Phenylhalocarbenes in zeolite Y: A laser flash photolysis and product study.

摘要

In the present thesis, the generation and reactivity of phenylhalocarbenes, particularly phenylchloro- and phenylbromocarbene, within alkali metal cation Y zeolites were studied. The techniques used for this investigation were laser flash photolysis, conventional (lamp) irradiation, and thermolysis. 3-Phenyl-3-halodiazirines were used as carbene precursors. These diazirines were readily prepared by the Graham reaction. Studies of phenylhalocarbenes in dry zeolites (MY, M = Li+, Na+, K+, Rb+ and Cs+) showed that the absolute reactivity of phenylhalocarbenes is dependent on the alkali metal cation. Accordingly, phenylchlorocarbene (PhCIC:) within NaY could not be directly detected, using our nanosecond laser system, and its formation was monitored through the carbene-ylide signal, using pyridine or 4,4′-dipyridyl.; Thermolysis or photolysis of 3-phenyl-3-halodiazirines in Y zeolites yielded benzaldehyde and 2,3-diphenyl-1,3,4-oxadiazole as the main products of the diazirine decomposition.; Co-adsorption of methanol, water or alkenes within Y zeolites rapidly quenched the absorption band of phenylhalocarbenes. (Abstract shortened by UMI.)