INDUSTRIAL AND ENGINEERING CHEMISTRY
640
Finally, although the acetone-insoluble material formed under the conditions of these experiments is colloidal, it should be recal!ed that the similar material obtained by Morrell a t a slightly lower temperature had molecular weights little more than double that of the original oil.
Vol. 19, No. 5
Acknowledgment
The author acknowledges the kindness of the University of Manitoba in placing its facilities a t the disposal of this research and thanks M, A. Parker and H. p. ilrmes for their interest in the work.
Chemical Mechanism of Linseed Oil Drying’ By Wm. Lloyd Evans, Paul E. Marling, and Stewart E. Lower THE LOWE BROTHERS CO.,DAYTON.O H I O
The relationship during drying between iodine number of linseed oil and the concentration of cobalt acetate and a comparison during drying of the acid values and iodine numbers of linseed oil containing dijerent driers. HIS paper presents a continuation of previously reported experiments,2 in which an attempt was made to establish the relationship between the acid values of drying linseed oil films and the variable concentrations of the cobalt acetate used as a drier, in which it was concluded that the acid value of linseed oil films containing cobalt acetate as a drier is an increasing function of the drying time and a logarithmic function of the drier concentration. If the chemical action taking place during drying is that of peroxide formation a t the ethenoid linkages of the unsaturated acids of the glyceride, and a subsequent splitting of these peroxides into aldehydes, which are in turn oxidized to acids, then it follows, in view of the experiments on the acid values of drying films, that the iodine number of these films should bear a general inverse relationship to the acid value. Furthermore, the concentration of the cobalt used should bear a definite relationship to the decreasing iodine value. To obtain experimental data in support of these views were two of the purposes of the present experiments. On account of the well-known influence which lead, cobalt, and manganese driers exert on the drying speed of linseed oil, it became of much interest to study the relative effect on both the acid value and iodine number of drying linseed oil films to which had been added previously equimolecular amounts of lead acetate, manganous acetate, or cobalt acetate.
T
Experimental
The general procedure was the same as that used in the previous paper.* The iodine number of the drying film was determined by the well-known modification of the Hub1 process. The linseed oil had the following constants: Specific gravity at 15.5’ C... . . . . . . . . . . . . . . . . 0 . 9 3 3 Refractive index. . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4615 Iodine n u m b e r , . . . . . . . . . . . . . . . . . . . . . . . . . . . . Molecular w e i g h t , . . . . . . . . . . . . . . . . . . . . . . . . . . Acid v a l u e . . ...............................
176.0 730.0 4.7
I n these experiments 0.01 mol of the crystalline acetates was incorporated in 200 grams of linseed oil and this value was chosen as unity in expressing the value of the drier concentration. To illustrate, 2.49 grams of cobalt acetate, i. e., cO(ooC ’ CH3)2‘ 100
4H20j
were dissolved in 200 grams of
linseed oil. This value is known as the 0.01 molar concentration of the drier. Presented under the title “A Comparison during Drying of the Acid Values and Iodine Numbers of Linseed Oil Containing Di5erent Driers” before the Division of Paint and Varnish Chemistry a t the 72nd Meeting of the American Chemical Society, Philadelphia, P a . , September 5 to 11, 1926. 2 THISJOURNAL, 18, 1229 (1926).
The temperature of 271” C. for 20 minutes was found to be high enough to incorporate the concentration of lead, cobalt, and manganese acetates that were used in the experimental work. The experimental results are shown in the accompanying graphs. Discussion and Summary
I n Figure 1 the iodine numbers of the drying linseed oil films are expressed as functions of the drying time. I n order to compare the relationship between the corresponding acid values and the drying time of these films, the previously reported acid values are shown by dotted lines. If the chemical mechanism of film drying is that given above, then the general inverse relationship of the iodine number and the acid value indicated in this graph is the one to be expected. I n Figure 2 the iodine numbers of the drying films are expressed as functions of the cobalt acetate concentrations chosen. These concentrations were 0.05, 0.10, 0.20, and 0.40 of the chosen unit. I n this drawing the previously reported relationships between the acid value and the drier concentration are also given by dotted lines. These general results were those expected. If the iodine number and the acid value of a drying film bear a general inverse relationship to one another, it is obvious that their product should yield a number which might be called the “drying constant.” It was found, however, that this product increased very rapidly in films containing driers and hence did not give a constant value. This is easily understood since the determined acid value is probably lower at the beginning of a drying period than that really formed in the drying process because of the volatility of some of the oxidation products. As an illustration of an oil to which no drier has been added, the following constants were obtained by multiplying the acid values and iodine numbers given by Spencer Kellogg and Sons, Inc.:3 HOURS 1.0 1.5 2.0 2.5
DRYINGCONSTANT 333.3 336.6 338.0 387.0
HOURS 3.0 3.5 4.0 4.25
DRYING CONSTAKT 368.0 357.8 344.5 355.2
Here we note the same gradual increase indicated above. The same calculation has been applied to Kellogg’s “Superior,”4 polymerized a t 315’ C., with the following results: HOURS 0.5 1.0 1.5 2.0 2.25
1
3 4
Laboratory Letters, p. 29. I b i d . , p. 30.
