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Updated: Aug 15, 2026

Continuous Flow Chemistry: Reaction of Diphenyldiazomethane with p-Nitrobenzoic Acid
Published on: November 15, 2017
Density functional theory computational study on the thermal cycloreversion of
Wojciech Czardybon1, John Warkentin, Nick Henry Werstiuk
1Department of Chemistry, McMaster University, Hamilton, ON, Canada L8S 4M1.
Abstract:
Three [3 + 2] cycloreversions of 2-acetoxy-2-methoxy-5,5-dimethyl-Delta(3)-1,3,4-oxadiazolines were examined by computation at the density functional level of theory. The lowest activation energies are those for cycloreversion to 2-diazopropane and acetic methylcarbonic anhydride and for cycloreversion to N(2) and a carbonyl ylide. Those are the reactions that are observed experimentally. A third cycloreversion, to acetoxy(methoxy)diazomethane and acetone, has a much larger barrier. The carbonyl ylide is a real intermediate, but it fragments easily to acetone and acetoxy(methoxy)carbene. The lifetime of the ylide may be so short, in some cases, as to blur the distinction between a two-step cycloreversion of the oxadiazoline and a concerted process that generates three fragments in one step.
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