VOL. 25The major constituent of the ketone was established as the 6 rather than the 7-keto derivative by formation of a monobenzal derivative, no dibenzal derivative being isolated.The ketone, 470 mg. (3.17 mmol.) was dissolved in 5 ml. of 5% potassium hydroxide in methanol9 and 1.1 ml. of benzaldehyde was added. After 20 hr. the mixture was diluted with 11 ml. of water and extracted with 10 ml. of hexane. The hexane layer was dried over magnesium sulfate and concentrated. Excess benzaldehyde was removed by maintaining the residue a t 60' (0.25 mm.) for several hours. The cooled semicrystalline residue was recrystallized twice from 3 ml. portions of hexane to give 0.151 g. (0.639 mmol., 20.1%) of pale yellow monobenzal derivative, m.p. 74.0-77.0'. Anal.Calcd. for C17H160: 0, 6.77. Found: 0, 6.63.The infrared spectra of all compounds encountered in this (9) K. Alder, K. Heimbach, and R. Reubke, Chem. BeT., 91, 1516 (1958); K. Alder and R. Reubke, Chem. Ber., 91, 1525 (1958). investigation were measured routinely and supported the proposed structures. In particular, these nortricyclene derivatives absorbed a t 12.3-12.4 microns, as first noted by Roberts and co-workers.10

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