DRYINGCONSTANT 361.2
356.7 356.7 366.8 359.0
INDUSTRIAL A N D ENGINEERING CHEMISTRY
N a y . 1927
64 1
I
..8
,
I
I
'
A
t
I
I,
I
'
I
I
'
1
I1
'
T ! M E -HOURS
Figure 1
,
-
1 .
I ?c" , ?.
2s-
..,
I 1
COMPARISON OF ACID VAIUES OFLINSEED OIL CONTAINING DIFFERENT DRIERS
The following exponential equations for the relationship between the concentration of the cobalt acetate and the iodine number have been derived by Prof. C. C. Morris, Department of Mathematics of the Ohio State University: Let x = the concentration of the drier and y = the iodine number. HOURS 0.5 1.0 1.6 2.0
2 .S
LOG Y
0.64747 X * 1.62207 X ? 1.88560 X * 2.30709 X ? 3.13775 ~2
- 0 . 3 7 9 6 8 %+ 2.23544 -
0.97822 x f 2.24659 1.21921 x 4- 2.22714 4- 2.21204 -t2.21386
- 1.53600 x - 2.07050 x
I n Figure 3 the acid value of linseed oil containing different driers is expressed as a function of the time. The specimens
of oil contain 0.20 of a unit of cobalt acetate, manganese acetate, and lead acetate. Although the drier is introduced in equimolecular amounts, it is not to be concluded that the linseed oil-drier systems contain the same number of molecules, because it is possible that these driers exist in different degrees of colloidal dispersion. The general difference in the behavior of these three specimens is in accord with the well-known relative difference in the drying speed of oils containing these driers. The iodine values of these same oils are shown in Figure 4. The general results obtained in these experiments are in accord with the mechanism of linseed oil drying which is predicated on the intermediate formation of peroxide with subsequent conversion into acids.
New Books Art de I'IngEuieur et MCtallurgie. RCsistance des Matdriaux et Donndes NumEriques Diverses. Extrait du Volume V-Tables Annuelles de Constantes et Donnges Numbriques. L. DESCROIX. 251 pp. GauthierVillars et Cie, Paris. Price, 105 francs. Bibliography of the Analysis and Measurement of Human Personality up to 1926. GRACEE. M.ANSON.No. 72, Reprint and Circular Series, National Research Council, Washington, D. C. 59 pp. Price, $1.00. Descriptive Bibliography on Oil and Fluid Flow and Heat Transfer in Pipes. JOE B. BUTLER. Vol. 9 , No. 4, Technical Series Bullelin, School of Mines and Metallurgy, University of Missouri, Rolla, Mo. 62 pp, Donndes Numdriques d'ElectricitC Magnetisme e t Electrochimie. Tables Annuelles de Constantes et DonnCes Numdriques. Extrait du Volume V. A. BUFFAT.G. I. HIGSON,K. GORDON,AND M. MALAPEKT. 518 pp. Gauthier-Villars et Cie, Paris. Price, 66 francs. Engines of High Output, Thenno-Dynamic Considerations. HARRYE. RICARDO.118 pp. Illustrated. D. Van Nostrand Co., New York. Price, $3 00.
L o w Temperature Carbonisation.
Vertical Retorts a t H. M. Fuel Research Station. C. H. LANDERA N D J. FRASER SHAW.Technical P a p e r 17. H. M. Stationery Office, London. Price, 6 d. net. Outlines of Physical Chemistry. GEORGE SENTER.441 pp. D. Van Nostrand Co., New York. Price, $3.00. Stories in Stone. WILLIST. LEE. 238 pp. D. Van Nostrand Co., New York. Price, $3.00. Supplement to a n Introduction t o Sedimentary Petrography. HENRYB. MILNER. 156 pp. D. Van Nostrand Co., New York. Price, $3.50. Technologie Chimique des M a t i k e s Premisres d e 1'Email. JULESGRUNWALD. Translated by H$LBNE HIRSCEA N D MARCEL THIERS. 316 pp. Dunod, Paris. Price, 48 francs. Transactions of the American Geophysical Union, Seventh Annual Meeting, April 29 and 30, 1926, Washington, D. C. No. 56, Bulletin of the National Research Council, Washington, D. C. 134 pp. Price, $1.25. ZerstYubungserscheinungen bei Metallen. JOSEPH FISCHRR. 70 pp. Gebrilder Borntraeger, Berlin. Price, 4.80 marks.
