ANALYTICAL CHEMISTRY
1202 Table V. Fraction 1 2 3 4 5 6
R
Molecular Weights of Fractionated Acids Weight Grams’ 463 499 284 97 39 17 535
AIolecular Weight 199 235 256 280 326 374 442
Moles 2.32 2.12 1.11 0.34 0.12 0.04 1.21
Mole ‘X 32.0 29.2 15.3 4.7 1.6 0.5 16.7
7.26
100.0
-
1934
Table V illustrate the use of the method in following fractional separation by solvents. In this separation about 2 kg. of the mixed acids, of average molecular weight 250, were subjected to a fractionation process by ether-pentane miutures. The weights of the fractions recovered and the average molecular weights found for each fraction are shovin. From these data the “number average” molerular weight is calculated. In view of recovery losses and the difficulty of complete elimination of solvents, the agreement of the number average, calculated from the fractionation data, with the value for the original mixture, is satisfactory and lends confidence to the values for both the original mixture and the fractions. LITERATURE CITED
sensitivity of the water thermometer with the higher boiling solvent, more than twice the rise per millimole, emphasizes the importance of having a differential thermometer filled with a l o m r boiling liquid than water if low boiling solvents such as acetone are to be employed. Differential thermometers filled with a number of different liquids have recently been described (5). The data of Tables I\‘ and F’ show the application of the method to the mixed acids recovered from the oxidation of coal. Those in Table IV refer to a typical unfractionated mixture such aa is recovered from the pilot plant operations and those in
(1) Fianke, N. W., and Kiebler, M . W., Chem. Inds., 58, 580 (1946). (2) Hanson, W. E., and Bowman, J. R., IXD.EN. CHEM.,ANAL.ED., 11, 440 (1939) ; also directions supplied with apparatus, W. E. Hanson. (3) Kitson, R. E., and Mitchell, J., A N A L .CHEM.,21, 404 (1949). (4) Mair, B. J., J . Research Natl. Bur. Standards, 14, 345 (1935). (5) Menzies, A . W. C., J . Am. Chem. Soc., 43, 2309 (1921). (6) Menzies, A . W. C., and Wright, S. L., Ibid., 43, 2314 (1921). (7) Shell Chemical Co., San Francisco, Calif., “Methyl Ethyl Ketone,” p. 23,1938. (8) Swietoslawski, W.,“Ebulliometrio Measurements,” pp. 64-9, New York, Reinhold Publishing Corp., 1945. RECEIYED March 10, 1949.
Determination of Organic Hydrazines SIDNEY SIGGIA AND LESTER J. LOHR General Aniline & Film Corporation, Easton, Pa.
A procedure is described for determining organic hydrazines by oxidation with cupric sulfate and measurement of the liberated nitrogen.
S
EVERAL oxidants have been used in determining hydraziries and hydrazine salts: potassium iodate (5, 6, 9), potassium permanganate ( 4 , 6 , 9 ) ,potassium bromate (IO),iodine (6,9), calcium hypochlorite (If ), chloramine T (8), potassium ferricyanide (7), ceric salts (S),and cupric ion (1, 2). The amount of hydrazine waa usually determined by measuring the oxidant consumed. When potassium ferricyanide was used as the oxidant (7), the nitrogen evolved was collected and measured. I n attempting to use the above oxidants to determine hydrazines of the type RKHSR,, it n-as found that the reaction wab slow, and a quantitative amount of the oxidant was not consunied. Heat caused undesirable side reactions such as the oxidation of side chains, but, although the warm oxidation proceeded in indeterminate manner, the nitrogen was liberated quantitatively from the hydrazine. A nitrometric method based upon these observations has, therefore, been developed. Potassium iodate, potassium permanganate, and ceric sulfate were tried as oxidants but were found to have disadvantages. Iodine was liberated from the potassium iodate which sublimed through the apparatus and into the nitrometer. Ceric sulfate and potassium permanganate caused the reaction to proceed in an indeterminable manner. Cupric sulfate in sulfuric acid oxidized the hydrazine quantitatively and could be easily handled in the apparatus. The oxidation for the monosubstituted hydrazines proceeds according to the following reaction:
---
CUSOl RNHNH~,H~SO~ P O1
rn=s
*
+
HSO~-
Heat
2H20 +ROH
Ht0
+ Xz + HtSO,
The reaction mechanism for the more highly substituted hydrazines is uncertain, but the nitrogen is liberated quantitatively. The time required for a determination varies from 46 minutes to 1.5 hours, depending upon the oxidizability of the hydrazine being determined. This procedure, because of its specificity for hydrazines, is preferred to methods that do not differentiate between hydrazines and other nitrogen-containing compounds, such as the Kjeldahl and Dumas methods. APPARATUS
The apparatus, shown in Figure 1, consists essentially of a r e action flask, F , in which the nitrogen is liberated, a Lunge nitrometer, J , in which the liberated nitrogen is measured over 50% potassium hydroxide, and a cylinder of purified carbon dioxide, A , which is used to displace the air from the apparatus prior to an analysis and to sweep the liberated nitrogen into the nitrometer. Tne 100-m1. reaction flask, F , is attached to the apparatus by a $24/40 joint. The reagents are introduced through the separatory funnel, G, and the delivery tube, L, which has a maximum diameter of 3 or 4 mm. and a constriction a t the bottom to prevent displacement of the liquid during decomposition of the sample. The reflux condenser, H , which is sealed to -11,has an internal diameter of 12 mm. and allows vigorous refluxing of the reactants. The carbon dioxide rate is controlled by the needle valve, B , and is estimated by the bubble counter, E , which is filled with an inert liquid such as butyl phthalate. Other essential parts of the apparatus me the safety manometer, C, the leveling bulbs, D and K , and the three-way stopcock, I , which permits by-passing the nitrometer. Commercial tank carbon dioxide is purified prior t o use by venting rapidly about 50% of the carbon dioxide from the cylinder. A cylinder of carbon dioxide purified by this procedure contains a negligible impurity and contains sufficient carbon dioxide for several hundred analyses.
