A Method for Heteroaromatic Nitration Demonstrating Remarkable Thermal Stability

Herein we report a novel heterogeneous pyrrole nitration that can be run on a large scale in batch mode. Activation of sodium nitrate by SO(3)(-)pyridine in acetonitrile leads to the formation of an insoluble nitronium sulfate intermediate that effects a high-yielding reaction. These conditions allow for a safer and practical nitration reaction with unique thermal stability that appears to be a function of the low solubility of the proposed nitronium ion carrier. Mechanistic insights gained from reaction kinetics as well as H-1 and N-15 NMR studies are presented to support this analysis.