68
INDUSTRIAL AND ENGINEERING CHEMISTRY
acetate iodine number determinations should be critically examined if the presence of free hydroxyl groups is suspected. EXPERIMENTAL
pure ester which had the following constants: b.p. 186" a t 1 mm., = 1.4510, saponification equivalent, 185.6 (theory, 184.3),acid value, 0.0, and iodine value, 68.5 (theory, 68.9). Automatic pipets were used to obtain aliquots of PROCEDURE. all standard solutions. An aliquot portion (10.96 ml.) of the compound and 24.98 ml. of the halogen reagent were mixed and allowed to react for the stated time interval, and the excess reagent was then titrated to obtain the results given in Table I. To determine the effect of mercuric acetate shown in Table 11, the ester and halogen reagent were mixed, and immediately treated with 10.0 ml. of 2.57, mercuric acetate in glacial acetic acid, and allowed to react for the intervals recorded, beginning with the addition of mercuric acetate. Blank experiments, without the presence of the unsaturated compound, were performed in all the series to e1:minate corrections necessitated by the presence of small amounts of oxidizable materials in the mercuric acetate solution.
PREPARATION O F hlETHYL RICINOLEATE (5). Castor oil was converted to castor oil methyl esters by saponification, isolation of the acids, and esterification with 2 to 47, sulfuric acid in absolute methanol. The esters (650 grams) were fractionally distilled through a 60-cm. (24-inch) Vigreux column, and methyl ricinoleate was collected at 157' to 158' C. at 1-mm. pressure. The yield was 474 grams of material having the following constants: n3 = 1.4596,iodine value, 82.0 (theory, 81.2). PREPARATION OF METHYLRICINELAIDATE ( 3 ) . From 2000 grams of castor oil, 530 grams of crude ricinelaidic acid were obtained by elaidinization of the acids with oxides of nitrogen ( 3 ) . The acids were converted to the methyl esters by refluxing with 2 to 4% sulfuric acid in absolute methanol and separated from nonvolatile material by distillation from a Claisen flask a t 1-mm. pressure. There was obtained 465 grams of impure product. (1) This was then fractionally distilled as above, and the main fraction collected, b.p. 181 a t 2 mm., and recrystallized twice from a mixture of Skellysolve F and diethyl ether. The yield was 290 (2) grams of pure methyl ricinelaidate, m.p. 30" to 31" C., ny = (3) 1.4582, iodine value, 81.5 (theory, 81.2). PREPARATION O F METHYL 0-PROPIONYLRICINOLEATE (6). (4) Castor oil methyl esters, prepared as above, were heated rapidly and briefly to 180" C. with two-thirds their weight of propionic (5) anhydride. The mixture was fractionally distilled to obtain the (6) O
Vol. 18, No. 1
LITERATURE CITED
Fat Analysis Committee of the American Oil Chemists Society and AMERICAN CHEMICAL SOCIETY, IND.ENG.CHEM.,18, 1346 (1926).
Hoffman, H. D., and Green, C. E., Oil and Soap, 16, 236 (1939). Kass, J. P..and Radlove, S. B., J. Am. Chem. Soc.,' 64, 2255 (1942).
Norris, F. A,, and Buswell, R. J., IND. ENG.CHEM.,ANAL.ED.. 15, 258 (1943). Uhrisr. K., and Levin, H., Ibid., 13. 90 (1941). Walden, P., Ber., 36,781-90 (1903).
Improved Device for Decomposition of Grease PFC. R I C H A R D W. T A R A R A ' Rock Island Arsenal Laboratories, Rock Island, 111.
IN
T H E laboratories of the Rock Island Arsenal, where the number of grease samples to be analyzed and the time available are determining factors, the standard method of the American Society for Testing Materials (1) for decomposing the soap in the grease was too time-consuming when a 30-gram sample was used, the time varying from 20 minutes with a light grease to 2 hours with some of the heavier greases. This method of soap decomposition consists essentially of shaking 8 to 30 grams of the sample, depending on the consistency of the grease, in a separatory funnel at room temperature with petroleum ether and 10% hydrochloric acid. Since the "boiling method" is used in many grease testing laboratories, its suitability for the Arsenal needs was looked into. Briefly, this method consists in placing about 30 grams of grease in a 400-ml. beaker, adding about 200 ml. of 10% hydrochloric acid solution, and then heating the mixture to the boiling point
* Present
addresa, c/o Dr. P. L. Tararrt, Mayo Clinic, Rochester, Minn
of the hydrochloric acid solution to accelerate the decomposition. It was found that the time required to break down the grease could be reduced to from 5 to 10 mihutes for the average grade to 20 minutes for the heavier grades. This method does not require the undivided attention of the analyst; however, unless the mixture is constantly stirred, steam has a tendency to build up pressure beneath the floating grease layer. In the case of the heavier grades of greases especially, this steam pressure may cause violent bumping with subsequent loss of material due to splattering. To overcome this, several procedures were tried but only two proved effective. The first, which was very effective but cumbersome, consists in placing a slow-speed motor on a rack over the hot plate and stirring the mixture as it boils. The second procedure is the percolator method. When the grease percolator, as shown in Figure 1, is placed in the beaker with the grease sample and the hydrochloric acid solution, the steam is provided with an outlet, thereby preventing excessive bumping due to the pressure buildup. The percolator serves a twofold purpose. Primarily, it serves to prevent violent bumping with its subsequent loss of sample and, secondly, it is used t o agitate the grease, thus accelerating the decomposition by exposing more surface to the acid solution. This secondary effect is accomplished by means of the twist in the steam tube (see diagram). When the mixture reaches the boiling point of the hydrochloric acid solution, steam and hydrochloric acid solution "boil up" through the percolator out of the tube and are forced back into the surface of the grease layer by their own pressure. By placing the exit tube at an angle, the steam and hydrochloric acid solution which spurt out with some force tend to agitate the grease layer, causing it to revolve on the surface of the hydrochloric acid solution. The percolator can be readily made in the laboratory from an ordinary 2.5-inch diameter 60-degree angle soft-glass funnel. Two or more venting grooves are bent in the lip of the funnel. The stem is then bent in the manner shown by the diagram. LITERATURE CITED
(1) Am. SOC. Testing Materials, Analysis of Grease, A.S.T.M. Serial
Designation D128-40, -4.S.T.M. Standards 1944, Part 111, p.
Figure 1
182.
