Acknowledgment. Acknowledgment is made to the donors of the Pet. roleum Research Fund, administered by the American Chemical Society, for support of this research. The authors wish to thank Mr. Joel Myerson and Mr. Todd Brookhart for some experimental assistance. We also wish to thank Professor HD Durst for a sample of 18-crown-6 and for helpful discussions. methoxybenzoin, 4254-17-5; diphenylacetaldehyde, 947-91-1. ...