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 a t 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 by 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
0.02 N Ceric Sulfate, Y
M 0 . / 6 ml.
%
MI.
1.00 5.00 10.00 15.00 20.00
0.02 0.10 0.20 0.30 0.40
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.
April 15, 1941
ANALYTICAL EDITION
The results obtained in comparing the reducing ProDerties fructose and sorbose bear out the hypothesis-oi and Reiner (6) that the configuration about the third and fourth carbon atoms of the hexose sugars is the imDortant factor in determining the reducing properties, and tha't, if the configurations of the hydroxyl groups on carbon atoms 3 and 4 of two sugars are Similar, these sugars Will have approximately the same reducing properties. Fructose and sorbose have the same 'Onfiguration On these atoms and their reducing powers are of the same order of magnitude. Of
235
Literature Cited (1) Fulmer, E. I., Dunning, J. W., Guyman, J. F., and Underkofler, L. A., J . Am. Chem. SOC.,58, 1012 (1936). ( 2 ) Hildebrand, F. C., and McClellan, B. A., Cereral Chem., 15, 107 (1938). (3) Pigman, W. W., and Isbell, H. S., J . Research Natl. B u r . Standards, 19, 443 (1937). (4) Smith, R. H., and Tollens, B., Ber., 33, 1285 (1900). ( 5 ) Sobotka, H., and Reiner, >I., Biochem. J . , 24, 394 (1930). PUBLISHED as Paper KO.1854, Scientific Journal Series, Minnesota Agricultriral Experiment Station.
Determining Copper and Nickel in Aluminum Alloys HENRY 4. SLOVITER, Test Laboratory, U. S. Navy Yard, Philadelphia, Penna.
I
N CONJUNCTIOS with the spectrographic analysis of aluminum alloys, this laboratory performs the routine chemical determination of copper in a large number and variety of aluminum alloys in which the copper concentration varies from 0.2 to about 10 per cent. The determination of nickel in aluminum alloys in amounts up to 2.5 per cent is also required. The commonly used methods for copper (2, 4, 5 ) call for solution of the alloy in caustic solution and subsequent filtration. This leaves copper n ith other caustic-insoluble material on the filter, from which it is then removed with hot dilute nitric acid and determined by electrodeposition. This procedure serves only to separate the alloying elements (except zinc) from the bulk of the aluminum, and as commonly employed involves the danger of loss of material by spray in the sometimes violent reaction which occurs when the precipitate is mashed from the filter with hot acid. The present work mas undertaken in an attempt to find suitable conditions for the direct electrodeposition of copper without preliminary separation of the bulk of the aluminum. Since aluminum alloys dissolve very slowly in acids other than hydrochloric and since hydrochloric acid is undesirable because i t must be removed before electrolysis, the procedure used involved solution of the alloy in caustic solution, and, after dilution, addition of an excess of nitric acid. This method has found use in this laboratory in other cases where chlorides are objectionable-for instance, in the determination of manganese it is much to be preferred to the very slow method of dissolving in a mixture of nitric and sulfuric acids. This treatment gives complete solution of the alloy, except that with high-silicon alloys some silicon remains undissolved. It was found that this introduced no error in the determination of copper. If appreciable quantities of tin or other elements which interfere with the electrodeposition of copper are present, this method may not be used. This method, since it cuts manipulation to a minimum, reduces the time required for a complete determination to less than one third of that required by the longer method. For a batch of twelve, the time elapsed between the completion of weighing the samples and the point a t which they are ready to be electrolyzed is no more than 30 minutes, as compared with 1.5 to 2 hours required by the longer method. The sources of error due to incomplete solution of copper from the filter paper and the possibility of loss by spray are eliminated and the method has the further desirable feature of being carried out completely in a single vessel.
After deposition of the copper, the electrolyte can be used for the determination of nickel. The method has been in continued use in this laboratory for some months and has proved satisfactory for routine analys1s.
TABLEI. DETERhIIN.iTION O F COPPER AND NICKELU. Alloy No.
Alloying Elements
% 1 2 3 4 5 6
7 8 9 10 11 12
Copper Found Short Long method method
%
%
7.68 4.07 4.68 4.58 9.84 4.43 7.18 0.73 3.86 5.77 1.34 4.45
7.67 3.97 4.55 4.54 9.78 4.31 7.16 0.76 3.86 5.72 1.29 4.42
Sickel Found Short Referee method method
%
..
..
%
.. I
.
2:38 1.75 0.79
2:43 1.71 0.81
..
..
..
..
All values except referee nickel values are averages of two or more determinations. 5
Procedures COPPER. A 1-gram sample is transferred to a 200-ml. electrolytic-type beaker and treated Tyith 15 ml. of 20 per cent sodium hydroxide. If the reaction is too vigorous, water is added. After the reaction subsides, the beaker is heated on the steam bath until the reaction is completed, as indicated by the cessation of effervescence. The solution is then diluted to 100 ml. with hot water and stirred thoroughly, and 30 ml. of 1 to 1 nitric acid are added. This causes precipitation of gelatinous aluminum hydroxide, which redissolves on stirring and warming on the steam bath. Then 2 ml. of 1 to 1 sulfuric acid are added, the solution is stirred, and after cooling to room temperature is electrolyzed at 2 to 3 amperes, using a gentle air stream as a stirring device. A platinum gauze cathode 45 mm. in diameter and 50 mm. in height is used. If the acid concentration is not sufficiently high, a white deposit of aluminum hydroxide will adhere to the copper deposit. This will be avoided if the quantities recommended above are used. SICKEL. The electrolyte from the copper determination is transferred to a 400-ml. beaker and 25 ml. of 25 per cent tartaric acid are added. The solution is then made ammoniacal and warmed on the steam bath. In order to facilitate the removal of silica, 5 ml. of a 5 per cent zinc chloride solution are added and the solution is stirred and warmed further. It is then filtered into a 600-ml. beaker and the residue is washed with hot water. The filtrate is made slightly acid with dilute hydrochloric acid and 20 ml. of 1 per cent alcoholic dimethylglyoxime solution are added (for samples containing over 2 per cent of nickel 5 ml. more are used for earh additional 1 per rent). Dilute ammonia is then
