Azides are also readily decomposed photochemically, and this is often the method of choice, particularly for mechanistic studies. Like diazo compounds, the decomposition of... 

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