In the development of analytical procedures and in general polarographic investigation involving organic compounds, the importance of calibration and study at the same level of ionic strength and buffer characteristics is indicated as a result of a survey of the factors affecting polarographic behavior. In order to evahtate the effects of the medium on polarographic behavior, a study has been made of a-bromo-n-butyric acid over the pI1 range of 1 to 12 and the normal working range (0.1 to 3 M) of ionic strength, using most of the commonly encountered buffer systems. The change in E0.6 was found to be dependent upon the nature of the buffer components, the concentration of the buffer components, the pH of the solution, and the ionic strength of the solution. Regions of ionic strength exist in which the measurement of Ea.& will yield values which are more valid when used to compare the results of various investigators than Eo.5 values nieasured in other regions. In order to obtain consistent results which will lend themselves to duplication and to comparison upon theoretical bases, the test solutions should be made up of definite ionic strength, the value of which should he stated in the same manner as the routine statement of capillary constants. The exact natiire and concentration of buffer coniponents sh011lrf be specified.LTHOUGH the importance of the effwt of pH on the A polarographic reducibility of organic compounds has been demonstrated in recent years, there has been no systematic study of the effect of ionic strength and its variat,ion due to the
The purpose of this article is to describe a method for coulometric titrations using a different type of silver coulometer and a versatile type of apparatus with which gas evolution causes no trouble.
yielded 1.40 g. (95%) of solid anít-7-norbornenol (IX), m.p. after vapor phase chromatographic purification, 117-118"; reported*• m.p. is 117-118". This material was hydrogenated to 7-norbomeol, identical with the 7-norbomeol obtained from VII and VIII above.Pyrolysis of the acetate (VII). Pyrolysis of the acetate (VII) was effected by injecting a sample into the sample inlet of a Beckman GC-2 heated at 225" with a column temperature of 130". No benzene could be detected among the many volatile products. The chief product, as shown by vapor phase chromatography, infrared and ultraviolet comparison with an authentic sample, was benzyl acetate.The acetate (VII) could also be pyrolyzed at 375°in a 9 in. column packed with glass helices to give good yields of benzyl acetate. With this apparatus the acetate (VII)was not pyrolyzed at 275®. Pyrolysis at a lower temperature in the gas chromatograph was probably promoted by carbonized materials known to be present in the inlet tube. Hydrolysis of 7-norbomadienyl acetate (VII). Hydrolysis of the acetate (VII) was attempted under the following conditions with uniformly negative results. In every instance the acetate was hydrolyzed but did not give the alcohol (VIII) . In most cases infrared analysis indicated ring opening.(1) IN hydrochloric acid/50% aqueous methanol at room temperature for 3 hr.(2) 2N hydrochloric acid/HiO at room temperature overnight.(3) IN potassium hydroxide/75% aqueous methanol overnight at room temperature under nitrogen.(4) IN sodium methoxide/methanol at room temperature for 2 hr. under nitrogen.Acid hydrolysis of the ether (VI) A solution of 0.5 g. (0.003 mole) of ether (VI) in 1 ml. of 50% sulfuric acid (0.018 mole) was allowed to stand at room temperature for 1 hr. Ice and water were added and the product was extracted with dichloromethane. None of the alcohol (VIII) could be detected in the product which appeared to consist chiefly of a saturated diol.
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