10-07-04 11:35
No 534805
In a recent publication, Joji Nishikido and co-workers at The Noguchi Institute used several catalysts in a fluorous biphasic catalytic system for Baeyer–Villiger oxidations.
Sn[N(SO2C8F17)2]4 was shown to give an excellent yield and selectivity of cyclic ketones by using 35% aqueous hydrogen peroxide. Furthermore, the catalyst was completely recovered and reused in the fluorous immobilized phase without loss of activity. Even after recycling the catalyst four times, the GC yield still remained higher than 90%.
Catalytic recycling of Sn[N(SO2C8F17)2]4 was also tested in the BV oxidation of cyclobutanone. It was found that there was almost no difference in the formation rate of gamma-butyrolactone (no loss of catalyst activity).
Xiuhua Hao, Osamu Yamazaki, Akihiro Yoshida and Joji Nishikido, TETRAHEDRON LETTERS 2003, 44:27:4977 - 4980.
(Hive Bee)
10-07-04 11:37
No 534806
Chances are this can also be used for bayer-villager oxidations of other interesting things, such as phenylacetones. Anyone know a prep of this catalyst, or can access the references?
(Hive Bee)
10-07-04 11:45
No 534807
More bayer-villager catalyst refs
Nature, 26 July 2001, Vol. 412, No. 6845, p. 423
Sn-zeolite beta as a heterogeneous chemoselective catalyst for Baeyer--Villiger oxidations
Avelino Corma, Laszlo T. Nemeth, Michael Renz and Susana Valencia
The Baeyer--Villiger oxidation, first reported more than 100 years ago, has evolved into a versatile reaction widely used to convert ketones---readily available building blocks in organic chemistry---into more complex and valuable esters and lactones. Catalytic versions of the Baeyer--Villiger oxidation are particularly attractive for practical applications, because catalytic transformations simplify processing conditions while minimizing reactant use as well as waste production. Further benefits are expected from replacing peracids, the traditionally used oxidant, by cheaper and less polluting hydrogen peroxide. Dissolved platinum complexes and solid acids, such as zeolites, or sulphonated resins, efficiently activate ketone oxidation by hydrogen peroxide. But these catalysts lack sufficient selectivity for the desired product if the starting material contains functional groups other than the ketone group; they perform especially poorly in the presence of carbon--carbon double bonds. Here we show that upon incorporation of 1.6weight per cent tin into its framework, zeolite beta acts as an efficient and stable heterogeneous catalyst for the Baeyer--Villiger oxidation of saturated as well as unsaturated ketones by hydrogen peroxide, with the desired lactones forming more than 98% of the reaction products. We ascribe this high selectivity to direct activation of the ketone group, whereas other catalysts first activate hydrogen peroxide, which can then interact with the ketone group as well as other functional groups.
(Chief Bee)
10-07-04 14:50
No 534818
I think the Tet. Lett. method is completely unworkable due to its cost.
Their preferred solvent is perfluoro(methylcyclohexane) at a cost of $50/25g and the starting material cyclobutanone is $175/5g (all prices from Aldrich). I don't even want to know what the catalyst itself costs.
The Hive - Clandestine Chemists Without Borders
(Hive Bee)
10-08-04 07:24
No 534922
Good point rhodium.
Although, would you have any idea on what the procedure is of doping zeolites is? zeolite can be pretty common, not so sure about beta zeolite, but if it was possible in a clandestine situation to make the tin-beta-zeolite, then, that would still be very handy and possibly more cost efficient than traditional peracid baeyer-villager oxidations of more 'friendly' phenylacetones.
(Hive Bee)
10-08-04 08:07
No 534925
As an alternative to zeolites..
Camblor, M. A., Corma, A., MartõÂnez, A. & PeÂrez-Pariente, J.
Synthesis of a titaniumsilicoaluminate isomorphous to zeolite beta and its application as a catalyst for the selective oxidation of large organic molecules.
J. Chem. Soc. Chem. Commun. 589±590 (1992).