TY - JOUR
T1 - Catalytic activity of choline modified Fe(III) montmorillonite
AU - Wallis, Philip
AU - Gates, Will
AU - Patti, Antonio
AU - Scott, Janet
PY - 2011
Y1 - 2011
N2 - A series of mixed-cation organoclays, containing both Fe(3+) and choline(+) cations, were prepared using montmorillonite and tested for catalytic activity in three Fe(3+)-mediated reactions: the oxidative coupling of 2-naphthol, coupling of anthrone and a Lewis-acid catalysed indole conjugate addition. Clays with different Fe(3+):choline(+) ratios were required to achieve maximum catalytic activity in each reaction. For coupling of both 2-naphthol and anthrone, the most effective catalysts, as measured by the turnover frequency (TOF), were mixed Fe(3+)/choline(+) clays of varying ratios, but the catalytic efficiency of Fe(3+) montmorillonite in the conjugate addition of indole with methyl vinyl ketone decreased with the addition of choline(+) This result could potentially be explained by the effect of choline(+) decreasing the accessibility of Lewis acid domains. The results of this study provide proof that it is possible to tune mixed-cation clays with maximum catalytic activity in specific reaction types for specific substrates. Such mixed-cation organoclays offer advantages over traditional clay-based sorbents in environmental remediation applications, as they have the potential to bind organic contaminants selectively, via interaction with surface-exchanged organic cations, and neutralise organic molecules through catalytic exchange cations that are also present on the clay surface.
AB - A series of mixed-cation organoclays, containing both Fe(3+) and choline(+) cations, were prepared using montmorillonite and tested for catalytic activity in three Fe(3+)-mediated reactions: the oxidative coupling of 2-naphthol, coupling of anthrone and a Lewis-acid catalysed indole conjugate addition. Clays with different Fe(3+):choline(+) ratios were required to achieve maximum catalytic activity in each reaction. For coupling of both 2-naphthol and anthrone, the most effective catalysts, as measured by the turnover frequency (TOF), were mixed Fe(3+)/choline(+) clays of varying ratios, but the catalytic efficiency of Fe(3+) montmorillonite in the conjugate addition of indole with methyl vinyl ketone decreased with the addition of choline(+) This result could potentially be explained by the effect of choline(+) decreasing the accessibility of Lewis acid domains. The results of this study provide proof that it is possible to tune mixed-cation clays with maximum catalytic activity in specific reaction types for specific substrates. Such mixed-cation organoclays offer advantages over traditional clay-based sorbents in environmental remediation applications, as they have the potential to bind organic contaminants selectively, via interaction with surface-exchanged organic cations, and neutralise organic molecules through catalytic exchange cations that are also present on the clay surface.
UR - http://www.sciencedirect.com/science/article/pii/S0169131710004266
U2 - 10.1016/j.clay.2010.12.010
DO - 10.1016/j.clay.2010.12.010
M3 - Article
VL - 53
SP - 336
EP - 340
JO - Applied Clay Science
JF - Applied Clay Science
SN - 0169-1317
IS - 2
ER -