ANALYTICAL EDITION
April 15, 1941
nine. All solutions contained 0.250 gram of quinine per 100ml. of solution. All points of the hydrochloric acid curve were determined in 30 per cent alcohol and all of the sulfuric acid curve in 60 per cent alcohol. The data in Table I1 show for both acids only a smooth curve with no breaks at any stoichiometric ratios. They show, however, why somewhat higher rotations have been obtained when excess acid has beenadded to either the sulfate or the dihydrochloride. The report of Liquier (6) concerning plateaus in the curve of optical activity us. p H corresponding to the neutral and basic quinine sulfates has not been confirmed b y the authors.
Summarj-
Data are presented to show the variation in optical activity of quinine as free base, dihydrochloride, and sulfate in mixtures of water and ethyl alcohol, and the variation as the free base is progressively neutralized with hydrochloric and SUI-
233
furic acids, each in t h a t water-alcohol solution which gives the maximum rotation for each salt.
Acknowledgment The authors wish to acknowledge the assistance of the Samuel S. Fels Fund in providing means for carrying out the work.
Literature Cited (1) (2) (3) i4j (5) (6)
18';
(9)
Allen, "Commercial Organic ilnalysis", 5th ed., Vol. VII, Philadelphia, P. Blakiston's Son & Co., 1929. Dietsel, R., and Soellner, K., Arch. Pharm., 268, 629 (1930). Hesse, O., Ann., 176, 205 (1875). Hesse, O., Ber., 4, 693 (1871). Lapp, C., Compt. rend, 201, 80 (1935). Liquier, J., Ibid., 183, 195 (1926). Oudemans, A. C., Ann., 182, 33 (1876). Schmidt, J., and Grafe, V., "Alkaloide", Berlin, Urban und Schwartzenberg, 1920. Schoorl, N., Pharm. Weekblud, 63, 4 6 9 (1926)
Effect of Temperature of Alcohol in Determination of Potash in Fertilizers C. W.HUGHES AND 0. W . FORD Purdue University Agricultural Experiment Station, Lafayette, Ind.
FOR
a number of years the referee on potash in fertilizers of the Association of Official Agricultural Chemists has recommended investigation of the solubility of potassium chloroplatinate in alcohol and acid-alcohol. Pierrat gives the solubility of potassium chloroplatinate in alcohol at 14" C. (3) b u t makes no reference to the solubility at the higher temperatures a t which most laboratory work is done. Allen reports on the greater solubility of potassium chloroplatinate in 80 per cent alcohol than in 95 per cent alcohol (1) b u t makes no reference to the temperature of the alcohol used. Archibald, JTilcox, and Buckley give the solubility of potassium chloroplatinate in alcohol-water mixtures of various alcohols at 20" C. (2) b u t do not mention the solubility in acid-alcohol. This work, while important in itself, has not been inclusive enough t o encompass the conditions existing in the determination of potash b y the official method, as, for example, the effect of temperature on the solubility of potassium chloroplatinate in alcohol and acid-alcohol. During the summer of 1939 a large number of lorn-analysis potash fertilizers analyzed in the authors' laboratory were found to be running below guarantee. The daily temperatures during this period were unusually high but after cooling the alcohol to about 18" C. the results were from 0.1 to 0.3 per cent higher. Since a rise of about 8" C. was noted upon addition of concentrated hydrochloric acid t o alcohol (when added at the rate of 0.6 ml. of hydrochloric acid t o 6 ml. of alcohol) and the temperature remained above room temperature for the 15-minute extraction period, it was found advisable to mix the acid and alcohol and cool before adding it to the po~~
TABLEI.
~
LOSS O F POTASSIUM CHLOROPLATIS4TE BY TION WTH ACID-ALCOHOL
(0 I-gram portions of K2PtC16 used) K20 LOBt Treatment 18' C 380 c .
Mixed acid-alcohol Acid and alcohol separate
EXTRAC-
48' C
MQ
MQ.
.WQ
5 1 7 6
8 2 9 7
10 8 11 6
tassium chloroplatinate. Subsequently the effect of temperature on the solubility of potassium chloroplatinate in acid alcohol was studied. Known concentrations of pure potassium chloride mere used for samples in place of commercial fertilizers in order to avoid other sources of error in the potash determination.
