2 Propane and butane dissolved in gasoline (given as percentage of liquid volume) are calculated to equivalent volumes as free gas.

No abstract

A correlatiora is established betueen the efecaccelerated oxidution lest and their critical oxida-OUREU aiid Dufraisae of oxidation of tlie alcoliols (17) have reviewed tiveness gasoline inhittitors as measured by used as inhibitors. Dhar (6') their own extensive ~~~h~ : zr : work on antioxidants. Earlier reported by Seyewetz and Sisley potentials between 0.600 and 0.800 volt; fair dized." ( 2 0 . Progress to date in au-inhibitors are in the range 0.800 to 1.043 volts. Monreu and Dufraisse (171, toxidation has been summa-compoun& ?,,ilh the lathr figare while assuming oxidation of the rized The by power Milas of (24). preventing ac-have practically no inhibiting action under the ~~~~~~ ::''I tion of free oxygen on sensitiveconditions Of test. ffydroquinone and cerlain tion and write, "One recovers niaterial is possessed largely by ethers show less i7hibiting action in the bomb the three bodies (oxidizable subsubstances which are them-kat than their potentials would lead one to stances, inhibitor, and oxygen) selves readily oxidized. This th,is is attributed to their tendency to in t.heir original state." Their mechanism, however, has been severely criticized by Milas (14) was by undergo direct oxidation. and Dufraisse (17) and pointed out earlier b y M i t t r a and and Perrin ($0). Dhar (16) who stated, "it seems possible that the pheuommon The chain theory of reaction meclianism is useful in of negative catalysis is possible only nhen the catalyst is explaining inliibitor action. The hypothesis of so-called liable to be oxidized." In contradiction, Milas (14) reports chains of reacting molecules was crystallized in 1924 by inhibition of oxidation of anethole by benzoqninone and Christiansen ( 3 ) . He stated that in a bimolecular reaction, anthraquinone, which, be st,ates, "are far from being easily unless it is immeasurably fast., only a fraction of the pairs oxidized." Of import in this connection is inhihition hy of molecules which collide are able to react. Those reacting l,%naphthoquinone, which was reported by Mat.ill (13) and are activated molecules w!iose energy exceeds a certain value. in Part I of this paper (7). Fieser (9) su~gcsts that tlie Just after reaction, "the molecules of the reaction products mechanisni of inliibition by this substance is addition of possess an available energy great.ly in exccss of t,be mean water to form a trili3.droxynaphthalene, an oxidizable subenergy at the temperature considered. Now, these very st,ance wlriclr is the actual inhibitor. Such an addition was 'liot' molecules have sufficient energy to activate molecules shown by Fieser and Peters (IO) to be the first step in the of the rcactants at the first encounter, and when these react, decomposition of 1,2-naplithoquinone, which is urLst.able in the resultants in their turn again are able to act as activators, solution.and so on. Consequently, it is possible that the occurrence During the period in which it protects a substance from of one elementary reaction mill give rise t,o a whole series of oxidation, an inhihi...

Few fields in hydrocarbon chemistry offer the variety and the interest presented by the reactions of polymerization and decomposition of the acetylene hydrocarbons. The many products include gases, aliphatic and aromatic liquids, tars, and solids of unusual properties. There is variety too, in the means used to cause reaction, which include heat, chemical reagents, detonants, electric discharge, alpha particles, cathode rays, light, and electro-magnetic fields.The interest in these reactions lies in part in their variability under changing experimental conditions. A single method of excitation, depending upon the conditions under which it is employed, may give rise to a gas, a low-boiling liquid, or an infusible solid. The elucidation of the mechanisms by which products so varied come from a single substance is a study of compelling interest. Attention is drawn to these reactions, moreover, by their commercial significance. Acetylenes have been proposed-and to some extent used-as a source of carbon, aromatic hydrocarbons, drying oils, synthetic rubber, and porous adsorbents.Reactions of polymerization and decomposition are considered together for two reasons.As in the case of hydrocarbons of other series, changes of both types may be produced by the same agencies, and they often occur simultaneously.Almost exclusively the investigations recorded concern acetylene itself. Only a few of the higher members of the series have been studied. This is understandable, as acetylene is readily obtained and there is hope of obtaining useful substances from it, while its homologs, even in the laboratory, are rarities.I. Acetylene A. Introduction.The outstanding properties of acetylene are its unsaturation and its endothermic character. To its unsaturation, enabling it to add to itself, or to other substances, may be attributed its ability to form simple and complex polymers. Its endothermic character tenders it unstable, so that violent excitation, particularly at somewhat elevated pressure, will cause it to revert to its elements, sometimes with explosive violence.Acetylene may be converted into polymers of comparatively simple structure by combination of two, three or four molecules, under the action of chemical reagents or the silent discharge, but only if reaction is carried out * Presented before the

This survey covers the changes occurring when ' .uns are subjected to heat or pressure, with or without the aid of catalysts, to a number of chemical reagents, to photolysis, to electric sparks or discharge, and to alpha particles. While these agencies are not alike in their effects on hydrocarbons of the ethylene series there are similarities in their action which justify their discussion together. The reactions occurring are of three types. There may be breakdown of the molecule consisting in some cases merely of hydrogen loss, and in others of more deep-seated change, which go so far as to produce carbon and hydrogen as sole products. As an alternative, the change can be one of synthesis giving rise to hydrocarbons with more atoms in their molecules than the starting substance. Or merely a molecular rearrangement takes place-usually a shift in the position of the double bond-without variation in molecular size. Under some conditions change of but one of these types occurs. But often changes of these three classes are brought about by the same means, either concurrently or simultaneously, the type of reaction changing with experimental conditions.The action of heat, for example, may produce changes of the three types With mild heating, rearrangement or polymerization reactions predominate, and may be the only ones occurring. They produce olefin or naphthene hydrocarbons of molecular weight greater than that of the starting substance. Change of this type is aided by superatmospheric pressure. At more elevated temperatures, while polymerization continues, there form simultaneously carbon, hydrogen, acetylene, and low molecular weight olefins and paraffins as a result of disruptive changes. At elevated temperatures the higher olefins produced by polymerization tend to become in part converted into aromatic hydrocarbons. At very high temperatures practically no polymerization takes place, and the primary products obtained from olefins are carbon and hydrogen. Catalysts notably lower the temperature at which changes in olefins take place. Some catalysts favor disruptive changes, while others aid polymerization.The electric spark or arc causes changes in olefins similar to those occasioned by high temperature-a small amount of polymerization occurs, but, in the main, there is decomposition to carbon, hydrogen, and methane. The reactions caused by the silent discharge, on the other hand, are indicated to be almost exclusively polymerization.The action of the chemical reagents discussed in this paper is largely polymerization, except that at elevated temperatures disruptive reactions occur.