英语翻译
size and the globular structure of the dendrimers enable efficient separation
by nanofiltration techniques.Nanofiltration can be performed either batchwise
or in a continuous-flow membrane reactor (CFMR),which offers major
advantages,particularly for reactions that benefit from low substrate (reactant)
concentrations or suffer from side reactions of the products.Membrane
reactors have been investigated since the 1970s [19].Although membranes
can have several functions in a reactor,the most obvious is the separation
of reaction components.Initially the focus has been mainly on polymeric
membranes applied in enzymatic reactions,and ultrafiltration of enzymes
is commercially applied on large scale for the synthesis of fine chemicals
(e.g.,L-methionine) [20–24].Membrane materials have been improved significantly
over those applied initially,and nanofiltration membranes suitable
to retain relatively small compounds are now available commercially (e.g.,
mass cut-off of 400–750 D).
Whether dendritic catalysis can compete successfully in commercial applications
with other strategies that allow recycling of the catalyst remains to be
seen.Dendrimer supports are still relatively expensive,but for applications
that do not require the well-defined structure of the dendrimer support,hyperbranched
polymers can offer a cheaper alternative.A recent novel strategy
in this research area that might provide the added value required to make the
step towards commercial applications involves the noncovalent functionalization
of dendritic support with catalysts (Fig.1).This offers several advantages
above the traditional covalent approaches.In this chapter we will review the
progress in the area of supramolecular dendritic catalysis.