Procedure The study is divided into two steps. 1. Extraction of weighed amounts of pure potassium chloroplatinate with definite volumes of acid and alcohol under controlled temperature conditions. Tenth-gram portions of pure potassium chloroplatinate were transferred to 250-ml. beakers. To these were added 137.5 ml. of acid alcohol at a definite temperature for the mixed acid-alcohol determinations and 125 ml. of alcohol and 12.5 ml. of concentrated hydrochloric acid for the determinations in which the acid and alcohol were added separately. The mixtures were stirred for 15 minutes a t controlled temperatures. Finally the determinations were filtered into sintered-glass crucibles and washed with 137.5 ml. more of alcohol at corresponding temperatures. Table I gives the amounts of potassium chloroplatinate lost by extraction. 2. Determination of the effect of the temperature of acidalcohol on the solubility of potassium chloroplatinate precipitated from two concentrations of pure potassium chloride. Two concentrations of potassium chloride were used. The first contained 6.25 grams of potassium chloride per liter, made to volume at 4" C. and kept at that temperature till used. The theoretical value of t.his solution is 0.3948 per cent KzO. The second solution contained 12.5 grams of potassium chloride per liter and the theoretical X 2 0value for this solution is 0.7896 per cent. Aliquots of the above concentrations (25 ml.) were measured into platinum dishes, measured amounts of chloroplatinic acid were added, and the solutions were evaporated to a thick paste on the steam bath. The dishes were then removed and to each dish were added 6 ml. of 83 per cent alcohol and 0.6 ml. of concentrated hydrochloric acid for the determinations in which the acid and alcohol were added separately or a mixture of 6 ml. of alcohol and 0.6 ml. of acid for the mixed acid-alcohol determinations. The samples were extracted for 15 minutes at 18' or at 38" C. The temperatures in each case were controlled by a constant-temperature bath. At the end of the &minute extraction, the s m les were washed with 125 ml. more of 83 per cent alcohol adjustef to the corresponding tem erature. It was estimated that 125 ml. of alcohol mere norrnafiy used in the potash deter-
INDUSTRIAL AND ENGINEERING CHEMISTRY
234
Vol. 13, No. 4
mination previous to the ammonium chloride washing, which was omitted in this case as no magnesium salts were present in the determinations. All filtrations were made in the same set of sintered-glass crucibles (Jena B. G. 3). Actual potash results were determined by difference (the potassium chloroplatinate being dissolved out and the crucibles weighed back). TabLe I1 gives the solubility loss of potassium chloroplatinate at different temperatures.
tilizers, there is a sharp rise in temperature of about 8' C. which does not entirely disappear a t the end of the 15-minute extraction period. This indicates that i t is advisable to mix the acid and alcohol and to control the temperature during the 15-minute extraction. The percentage losses in Table I1 are greater at the lower concentration of KzO. This may be due to the solvent action of the alcohol on the smaller crystals of potassium chloroLoss OF POTASSIUM CHLOROPLATINATEplatinate which are formed in the lower concentration of KzO. TABLE11. SOLUBILITY (Calculated as per cent KzO in acid-alcohol at 18' and 38' C.) The small crystals present greater surface area than the larger No. of KzO At 18' C. At 38" C. crystals formed with the higher concentrations and therefore Analyses Theoretical Kz0 Kz0 Kz0 KzO Treatment Averaged Value found lost found lost have a greater solubility. hlixed acid-alcohol Acid and alcohol separate hfixed acid-alcohol Acid and alcohol separate
%
%
%
%
%
50
0.7896
0.7851
0.57
0.7760
1.72
Conclusions
50 50
0.7896 0.3948
0.7794 0.3907
1 . 2 9 0.7640 1 . 0 4 0.3848
3.24 2.53
50
0.3948
0,3852 2.43
There is a definite increase in temperature when the acid is added to the alcohol, as outlined in the A. 0. A. C. method for the determination of potash in fertilizers, which gives an error particularly under summer laboratory conditions. This can be prevented by mixing the acid and alcohol beforehand. I n order to eliminate the effect of temperature i t is advisable to cool the acid-alcohol mixture as well as the wash alcohol before using.
