INDUSTRIAL A N D ENGINEERING CHEMISTRY
August, 1927
Acknowledgment
The author wishes to acknowledge the assistance and criticisms of the members of the Research Division of the New
90 1
Jersey Zinc Company, and the aid rendered by his assistant, c. Hall, in making the observations.
Action of Cathode Rays on Drying Oils By J. S. Long and C. N. Moore LEHICHUNIVERSITY,
BETFILEHEM,
P A . ,A N D GENERALELSCTRIC COMPANY,
HE production of high-voltage cathode rays outside of the generating tube has been described by Coolidge' and some experiments with these rays outside of the generating tube are described by Coolidge and In a description of this work3 it was mentioned that castor oil exposed to the rays was changed to a solid. The relations which occur when drying oils are thickened by heating are quite different than those when the oil is thickened by the action of ultra-violet light, and these differ from the actions when the oil is oxidized by blowing. It was believed that this thickening by the action of high-voltage cathode rays might be of service in indicating the types of reactions occurring in the process of thickening and that during raying there might be actions which did not take place in other methods of bodying. Accordingly, series of samples of linseed, perilla, and China wood oils were prepared as described. Some or all of the constants-specific gravity, refractive index, iodine number, molecular weight, and hexabromide number-were determined on these samples. The samples were than rayed and the constants again determined. The results produced by the raying are given in Table I to 111.
T
Table I-Effect
of T i m e of E x p o s u r e to C a t h o d e R a y s on L i n s e e d and P e r i l l a Oils
REFRACTIVE IODINE MOLECULAR HEXABROMIDE PI-UMBER WEIGHT NUMBER
EXPOSURE INDEX Mtnufes
S E T 1-LIHSEED
0 1 2 3 5 10
1.4776 1,4778 1.4780 1,4782 1.4786 1.4799
0
1.4804 1.4805 1.4806 1.4808 1.4812 1.4819
S E T I-PERILLA
1 2 3
5 10
OIL
187.6 187.4 187.4 187.6 185.5 181.0
762 781 832 870 883 967
37.6 22.6 22.3 24.3 19.5 21.6
785 810 817 834 878 925
47.8 42.2 41.1 38.8 37.0 31.2
OIL
205.5 205.5 202.6 202.3 198.7 195.3
T a b l e 11-Linseed 011-50 Seconds' Exposure t o C a t h o d e R a y s AFTER REFRACTIVE INDEX MOLECULAR WEIGHTIODINEUMBER HEATINGBefore After Before After Before After Hours S E T 2-HEATED
a
1 2
2 5
1.4776 1 4836 1.4890 1.4903
1.4810 1 4842 1.4895
...
A T 253O C.
970 1096 1728 2330
S E T 3-BLOWN 0
3 9
1.4781 1.4790 1.4796
1.4788 1.4800 1.4820
S E T 4-HEATED
0.5 1 0 1.25 1.5 1.75 a
1.4825 1.4855 1.4886 1.4901 1,4910
1,4830 1.4857 1.4892 1.4904 1.4915
A T 138'
788 833 893 A T 253'
1038 1209 1540 1617 1840
177.2 148 117.5
147' 112.6
C.
818 929 1025
184.0 175.6 160.5
183.7 173.2 159.3
C. W I T H U M B E R
1046 1220 1571 1658 1904 Gel
Time required t o raise oil t o temperature used.
J . Fvankiin Insl., 202, 693 (1926). I b i d . , 202, 722 (1926). 8 J . Chem. Educ.. 3. 13G9 (1026). 1
2
856 1132 1989 Insoluble gel
155.2 142.2 135.9 132.0 129:s
144.2 128.8 120.3 114.7 103.2
T a b l e 111-Perilla
SCHENECTADY,
N. Y.
a n d C h i n a Wood Oils-50 C a t h o d e Rays
S e c o n d s ' E x p o s u r e to
REFRACTIVE I X D E XMOLECULAR WISIGHTIODINEh T HEATING Before After Before After Before After Hours AFTER
S E T b P E R I L L A OIL H E A T E D A T 293'
1.4806 1.4869 1,4900 1.4917
1.25 1.75 2.25 2.76
1.4811 1.4873 1.4906 1,4920
S E T 7-PERILLA 4
0.5 0.92 1.10 1.24
1.4808 1.1850 1.4888 1,4906
C.
