During constant-rate heating to 350°C in concentrated NaOH solutions, cubic Zr02 crystallized at = 120°C from hydrated amorphous Zr02; these tine cubic Zr02 particles abruptly changed into needlelike monoclinic Zr02 single crystals at 300°C. Crystallization and phase transformation were studied by XRD, TEM, and EPMA. Cubic Zr02 appears to crystallize via collapse of the Zr02'nH20 structure and subsequent slight rearrangement of the lattice. The abrupt formation of monoclinic Zr02 was considered to result when the very tine cubic Zr02 particles coagulated in a highly oriented fashion.

The reaction of epoxides with nitrogen heterocycles such as indoles, pyrroles, imidazoles, and pyrazoles was studied under both high-pressure and silica gel-catalyzed conditions. Whereas it has been reported that the treatment of indole with styrene oxide at 10 kbar and 42 °C for 24 h gave 2-(3-indolyl)-2-phenylethanol in 56% yield, the same compound was obtained in 88% yield when the reaction was conducted on silica gel at rt for 1 week. Similarly, efficient reaction of epoxides with pyrroles, imidazoles, and pyrazoles was achieved. In terms of stereochemical features, the epoxide ring opening reaction of (R)-(+)-styrene oxide with indole was found to proceed stereoselectively in an SN2 fashion at the benzyl carbon, in either case.

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