Cu2 + -exchanged zeolites

Paetow and Riekert (28, 29) in a careful study have compared the relative activities of Cu2 +-exchanged zeolite T and mordenite with various copper-containing compounds. On the basis of turnover numbers per CO chemisorption site the Cu2 +-exchanged zeolites are 2-4 orders of magnitude less active than CuO, CuMn204, and CuCr204. This was considered to be consistent with the involvement of lattice oxygen as an intermediate which is easier to remove in oxides than zeolites. 

In this paper we have described a design approach for heterogeneous enantioselective catalysts. The approach is based upon modification of the counter-cation of zeolites or mesoporous alumino-silicates with a suitable chiral ligand.7 We have demonstrated the approach with two examples (a) enantioselective aziridination of alkenes using Cu2+-exchanged zeolite Y modified with chiral oxazolines and (b) the modification of... 

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