Abdul S. Mahomed

A Comparative Study of NiO/Al2O3 Catalysts Prepared by Different Combustion Techniques for Octanal Hydrogenation

Four catalysts with the molar ratio of Ni:Al (1:2) were prepared by solution combustion synthesis (SCS) and sol–gel auto combustion synthesis (SGCS) techniques. Two fuels [urea and oxalyldihydrazide (ODH)] with distinct oxygen/carbon (O/C) ratios and chelating capability were chosen for investigating the effect of the fuel on the syntheses of these catalysts. All catalysts were fully characterized by PXRD, ICP-OES, TEM, H2-TPR, pyridine IR, H2-chemisorption and nitrogen physisorption. Pure NiO/Al2O3 (free of spinel) was achieved by application of SGCS and urea as a fuel. Thus, catalysts prepared by urea as a fuel showed high activity for hydrogenation of octanal even under moderate conditions (110 °C). Optimisation showed that the catalyst prepared via SCS using ODH as a fuel gave the best comparative aldehyde conversion and alcohol selectivity (98 and 97 %, respectively) albeit at a higher temperature of 150 °C. The catalysts with NiAl2O4 as the dominant phase presented the lowest acidity, likely due to the non-availability of acidic sites of alumina via formation of the spinel, thus making these catalysts highly selective and also offering a slow release of fresh Ni sites.Graphical Abstract

Efficient and expeditious chemoselective BOC protection of amines in catalyst and solvent-free media

A green and eco-friendly route for the almost quantitative BOC protection of a large variety of aliphatic and aromatic amines, amino acids, and amino alcohols is reported in catalyst and solvent-free media under mild reaction conditions. The products were confirmed by 1H, 13C NMR, IR spectroscopy, and in some cases, elemental analysis. This protocol does not require any water quenches, solvent separations, and purification steps, such as recrystallization and column chromatography.