THE CHEMICAL WORLD THIS WEEK
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Just prior to the Palladium Medal Award Address, Karl F . Hager of Redstone Arsenal surprised medallist Carl Wagner of MIT with a special citation from a group of Dr. Wagner's former associates in the Ordnance Department
Electrochemical Society A w a r d s Palladium M e d a l to Carl W a g n e r C&EN
REPORTS: E l e c t r o c h e m i c a l S o c i e t y , 1 0 0 t h Annual M e e t i n g
DETROIT.—For his "outstanding achievements in the study of corrosion of metals, and its control," Carl Wagner, visiting professor of metallurgy at MIT, was honored here recently as first recipient of the Palladium Medal of the Electrochemical Society. Established in 1950, the medal will be awarded every two years to a scientist, either U. S. or foreign, for notable contributions to the knowledge of metal corrosion. Dr. Wagner is best known in the corrosion field for his theory that metal oxidation is not a direct chemical reaction, but can be interpreted as an electrochemical process. This theory, first advanced in the early 1930's, formed the foundation for Dr. Wagner's award lecture, which he presented at a special session during the society's 100th meeting. Registration at the meeting surpassed the 500 mark; the technical program included about 50 formal papers and several round table discussions, in which seven of the society's nine technical divisions were represented. In the electrolytic reduction of nitrobenzene, which yields both p-arninophenol and aniline, any increase in the temperature or in the acid strength of the electrolyte will cause an increase in the yield of the phenol, at the expense of the amine. 4476
For example, as acid strength is increased from 5 to 40%, according to Christopher L. Wilson of Ohio State University, the fraction of phenol in the product is increased from 50 to 75%. Yields are not affected by changes in current density if the cathode is being rotated at 1000 r.p.m. or faster, or if the electrolyte is subjected to strong agitation. At a given current density, however, rotation of the cathode raises the proportion of aminophenol formed, and increases current efficiency to virtually 100%. This phenomenon, said Dr. Wilson, signifies that diffusion to or from the cathode is the rate-controlling
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CHEMICAL
step in this process—at least up to the point where a definite rninimum rate of shear as reached. Under optimum conditions, Dr. Wilson added, a wide variety of aminophenols may be produced in yields from 70 to 85%, by electrolytic reduction of the proper aromatic nitro compounds. In electro-organic reductions where carbon cathodes are indicated, graphite is most likely to give favorable results. Describing experiments in which a wide variety of organic compounds were electrolytically reduced with graphite, gasbaked coke, and lampblack cathodes, Sherlock Swann, Jr., of the University of Illinois reported that in nearly all cases the graphite cathode proved equal to the better of the other two types. In the majority of cases, the graphite excelled both the coke and lampblack types. The most notable exception, said Dr. Swann, was found in the reduction of azobenzene; in this reaction, the coke cathode gave a yield of about 73%, as compared with values of about 58% for both the other carbon types. In an attempt at bi- or polymolecular reduction of pyridine in acid solution, Dr. Swann continued, graphite was the only cathode which produced high-boiling materials, believed to be the desired coupling products. But for an uneconomic ally high rate of lead anode corrosion, chloroacetic acid could probably be produced commercially, and at competitive prices, by the electrolytic oxidation of ohloroacetaldehyde. Using a sheet lead anode in 30% sulfuric acid, FI. H. Roth of the Dow Chemical Co. obtained current efficiencies of 8 1 % and a yield of 89% at a conversion of 2 1 % to chloroacetic acid. The loss of one pound of lead for each 202 pounds of acid formed, however, makes the process too costly for commercial application, said Dr. Roth. Several lead alloys were tested as anodes, he added, but all were characterized by unsatisfactory corrosion rates. In the discussion which followed Dr. Robh's paper, Hans Neumark of General Chemical Co. suggested that calcium-lead and lithium-lead alloys be tested for this application. These alloys have demonstrated remarkable corrosion-resisting properties in other applications, Dr. Neumark recalled. Phenylmercuric compounds and mercurated allylanddes are reduced at the dropping mercury electrode, with the acquisition of two electrons and the intermediate formation of organomercury free radicals, according to Reinhold Benesch of Northwestern University. This phenomenon makes possible a specific and direct assay of organically bound mercury, important in physiological studies, in which organic mercury compounds are useful in the quantitative determination of sulfhydryl groups. AND
