Joseph Shabtai

Gas liquid partition chromatography of mixtures of methylenecyclohexane and the isomeric methylcyclohexenes

Abstract Smooth separation and quantitative analysis of mixtures of methylenecyclohexane and the three isomeric methylcyclohexenes can be accomplished by gas liquid partition chromatogrphy on a column of 2 m length, with saturated silver nitrate/glycol as the stationary phase. The mean deviation of the results was found to be 0.6-0.7% of the totla and the maximum deviation. 1.2%.

Gas-liquid partition chromatography of isomeric alkylcyclopentenes and alkylidenecyclopentanes

Abstract Gas-liquid partition chromatography of C 6 and C 7 alkylcyclopentenes and alkylidenecyclopentanes over a saturated silver nitrate-glycol solution has been studied. Mixtures of isomers, including those whose boiling points differ by only 0.1°, could be easily separated and analysed quantiatively.

Gas chromatography with stationary phases containing silver nitrate. III. Isomeric C8 and C9 cyclohexenes and p-menthenes.

Abstract Retention volumes of isomeric C8 and C9 cyclohexenes and p-menthenes have been determined, using stationary phases containing silver nitrate. As in the case of lower cyclic olefins, it is found that closely boiling isomers can be separated and determined quantitatvely on a 30% silver nitrate-glycol solution at 20–30°. The correlation between olefin structure and retention volume is discussed.

Gas chromatography with stationary phases containing silver nitrate IV. The methylcyclobutenes, methylenecyclobutane, C5 dienes and related compounds

Abstract The retention volumes of the methylcyclobutenes, methylenecyclobutane, a series of C5 open chain mono- and diolefins and of some related compounds have been determined using silver nitrate—glycol as the stationary liquid. As in the case of other groups of olefins, the complex-forming phase has been found to be highly selective, permitting ready separation of almost all compounds examined. By comparing the retention volumes of close boiling isomers, correlations between structure and stability of the silver ion—olefin complexes formed have been established. The main conclusions are as follows: (1) Cyclobutenes have less tendency to complex formation than the corresponding five- and six-membered cycloolefins; (2) in contrast to findings in aqueous solution, conjugated dienes do not show reduced complex stability in ethylene glycol; (3) unconjugated dienes coordinate strongly, probably as a result of chelation.

GAS CHROMATOGRAPHY WITH STATIONARY PHASES CONTAINING SILVER NITRATE. VI. THE METHYLCYCLOHEPTENES AND METHYLENECYCLOHEPTANE.

Abstract The gas chromatographic behavior of the isomeric methylcycloheptenes and methylenecycloheptane was investigated using: (a) packed tubes containing conventional non-complex forming phases; (b) capillary tubes coated with squalane and polypropylene glycol; (c) packed columns containing complex forming silver nitrateglycol solutions as the stationary liquid. Smooth separation of a mixture of the isomers is achieved on a silver nitrate-triethylene glycol column; by proper choice of salt concentration and working temperature the components can be quantitatively determined with an accuracy of ±1%. On a preparative scale, the method was conveniently employed for the isolation of the previously unknown 4-methylcycloheptene. By compring the relative retention volumes of the isomers, correlations between complex stability and olefin structure were deduced, taking into consideration the peculiar conformations of the seven-membered ring system.

Splitting of the CC stretching vibration of 3-substituted cyclenes

Abstract Pure samples of 3-methylcyclobutene, 3-methylcyclopentene, 3-methylcyclohexene and 3-methylcycloheptene were synthesized and their infrared absorption spectra measured. While 3-methylcyclobutene shares the CC stretching band splitting of the 3-substituted cyclopentenes and cyclohexenes, 3-methylcycloheptene does not. This fact is ascribed to the flexibility of the cycloheptene ring.