891 1207 1527 1959
201.4 157.4 143 4 134.1
196 6 155.3 142.5 Gel
OIL A I R - B L O W N >IT 283' C.
1.4812 1.4852 1.4892 1.4910
S E T 8-CHINA
790 1123 1388 1719 Solidified 785 1078 1440 1753 Solidified
864 1131 1524 1857
W O O D OIL H E A T E D AT 190'
0 1.5148 1.5144 873 888 0.5 1.5134 1.5132 991 1020 1.0 1.5116 1.5114 1098 1160 1.5 1.5103 1.5100 1371 1453 2 1994 Gel a Time required t o raise oil t o temperature used.
200 161.2 151.6 131.7 C.
.. .
1si:l 146.1
195.7 162.5 142.1 131.8 157 157 153.8 145.6
Materials
Perilla oil of suitable purity for research work was kind7y furnished by Maximilian Toch. It had the following characteristics when used in this work: Specific gravity a t 15.5'/15 5' C. Refractive index a t 25' C. Iodine number, U'ijs (30 minutes) Hexabromide number Acid value Molecular weight
0 1 205 47 3 765
935s 4804 8
08
Linseed oil derived from selected northwest seed was treated to remove the break, chilled to 6.6" C. to separate part of the saturated glycerides, and filtered cold. This oil showed the following characteristics when used in this work: Specific gravity a t 15.9°/15.50 C. Refractive index a t 25' C. Iodine number, Wijs (30 minutes) Hexabromide number Acid value Molecular weight
0.9395 1.4776 187.6 37.6 4.38 760
The China wood oil had the following characteristics: Specific gravity a t 15,5°'15,50 C. Refractive index a t 2 5 O 'c. Iodine number, Wijs Browne heat test minutes
0,9405 1.5160 163 9.5
Preparation of Sets of Samples
SET 1-Two and a half cubic centimeters of linseed oil were placed in a glass Petri dish of 10 cm. diameter. T h e dish was fastened to a shaft inclined at an angle of 27 degrees and rotated at about 60 r. p. m. The center of the Petri dish was 5 cm. from the window of the cathode ray tube. In all cases the tube was operated at 250,000 volts (maximum) and 1 MA. The oil spread itself quite evenly over the bottom of the Petri dish in a layer about 0.3 nim. thick. Five samples were exposed 1, 2, 3, 5 , and 10 minutes. SET 2-Six hundred grams of linseed oil were heated a t 293" C. in a 1000-cc. three-neck Pyrex flask with mechanical stirring at 200 r. p. m. Air carrying moisture equivalent to 62.6 per cent relative humidity a t 25" C. was passed over
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I N D U S T R I A L A N D ENGINEERING CHEMISTRY
902
Vol. 19, No. 8
the surface a t the rate of 4.25 liters per minute. Samples taken when the temperature reached 293" C. and after 1-, 2-, and 2.5-hour intervals were exposed for 50 seconds to the cathode rays in exactly the same manner as described for set 1. SET 3-One thousand grams of linseed oil were heated at 138" C. and air carrying moisture equivalent to 50 per cent relative humidity a t 25" C. was blown through the oil a t the rate of 5.6 liters per minute by a bubbler tube with fine holes. Samples taken at the start and after intervals of 3 and 9 hours were exposed to the cathode rays for 50 seconds. SET4-One hundred and ninety-four kilograms of aged linseed oil were heated in a wrought-iron kettle with 1.6 kg. of umber. The oil, which had been blown previous to use, had the following characteristics:
The samples were too small to permit the determination of specific gravity or viscosity. It was believed, however, that the change in specific gravity would be indicated by the change in refractive index, which was accordingly determined. It was found that the raying increased the refractive index in all samples of linseed and perilla oils and decreased it in the case of China wood oil. The molecular weight increased steadily in all cases. It is noticeable that the gain in molecular weight for equal exposure is in a general way dependent on the molecular weight of the sample exposed to the rays; thus, in sets 1, 5, and 3 the molecular weight gain is from 15 to 30 for samples having low molecular