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V O L U M E 27, N O . 1, J A N U A R Y 1 9 5 5 factors seemed to be most important, the moisture content and the temperature. Accordingly, alumina of two different activities was prepared by controlling the humidity and temperature of the atmosphere surrounding it. The temperature was maintained a t 77’ F. in both cases; but the relative humidity of the air-conditioned room was kept a t 50% for one preparation while the second system used a desiccator containing anhydrous calcium chloride. After standing for 6 days, the alumina was found to have a constant activity. The absorbent equilibrated a t the lower humidity had the higher activity. Alumina prepared in this manner had a remarkably constant activity which could be reproduced without need of standardization. Ewing, Sharpe, and Bird (15) used the same idea by employing a constant humidity produced with sulfuric acid solutions. Most of the variables affecting columnar chromatography, as treated by Weil-Malherbe (E?),were carefully controlled. The initial volume of the solvent was larger than that usually employed, but this amount was found necessary in order to ensure proper solution of the sample. The principal ingredient of each of the antioxidants studied was eluted in the first six fractions of Procedure A . As the method was designed for the isolation and identification of the accelerator, Zniercaptobeneothiazole, as well as the antioxidants in the acetone extract, this procedure was necessary. I n a few cases, a direct separation of antioxidants employing Procedure B without prior use of Procedure A produced the same results as were obtained when both procedures were used. Hence, it would seem that the preliminary separation by Procedure A is not necessary for the isolation of antioxidants. Other compounding ingredients may hasten or retard elutions. Even though elutions were usually in the same fractions, it was found to be advisable to inspect two or three fractions on either side of the one ordinarily examined before an antioxidant was stated as absent. ZMercaptobenzothiazole, pine tar, sulfur, paraffin, stearic acid, and the extracts from HAF carbon black and smoked sheet \\ere examined. Pine tar interfered somewhat with the ultraviolet spectrum of B-LE; but no difficulty has been experienced
in detecting this antioxidant in the vulcanizates studied, some of which contained pine tar. There is a fraction of the acetone extract from smoked sheet eluted in the fractions containing 12’phenyl-2-naphthylamine and 2,2,4-trimethyl-6-pheny1-1,2-dihydroquinoline but the ultraviolet absorption was less than an absorptivity of two for the entire range from 220 to 400 mp. The rest of the compounding ingredients do not interfere. LITERATURE CITED (1) Bellamy, L. J., Lawrie, J. H., and Press, E. W. S., Trans. Inst. Rubber Ind., 22, 308 (1947). (2) Ibid., 23, 15 (1947). (3) Brockmann, H., and Schodder, H., Ber., 74B, 73 (1941). (4) Budig, K. H., Kautschuck u . Gummi, 1, 305 (1948). (5) Burchfield, H. P., and Judy, J. N., ANAL. CHEM.,19, 786 (1947). (6) Burmistrov, S. I., Zavodskaya Lab., 14, 787 (1948). (7) Craig, D., IND. ENG.CHEM.,ANAL.ED.,9, 56 (1937). (8) Deal, A. J. A., Trans. Inst. Rubber Ind., 23, 148 (1947). (9) Endb, H., J . SOC.Chem. I n d . , J a p a n , 38, Suppl. binding, 618 (1935). (10) Ibid., 39, Suppl. binding, 11 (1936). (11) Ibid., p. 12. (12) Ibid.. D. 17. (13j Ibid.; 52. (14) Ibid., p. 146. (15) Ewing, D. T., Sharpe. L. H., and Bird, 0. D., ANAL.CHEM.,2.5, 599 (1953). (16) Howland, L. H., and Hart, E. J., IND.ENQ.CHEM.,ANAL.ED., 12, 81 (1940). (17) Koide, T., Kubota, T., Furuhashi, M.,and Sato, T., J. SOC. Rubber I n d . J a p a n , 22, 108 (1949). (18) Koide, T., Kubota, T., and Sato, T., Ibid., 22, 256 (1949). (19) Mann, J., Trans. Inst. Rubber Ind., 27, 232 (1951). (20) Muller, P. B., Helv. Chim. Acta, 26, 1945 (1943). (21) Ibid., 27, 404 (1944). (22) Parker, C. A., and Berriman, J. M.,Trans. Inst. Rubber Ind., 28, 279 (1952). (23) Weil-Malherbe, H., J . Chem. SOC.,303 (1943).
i.
