On the other hand, Castanheiro et al. also mentioned on clays, which can
act as solid catalyst for a wide range of organic reactions and a subgroup
of clays, Montmorillonite, is particular useful. By using Montmorillonite
as catalyst in reaction, the reaction can proceed under mild condition
instead of vigorous condition. Besides, it brings lots of benefits such as
selectivity, good yields and shorter reaction time. Furthermore, this
catalyst can be easily separated from reaction mixture and regenerated for
future use.