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Corrosion Division It has -been established with some certainty that the rates of reaction of pure evaporated iron films can be altered by first exposing the films to gaseous oxygen or carbon monoxide, or to a solution of potassium dichromate. In experimental studies, any of these agents reduced the reaction rate of iron in nitric acid, said H. H. Uhlig of MIT. The effect could be partially reversed by evacuation to remove the protective gases, or by washing in the case of the dichromate solution. Through the use of radioactive tracers, it is possible to measure directly, by a count of gamma emission, the amount of sodium chromate adhering as a passivating layer to a steel surface. According to Robert A. Powers of the University of Texas, the amount of radioactivity remaining on a treated steel surface indicated that a monolayer of chromate 0.65 complete adhered after washing. Radioaudiographs showed that t h e partial monolayer was uniformly distributed, except when experimental conditions were such that local currents flowed between metal and solution, E>r. Powers stated. In a study of the mechanism of dissolution of titanium in acids, M. E. Straumanis of the University of Missouri reported that in the presence of fluoride ion, titanium approaches its thermodynamic potential, because the fluoride forms a complex with the titanium, and thereby prevents precipitation of the oxide by hydrolysis. Under these conditions, said Dr. Straumanis, the electrochemical concept for dissolution rates of titanium, and probably of other metals, can be used to express quantitatively the relationships for the kinetics of dissolution. Although titanium exhibits extraordinary resistance to attack by many highly corrosive agents, such as nitric acid and sea water, it is rapidly attacked by either hydrochloric or sulfuric acid. The extent of such corrosion may be greatly reduced, said Joseph R. Cobb of MIT, by the addition of ferric or cupric ions as inhibitors. For samples of titanium in boiling 10% sulfuric acid, the corrosion rate was cut from about 10,000 to about 5 to 55 milligrams per square diameter per day by the addition of 3 to 5 millimoles of cupric or ferric ions per liter. Concerning the mechanism of this inhibitory action, H. H. Uhlig, the coauthor, expressed the belief that titanium oxide is not responsible for the protection, although this oxide is undoubtedly formed. It appears, said Dr. Uhlig, that inhibitor (ferric or cupric ) ions are adsorbed on the metal surface, where each borrows an electron from the titanium, to form a dipole monolayer with its negative charge extending outward. The characteristic color of the inhibitory film—dark blue in the case of copper, and reddish brown in the case of iron—is probably caused by the occlusion of salt particles in the titanium oxide and protective monolayer. For oxidations of copper in the temperature range of 200° to 400° C , cuprous oxide is found to be the principal oxide in VOLUME
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INDUSTRY selects FURFURYL ALCOHOL
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2. CHEMICALLY INERT RESIN: FA is extremely reactive in the presence of acids with or witlhoiu: the application of external heat. W h e n such resin is cured, acid, solvent, and alkali inert products are formed.These resins form the basis for corrosion resistant mortars, cements, reinforced linings, and molded chemical-inert equipment.
3. RING OPENING REACTIONS: Although not yet as commercially important as the solvent and resin applications, reactions involving the FA ring offer potentially valuable routes to chain compounds such as levulinic acid. N o w is the time to write for a bulletin about FA and tc Income better acquainted with the properties of this industrial chemical. *Reg. U. S. Pat. Off.
Eg Th^ Quaker Qate(pmpany 333K THE M E R C H A N D I S E M A R T CHICAGO 54, ILLINOIS N « w Y o » k , Room 533K, 1 2 0 Wall St., N . y . 5 , N . Y. I n San Francisco, The Griffin Chemical Company • In Australia, Swift & Company, Pty. Ltd., Sydney* In Europe, Quaker Oats-Graanproducten N. V . , Rotterdam,The Netherlands; QuakerOats (France) S. A . 4 2 , Rue Posquier, Paris 8E, France • In Japan, F. Kanematsu & Company, Ltd., Tokyo
OCTOBER
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THE CHEMICAL WORLD THIS WEEK t h e surface layer, according to E a r l A. Gulbransen of Westinghouse Research Laboratories. In long oxidation periods a t 400° and 5 0 0 ° , cupric oxide also is formed; i n high vacuum the cupric oxide disappears, through solid phase reaction w i t h copper to form cuprous oxide. These observations show, said Dr. Gulbransen, t h a t at temperatures of 200° to 5 0 0 ° C , the cuprous ion diffuses through t h e cuprous oxide structure. Reflections having spac-ings of about 2.75 A. and 2.00 A.,
The Cover
Carl W a g n e r ' • p w o years ago there appeared on the -"- campus of M I T a small, quiet man, with a fading German accent who 20 years ago brought disorder into the theory of physical chemistry a n d thereby provided the key to the understanding of many of the more obscure physical-chemical phenomena. His n a m e was Carl Wagner, and with seeming improbability he came to join t h e d e p a r t m e n t of metallurgy. But his new appointment was merely another evidence that the -basic theory that he helped to discover many years ago h a d proved a p plicable in yet another practical area— that of t h e behavior of metal alloys. Already, workers in photochemistry, luminescence, electrical conductivity, and many other fields h a d acknowledged their debt to him. T h e thread of theory that Dr. W a g ner picked u p early in his career and that has led him through many fields and many laboratories on two continents is t h a t of the irregularities in crystal structures. He was trained as an electrochemist u n d e r Max L e Blanc at the University of Leipzig and soon became interested in diffusion and conductivity phenomena in solid salts. Like almost all chemists of a mathematical turn of mind he sought his solutions in terms of thermodynamics and reaction kinetics. His thermodynamic studies led him to W. Sohottky and with him ultimately to an expl n^**oa of solid state p h e n o m e n a in term* "rder, and deviations from ideal stoichiometric proportions in the crystal lattice. Once the existence of such lattice imperfections was granted il b e c a m e possible for ions a n d electrons to move through the solid and transport charges. A perfect lattice was almost insurmountably stable—the introduction of "disorder" m a d e it flexible and began to explain t h e phenomena of the solid state. A n unassuming nature and a sincere modesty has kept Dr. W a g n e r out of