V O L U M E 21, NO. 10, O C T O B E R 1 9 4 9
1203
PROCW U R E
Table I. Experimental Results The apparatus is pre ared Time for an analysis by cornpi)etely Kitrogen Found Deviation Required Nitrogen From calcd. From Dumas for Dumas This displacing the air with carbon Hydrazinc Calcd. method method x N Analysis dioxide up to the reaction % % % 70 Hour8 % flask, F. The mercury in the Phenylhydrazine hydrochloride 19.38 19.33 19.23 -0.15 -0.10 0.75 safety tube, C, is lowered to a 19.32 -0.06 -0.01 point slightly below the curved o-Tolylhydrazine hydrochloride 17.64 17.42 li.40 -0.24 -0.02 0.75 section of the manometer, so 17.32 -0.32 -0.10 that carbon dioxide can be Rrnaaldehpde phenylhydrazone 14.27 14.11 14.15 -0.12 +O.Ol 1 passed through the manometer 14.18 -0.09 +0.04 to the atmosphere. After the Y-Acet?.l-l-benzoyl-l-phrn3.l hydrazine 1 1 . 0 2 10.90 10.82 -0.20 -0.08 1.5 air is completelv d i s p l a c e d in.07 -0.05 +0.07 from the manometer, the leveling bulb, D, is raised until .~~-~___-____t,he mercury level is approsimately halfway up the nilinometer. The carbon dioxide rate is then increased, and in several Espcrimental results are presented in Table I. The two analytiminutes the air will be completely displaced up to F. The decal procedures check well with each other, thus establishing the livery tube, L,is filled with water. validity and usefulness of the method. Both procedures give reA sample that will give from 15 to 25 cc. of nitrogen is weighed .suits which are somewhat low compared with calculated values for into F , which is securely fastened to the apparatus by tension springs. Stopcock Z is opened to the atmosphere, and carbon nitrogen. The new method can be carried out rapidly to give redioside is rapidly passed through the ap aratus until the air is sults that compare favorably with the older Dumas procedure. completely displaced by carbon dioxide. h i s will acquire from 5 The better agreement between the experimental nitrogen to 10 minutes. After displacing the air, the carbon dioside rate is values than between the experimental and calculated values can reduced to 1 to 2 bubbles per second. Z is closed so the carbon dioxide passes into the nitrometer, and after several minutes be attributed to the slight decomposition of the hydrazines when microbubbles are obtained. The air collected in the nitrometer is recrystallized from warm solution. displaced, and the leveling bottle lowered until it is about level The volume of the blank, the vapor pressure of the potavsium with the nitrometer inlet tube. Forty milliliters of saturated hydroxide, Charles' law, and Boyle's law were taken into concopper sulfate, 15 nil. of 95% sulfuric acid, and 10 ml. of dist'illed water are drawn into the reaction flask. The solution is boiled sidrration in the calculation of results. until the reaction is complete and microbubbles are obtained. The carbon dioxide rate can be increased after the reaction appears complete to speed up sweeping the liberated nitrogen into ACKNOWLEDGMENT the nitrometer. A blank is then determined on an equal volume of copper sulfate, sulfuric acid, and water and is usually about 0.0 The authors are indebted to Donald E. Sargent for the prepare ml . tion of the di- and trisubstituted hydrazines, and to ,Joqeph Kervenski for some of the experimental work. Four different hydrazines representing two monosubst'ituted aryl hydrazines, a trisubstituted and a tetrasubstituted derivative, respectively, were prepared, purified, and subsequently subLITERATURE CITED iected to analysis using the procedure outlined above. Nit'rogen content was also determined by the conventional Dumas mrthod. (1) Britton, H. T. S., and Clissolo, E. M., J . Chem. Soc., 1942, 528. (2) Britton, H. T. S., and Konigstein, M.,Ibid., 1940, 673. (3) Dernbach, C.
J., and Mehlig, J. P., IND. ENG. CHEM., A N A L . ED., 14, 58-60 (1942). (4) Houpt, A. G., Sherk, K. W.,and Browne, A.
3
W . ,I b i d . ,
7 , 54-7
(1935). (5) Jamieson, G. S., Am. J. S C ~ .33, , 352-3 (1912). (6) Penneman, R. A., and
Audrieth, L. F., ANAL. CHEM.,20, 1058 (1948). (7) Ray, P. R., and Sen, H. K., Z . unorg. Chem.,
I
A
Figure 1.
Diagram of Apparatus
76, 38G6 (1912). (8) Singh, B., and Rrhman, A., J . I n d i a n Chem. Soc., 17, 169-72 (1940). (9) Stelling, O., Scensk Kern. Tiod. 45, 3-18 (1033). (10) Sxebellkdy, L . . a n d Somagyi, Z., Z. r ~ d . Chem., 1 1 2 , 3 9 1 - 9 5 (1938). (11) TomiCek, O., and Filipovie, P., C o l l e c l i o n Czech. Chem. Conintun., 10, 415-29 (1938).
RECEIVED Sovemhpr 29, lOlS
