I,VDUSTRIAL AiVD ESGINEERISG CHEMISTRY
May, 1927
devoting its energies to quantity production and so its numerous findings with respect to ethylene dichloride's usefulness have become in a sense research by-products. To put these into operation in its own plants ~ o u l dclash x i t h
639
established policy and might seriously jeopardize other projects, to it more important. Hence these researches, both patents and supplementary data, are available on very favorable terms t o potential users.
-
Fractionation of Linseed Oil at 293" C.' By H. D. Chataway UNIVERSITY OF
I
MANITOB ~ VAI , N N I P E GM , AN.
S COSNECTIOK with the researches of Long and
his co-workers2 on the changes in the iod:ine number, molecular weight, and other constants occurring during the heating of linseed oil a t 293" C., i t seems of interest to recall the fact that in 1915 hlorrel13 published the results of his studies of the products obtained by heating linseed oil a t 260" to 280" C. for from 28 to 60 hours, more especially that he isolated an intermediate product soluble in light petroleum but insoluble in acetone. I n view of' this i t was decided to carry out an experiment under the conditions described by Long in order to determine whether under these conditions a fraction of the oil became insoluble in acetone. This was found to be the case and the results are given herein. Procedure
The linseed oil used had the following constants: Iodine number.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Saponification number, . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acid number.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Specific gravity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
199.5 191.2 2.07 0,9327
Two 100-gram batches of oil were placed in 250-cc. distilling flasks and heated in an oil bath a t 110" c. for 2 hours, during which time carbon dioxide was passed over the surface. The next day the flasks were heated in the oil bath at 185" C. for 5 hours under approximately 15 mm. pressure. They were allowed to stand for a day and then heated for 7 hours over a bare flame a t 293" * 4" C. One batch, A , was a t atmospheric pressure; the other, B, was a t approximately 15 mm. pressure. From each batch two samples were removed every hour. Half the samples were used to determine their molecular weights. Each of the remaining samples were quantitatively separated into two fractions, soluble and insoluble in acetone, and the molecular weight of each fraction was then determined. The molecular weights were determined by the freezing point method using benzene, the concentration being approximately 4 per cent. The method of determining the percentage of material insoluble in acetone was an empirical one used by the author previously in the study of the action of sulfur on linseed oiL4 To the weighed sample was added a number of cubic centimeters of acetone equal to twenty times the weight of the sample in grams. After thorough stirring i t was allowed to stand for one hour, whereupon the supernatant acetone solution was poured off into a weighed flask together with an additional cubic centimeter (approximately) of acetone to wash the surface of the acetoneinsoluble material remaining in the beaker. After standing for 2 hours in an electric oven a t 80" C., this acetone-in1
4
Received Fehruary 21, 1927. THIS JOURNAL,19, 62 (1927). J Soc. Chem. I d , 34, 105 (1915) Ibrd , 46, 115 (1926).
soluble material was weighed and its percentage of the original sample calculated. This method does not aim a t a complete separation of the acetone-soluble and -insoluble fractions, but it is a rapid method which map easily be duplicated. It should be noted, however, that variations in the acetone used h a r e a marked effect on the results obtained. Results
The results are given in Tables I and 11. T a b l e I-Separation
TIME MOLECULAR a'EIGHT
A B 750 830 930 1030 1010 1180 1160 1270 20.6 1550 1320 29.5 1410 1620 ... 1950 1950 49.6 2300 2220 54.8 required t o raise temperature to 293' C.
Hours a
1 2 3 4 5 6 7 Time
of Fractions PER CENT OF ACETOKE-INSOLTJBLE A B
15.2 26.9 39.3 48.5 56.1
T a b l e 11-Molecular Weight D e t e r m i n a t i o n s TIME ACX$TONE-~NSOLUBLEACETONE-SOLUBLE Hours A B A B 7400 1160 10,820 1160 m 23,530 1140 970 m ... 1130 980 m 1300 1020 6S40 1120 1070 4950
...
A-ofe-It will be noticed that the individual results are decidedly irregular, though taken a s a whole they indicate definite and regular changes I n the opinion of the author the iriegularities are due t o the fluctuations in the temperature which are not easily eliminated a t 293' C This view is based upon the author's previous experience of the sensitivity to slight changes in temperature of the somewhat similar reaction which occurs during the sulfuration of linseed oil at 160' C
The molecular weights of the acetone-insoluble fraction indicate that i t is essentially colloidal, the small depressions observed in some cases being probably due to imperfect separation of the two fractions. Similarly, the fact that the acetone-soluble material has an apparent molecular weight greater than that of the original oil may be due to its possible content of a small amount of acetone-insoluble material. The fact that such material cannot be detected until the heating has continued for some time is also in accordance with this hypothesis. Qualitatively the acetone-soluble fraction is of the same consistency as the original oil and has no marked drying properties. The acetone-insoluble material, on the other hand, is viscous and upon prolonged heating a t 80" C. sets throughout to a solid mass. There seems to be no doubt that the viscosity and setting power of the treated oil are due to this fraction. Preliminary experiments, however, indicate that raw oil heated a t 293" C. without previous heating a t 185' C. i n vacuo does not give rise to an insoluble fraction unless or until reduced pressure is applied, although its viscosity increases normally.
.
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
