IKDUSTRIAL AND ENGINEERING CHEMISTRY
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(4) Cameron, E. J., and Esty, J. R., J . Infectious Diseases, 39, 89(5)
(6) (7) (8) (9) (10) (11)
105 (1926). Cameron, E. J., and Williams, C. C., Centr. Bakt. Parasitenk., I1 Bbt., 76, 28-37 (1928). Cameron, E. J., and Yesair, J . , Canning Age, 12, 239 (1931). Cheney, E. W., J. Med. Research, 40, 177 (1919). Donk, P. J., J. Bact., 5 , 373 (1920). Esty, J. R., and Stevenson, A. E., J . Infectious Diseases. 36,486 (1925). James, L. H., J . Bact., 13, 409 (1927). James, L. H., Food Industries, p. 265 (1928).
Vol. 24, No. 9
Kuhr, Wohlzogen Arch. Zuckerind., S o . 31 (1923). Owen, W. L., La. Agr. Expt. Sta., Bull. 125 (1911). Weinsirl, J., J . Med. Research, 39,349 (1919). Werkman, C. H., Iowa Agr. Expt. Sta., Station Bull. 117, 16380 (1929). (16) Werkman, C. H., and Weaver, H. J., Iowa State Coll. J . S a . , 2, 57-67 (1927).
(12) (13) (14) (15)
RECEIVED April 8 , 1932. Presented before the Division of Sugar Chemistry at the 83rd Meeting of the American Chemical Society, New Orleans, L a , March 28 t o April 1, 1933.
The Yellowing of Oils 111. Relation between Color and Chemical Constitution of Oxidized Drying Oils A. C. ELMAND G. W. STANDEN, The New Jersey Zinc Company, Palmerton, Pa.
A
NUMBER of investigations (3, 7 ) have established the fact that the yellowing of oils upon interior exposure and in the absence of light is caused by the formation of colored oxidation products of the more highly unsaturated glycerides. The various investigators of this field, however, disagree as to the exact chemical constitution of these oxyns. Elm (2) adopted Scheiber’s theory that the colored compounds are polyketones, whereas Morrell and Marks (8) came to the conclusion that yellowing is caused by the keto-enol tautomerism of ketohydroxy compounds formed from the oil peroxides by a simple intramolecular rearrangement. -4final decision in favor of one or the other hypothesis on the basis of the chemical evidence is extremely difficult, although there are indications that these compounds are present
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able to formulate widely accepted theories as to the relation between the color and chemical constitution of organic compounds. A detailed discussion of the relations between color and molecular structure is unnecessary here, for, ever since it was first discussed by Graebe and Liebermann in 1867, this subject has received so much attention that a t least a brief account of it is found in every good textbook on organic or physical chemistry, as the one by Smiles, for example (9). When comparing the structures of colored compounds with those of colorless derivatives, it is evident that the color of the former is caused by the presence of certain groups, called “chromophores.” The dicarbonyl group, -CO-CO-, is among the more important chromophores and induces yellow color as demonstrated by diacetyl (CHICOCOCH,), b e n d (CJ&CO.COCJ&), and others. Statements as to the chromophoric properties of the ketohydroxy or its tautomeric form -C(OH)= group -COCH,OHC(0H)- in aliphatic compounds could not be found in the literature. Although for reasons of analogy (for example, benzoin CeHsCOCHOHG-Hs, and ketoses) this grouping of atoms is not expected to cause selective absorption of light in the visible region of the spectrum, it was thought advisable to investigate this point, for one of the outstanding theories of yellowing is based on the presence or formation of such compounds in drying-oil films.
EXPERIMENTAL PROCEDURE Ketohydroxy- and diketostearic acids were prepared by progressive oxidation of oleic acid as illustrated by the following scheme: ,?OM
yY)O
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O Y I U T I O N FREQUENCY
FIGURE1
in oxidized drying oils. Attempts a t their isolation and identification have proved unsuccessful because the chemical reactions necessary to unravel the complicated mixture making up drying-oil films usually result in the disruption of the oxyns. I n the course of the analysis new compounds are formed which make it unusually difficult to draw any definite conclusions as to the exact chemical constitution of the oxidized glycerides as present in the films. The history of organic chemistry is full of similar cases in which, after the usual chemical methods had failed, physical and especially optical measurements formed the basis for the final decision. Especially the dyestuff chemists have made frequent and successful use of these methods and have been
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The methods followed are described by Lewkowitch (6) and Holde and Marcusson (4). The transmission spectra of alcoholic solutions of these compounds were determined using a Baly cell ( 5 ) and a Hilger spectrograph (1). The light source was an iron arc, the time of exposure one minute. Photographs were taken of the original (0.2 11‘) and the diluted (0.02 N ) solutions a t a distance between the cell windows of 40,30,20,10, and 5 mm. The results (Figure 1) are set forth in the usual manner-
September, 1932
I N D U S T R 1.4 L A N D E N G I N E E R I N G C H E M I S T R Y
that is, by plotting the oscillation frequencies of the limits of the absorption bands against the logarithms of the relative thicknesses of the solutions (10). DISCUSSIONOF RESULTS As anticipated, the diketostearic acid is yellow, while the ketohydroxystearic acid is colorless. The position and the persistence of the absorption bands are clearly shown by the curves. The diketostearic acid has a well-defined absorption band in the blue end of the visible spectrum and shows the same light absorption characteristics as the diacetyl and the thymoquinone whose absorption curves are reproduced from Smiles ( 1 1 ) for comparison. The ketohydroxystearic acid shows a less pronounced selective absorption which, however, is entirely located in the ultra-violet region and, therefore, cannot produce visible color. Even the addition of an excess of alkali does not produce visible color. It is obvious, then, that the yellowing of oxidized drying oils be due to the presence Or formation Of ketohydroxy Of the problem in the The therefore, be sought in a different direction.
