Mild Lewis acid catalyst. Prepn: F. Bischoff, H. Adkins, J. Am. Chem. Soc. 46, 256 (1924). Vibrational spectra: P. D. Moran et al., Inorg. Chem. 37, 2741 (1998). Kinetic behavior in asymmetric epoxidation: S. S. Woodard et al., J. Am. Chem. Soc. 113, 106 (1991). Kinetics in prepn of titanium dioxide, q.v., thin films: V. Gourinchas-Courtecuisse et al., High Press. Chem. Eng. 1996, 133; G. A. Battiston et al., Metalurgija 8, 183 (2002); of sol-gel process: A. Soloviev et al., J. Mater. Sci. 38, 3315 (2003). Use as complexing agent in sol-gel process: B. Wang et al., Polym. Commun. 32, 400 (1991); H. Arce et al., Rev. Soc. Quim. Mex. 47, 73 (2003). Review as reagent in stereoselective synthesis: R. Mahrwald, J. Prakt. Chem. 341, 191-194 (1999); as catalyst: F. Lake, C. Moberg, Russ. J. Org. Chem. 39, 436-452 (2003). Brief review in a variety of organic syntheses: O. López, Synlett 2003, 2261-2262.