The Mechanisms of Base-Catalyzed Decomposition of Cyclopropanecarboxaldehyde p-Tosylhydrazone in Protic Solvents

Gas phase protonation of diazirines: a route to N-protonated diazomethanes

“…An early study by Wiberg 1 postulated N-protonation, which was subsequently revised in the light of more extensive data. [2][3][4] Conventionally, protonation occurs at the C atom of the diazoalkanes. Since their discovery in 1966, the diazirines, cyclic diazo compounds with three-membered rings, have been added to the ranks of the wellknown aliphatic diazo compounds.…”

“…The detectable intermediates in the cell are evidently either the protonated diazirines 3a-d or the N-protonated diazoalkanes 4a-d. Since the spectra gave only the masses of the protonated species, it is not possible to distinguish whether the protonated species appear in the closed (3) or open form (4).…”

“…attained after a reaction period of several hundred milliseconds to 1 s. The observed free energy changes [eqn. (3)] for DG° = 2RT in K (3) respective proton transfer equilibria and the selected GB values are summarized in Table 1. For the case of 1d, we adopted the threshold technique 8 instead of the equilibrium method because the amount of the conjugate acid ion formed in the cell was too small to be measured quantitatively.…”

Synthesis of vinyl halides and vinyl silanes via alkaline decomposition of 5,5-dialkyl-3-nitrosooxazolidinones

“…Further work From our experience to date apparently unsaturated carbonium ions (such as B) are involved in protic solvents whereas unsaturated carbenes (such as D) are involved in aprotic media. 12…”

Mechanistic and exploratory organic photochemistry. XLVI. Constrained 2,5-cyclohexadienone which cannot rearrange photochemically

“…Further work From our experience to date apparently unsaturated carbonium ions (such as B) are involved in protic solvents whereas unsaturated carbenes (such as D) are involved in aprotic media. 12 Mechanistic and Exploratory Organic Photochemistry. XLVI.1 A Constrained 2,5-CycIohexadienone Which Cannot Rearrange Photochemically Sir:…”