Gas–liquid Chromatography of Terpenes: Part Iii. The Use of Oleic Acid Esters as Liquid Phases

Abstract

'The separation of several cyclic terpene hydrocarbons and some oxygenated derivatives was s t~~d i e d on a variety of triglyceride and dioleate ester columns. Use of rapeseed oil, partially hydrogenated rapeseed oil, olive oil, triolein, tristearin, methyl oleate, and p o t a s s i~~~n oleate as liquid phases led to the conclusion that the presence of an esterified mono-unsaturated long-chain acid is a desirable constituent of the liquid phase. Dioleate esters of 1,s-propanediol, 1,4-butanediol, 1,6-hesanediol, diethylene glycol, and polyethylene glycol showed useful differences in the degree of separation of both terpene hydrocarbons and oxygenated derivatives. Ether linkages, as in the di-and poly-ethylene glycol ester, also were associated with favorable separations. When the liquid phase contained free hydroxyl groups, the degree of separation of hydrocarbons and ketones was i n general less favorable. The spacing of the ester groups was found to have some effect on retention data. The separation of such critical pairs of isomers as tricyclene and a-pinene, a-fenchene and camphene, and also geometrical isomers of osygenatecl derivatives is facilitated by use of several of these liquid phases.

Gas–liquid Chromatography of Terpenes: Xv. The Volatile Oil of Mentha Arvensis Var. Glabrata Ray

“…For very small samples a model 600-D Aerograph instrument equipped with a flame-ionization detector was used. Retention times were measured from the time of injection to the initial emergence of the peaks (16,17). The percentage compositio~i of the oil was calculated by summation of the areas tinder the peaks (triangulation method); the errors were similar to those reported by Janak (18).…”

The Preparation and Stereochemistry of Pinane Derivatives

“…Most glc analysis has involved the use of one column under one set of operating conditions, and homogeneity of sample under such conditions is no absolute criterion of purity when mixtures of stereoisomers of unknown chromatographic properties are studied. Ideally, homogeneity should be shown on at least three different analytical-type glc columns, containing carefully chosen packings suitable for for the compound on hand and operated at the lowest practicable temperature (76, 99,107,157), before purity can be reasonably claimed. However, in the absence of this ideal situation, the glc criterion of purity is the best available.…”

GAS–LIQUID CHROMATOGRAPHY OF TERPENES: PART VII. THE DEHYDRATION OF p-MENTHAN-8-OL

“…The gas chromatographic equipment and techniques have been described previously (1,2,10). All columns were made up with the stationary phase on Chroinosorb W (60-80 mesh) in the weight ratio of 1:6.…”

“…All columns were made up with the stationary phase on Chroinosorb W (60-80 mesh) in the weight ratio of 1:6. Retention times were measured from the time of injection to the initial emergence of the peaks (1,10). The percentage compositions of terpene mixtures were determined by measuring the area under the curves (triangulation method), the error being i l to i 5 % depending on peak size (see also ref.…”

“…Terpene hydrocarbons were analyzed a t 65' C (2 mX0.6 mm O.D. columns) or 80' C (4-in columns), and the p-menthan-8-01 isomers and unreacted a-terpineol a t 100-110' C. The retention tiines of p-menthenes, p-cymene, a-terpineol, and the p-menthan-8-01s have been described previously (1,2,10,12). The relative rentention times (RRT) of trans-and cis-p-menthane with respect to limonene (= 1.00) mere 0.29 and 0.355 on the adipate polyester colun~n (at 65' C) and 0.30 and 0.35 on the polyethylene glycol 1540 coluinn (at 65' C) respectively.…”