weights-. g., 762, 785, and 788. The corresponding gain for samples having molecular weights of double this value and upwards is more nearly 100 to 200 points Iodine number, Wijs (30 minutes) 161 for the same exposure (50 seconds), except in set 4, in which 186.9 Saponification value 3.64 Acid value driers were boiled into the oil. I n this set the molecular Specific gravity a t 15°/150 C. 0.9884 weight gain on exposure is smaller but increases steadily The umber contained Fe203 A1203, 50.22; SiOz, 17.98; with increase in the molecular weight of the successive samMnr04, 15.76; and volatile matter 14.74. Two hours were ples. The iodine number decrease is greatest in this set, which required to raise the temperature to 293" C. The oilwas stirred with a ladle. Samples were taken when just up t o contains driers. I n the raying process a considerable amount 293" C. and after time intervals of 0.5, 1, 1.25, 1.75, and 2 of ozone is produced in the air. Some of the reactions which hours. These samples were exposed t o the cathode rays for occur during the raying are affected by this, particularly with oils containing iron. 50 seconds. I n set 1 there is a sharp drop in hexabromide number withSET &-Perilla oil mas exposed for 1, 2, 3, 5, and 10 minutes in exactly the same manner followed for linseed oil (set 1). out any change in iodine number in 3 minutes' exposure. SET 6-Five hundred grams of perilla oil were heated t o The increases in molecular weight and refractive index are 293" C. and held at that temperature in a 1000-cc. three- very small in this period. This seems to be best explained neck Pyrex flask. The oil was stirred at 200 r. p. m. A as a change in the linolenic glyceride to an isomer which does stream of pure dry nitrogen was passed over the surface a t not yield solid hexabromide. Further evidence supporting this the rate of 4.25 liters per minute. Samples withdrawn at premise is obtained from the results in the raying of China specified times were exposed to the cathode rays for 50 seconds. wood oil. The samples up to 1.5 hours were homogeneous. SET 7.-Five hundred grams of perilla oil were heated to No gel could be detected. After 50 seconds' exposure to 293" C. and air blown through it at that temperature at the the cathode rays all samples contained gel lumps easily noticerate of 4.25 liters per minute from an air bubbler. The air able by rotating the sample tube. These lumps dissolved in carried HzO equivalent to a relative humidity of 50 per cent benzene, giving solutions which when poured through dry filter a t 25" C. The oil set to a gel in 1.75 hours. Samples with- paper did not leave gel lumps on the paper. Further, drawn at specified times were exposed to the cathode rays for the molecular weights are relatively low. This behavior would not be inconsistent with the idea of change to p-eleo50 seconds. SET &Two hundred and fifty grams of China wood oil stearic acid, and it seems difficult to explain the results in any were heated a t 190" C. in a 500-cc. three-neck Pyrex flask and other way. The identification and properties of the different isomers stirred mechanically at 200 r. p. m. Air carrying moisture equivalent to 62.5 per cent relative humidity at 25" C. was of linolenic acid is a task far from complete, but there is evipassed over the surface a t the rate of 2.26 liters per minute. dence that the drying of oils is somewhat dependent on the Samples were withdrawn when the oil reached 190" C. and relative proportions of these isomers. a t 30-minute periods thereafter. The samples were exposed In order to see whether the rate of drying of the oils before and to the cathode-ray stream for 50 seconds in the same manner after exposure to the cathode ray discharge would support the idea of isomeric change, drops of linseed and perilla oils before as in other runs.
