TITLE:
Environmentally Friendly Room Temperature Synthesis of 1-Tetralone over Layered Double Hydroxide-Hosted Sulphonato-Salen-Nickel(II) Complex
AUTHORS:
Samiran Bhattacharjee, Mohammad A. Matin, Hasina Akhter Simol, Anowar Hosen
KEYWORDS:
Sulphonato-Salen-Nickel(II), Layered Double Hydroxide, Tetralin Oxidation, Room Temperature, 1-Tetralone
JOURNAL NAME:
Green and Sustainable Chemistry,
Vol.13 No.1,
February
6,
2023
ABSTRACT: 1-Tetralone, a useful synthetic intermediate in the
manufacture of pharmaceuticals, agrochemicals and dyes, can be prepared by
liquid phase catalytic oxidation of tetralin. Selective oxidation of tetralin
to 1-tetralone is still a big challenge with
low-temperature processes using environmentally friendly routes even after decades of research. Herein, we
demonstrate room-temperature oxidation of tetralin to 1-tetralone over layered double
hydroxide-hosted sulphonato-salen-nickel(II) complex, LDH-[Ni-salen]. The
layered double hydroxide-hosted sulphonato-salen-nickel(II) compound was
characterized by powder X-ray diffraction,
Fourier transform infrared spectrometer (FTIR), UV-Visible diffuse
reflectance spectra, scanning electron microscopy (SEM) and elemental analysis.
The theoretical calculations of free sulphonato-salen-nickel(II) complex using
Density Functional Theory/CAM-B3LYP at the 6-311++ G(d,p) level of theory were
also used to determine the orientation of the Ni-salen compound within the
layered structure. The immobilized compound, LDH-[Ni-salen] was found to be an
effective reusable catalyst for the oxidation of tetralin to 1-tetralone using
a combination of trimethylacetaldehyde and molecular
oxygen (14.5 psi) and at 25°C. At 45.5%
conversion, tetralin was converted to 1-tetralone with 77.2% selectivity at
room temperature and atmospheric pressure after 24 h. The catalyst recycles test and hot filtration
experiment showed that oxidation proceeded through Ni(II) sites in
LDH-[Ni-salen]. The catalysts were reused several times without losing their
catalytic activity and selectivity. The present results may provide a
convenient strategy for the preparation of 1-tetralone using layered double
hydroxide-based heterogeneous catalyst at ambient temperature for industrial
application in near future.