New method for preparation of MWCNT-SO3H as an efficient and reusable catalyst for the solvent-free synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones

Multiwalled carbon nanotubes (MWCNTs) have been functionalized with -SO3H groups using new three steps chemical routes. Firstly, OH groups have been attached to CNT surfaces through a radical reaction. The second step involves converting the hydroxyl groups into the oxide one and last step included the attachment of –SO3H groups on the MWCNTs surfaces in the presence of 1-butyl-3-methyl imidazolium tetrafluoroborate [bmim]BF4 ionic liquid as catalyst. Functionalized MWCNTs were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman Spectroscopy. Obtained product have be used as acidic nano catalyst in the Biginelli reaction for the synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives. The reaction was performed under solvent-free conditions with excellent yields and short reaction times in the presence of a reusable efficient catalyst.