We report a 2.5-year study of the photolytic degradation of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) with variations in temperature, humidity, and illumination by fluorescent and UV light (254, 312, and 365 nm). The free-radical decomposition product was monitored with electron paramagnetic resonance (EPR). The EPR spectrum of the green powder allowed reliable quantitation with a single peak (fwhm = 29.1 G). The variations in humidity showed little effect in accelerating the degradation of TATB. The only significant temperature effect was noticed at −10 °C, where fewer radicals formed. The radical production rates at −10 °C were some of the highest measured, however, suggesting that the rates under other temperature conditions had slowed, perhaps as a result of extensive conversion of surface molecules to radical species. We show that a substantial amount of radicals can be generated with UV light, and work is ongoing to modify our EPR spectrometer so that TATB can be irradiated in the EPR cavity to measure the initial rates of radical formation.
Extraction is a method often used for the rapid separation of mixtures containing acidic and/or basic organic compounds. Consequently, most undergraduate organic courses devote one laboratory period to the study of this technique. Separation, which involves acid-base reactions, is accomplished by the movement of dissolved organic compounds between two mutually insoluble layers. Frequently, students are provided with a mixture of two white organic solids, and upon separation they obtain two white solids, thus providing no visual evidence that the compounds have been separated. We have modifed this popular experiment, through the use of various colored organic compounds; namely azobenzene (orange), benzoic acid (white), and m-nitroaniline (yellow). Separation of this mixture not only allows the student to obtain the usual melting point data for identification, but also it furnishes three different colored compounds, thereby providing immediate visual evidence that the compounds have been separated. This procedure furnishes pure samples of all three compounds, as evidenced by melting point, color, and yield.Experimental.1 Dissolve a mixture of benzoic acid (1 g), m-nitroaniline (1 g), and azobenzene (1 g) in 75 ml of ether (Caution: no flames!). Pour the mixture into a separatory funnel, add 40 ml of 10% sodium hydroxide solution, shake thoroughly, and drain off the lower layer into a beaker. Heat the beaker to evaporate any ether, then add 20 ml of 6M hydrochloric acid until a pH of 1 is reached. Cool to room temperature and collect the precipitated benzoic acid.To the ether solution add 50 ml of 3M sulfuric acid, shake thoroughly, and drain the lower layer into a beaker. Heat the beaker to evaporate any ether, then add 120 ml of 10% sodium hydroxide until a pH of 10 is reached. Cool to room temperature and collect the precipitated m-nitroaniline.Add 50 ml of saturated sodium chloride solution to the separatory funnel, shake, and drain off and discard the aqueous layer. Dry the ether layer with 5 g of anhydrous magnesium sulfate and then evaporate the ether. Cool in an ice bath and collect the precipitated azobenzene.1 Good laboratory technique always requires the wearing of safety glasses and hand protection.
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