RECEIVED for review April 28, 1954. Accepted August 27, 1954. Preaented a t the Pittsburgh Conference on Analytical Chemistry a n d Applied Spectroscopy, March 5 , 1954. Contribution No. 185 from the Goodyear Tire and Rubber Co., b k r o n , Ohio.
Halogen-Co balt (II) Acetate-Ace tic Acid Solutions in Organic Qualitative PHILIP C. DAIDONE The Baker Castor
Oil Co.,
Bayonne,
N. J.
The presence of active unsaturation is indicated by testing the substance with a solution of halogen and cobalt(I1) acetate in acetic acid to give a blue color. Other groups, in general, fail to give any color or give different colors which can assist in their identification as a class.
T
HE use of bromine solutions to spot-test for active unsaturation is standard procedure in organic qualitative analysis. In’dealing with minute samples, however, the test has its limitations, as the disappearance of the color may result from dissolution of the bromine as well as bromination by substitution. Other spot tests usually serve to supplement the bromine test. In order to provide an additional supplementary test for groups that halogenate easily, the writer performed rather interesting tests which provide information which could be useful in qualitative analysis. The work is by no means exhaustive, but merely a starting point, so that others niight evaluate its potential usefulness.
Various organic compounds were halogenated with bromirie and with chlorine in the presence of cobalt(I1) acetate tetrahydrate, with the result that a very sensitive color test was developed, primarily t o provide experimental proof for the existence of an ethylene bond, or an easily substituted hydrogen. Further observations indicate a possible extension to oxygenated compounds, but exceptions were apparent. Tables I and I1 contain the observations made when the test was applied to a variety of compound. DISCUS SIOh
The formation of a blue color indicates the conversion of cobalt(I1) acetate to either cobalt(I1) chloride or cobalt(I1) chloride-acetate. At the same time chloroacetoxylation of tht. unsaturated linkage occurs. This view agrees well n i t h experience, for it is known that ethylene will form P-chloroethyl acetate when it is chlorinated in the presence of sodium acetate (1). The blue color formed by hubl)ling dry hydrochloric acid into an acetic acid solution of
ANALYTICAL CHEMISTRY
104
cohalt(I1) acetate was about the same as observed when the writer performed the test herein described. The colors resulting from oxygenated compounds present a more complex problem, and i t is suggested that somesortof coordination complex forms involving the unshared pair of electrons present on the oxygen. Ether responds to give a green color. Ether and cobalt(I1) acetate alone do not form a color, which proves the necessity for halogen in the test. The fact that ether and dioxane can form onium salts may account for the green color produced in the test. The colors resulting from aldehydes cannot be correlated with the failure of acetone t o give a rapid color formation. Both types-namely, aldehydes and ketoneshowever, do give colors, as would be expected from their ahydrogen Yrtivitr.
Table 1.
Color Formation Resulting from Bromination of Organic Compounds
Compound Blank Pyridine Monoethanolamine Dicyandianiide Heptaldehyde Benzaldehyde Acetaldol Acetone n-Butanol Glycerol Ethylene & col Hexamethylene glycol hl et hanol
Color o n Reaction Yellon Lavender Lavender Green Green-blue Olive green Straw Yellow Green Yellow Yellow Yellow Yellow
Dioxane Methyl ricinoleate Linoleic acids Oleic acid Butyl oleate Methyl undecylenate a-Pinene Benzene Toluene r u m a r i c acid Dibutyl sehacate Petroleum ether Chloroform E t h j l acetate %Naphthol
Green Blue Blue-green Blue Blue Blue Blue Yellow Yellow Yellow Yellow Blue Yellow Yellow Green
Color after 2 IIoiirs Yellow Lavender Lavender Green Olive green Green Straw Blue Blue-green Yellow Yellow Green Yellow Blue-green Green Rhir
Table 11. Color Formation Resulting from the Chlorination of Organic Compounds Compound Pyridine Aniline Dimethylaniline hlonoethanolamine 2.4-Dinitrophenylhydrazine Dicyandianiide Acetone Heptaldehyde Benzaldehyde Isophorone Phenol Phloroglucinol 2-Naphthol Methanol Isopropyl alcohol 1-Butanol 1IethyI isobutyl carbinol Glycerol Ethylene glycol Hexainethj lene gl) col Dioxane Ether Benzene Tohiene Xylene p-Toluenesulfonic acid a-Pinene Oleic acid But? 1 oleate Methyl ricinoleate hlethyl undecylenate Ethyl acetate Petroleum ether Chloroform Dibutyl sebacate Iso-octane Starch Fumaric acid
Color on Reaction Purple Dark br0u.n Dark green Deep blue Green Blue
Color after 2 Hours Purple Dark brown Very dark grrrn Deep blue
..
