Controlled photocatalytic hydrolysis of nitriles to amides by mesoporous MnO2 nanoparticles fabricated by mixed surfactant mediated approach

- Synthesis of mesoporous MnO2 by using mixture of cationic and anionic surfactants with variable pore volume.
- The cat-anionic surfactant yields 5 times higher surface area (195.32 m2/g) than their corresponding individual form (CTAB 29 m2/g and SDS 36 m2/g).
- Synergic effect, low critical aggregation concentration of cat-anionic surfactant is endorsed for its high surface area.
- The mesoporous MnO2 as a novel catalyst for the hydrolysis of nitriles to amides.
- Higher yield (90%) in basic reaction medium compare to neutral medium (70%).

The solid-phase MnO2 nanoparticles fabricated by surfactant template method were exploited as the photocatalyst for the effective one-step synthesis of amides. Cationic or anionic surfactants and their combinations were used as porous templates to obtain the mesoporous MnO2 nanoparticles with variable pore volume (0.23-1.95 cm3/g). The morphological and structural observation of the material confirms the uniform facet structure (37.68 nm) of MnO2 nanoparticles. The surface elemental state was confirmed by XPS analysis confirming Mn 2p3/2 (642.5 eV) and Mn2p1/2 (654.7 eV) spin states, that are common for the tetravalent Mn ions. Presence of surfactant as stabilizer was also witnessed with a strong peak of C 1s (283-286 eV). The textural parameters obtained from XRD and Raman analysis depicted the β-phase and rutile type framework of MnO2. The selective conversion of nitriles to amides was studied without any acid by products under visible light irradiation in the basic/neutral medium. Amides were obtained from various substrates (nitriles) with excellent yields (70-90%).

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