ANALYTICAL CHEMISTRY
1194 resin is suspected of being exhausted with ions below nitrate, increasing the concentration of the hydrochloric acid used as a regenerant is recommended. For example, the perchlorate form of a quaternary resin has been regenerated to its original capacity by the use of 2 liters of 2M hydrochloric acid. Concentrations as high as 7 M have been used with no detrimental effect on the resin, but are not recommended for routine use because of the large amount of reagent consumed per sample.
Kenny, Jennie Levin, and Robert Rowe for assistance in various phases of the experimental work reported in this paper. LITERATURE CITED
(1) Bauman, W.C., Skidmore, J. R., and Osmum, R. H., Ind. Eng. Chem., 40, 1350 (1948). (2) Gregor, H. P., Belle, J., and Marcus, R. d.,J . A m . Chem. SOC., 76, 1984 (1954). ( 3 ) Kunin, R., and Myers, R. J., “Ion Exchange Resins,” Wiley,
New York, 1949.
ACKNOWLEDGMENT
The authors wish to express their indebtedness to Diana
RECEIVED for review September 23, 1954. Accepted February 8, 1955.
Weighing Titanium(lU) Chloride for Quantitative Chemical Analysis I. J. DZlKOWSKl and R. G. NOVAK Engineering Division, Engineering Laboratories, Crane Co., Chicago 5,
A procedure has been developed for the preparation of titanium(1V) chloride for use in quantitative chemical analysis using standard serum bottles and a dry box.
T
H E hydrolysis of titanium(1V) chloride, when exposed to the atmosphere, has made its accurate sampling for quantitative chemical analysis difficult. The general procedure for obtaining a sample of the tetrachloride requires the use of a eighed, evacuated thin-walled glass ampoules, which must be made and prepared in the laboratory ( 1 ) . Since a relatively large surface area of the tetrachloride is exposed in filling the ampoules, this operation and the resealing of the ampoules must be performed in a completely dry and inert atmosphere. Generally, regardless of the care exercised, some hydrolysis occurs in the ampoules. Furthermore, control of the sample size is not an easy task. The filled ampoules are weighed, placed in a suitable acid solvent, and broken to permit the tetrachloride to be dissolved The latter operation results in a rapid hydrolysis of the anhydrous chloride accompanied by a vigorous evolution of gases, which is difficult to control and may cause a loss of sample. The search for a reliable sampling method resulted in the folloning technique, which requires materials obtainable from any supplier of chemical apparatus and a suitable “dry box” of a positive pressure type employing a dry inert gas. All operations involving the transfer of titanium(1V) chloride are performed in the dry box. The materials required are: Serum bottles, U. S. Army Medical Corps type, 60-ml. capacity. Serum bottle rubber stoppers, U. S. Army Medical Corps type. Hypodermic syringe, 5- and 10-ml. Hypodermic needles, 22-gage stainless steel. To facilitate the manipulation of the serum bottles and hypodermic syringes, rubber surgeon’s gloves should be worn when working in the dry box. The bottles are cleaned, dried in an oven, and cooled in a desiccator. When cool they are quickly stoppered to prevent moist air from entering them, weighed, and placed in the dry box. The titanium(1V) chloride to be analyzed (40 to 50 ml.) is stored by pouring it quickly into a dried, unweighed serum bottle, which is immediately restoppered. Procedure. Using a 5-ml. syringe, withdraw a 0.5-ml. sample of titanium(1V) chloride for each determination to be made and inject the 0.5-ml. portions into the necessary number of weighed serum bottles. Any tetrachloride that may remain on the outer
111.
surface of the bottles or stoppers should be carefully removed with a cloth or ball of cotton moistened with n-heptane. The bottles should then be removed from the dry box and placed in a desiccator to bring the outer surfaces to the same condition as existed in their previous weighing. The bottles may be reweighed to determine sample weights after they have been allowed to stand in the desiccator for about 20 minutes. Syringes used to transfer tetrachloride should be flushed with heptane and disassembled before removal from the dry box to prevent freezing of the pistons in the syringe barrels and plugging of the hypodermic needles. Draw 8 to 9 ml. of heptane into a 10-ml. syringe and inject this into each serum bottle containing a weighed amount of tetrachloride. The hypodermic needle must not be allowed to come in contact with the tetrachloride during this addition. When all but 0.3 ml. of the heptane has been added, withdraw the needle from the bottle while keeping a slight positive pressure on the piston of the syringe to prevent any tetrachloride vapor from being trapped in the needle. Mix the tetrachloride with the heptane by sn irling gently. After the titanium tetrachloride and heptane are thoroughly mixed, slowly inject 9 to 10 ml. of 20% sulfuric acid solution, using a 10-ml syringe and observing the same precautions as in the heptane addition. Since there is a greater increase in pressure during this addition, positive pressure must be maintained on the piston of the syringe a t all times. Withdraw the needle as before and, with shaking, cool the bottle and its contents in a water bath for 1 to 2 minutes, during which time most of the tetrachloride will have dissolved in the acid. Khen cool, the bottles are left in the water bath until the tetrachloride is completely dissolved in the acid. This will take about 1 hour and will result in a clear liquid which will have separated into two layers. Before removing the rubber stopper, insert a hypodermic needle through the diaphragm to release the pressure within the bottle. Then remove the stopper and transfer the contents of the bottle to a 250-ml. Erlenmeyer flask with careful and thorough washing of the stopper and bottle mith distilled water. This should result in a sample volume of 80 to 90 ml. To the sample in the Erlenmeyer flask add 50 ml. of concentrated hydrochloric acid to prevent hydrolysis. Place on a hot plate and boil gently until the heptane has evaporated, which will require approximately 5 to 10 minutes of boiling. The weighed sample of titanium(1V) chloride is now ready for analysis. In the event that a chloride analysis is required, sulfuric acid should be used for the final addition. The possibility of a loss of hydrogen chloride in relieving the pressure increase caused by the displacement of air in the serum bottles can be avoided by the addition of a precipitant for the chloride before the pressure is released. LITERATURE CITED
(1)
McTaggart, F. K., J . Council Sci. Ind. Research, 18, 24 (1945).
RECEIVED for review January 21, 1954.
.4ccepted February 19. 1995.
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