The 28th and 29th JUACEP Seminars

Professor Richard Laine, University of Michigan gave two lectures at Nagoya University.

• The 28th Seminar:'F- Catalytic Rearrangements of Silsesequioxanes (SQs) and Analogs: New Cage Sizes and Unusual Reactive Properties'
• We have been exploring the use of tBu4NF as a means to transform either polymeric T resins or single functional group T8 cages into mixed functional T10 and T12 SQs as illustrated in the two following reactions.1-3
  To this end, we have now developed simple, multigram routes to pure PhT8, PhT10¬ and PhT12. The PhT8 system offers cubic symmetry whereas the PhT10 system offers five fold symmetry and is therefore a very unusual molecule. In contrast, the PhT12 compound has no symmetry. We have also been able to identify and isolate still larger cages as will be discussed. The various cage sizes allow us to explore the effects of symmetry and size on a wide variety of properties. For example, the PhT8 cage brominates almost exclusively in the ortho position. The PhT10 also brominates preferentially in the same position whereas the PhT12 is less selective. Modeling studies seem to explain the observed behavior. We have also used Heck catalytic cross coupling to functionalize the ortho-bromo derivatives of the cages and explored their photophysical properties.


• The 29th Seminar:'Escaping the Tyranny of Carbothermal Reduction. Conversion of Biowaste Silica to Alkoxysilanes without using Silicon'
• Agricultural byproducts used as alternate energy sources generate considerable waste. Harvested rice is milled producing rice hulls that are often burned to generate electricity also producing rice hull ash (RHA). In the U.S. some 100k tons of RHA are produced annually. RHA consists of 70-90 wt % low impurity, high surface area (20-80 m2/g) amorphous, porous silica mixed with low impurity, amorphous carbon.
  The rice plant does not extract heavy metals from the ground and as such the resulting RHA is relatively pure. Furthermore, it is very easily purified using simple acid extraction to remove small amounts of phosphates and other minor minerals. In this presentation we describe methods of directly depolymerizing RHA SiO2 to transform it into distillable alkoxysilanes.

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