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Abstract: Use of highly monodispersed, easily recyclable and cheap nickel nanoparticles for oxidative coupling of aliphatic, aromatic, cyclic and heteroaromatic thiols to their corresponding disulfides has been reported. Ni-nanoparticles act as a green catalyst that can selectively catalyse oxidative coupling of thiols to disulfides without producing any over-oxidized products. The catalytic reaction occurred at room temperature with excellent yield under air atmosphere and high TON and TOF value could be achieved. Effect of solvent polarity and size distribution of the Ni-nanoparticles on the catalytic efficiency have been investigated. Nickel nanoparticles could be easily recovered by mild centrifugation. [Copyright &y& Elsevier]

An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activated and deactivated aromatic carbonyl compounds with 1,2-ethanedithiol in the presence of a catalytic amount of inexpensive, easily recyclable, monodispersed, chemoselective Ni-nanoparticles having high TON and TOF is reported. An efficient method for the chemoselective thioacetalization of ketones in the presence of aldehydes using Ni-nanoparticles is also reported in this article. Our reaction is kinetically controlled and the method is relatively expedient, avoids the use of cost-prohibitive reagents, high temperatures and leads to excellent yield. Selective Protection of Carbonyl Compounds Over Nano-sized Nickel Catalysts Ajeet Kumar,a Santosh Kumar,a Amit Saxena,a Arnab De,b Subho Mozumdara* aDepartment of Chemistry, University of Delhi, Delhi, 110007, India; b Department of Chemistry, Indiana University, Bloomington, USA; subhoscom@yahoo.co.in An efficient method for the preparation of 1,3-dithiolanes of aliphatic and both activated and deactivated aromatic carbonyl compounds with 1,2-ethanedithiol in the presence of a catalytic amount of inexpensive, easily recyclable, monodispersed, chemoselective Ni-nanoparticles having high TON and TOF is reported. We report an efficient method for the chemoselective thioacetalization of ketones in the presence of aldehydes using Ni-nanoparticles. Our reaction is kinetically controlled and the method is relatively expedient, avoids the use of cost-prohibitive reagents, high temperatures and leads to excellent yield. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]