PETROLEUM, natural gas and olefine-containing refinery gas may all be looked upon as chemical raw materials of great importance. The study of the chemistry of the aliphatic hydrocarbons occurring in petrol fractions is far from complete. Valuable information is being acquired, however, on constituents of the lowerboiling fractions obtained from certain crude oils.

Natural gas is discussed as a potential source of hydrogen, carbon monoxide-hydrogen mixtures (and hence methanol and higher alcohols), formaldehyde and acetylene. The dehydrogenation of paraffin gases to olefine gases is of importance in their possible utilisation. The pyrolysis of paraffin and olefine gases gives appreciable yields of aromatic liquids of which about half is benzene.

Refinery gases from vapour-phase oil-cracking processes can supply large quantities of olefine gases, and smaller quantities of diolefines. The syntheses of alcohols, esters and. other organic chemicals, valuable. in synthetic processes orassolvents, plasticisers, etc., are discussed. The formation of synthetic lubricating oils and the production of resins by polymerisation and condensation of olefines are interesting recent developments.

Recent work on the separation of pure hydrocarbons from crude oil is described. In the separations elaborate fractionation methods were used.

The identification of the sulphur compounds present in petroleum distillates arouses interest as regards their utilisation m the preparation of thioethers, sulphonium compounds, sulphonaces, sulphonal, etc.

Some minor constituents of petroleum. distillates such as nitrogenous bases, phenols and naphthenic acids are briefly described.

Oxidation may become important in the chemical utilisation of petroleum and petroleum gases, but the difficulties of controlling reactions of this type are appreciable. Aromatic hydrocarbons are readily oxidised by air in the vapour-phase in the presence of vanadium pentoxide. Recent work suggests that pressureoxidation of aliphatic hydrocarbons in the presence of a limited supply of air is a process worth further investigation.

Chlorination has already proved its importance in the production of alcohols, etc., from the pentanes by way of chloro-compounds. Chlorination reactions again need careful control.

Many suggested processes for the use of petroleum and petroleum gases appear from time to time, especially in the patent literature. It will be easier to estimate the importance of these when further experimental research is published.

The paperds presented not as an exhaustive account of the potentialities of petroleum and petroleum gases as chemical raw materials, but is intended to indicate several directions in which development may take place.

Petroleum in the past was looked upon solely as a source of liquid fue

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