+
Discussion of Results
I n set 5 the over-all decrease in hexabromide number corresponds to 0.166 gram of hexabromide per gram of oil, which in turn corresponds to a decrease per gram of oil of
278. 24X 757.74
0.166 = 0.0609 gram of that linolenic acid which
forms an insoluble hexabromide. If the linolenic acid underwent a change whereby one ethylene linkage was closed, then the decrease in iodine absorbed would be 2 X 126.93 grams for 278 grams of lino126'93 X 0.0609 = 0.0556 gram of lenic acid or 278.24 iodine for the 0.0609 gram of linolenic acid. The actual decrease in iodine number is 0.102 gram of iodine per gram of oil, which is nearly twice this value and might be accounted for on the assumption that two of the three ethylene linkages in each molecule of linolenic acid were closed.
raying and after raying for 1, 2, 3, 5, and 10 minutes were put on a glass plate and the plate was then inclined so that the drops ran down t o the edge, making series of thin films the width of the drop. The glass plates were dried in an oven a t 60' C. The time required for the oil, without driers, to become dry t o touch or to dry hard was found to decrease in a regular manner as the time of exposure t o cathode rays increased up to 10 minutes. Perilla oil, without driers, rayed for 10 minutes was dry to touch in 2 hours and hard in 5 hours. Linseed oil rayed for 10 minutes was dry to touch in 3 hours and hard in 6 hours a t 60" C. Raw perilla and linseed oils, without driers, flowed on the same glass plates a t the same time were wet and not much changed when the progressively thicker films from rayed samples were all dry. In another set, raw linseed oil in a n oven a t 75" C. required 8 hours to become dry t o touch, whereas the same oil rayed for 10 minutes was dry hard in 4 hours. Raw perilla oil was dry t o touch after 7 . 5 hours and the same perilla oil rayed 10 minutes, was dry hard in 3.5 hours. Raw linseed oil on glass in the open room at 20" C. became dry after 45 hours; raw perilla after 43 t o 44 hours. The same linseed oil rayed I O minutes was dry a t the end of 24 hours. The same perilla oil rayed 10 minutes was dry at the end of 24 hours.
903
INDUSTRIAL AND ENGINEERING CHEMISTRY
August, 1927
Aside from any support given to the premise of isomeric change during the raying process, these results are not without significance in the treatment of drying oils for various purposes. In all cases the oils were greatly bleached by the raying process. The linseed oil samples in sets showed progressive decrease in color from sample to sample as the time of raying increased. The sample rayed for 10 minutes is practically
water-white. The perilla samples rayed 3, 5, and 10 minutes are also practically water-white. More work is in progress to confirm and amplify these observations. Acknowledgment
We gratefully acknowledge the help of W. S. Egge and P. C. Wetterau in obtaining these data.
Action of Heat and Blowing on Linseed and Perilla Oils and Glycerides Derived from Them By J. S . Long, W. S. Egge,' a n d P. C. Wetterau2 LB:HICHUNIVERSITY, BETHLEHEM, PA.
N PREVIOUS work designed to establish fundamental data regarding the behavior of drying oils when heated, blown, or thickened by ultra-violet light, rariations were observed which seemed to be traceable to variations in the constituents of the oil. Thus the presence of only a small percentage of mucilaginous matter and phosphatides derived from the seed was shown to exert a relatively large influence on the rate of thickening of linseed oil when heated. I n extending the work it was decided to use less complicated mixtures and to attempt to synthesize some of the constituents of the oil. A glyceride of linolenic acid was synthesized4 and the rate of molecular weight increase determined when this glyceride was heated. Since perilla oil is richer in linolenic compounds than linseed oil, it was used as a starting point. Linseed and perilla oils also contain different proportions of alpha and beta isomers of linolenic acid. The glyceride is synthesized from the crystalline hexabromide. This should eliminate the beta form if the hexabromide is not a mixture. However, in order to see whether there is any difference in the glycerides synthesized in this way from the two oils, both linseed and perilla oils were used. This paper contains data showing the rate of change of certain analytical figures when the synthesized glycerides are heated, as well as similar data for the natural linseed and perilla oils for comparison. It was previously stated4 that the synthesized glyceride dried to a smooth, elastic film. Data on a few films are given and a new method of making films for study is described.
