Novel Efficient Pd-Free Ni-Layered Double Hydroxide Catalysts for a Suzuki C–C Coupling Reaction

Abstract

The Suzuki cross-coupling reaction has developed as one of the foremost effectual approaches for the synthesis of biaryls or substituted aromatic moieties from aryl halides and arylboronic acids with a palladium-catalyst in the past two eras. In this study, Pd-free layered double hydroxides (LDHs) nickel-containing catalysts were prepared by a coprecipitation method under ultrasonic irradiation and N2 atmosphere with different molar ratios of Ni:Mg:Al and coded as (1NiLDHs−Dr), (1.5NiLDHs−Dr) and (2NiLDHs−Dr). A series of reduced catalysts under 5% H2/N2 at 200 °C were coded as 1NiLDHs−R200, 1.5NiLDHs−R200 and 2NiLDHs−R200. Deep investigation of all catalysts was done using different techniques such as inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), thermogravimetric analyses (TGA), Fourier transfer infrared (FTIR), scanning electron microscopy (SEM) connected with energy dispersive X-ray (EDX), transmission electron microscopy (TEM) and N2-physisorption at –196 °C. The results attained verified that ɑ-Ni(OH)2 was fashioned for a 2NiLDHs−Dr catalyst and that the enclosure of nickel ions in the cationic sheet of the layered structure was responsible for the fascinating catalytic efficacy rather than the basic nature of material. The Ni-containing LDHs catalysts encourage forthcoming studies in Pd-free catalyzed C−C coupling reactions.