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found in electron diffraction studies of the cupric oxide structure, probably are caused b y an impure oxide, Dr. Gulbransen o b served. T h e impure oxide, probably lead, may b e derived from the copper sample itself, and concentrated in the surface layer during oxidation, or it m a y be picked up from the environment during the experiment. Electrodeposition A new and highly effective bath for the
the limelight, even among his professional colleagues outside of his own field. However, his reputation was sufficiently impressive that h e was among the first scientists contacted by American occupation forces when they entered Germany, a n d h e was immediately transported from his laboratories in Darmstadt to a place of greater safety in Great Britain. Soon after the war ended h e came to the United States as scientific advisor to the ordnance and development division of t h e Army at Fort Bliss, Tex. W h e n his contract with the Army expired Dr. W a g n e r elected to remain in this country a n d accepted the appointment at MIT. H e has now applied for American citizenship. At H o m e in America Especially since he has moved into a civilian atmosphere more nearly comparable to his former life h e finds himself remarkably at home in the American environment. Having been at various times on the faculties of the Universities of Munich, Berlin, Jena, Hamburg, and the D a r m s t a d t Technische Hochschuie, Wagner is in an excellent position to compare t h e educational systems of Germany a n d the United States. His observation h a s been that the similarities are more surprising than the differences. T h e differences he has observed have been in minor points of procedure and protocol. The fundamental approach to teaching and the philosophy of education, h e says, are almost indistinguishable in the two countries. There are a few phases of his present work that Dr. W a g n e r would like to tie into a neat package. There is a paper that was almost finished in 1936 and has since been sidetracked by more topical studies including consulting work for the Pennemunde Laboratories. T h e paper deals with the oxidation of metal alloys and Wagner's present position at M I T should permit him to finish this work. This work was p a r t of his study of high temperature oxidation which has brought him his most recent acclaim and for which he is currently being honored with the Palladium Medal. In a series of papers, some published in this
CHEMICAL
electrodeposition of aluminum, described by D w i g h t E. Couoh of the National Bureau of Standards, consists of a solution of aluminum chloride in ethyl ether, to which lithium hydride has b e e n added in t h e amount of 0.5 to 1.5 moles per liter. T h e aluminum deposits are ductile, said Dr. Couch, and can be made in excellent quality up to relatively great thicknesses; platings from 0.75 to 1.0 m m . thick have already been prepared. Lithium hydride has an advantage in that its solubility is more
country since the war, W a g n e r has proved that the oxidation of metals in a gaseous atmosphere after the first instant of contact may be regarded as an electrochemical reaction with the oxide layer acting as a solid electrolyte. This concept has been checked by careful measurements of t h e oxidation rates of certain metals and has made possible the interpretation of the mechanism of such oxidations in many others. This contribution has been called the most important addition to corrosion theory since the proposal of t h e electrolytic nature of corrosion in aqueous media. F r o m t h e nature of his contributions it might b e assumed that Carl W a g n e r is pretty much of a desk and slide rule chemist and in some respects that is true. Mathematics is both a facile tool and an irrefutable proof in his scheme of research and he believes in spending much time in mental analysis of the problem both before and after the experiment. But he does believe in the experiment, and when h e has conducted the experimental work himself it has been characterized not only by simplicity and unassailable pertinence but by consummate technique as well. Although his present post of visiting professor casts him in the role of a "thinking" scientist rather than an experimenting one it is reported that he is often seen in the laboratories carrying out some of the experimental work that comes under his direction. If asked insistently about his recreations W a g n e r would list those of the typical intellectual bachelor: music, lectures, t h e theatre, provocative conversation, plus, of course, walking. But then he would add t h a t you really must consider his flights into mathematics as recreation because h e does sometimes make them just for sheer enjoyment. If they are to b e called recreation, however, they must b e considered as a highly constructive pastime since they have resulted in some new ideas even in the field of pure mathematics. Wagner's one other nonchemical pursuit is sight-seeing, b u t he insists that it is not a recreation. This is something that one "should do."
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