When present in smokeless powder, 2,4-dinitrotoluene may be extracted with ether and determined by reduction with standard titanous chloride solution.By the use of sodium acetate or sodium citrate buffer, the reduction is caused to take place very rapidly at room temperature. This modification shortens the usual procedure.
INTHE manufacture of certain types of smokeless powders, 2,4-dinitrotoluene is added for specific purposes. During World War II, a rapid method for its determination was essential. After extraction with ether, the dinitrotoluene (DNT) was reduced to the corresponding diamine by refluxing for 5 minutes with 100% excess of standard titanous chloride solution. The excess was titrated with standard ferric alum solution, using ammonium thiocyanate indicator.The determination of dinitrotoluene by this procedure was developed by Knecht (ß: S), and adapted to the analysis of nitroglycerin-dmitrotoluene mixtures by Becker (1). Kolthoff and Furman (4) state that the reduction of nitroaromatic compounds by titanous chloride is almost instantaneous at room temperature if an alkaline buffer, such as sodium citrate, is added. This raises
Diacetyl removal from beer was studied with whole cells and crude enzyme extracts of yeasts and bacteria. Cells of Streptococcus diacetilactis 18-16 destroyed diacetyl in solutions at a rate almost equal to that achieved by the addition of whole yeast cells. Yeast cells impregnated in a diatomaceous earth filter bed removed all diacetyl from solutions percolated through the bed. Undialyzed crude enzyme extracts from yeast cells removed diacetyl very slowly from beer at its normal pH (4.1); at a pH of 5.0 or higher, rapid diacetyl removal was achieved. Dialyzed crude enzyme extracts from yeast cells were found to destroy diacetyl in a manner quite similar to that of diacetyl reductase from Aerobacter aerogenes, and both the bacterial and the yeast extracts were stimulated significantly by the addition of reduced nicotinamide adenine dinucleotide (NADH). Diacetyl reductase activity of four strains of A. aerogenes was compared; three of the strains produced enzyme with approximately twice the specific activity of the other strain (8724). Gel electrophoresis results indicated that at least three different NADH-oxidizing enzymes were present in crude extracts of diacetyl reductase. Sephadex-gel chromotography separated NADH oxidase from diacetyl reductase. It was also noted that ethyl alcohol concentrations approximately equivalent to those found in beer were quite inhibitory to diacetyl reductase.
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