The absorption of oxygen by bitumens in the light and in the dark was measured at ambient temperature with stirred solutions in an indifferent solvent to avoid problems owing to diffusion effects. The rate of absorption was considerably increased by light (fluorescent lighting) and by traces of certain metals. All chemicaltype fractions prepared from bitumens by chromatographic separation oxidized in the light, but only the asphaltenes and resins absorbed oxygen in the dark, this reaction being probably initiated by the stable free radicals present in bitumens. The concentration of reactive components in dark-colored bitumens is higher than in light-colored ones, but in practice the dark color acts as a protection against excessive oxidation in the light. Few of the compounds known to inhibit oxidation reactions appeared to affect bitumen oxidation. Those that were active accelerated oxygen absorption in the light but had hardly any effect in the dark. The effects found with these substances in the light experiments were checked with Weather-O-meter experiments.A study of bitumen oxidation is of importance for several reasons.

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The free-radical addition of 1-propanethiol, benzenethiol (thiophenol) and a-toluenethiol (benzyl mercaptan) to allene in benzene solution has been investigated.At high allene/thiol ratios the two sulfides resulting from the addition of one mole of RSH to allene (isopropenyl-SR and allyl-SR) are formed in yields of the same order of magnitude.At low allene/thiol ratios the more reactive isopropenyl sulfide is not present among the products, since it is quantitatively converted into 1 ,2-di-SR-propane. Thiol addition to the ally1 sulfide to yield 1,3-di-SR-propane is a much slower process.

KONINK LIJKE/SHELL-LABOR ATOR UM, AMSTERDAMThe syntheses of the five methyl-cis-bicyclo[3.3.0]octanes are described. The exo-3 compound could only be obtained as a mixture with an equal amount of its endo-3 isomer. IntroductionIn the course of our investigation into the isomerization of perhydroindane 1 we required authentic samples of the five methyl-cis-bicyclo[3.3.0]-octanes for identification purposes.A literature search revealed that none of the isomers, I-, endo-Z, exo-2-, endo-3-, and exo-3-methyl-cis-bicyclo[3.3.0]octane had been described before. Mair et a1.2 have demonstrated the presence of only one of them in petroleum, but could not establish its spatial configuration.

The pyrolysis, hydrogenation, and gas-liquid chromatography techniques were applied to bitumens and bitumen constituents in order to enlarge our knowledge of their chemical constitution. The pyrograms could be satisfactorily interpreted on the basis of data obtained with model compounds. Bitumens can be rapidly characterized as to their cyclic or paraffinic nature by the chemical constitution of their pyrolyzates.