It was discovered that olefinic double bonds are readily oxidized in an aqueous solution of periodate which contains only catalytic amounts of permanganate. The data suggest that in the effective pH range of 7 to 10 the permanganate is not reduced at once beyond the manganate state and that it is regenerated from this state by periodate action. Evidence was obtained that the main course of the oxidation of an olefin of type —CH=CH— involves first permanganate oxidation to hydroxyketones which are then rapidly cleaved by periodate to products which may subsequently be oxidized by the permanganate.

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The periodate-permanganate reaction with methyl oleate and triolein has been studied in media containing a variety of organic solvents. The oxidation proceeded favorably in media containing tertiary butanol or pyridine and conditions have been found which permit the quantitative analysis of unsaturated lipids. INTRODUCTIONThe quantitative oxidation of unsaturated fatty acids to specific and easily identifiable end products was described previously (8). I t was shown that the periodate-permanga~late oxidation of such acids adheres strictly to the reaction scheme Erucic acid, methyl esters, and triglycerides were not soluble in the wealtly alkaline, dilute aqueous reaction mixture (5) and did not give satisfactory results. The solubility of these lipids was increased by using a modified reagent (7) containing pyridine, and quantitative results could be obtained in the oxidation of erucic acid and methyl linoleate. Methyl oleate and triolein, however, were incompletely oxidized under these conditions (8).Conditions have now been found which permit the quantitative oxidation of these latter unreactive compounds. Thus when methyl oleate was shalten in media containing 20 to 50% pyridine and a small amount of potassium carbonate, oxidant equivalent to the theoretical value of four oxygen atoms was consumed in three to six hours' reaction time (Table I ) , and this value was not appreciably exceeded during three days' reaction time. Chromatographic analysis of the saponified oxidation products gave pelargonic and azelaic acids in 96 and 98% (~1 % ) of the theoretical yield respectively. The quantitative oxidation of triolein in media containing pyridine was not possible, mainly because of the very low rate of reaction (Table I). Increasing the rate of oxidation by employing higher temperatures, pH, or concentrations of permanganate (5) was not feasible because of overoxidation after correspondingly shorter reaction times. Virtually theoretical results, however, were obtained with triolein, as well as with methyl oleate, by using tertiary butanolwater as solvent (Table I ) , and 98 to 99y0 of the calculated amount of azelaic acid was isolated after four to eight hours' reaction time.Oleodistearin reacted to completion in media containing 60% tertiary butanol (Table I ) , and sunflower-seed oil and linseed oil, i.e. triglycerides 'Manuscript

of excess pyridine, has been described recently by Motl et al. (1, 2), who obtained a mixture of isomeric hydrocarbons from both selin-4-01 and dihydro-a-cadinol. When this reagent was used in the current study with a-terpineol, dipentene (70Y0) and terpinolene (21y0) were obtained and no other isomeric hydrocarbon was detected by gas-liquid chromatography (GLC). This is a considerable reduction in the number of isomers formed over t h a t obtained when acidic reagents were used (3). However, because of the large excess of pyridine used wit11 this reagent, the reaction is cumbersome. A much more convenient, and in some instances more specific, dehydration has now been obtained by heating the alcohol under reflux a t 200 t o 230" from 1 t o 6 hours in the presence of twice its weight of neutral alumina (Woelm, activity grade I ) t o which 1 t o 2% of pyridine or quinoline had been added. This reagent gave highly satisfactory results with a-terpineol, dihydro-a-terpineol, menthol, borneol, cedrol, and dihydroeudesinol, although the products obtained from linalool and isopulegol were more complex.T h e amount of a-terpineol which had reacted with the reagent during 1 hour a t 180°, 200°, and 220" C was 10yo, 40y0, and 82y0 respectively. T h e dehydration was virtually coinplete after 6 hours a t 220' C , when dipentene (83y0) and terpinolene (6yo) were the only compounds detected by GLC. When a-terpineol was heated under reflux with neutral aluinina alone, the steam-volatile product was found to be con~posed of a-terpinene (13y0), dipentene (31y0), p-cymene (1670), y-terpinene (9%), terpinolene (26%), and 9-mentha-2,4(8)-diene (5y0), a composition very similar t o t h a t obtained wit11 aqueous acidic reagents (2).With dihydro-a-terpineol this base-modified alumina gave trans-(47y0) and cis-(44y0) 9-nlenth-8-ene and p-menth-4(8)-ene (770) after 1 hour reaction time. Since the ratio of cis t o trans isoiners in the starting material was 1:1 there appears to be no preferential reaction of either of the two isomers. Using t h e reagent of Motl et ad. (1) the same mixture of hydrocarbons was obtained, but the yield of the p-menth-8-ene isomers was only 70y0. Menthol, when treated with the new reagent for 1 hour, gave p-menth-2-ene (40y0) and p-menth-3-ene (6y0), whereas borneol was dehydrated t o a misture of camphene (68%) and tricyclene (16y0). These results are very similar t o those described by Pines and Pillai (4), who carried out the dehydration reaction of menthol, borneol, and neopentyl alcohol over ammoi~ia-modified alumina in the gas phase. These authors propose that the dehydration takes place by a concerted mechanisn~ involving both acidic and basic sites on the catalyst, whereas isomerization is suppressed by the preferential poisoiling of the "stroilg acid sites" (5). Neutralization of acidic sites was confirnled in this study by evacuating the pyridine-treated alumina for 6 hours, when about 0.8% base was retained and no change in the reaction with a-terpineol was observed. Recently, Beranek et al. (6) ...

The volatile oils of the leaves and twigs of alpine fir, and western and eastern Canadian balsam fir were analyzed by gas–liquid chromatography. Many qualitative similarities were found and the within-tree and tree-to-tree variation of the quantitative terpene composition of the leaf oil was sufficiently small to permit a chemosystematic study. Abies lasiocarpa and A. balsamea may be differentiated by the relative amounts of β-pinene, 3-carene, β-phellandrene, trans-ocimene, piperitone, methyl thymol, and thymol. Consistent quantitative differences were also found between eastern and western A. balsamea, and the populations in the Lesser Slave Lake and Battle Lake regions of central Alberta gave intermediate terpene data, which suggests introgression between A. lasiocarpa and western A. balsamea. Thus a cline between A. lasiocarpa and A. balsamea, with western balsam fir populations as bridge, may have existed after the last glaciation. The alpine fir populations of southern Alberta, and eastern and central British Columbia gave uniform terpene data, but five trees sampled on Green Mountain, Vancouver Island, gave significantly different terpene data. These results were substantiated by morphological characters as well as twig oil analysis, but the latter two methods gave less consistent data than leaf oil analysis.