S o change Medium green Light olive green Blue Blue green Blue green Blue green S o change Blue Light green Green X o change N o change S o change Green Green S o change Light green Blue N o change Blue Blue Blue Blue Blue Blue Blue S o change S o change S o change S o change h-0 change
...
...
. . ...
...
...
Oi&
green Light blue Blue green Faint lavender Faint lavender Yelloa Green Yellow Yellow Blue Yellow Blue
Nitrogen compounds were quick to respond to color formation. Aniline derivatives gave very intense colors which could not be correlated. Compounds known to be resistant to halogenation-cg., dibutyl sebacate-resisted color formation and merely diluted the test solution. Compounds of low molecular weight-e.g. , ethyl a c e t a t e - n ere evidently not resistant to halogen. Like many qualitative tests, there are exceptions, but from a knowledge of the physical properties (molecular weight) and the general type of chemical, its purity as regards unsaturation in very small concentration may be qualitatively shown to be present or absent. .is in other analytical tests, there are interfering substances, but the application of the test described can be used to advantage in specific cases. The degree of hydrogenation, for example, can be followed by spot testing with the cobalt acetate-bromine reagent, the color intensity being the guide. Halogenation may similarly be followed qualitatively by the test procedure employed for following hydrogenation. EXPERIMENTAL
Preparation of Bromine-Cobalt Acetate-Acetic Acid Solution Three liters of reagent may be prepared by dissolving 2.5 grams of cobalt(I1) acetate tetrahydrate in 1 liter of glacial acetic acid. T o this are added 8.1 grams of bromine in about 1 liter of glacial acetic acid. The reagent is then diluted to the 3-liter mark. The reagent is stored in a n amber stork b?ttle.
Preparation of Chlorine-Cobalt Acetate-Acetic Acid Solution. A solution of 2.5 grams of cobalt( 11)acetate tetrahydrate in 1 liter of glacial acetic acid is saturated with chlorine gas. The solution must be used freshly for testing organic compounds for color formation, as the chlorine is gradually lost to the atmosphere. -4modified procedure consists in preparing the solution in a funnel and maintaining a slow but steady flow of chlorine through the solution, taking the neccssarv steps to have an exhaust leadoff out of the work area. Running the Color Test. The mixture of almost any quantity of sample with an equal amount of halogen reagent is sufficient for color development to take place. Samples as small as 1 mg. mixed with about 0.5 ml. of reagent give unmistakable colors. For the purpose of this paper, 0.5 cc. of sample was nii\ed Mith about 1.0 cc. of reagent. The ratio of one to the other determined the depth of color as well as hue. I n applying the test to follow hydrogenation or halogenation, a standard amount of sample and reagent must be used to develop a comparative series of colors. The presence of other metallic ions may affect the color, and their effect should be determined independently of the test reported herein. The analyst, in running this test, should look for instantaneous color formation as a positive indication of reactive groups. When a blue color is observed, isolated double bonds and compounds of low molecular weight are usually present. The latter type, of course, are generally knoxn to be present if they are extremely volatile, Resonating structures, like benzene and fumaric acid, do not respond. This type of unsaturated group may be suspected when a negative test results. Oxygenated compounds like aldehydes, ethers, and ketones tend to give various shades of green. Such structures should be suspected when a positive green color results either immediately or on standing. LITERATURE CITED (1) Weber, F. C.. Hennion, G. F., and Vogt, R. R., J . A m . C h m . SOC.,61, 1457-8 (1939). R E C E I ~ Efor D review M a y 21, 1'954
4cc:pted
September 25, 1954.
