C. (See Discussion.) Solid curves based on ion size parameter 4.3 A. for carbonate and phosphate systems dashed curves based on 6.0 A. Diameter of circles equals 0.008 in pK¡.Konopik and Leberl,18 who reported a value between 11.70 and 11.95 from colorimetric data but with very insecure treatment of activity coefficients. Both references17•18 summarize older data for historical interest.Acknowledgments.-We wish to express our appreciation to the sources listed in Ref. 2 for fellowships supporting the junior author (A.
Xenon and fluorine combine readily. Xenon tetrafluoride is a colorless crystalline material, stable at room remperature. The existence of at least one other fluoride and two oxyfluorides has been demonstrated. The heaviest "inert gas," radon, also reacts with fluorine, yielding a compound less volatile than xenon tetrafluoride.
age [BFg • 0Et2-(CH3C0)20, -10°, three products in 70%], bromination (1 equiv of NBS, 98%), and dehydrobromination (LiCl-DMF, 130°, 77%) gave the tropone 13.9 3-Isopropylcyclohepta-2,6-dienone, one of the ether cleavage products, was also converted to 13 by treatment with DDQ-p-TsOH (benzene, 100°) in 80% yield. The tropone 13 was transformed to the tropolone 14 by the usual procedure (NH2NH2 • H2O at 25°and then 2 N KOH at 80°, 100%).10 The product was identical in all respects with the naturally occurring material.11 2-Isopropyltropone ( 16) has been prepared from 15 (derived from l,l,3,3-tetrabromo-4-methylpentan-2-one and furan) by sequential treatments with H2 over 10% Pd/C in C2H5OH (96%), BBrs in CH2CI2 at -78-25°( giving 6bromo-2-isopropylcyclohept-2-enone as major product in 70%), 1 equiv of Br2 in CCI4 (100%), and LiCl in DMF at 150°( 20%). The tropone 16 can be converted to a-thujaplicin ( 17) by the known method.12,13
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