700 CREATIVE CHEMISTRY Large-scale production of 100 octane motor fuels may make it to produce smaller engines, which can be placed in automobiles, thus revolutionizing their design. possible the back end of Superior lubricating oils are also being produced by the polymerization of refinery gas products. Although the fractions boiling in the gasoline range may consist of literally hundreds of hydrocarbons, so much progress has been made in distillation and solvent extraction that it now is possible to prepare less complex mixtures and even some very pure compounds. The petroleum industry is now looking forward to the time when petroleum will be used as a source of raw materials from which relatively pure hydrocarbons may be prepared by synthetic processes. W'e are so breathless with the progress already made that few of us are able to see where this road along which we have moved so rapidly over the last few years will lead us. Apparently it is leading us in the direction of converting the natural hydrocarbons of petroleum into simpler compounds of less molecular weight, and then recombining these simpler compounds in new ways to obtain an entirely new molecule having the characteristic that we want, and which we cannot obtain in the natural molecule.^ There Is a Great Future for the Use of Petroleum as the Starting-point for the Preparation of Many Valuable Products. Ethylene, C2H4, which is obtained in large quantities by cracking petroleum, is now combined with bromine, obtained from sea water, to produce ethylene dibromide, C2H4Br2, which is added in small amount to tetraethyl lead in "ethyl" gasoline to form lead compounds which pass out through the exhaust, thus preventing accumulation of lead in the combustion chamber. Ethylene also combines directly with chlorine to produce ethylene dichloride, C2H4CI2, which is useful as a fat solvent and is also added to "ethyl" gasoline with ethylene dibromide. It will react with water to produce ethylene glycol ,2 C2H4(OH)2, which is used in automobile radiators as an antifreeze. Glycol is converted into other substances such as "cellosolve" and "carbitol," which are used as solvents, and glycol dinitrate, which is used in low-freezing dynamite. A method for the preparation of toluene, CeHsCHs, from petroleum has made the United States independent in regard to this raw material from which T.N.T. (trinitrotoluene), the high explosive, is manufactured. It is now possible to produce from petroleum the important aromatic compounds which were formerly obtained only from the destruc- 1 F. A. Howard, Chemical Metallurgy Engineering, Vol. 46. No. 751, 1939. 2 Most of the glycol made in the United States is produced by a different process.
"BETTER THINGS" FROM PETROLEUM 701 tive distillation of coal; for example, benzene, toluene, xylenes, alkyl naphthalenes, and high-solvency naphthas high in aromatics. Cresylic acid (a mixture of phenols), formerly obtained from coal tar alone, is now obtained from petroleum at a lower cost. It is used for the preparation of germicides and insecticides and on a large scale in flotation processes for the recovery of ore particles from crushed rock. In the process of cracking large molecules to form molecules suitable for gasoline, the production of smaller fragments, which are too volatile to be used in gasoline, is unavoidable. Between 7 and 8 per cent by weight of the total crude oil processed in our refineries becomes gas. This amounts to about 14,000,000 tons per year. One company alone was making over one hundred synthetic chemicals from these refinery gases in 1940. Propane and butane, refinery gases formerly burned as fuels in the refinery boilers, are now liquefied and sold as "bottled gas" for use where neither natural gas nor manufactured gas is available and even in trucks and buses; 128,000,000 gallons of "bottled gas" were sold in 1939. One interesting use for propane is the removal of wax, asphalts, and resins from lubricating-oil stocks. Dewaxing Is effected by dissolving the oil in liquefied propane, evaporating a portion of the propane and thus chilling the mixture, and subsequently filtering or settling the wax crystals so formed. Residual stocks are deasphalted by partial solution in liquefied propane. Furthermore, by proper selection of the concentration and temperature, the very heavy portions of the oil, nonasphaltic but "resinous," may be separated from the balance of the oil. Thus deasphalting and deresinating are in effect a substitute for high-vacuum distillation. Olefinic and other easily oxidized constituents of lubricating oils, as well as materials having poor viscosity-temperature characteristics, are separated from lubricating oils by solvent extraction. Examples of selective solvents are sulfur dioxide, chlorex, furfural, and phenol. The result of the combination of these processes is the production of extremely highquality motor oils with excellent viscosity-temperature coefficients, high stability, and low pour-point. Already refinery gases (former waste products) are being used to produce ethylene glycol (antifreeze), glycerine, acetone, and ethyl alcohol. Instead of using alcohol derived from the fermentation of carbohydrates to replace gasoline as a fuel, as has been done in other countries, we have seen petroleum used to produce cheaper and purer alcohol to compete with fermentation alcohol in all of its many applications.