Abstract: | Wet molybdate sulfuric acid (= dioxo[bis(sulfato‐κO)]molybdenum; MSA), a new solid acid, can be used in combination with sodium nitrite (NaNO2) to transform a variety of secondary amines to the corresponding N‐nitroso compounds under mild, heterogeneous conditions (Table). The process has several advantages: the reagents are inexpensive and non‐hazardous, the reaction is clean, fast, and high‐yielding, and MSA can be readily removed by filtration and re‐used (after treatment with HCl) without loss of activity. Further, only N‐nitrosation was observed, but no C‐ or O‐nitrosation. |