ORGN 488 |
| Reinaldo Moya-Barrios, Frances L. Cozens, and Norman P. Schepp. Department of Chemistry, Dalhousie University, Halifax, NS B3H 4J3, Canada |
| We have recently reported the first direct detection of reactive carbenes within the cavities of cation-exchanged Y zeolites. Herein we provide further insights into the mechanisms for intrazeolite carbene decay. The absolute reactivity of the arylhalocarbenes was investigated as a function of the counterbalancing cation and the carbene substituent using the technique of nanosecond laser flash photolysis (LFP). Arylhalocarbenes were generated from the corresponding 3-aryl-3-halodiazirines. LFP of arylhalocarbenes in dry zeolites (MY, M = Li+, Na+, K+, Rb+ and Cs+) showed that the absolute reactivity of these species is dependent on the alkali metal cation. In addition, the reactivities of arylhalocarbenes included in the zeolite cavities differ greatly from that observed in hydrocarbon solution. Neither highly nucleophilic nor highly electrophilic carbenes could be directly observed within Y zeolites. These results suggest that more than one mechanism operates in the rapid intrazeolite carbene decay. |
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Total Synthesis, Process R&D, Combinatorial, Bioorganic, Physical Organic Chemistry
8:00 PM-10:00 PM, Tuesday, August 24, 2004 Pennsylvania Convention Center -- Hall D, Poster
Sci-Mix
Division of Organic Chemistry |