908
Vol. 14, No. 11
INDUSTRIAL AND ENGINEERING CHEMISTRY
that good stirring is obtained without throwing the li uid too high up the sides of the flask or causing the magnet tolose the stirrer. The apparatus is swept out with hydrogen which has been saturated with the solvent used in the flask by bubbling through a wash bottle having a fritted-glass distributor. The confining liquid in the reservoir may be either mercury or solvent. After the air has been swept out, the desired amount of hydrogen is trapped in the buret, the stopcock on the flask is closed, and stirring is continued until the volume of hydrogen as read on the buret no longer changes, a t which time the stirring is stopped and the temperature and barometric pressure are noted. After slightly reducing the pressure in the flask by lowering the reservoir, the latinum oxide or alladium oxide catalyst is introduced by tEe following procelure: The catalyst is wei hed into a narrow glass or metal scoop and a measured volume ofsolvent, usually 5 cc., is drawn into a pipet. A few drops of solvent are run into the cup, the catalyst is added, and the scoop is washed with a few more drops of solvent. The catalyst is then drawn in through the stopcock and washed in with the remainder of the solvent, care being taken not to admit air. This procedure has the advantage of permitting reduction of the oxide catalyst in the presence of the compound t o be reduced, which gives a more active catalyst than reduction in solvent alone. It was not found
possible t o have the catalyst present while the apparatus is being swept out with hydrogen, because the rate of solution and diffusion of hydrogen is so great that hydrogen is absorbed at the rate of about 0.5 cc. per minute even without stirring. After addition of the catalyst, stirring is started and continued until hydrogenation is complete, when the volume, barometric pressure, and temperature are read again. The volume of the catalyst and wash solvent and the hydro en absorbed by the catalyst and solvent are determined in a blant run. While this apparatus has been used only for semimicro work and not for measuring the volume of hydrogen absorbed with great accuracy, there seems to be no reason why it cannot be adapted to micro work or why it should not yield results as accurate as most other forms of apparatus, if the corrections and calculations described by Johns and Seiferle (1) are applied.
Literature Cited (1) Johns, I. B.,a n d Seiferle, E. J., IND. ENQ.CHEM.,ANAL.ED., 13, 840 (1941). (2) W e y g a n d , C., and W e r n e r , A., J. ptakt. Chem., 149,330(1937).
Quantitative Decomposition of Organic Bromine and Iodine Compounds by the Lime-Fusion Method WILLIAM M. MAcNEVIN
AND
GLENN H. BROW", Department of Chemistry, Ohio State University, Columbus, Ohio
T
HIS paper presents data to show that the lime-fusion method of decomposing organic compounds of chlorine
TABLE 11. DETERMINATION OF IODINE
(1) can be applied to the analysis of similar compounds of
bromine (Table I) and iodine (Table 11),and also describes an improvement in the bomb for heating the sample with lime and a method for testing i t for leaks. Semimicrosamples have been used throughout. The construction of the bomb has been modified by providing the contact face of the bomb chamber with a sharp ridge approximately 0.5 mm. in height. When the bomb is closed, this sharp ridge is embedded in the copper washer and a tight seal is thus easily obtained. Bombs, especially when new, should be tested occasionally in the following way for the tightness of the seal. This test for tightness is strongly recommended to those who use the bomb for the first time. The bomb is half-filled with dry ice, sealed, and inverted in a beaker of warm water. If bubbles Present address, Department of Chemistry, University of Mississippi, University, Miss. 1
TABLE I. DETERMINATION OF BROMINE Weight ComDound Hexabromoethane Tetrabromobutane hlonobromobenzenea Bromomesitylene a I-Bronio-2,7-dimethylnaphthslenea 1-Bromo-4-nitrobenzene0 p-Bromoacetanilide 0
of
Weight of AeBr
10.87 12.21 17.35 20.31 23.58 17.80 22.91 22.43 15.43 16.23 14.67 15.80 11.92 11.44 15.58 17.22
SamDle Mi.
Br Theoretical
Mg.
Br Calculated %
%
%
24.27 27.25 34.83 40.80 28.11 21.12 21.48 21.09 12.17 12.90 13.58 14.64 10.53 10.08 6.38 7.08
95.01 94.97 85.44 85.49 50.72 50.49 39.89 40.00 33.56 33.83 39.38 39.43 37.59 37.48 17.43 17.49
95.23
-0.22 -0.26 -0.09 -0.04 -0.19 -0.42 -0.24 -0.12 -0.43 -0.16 0.19 -0.14 +0.24 4-0.13
Research compound, CsHloOsBr 4 100 mg. of KNOa added to ignition mixture.
85.53 60.91 40.15 33.99 39.57 37.35 17.40
Difference
-
+0.03 +0.09
Compound0 p-Iodonitrobenzene p-Iodoaniline 8-Iodopropionic acid Methyl-p-iodobenzoate p-Iodoazobenaene p-Iododiphenyl 0
Weight of Sample
Weight of AgI
I Calculated
I Theoretical
MO.
Me.
%
%
70
20.32 21.04 15.86 20.12 15.86 15.71 18.00 26.03 16.97 4.92 12.91 14.93
19.12 19.92 17.02 21.55 18.67 18.36 16.05 23.25 12.93 3.75 10.79 12.50
50.87 51.18 58.01 57.90 63.64 63.18 48.20 48.28 41.19 41.20 45.18 45.26
50.97 57.98
-0.10 +0.21 4-0.03 -0.08
63.46
+0.18
48.43
-0.28 -0.23 -0.15
41.19
Difference
+o.oo
+0.01
45.31
-0.13 -0.05
100 mg. of KNOa added to ignition mixture in every case.
do not appear, it may be assumed that the method of closing the bomb is satisfactory. The analytical method of determining the halogen in the ignition product is the same as that described earlier for chlorine ( I ) , except that provision is made for the reduction of possible bromate and iodate. The reduction is carried out by adding 200 mg. of hydrazine sulfate (Eastman) to the water suspension of the ignition product and warming the mixture to 75" to 85' C. for 5 minutes. The calcium oxide suspension is then cooled under tap water and dissolved with stirring in the minimum amount of nitric acid. Fine grinding of the sample and its intimate mixing with the calcium oxide have been found necessary for obtaining satisfactory results. It is also recommended that a blank be determined on the combined reagents. The method has i f i c i e n t accuracy for the determination of the number of halogen atoms in the organic molecule.
Literature Cited (1) MacNevin, W. M., a n d Baxley, W. H., IND.ENQ.C ~ M ANAL. .,
ED.,12, 29 (1940).
