The polarographic reduction of mono-and dinitrotetralins was studied in buffered solutions at four different pH values. The reduction became more difficult and was less complete with increase in pH. The relative heights of the multiple waves were interpreted in terms of certain electron changes, and these were checked by coulometric measurements at controlled potentials. The first stage in reduction in the tetralin series appears generally to be a fourelectron change as it is in the benzene series.In the course of other work in this laboratory it was found necessary to prepare most of the isomeric dinitrotetralins. From a search of the literature it became evident that a study of the polarographic behavior of the dinitrotetralins would be a logical extension of the work carried out by Pearson (1) on various dinitro compounds in the benzene series.For the sake of completeness all four possible dinitrotetralins as well as the two known mononitrotetralins were prepared; 5 x 10-~M solutions of the nitro compounds in 80% ethanol were studied in four buffered solutions. The compounds were also studied by constant potential coulometry to determine the number of electrons associated with each polarographic wave. Experimental 6-Nitrotetralin (2), 5-nitrotetralin (3,4), 5,6-dinitrotetralin (2), and 5,7-dinitrotetralin (2) were prepared by methods given in the literature. (5) was nitrated (2) to give a low yield of 8-nitro-5-aminotetralin. One gram of the nitroamine was stirred into a mixture of 4 ml trifluoracetic acid and 0.5 ml 90% hydrogen peroxide (6); the solution was kept below 50 ~ for 1 hr. At the end of this time the reaction mixture was poured over ice. The solid dinitro product was filtered off and recrystallized from ethanol. Yield, 0.1 g, mp 88.0~ ~ [Literature: 87-88 ~ (7)]. 6,7-Di.nitrotetralin.--6-Aminotetralin (3, 4) was transformed by nitration (2) to give 7-nitro-6-aminotetralin. One gram of the nitroamine was oxidized by trifiuoroacetic acid and 90% hydrogen peroxide as described previously. The dinitro product was recrystallized from methanol. Yield, 0.3 g, mp 109.0~ ~ [Literature: 108 o (2)]. Polarographic procedure.--The polarograph employed was a Fisher Elecdropode which had been calibrated against a Type K L&N potentiometer. The electrolysis cell was a modified H-type cell. At a drop time of 4.0 sec with an open circuit and using an alcohol solution buffered by acetic acid and sodium acetate, the drop weight was 6.5 mg. The electrolysis celt was immersed in a thermostat maintained at 25 ~ 0.2 ~ and a saturated calomel electrode was used as the anode. Dissolved oxygen was removed by bubbling prepurified nitrogen through the solution for 20 min; the gas was previously passed through another sample of the solution under test. The polarographic curves were plotted as the experimentally determined currents minus the blanks. The half-wave potentials were corrected for IR drop. 5,8-Dinitrotetralin.--5-AminotetralinThe solutions were made by adding 10.0 ml of the proper buffer solution to 40.0 ml of 95% et...
Three years ago, a joint project was established by the Wright Aeronautical Division, Curtiss-Wright Corp., at the Jet and Flame Laboratory of New York University, to study the preparation and behavior of pyrophoric organometallic compounds. The aluminum alkyls have been one of the most interesting groups studied to date, from an ignition standpoint.Compounds capable of ready spontaneous ignition with air are of considerable potential importance for certain types of air-breathing power plants. Certain thermal theories of flame propagation suggest that the flame is propagated by virtue of continuous spontaneous ignition occurring on the leading edge of the flame front; in such a case, the time lapse before the flame appears-ignition delay-would be an important factor.Although aluminum alkyls have been known for some time, it has been only during the past few years that these compounds have been the subject of extensive research, largely because of the use of these compounds by Ziegler as catalysts for olefin polymerizations at low pressures. Preparation of Aluminum AlkylsA convenient method for the preparation of small quantities of these compounds involves a displacement reaction between aluminum metal and the alkyl compound of some less active metal (which can be readily prepared)-e.g., the reaction of dimethylmercury with an excess of aluminum yields trimethylaluminum and mercury (2) :Although this procedure gives good yields for lower members of the series, the decreased stability of the higher mercury alkyls limits its usefulness. The cost of such a method would be high.Recently Ziegler has developed several new methods of preparing aluminum alkyls using olefins as the starting reagents (10, 11).At about 100° C. lithium aluminum hydride reacts with ethylene and tetraethylaluminum lithium is formed:When this quaternary salt is treated with aluminum chloride, triethylaluminum is formed :This method has been used to prepare the corresponding η-propyl and n-hexyl com pounds.A more economical process for the large scale production of these compounds involves spraying aluminum into an atmosphere of hydrogen and an olefin (12): 172 METAL-ORGANIC COMPOUNDS Downloaded from pubs.acs.org by UNIV OF CALIFORNIA SAN DIEGO on 06/09/15. For personal use only.
The polarographic reductions of 1,8‐dinitronaphthalene, 5,6‐dinitroacenaphthene, 3,4‐dinitroacenaphthenequinone, and 4,5‐dinitronaphthalic anhydride, were studied in buffered solutions at four different pH values. The relative wave heights of the multiple waves could be interpreted reasonably in terms of certain electron changes. A semi‐empirical equation was derived to confirm certain electron changes in the polarographic reductions. These electron changes were also checked by coulometric measurements on electrolyses run at controlled potentials. Results indicated that in all but one instance there was agreement between the values for the electron changes obtained in the parallel analyses. The one exception was 3,4‐dinitroacenaphthenequinone.
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