This research article is dedicated to Prof. S. Chandrasekaran, Department of Organic
Chemistry, Indian Institute of Science, Bangalore, India on the occasion of his 74th birthday
Abstract
Sulfonated reduced graphene oxide (SrGO) has displayed great potential as a solid
acid catalyst due to its efficiency, cost-effectiveness, and reliability. In this
study, SrGO was synthesized by the introduction of sulfonic acid-containing aryl radicals
onto chemically reduced graphene oxide using ultrasonication. The SrGO catalyst was
characterized by Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy,
powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), scanning electron
microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy
(TEM). Further, SrGO was effectively utilized as a metal-free and reusable solid acid
catalyst for the chemoselective N -t -Boc protection of various aromatic and aliphatic amines under solvent-free conditions.
The N -t -Boc protection of amines was easily achieved under ambient conditions affording high
yields (84–95%) in very short reaction times (5 min–2 h). The authenticity of the
approach was confirmed by a crystal structure. The catalyst could be easily recovered
and was reused up to seven consecutive catalytic cycles without any substantial loss
in its activity.
Key words Boc protection - sulfonated reduced graphene oxide - solvent-free - metal-free - heterogeneous
catalysis
