Substituted nitrobenzenes were among the first organic compounds to be investigated using the polarographic technique. The early work was performed by the Japanese, Shikata and his co-workers, and from this work Shikata and Tachi3 formulated the "electronegativity rule of reduction potentials," i. e., that organic compounds are more easily reduced as more electronegative groups are substituted in the same molecule.These investigators measured the reduction potentials by the tangent method us. the normal calomel electrode. This method of measurement deviates from present practice. I t was felt desirable to extend their investigations of substituted nitrobenzenes and to determine the relative effect of the position of the substituent upon the reduction process.The ortho-, meta-and para-isomers of nitrobenzoic acid, dinitrobenzene, nitrochlorobenzene, and nitrotoluene were selected for study. The reduction of these compounds a t the dropping mercury cathode from carefully buffered solutions over the PH range 2 to 14 was investigated to determine the nature of the reduction process and the effect of the position of the substituent groups upon the half-wave reduction potential.
ExperimentalAll of the compounds investigated were obtained from Eastman Kodak Company and were further purified before use. Water solutions of 0.002 M concentration of oand m-nitrobenzoic acids and of 0.001 M concentration of
A study has been made by electron microscopy of the size and size distribution of 22 synthetic latices. Included are GR-S latices Types II, III, and V, polystyrene latices, and several latices of special character.
Details are given on sample preparation, measurement, application of corrections, calculation of number, volume to surface, and molecular weight average diameters, as well as the number and weight average distributions.
The weight average particle size range covered was 730 to 3920A. The smallest sizes were shown by Type II latices, followed in order by Type III, polystyrene, Type V, and some of the special latices. The latices were all nonhomogeneous in size and showed size distributions both on a number and weight basis which in some instances contained single and in some cases double maxima.
The dissolution of Zircaloy‐2 has been studied in the temperature range 15.6°–37.8°C in unagitated and agitated hydrofluoric‐nitric acid solutions. The dissolution rate was found to increase with
HF
concentration and agitation. The energy of activation for the Zircaloy‐2 pickling process compares very well with the value for the unalloyed zirconium pickling process, 3.3 kcal/mole. The energy of activation does not depend on agitation.
Wave length, 655 µ Slit width, 0.130 mm.Cell, 1-cm. Composition of final solution: Indicated volume of standard solution of KTcO< (0.207 mg. of Tc(VII)/ml.); 1.0 ml. of 10% v./v. thioglycolic acid solution of pH 8.0 ± 0.2; 1.0 ml. of 1M sodium acetate solution; and water, to make a total volume of 5.0 ml.
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