Dimerization of N,N′-diethyl-aniline into montmorillonite clay: A spectroscopic and DFT investigation

Abstract

The synthesis and the spectroscopic characterization of intercalated N,N′-diethyl-aniline (DA) into natural smectite Montmorillonite clay are reported in this paper. The XRD data confirms the intercalation and Si K X-ray absorption spectra confirms that clay layers are not deformed by intercalation. The investigation of the oxidation of a key monomer into the clay layers can help to understand the mechanism of oxidation and polymerization of polymers derived from aniline. The resonance Raman data at four laser lines show the formation of 4,4‘-disubstituted biphenyl (benzidine like rings) compounds in montmorillonite by intercalation and oxidation of DA molecules. The formation of benzidine-like rings was also verified in FTIR data, in addition to the presence of intercalated DA. The presence of ethyl groups bonded to nitrogen precludes the polymerization, as observed for aniline intercalated into MMT clay. This result is important to show that tail-to-tail (benzidine) is the first reaction promoted by the clay, this kind of bonding is favored inside the clay galleries and probably is a consequence of the intercalation in reduced spaces.