0.3783
4.18
Discussion of Results Tables I and I1 indicate that a rise in temperature of the alcohol is accompanied by a n increase in solubility of the potassium chloroplatinate. Although the differences in the amount of potassium chloroplatinate extracted when the acid and alcohol were added separately and when the mixed acidalcohol was added are small, there is a significantly greater solubility with the former. This may be due to the increased temperature resulting from the mixing of the acid and alcohol. When alcohol and acid are mixed in the proportions outlined in the official method for the determination of potash in fer-
Literature Cited (1) Allen, H. R., J. Assoc. Oficial Agr. Chem., 22, 162-7 (1939).
(2)
Archibald, E. H., Wilcox, W. G., and Buckley, B. G., J .
Am.
Chem. SOC.,30, 747-60 (1908). (3) Pierrat, M., Compt. rend., 172, 1041-3 (1921). PRESENTED before the Division of Fertilizer Chemistry at the 100th Meeting of the American Chemical Society, Detroit, Mich.
The Reducing Properties of LSorbose F. K. BROOME AND W. M. SANDSTROM University of Minnesota, St. Paul, Minn.
w
ITH the current commercial use of Gsorbose i t seemed desirable to determine its reducing property b y one of the standard methods and t o compare this property with that of the other available ketohexose, fructose. The 2-sorbose was prepared by the method of Fulmer and others (1) and yielded eight-sided crystals in the orthorhombic system. The sugar was not fermented by Saccharomyces cerevisiae (a commercial baking strain and one isolated from cheese) nor by two strains of Torula. The product lost no weight upon heating for 2 hours in a vacuum oven at 70" S. Various samples melted wit; darkening from 162.4' to 164.2 , with a mean value of 163.5 (corrected), and the osazone melted at 163" (corrected). A 6 per cent solution showed [CY]~DO = -42.9' when corrected for temperature and concentration by the formula of Smith and Tollens (4); A recent value by Pigman and Isbell (3) records [cY]*DO = -43.4 for a 12 per cent solution. TABLEI. CERICSULFATE EQUIVALENTS AT VARYING CONCENTRATIONS OF SORBOSE Sorbose Concentrations 2 Mp./6 ml. % 0.001 0.05 0.10 0.002 0.50 0.01 1.00 0.02 5.00 0.10 1o.oc 0.20 1 6 . 0 0 0 20.00 0 .. 34 00 25 00 0.50 0.60 30 00 35.00 0.70
0.02 N Ceric Sulfate, u M1. 0.20 0.19 1.21 2.46 11.40 20.29 32 68 .. 44 67 43.94 51.18 58.42
Factor, Z/Y 0.250 0 . 45 12 36 0.407 0.439 0.493 0 . 5 24 79 0.569 0.586 0.599
TABLE11. CERICSULFATE EQUIVALENTS AT VARYINGCONCENTRATIONS OF FRUCTOSE
FrTtose Concentration
M 0 . / 6 ml.
%
1.00 5.00 10.00 15.00 20.00
0.02 0.10 0.20 0.30 0.40
0.02 N Ceric Sulfate, Y MI. 2.77 12.24 21.66 30.88 40.01
Factor, z/u 0.361 0.408 0.462 0.486 0.500
Fructose Sorbose 1.13 1.07 1.08 1.08
1.10
The reducing power was determined by the method of Hildebrand and McClellan ( 2 ) . I n each case the desired quantity of the sugar was contained in 5 ml. of solution which was allowed to react with 10 ml. of the alkaline ferricyanide solution. The values are corrected for the blank which was determined daily and never exceeded 0.7 ml. of a 0.01773 N ceric sulfate solution. All data are recorded as equivalents of 0.02 N ceric sulfate and represent the mean of at least triplicate determinations. I n a similar way the equivalent reducing power of a sample of Pfanstiehl's c. P. special fructose was determined for comparative purposes. The data are recorded in Table 11,where the last column indicates the relative reducing properties of the two ketosugars. The data indicate that the direct titration with ceric sulfate of the formed ferrocyanide is satisfactory for sorbose in the concentration range of from 0.01 to 0.70 per cent. At concentrations below this range the accuracy is considerably reduced, and a t higher concentrations the ferricyanide is completely reduced.