I
Specific gravity a t 15.5°/15.50 C. Refractive index at.25' C. Iodine number (Wils, 30 minutes) Hexabromide number Acid value Molecular weight
Linolenic glyceride was synthesized by essentially the same method as previously d e ~ c r i b e d ,with ~ the following modifications in order to give a purer product and to facilitate the preparation: Three hundred grams of the fatty acids are dissolved in 900 cc. of ethyl ether containing 10 per cent of glacial acetic acid and 3 per cent of absolute ethyl alcohol. The mixture is then brominated in the usual way. The resulting hexabromide is crystalline and is easily purified. The crystalline hexabromide is carefully washed with ethyl ether and finally removed from the ethereal solution by centrifuging. The product is recrystallized from hot xylene until it shows a melting point of 178179" C. Since the purity and texture of the hexabromide greatly affect the rate of formation of the glycerol ester, the recrystallization from xylene is practically essential. The esterification is greatly aided if the glycerol is kept saturated with hydrochloric acid by passing the dry gas along with the carbon dioxide into the reaction chamber, the tube leading below the surface of the reactants. Usually carbon dioxide containing 5 to 10 per cent of dry hydrogen chloride is sufficient. I n this way the reaction time is reduced to about 8 hours.
The glycerides thus prepared have the following characteristics: THEORETICAL LINOLENIC
FOR
Refractive index a t 2 5 O C. Iodine number (Wijs, 30 minutes) Molecular weight (F. P. benzene) Hexabromide number
Materials
furnished by Maximilian Toch. It had the following characteristics when used in this work: 0.9358 1.4804 205 47.8 3.08 765
Linseed oil derived from selected northwest seed was treated to remove the break, chilled to 6.6" C. to separate part of the saturated glycerides, and filtered cold. This oil showed the following characteristics when used in this work : 1 2
3 4
PERILLA
LINSEED
1.4864 211.2 708 28.8
1,4832 212.2 677 28.:
MONOGLYCERIDE
217.7 352
Ultimate Analysis (Finures in oer cent) . -----,
Perilla oil of suitable purity for research work was kindly Specific gravity a t 15,5°/15.50 C. Refractive index a t 2 5 O C. Iodine number (Wijs, 30 minutes) Hexabromide number Acid value Molecular weight
0.9355 1.4776 187.6 37.6 4.38 760
New Jersey Zinc Company Research Fellow a t Lehigh University. Callender-Carnell Fellow at Lehigh University. Long and Wentz, THISJOURNAL, 18, 1247 (1926). Long, Knauss, and Smull, Ibid., 19, 62 (1927).
~I ~~~
SAMPLE Carbon Hydrogen Oxygen
~~
I~~
GLYCERIDE SYNTHESIZED FROM: Perilla Oil Linseed Oil 1 2 3 4 71.85 71.97 71.68 71.77 10.06 10.27 10.12 10.19 18.09 17.76 18.13 18.11
THEORETICAL FOR LINOLENIC :
Monoglyceride 71.53 10.28 18.17
Diglyceride 76.40 10.54 13.06
The figures for iodine number and ultimate analysis indicate that the product is linolenic monoglyceride and that it is fairly pure. The molecular weight is about double the theoretical value. It is possible that this dihydroxy body shows association in benzene. Work is now in progress t o determine what types of compounds give abnormal molecular weights in benzene and other solvents. Experimental
EFFECT OF H ~ a ~ 1 ~ cruns - h 65,66, 67, and 68, 500 grams of perilla oil were heated in a 1000-cc. three-neck Pyrex