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ACKNOWLEDGMENT The authors wish to thank J. s. Long and J. G. SmuU of Lehigh University for the preparation and identification of the ketohydroxy- and diketostearic acids. LITERATURE CITED Baly, “Spectroacopy,” 3rd ed., Vol. I, p. 117, Longmans, 1924. (2) E l m , IXD. ENG.CHEM., 23, 885 (1931); Paint V a r n i s h Prodiiction Munager, 30 (Sept., 1931); Qfiiciul Digest, 105, 474 (1931). Elm, ISD.ESG. CHEM.,23, 886, literature cited (1931). (3) (4) Holde and Marcusson, Ber., 36, 2657 (1903). (5) Houben, “Die Methoden der organischen Chemie.” 3rd ed., P a r t I, p. 280, Georg Thieme, Leipzig, 1925. (6) Lewkowitch, “Chemical Technology of Oils, Fats, and Waxes,” 6th ed., Vol. I, p. 575, hlacmillan, 1921. (7) Morrell and Marks, J . SOC.Chem. Ind., 50, 27 (1931). ( 8 ) Morrell and Marks, I b i d . , 50, 30 (1931). (9) Smiles. “Relations between Chemical Constitution and Some Physical Properties,” pp. 324-423, John Long, London, 1910. (10) Smiles, Ibid., p. 329. (11) Smiles, I b i d . , pp. 372 and 374. RECEIVEDApril 7. 1932. Presented before the Division of Paint and Varnish Chemistry at the 83rd Meeting of the American Chemical Society, New Orleans, La.. March 28 to April 1, 1932.
Moisture Sorption b.y Carbon Black CHARLES S. DEWEYAND PAUL K. LEFFORGE, Godfrey L. Cabot, Inc., Boston, Mass.
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G o o d w i n and Park also comH E s o r p t i o n of water The moisture content of carbon blacks is pared natural moisture with that vapor on carbon blacks dependent upon the concentration of water a t a low-temperature saturation. has received considerable vapor. The znriation, however, is not repreLeBlanc, K r o g e r , and Kloz attention from t h e p r a c t i c a l sented by Freundlich’s equation for adsorption, carefully determined the rate of standpoint. There is, in addinor by simpler straight-line functions such as moisture sorption for a variety of tion, a definite relationship beblacks. Their samples were extween m o i s t u r e sorption a n d Henry’s law. The isotherms are generally S posed in shallow layers. In 15 other chemical properties of this shaped, varying widely f r o m slightly irregular to 20 minutes they acquired apmaterial which as yet has relines io the accentuated curves f o u n d with acproximately half of the increased ceived scant public a t t e n t i o n . t icated charcoal. water content whichwasobserved This relationship can be indiA210isture sorption data obtained with cona t equilibrium after 4 to 5 hours. cated by a comparative study of A more a c c u r a t e study has various carbon blacks and other trolled humidity can be definitely correlated to been indicated by Wilson and carbons, such as lampblack and other adsorption tests f o r both carbon blacks and Fum-a (34, who r e p o r t e d the activated charcoal. charcoal. They are readily reproducible, and moisture content of various maThe practical significance of indicate the practical possibilities of this admoisture c o n t e n t was emphaterials for a large range of humidisorption indt>x. ilpplication to trade requiresized by Johnson in 1928 (17). ties. They found that carbon He called the attention of the black (for rubber) took up 6 per ments in pigment carbons m a y be developed by rubber industry to the effect of cent water when a t equilibrium a n expansion of this study. atmospheric humidity upon the in an atmosphere of 90 per cent humidity a t 25” C. Activated m o i s t u r e content of custompacked carbon black. He showed that the weight of water in- charcoal under the same conditions contained 33 per cent side a packed sack varied with changes in air conditions, corn- water on the dry basis. ing to an equilibrium with any continued condition after The reverse effect-that of removing water from carbon black by means other than heat-is mentioned in the literaseveral days. The sorption on carbon black of water vapor from a satu- ture less frequently. S e a l and Perrott studied this, as noted rated gaseous phase has been reported by Neal and Perrott above. LeBlanc, Kroger, and Kloz dried their samples for ( 2 4 , Wiegand and Boggs (52), Goodwin and Park ( 1 4 , and saturation study over phosphoric anhydride. Moisture adby LeBlanc, Kroger, and Kloz (19). The conditions covered sorption and desorption (the term “sorption” is used in this have varied from thermostatic room-temperature control paper to represent the acquisition and retention, by various to storage in an ice box. Kea1 and Perrott reported initial materials, of moisture in equilibrium with water vapor, except moisture a t a natural humidity of about 60 per cent, loss in when modifying ideas are to be expressed) on charcoal have weight by drying over sulfuric acid, and moisture regain over been carefully studied by many investigators, notably by water, all a t 25” C. Wiegand and Boggs refer to a “moisture Lowry and Hulett (20-22), Coolidge (9-11), and Allmand and index” which seems to correspond roughly with their di- eo-workers (1-3). phenylguanidine and potassium hydroxide adsorption indices. In contrast with charcoal, apparently little work has been
