Lithium Aluminum Hydride Reactions in Pyridine Solution. Reductive Cleavage of Ketones1

contain 5.1 g. of 3-ethylpentane by vapor phase chromatography. The above material was purified by shaking with potassium permanganate solution followed by vapor phase chromatography ($6~ 1.3929). Final purification was effected by dissolving it in 10 ml. of acetic acid and adding solution of sodium dichromate and perchloric acid in 90% acetic acid until the orange color persisted. Water was added, the hydrocarbon was taken up in ether, washed with sodium bicarbonate solution and isolated by vapor phase chromatography. The mass spectrum, determined a t an ionizing potential of 20 v., indicated the presence of a t least 97% of one deuterium (based on the parent peaks). Kinetic Method.-Equal volumes of solutions of the hydrocarbon in glacial acetic acid (purified by distillation under reduced pressure from chromium trioxide) and of sodium dichromate (2 X M ) and perchloric acid (1.333 M) in 90yc acetic acid were placed in the two arms of a Utube which had been sealed onto a 10-mm. Beckman cell. The solutions were degassed under reduced pressure and brought to 25.0'. The solutions were mixed and transferred to the Beckman cell by inverting the tube. The rate of disappearance of chromium( VI) was followed by the change in absorbance at 390 mp. Plots of log ( A A m ) against time gave a good linear relationship. The rate constants are given in terms of the natural logarithm. Oxidation of cis-Decalih-Commercial cis-decalin was purified by vapor phase chromatography. The hydrocarbon (6 8.) was added to a solution of.50 g. of sodium dichromate, 40 ml. of water and 141 g. of 72% perchloric acid in enough acetic acid to make 1 1. of solution. The oxidation was carried out at 8' for 30 min. The reaction mixture was worked up as described above for the oxidation of 3-methylheptane giving 1.1 g. of material, b.p. 60-70" at 0.5 mm., which was largely cis-9-decalol. Recrystallization from aqueous ethanol gave pure cis-9-decalo1, m.p. 64-65'