No abstract

No abstract

No abstract

MIROSLAW CYCLER, MARIA PRZYBYLSKA, and RICHARD MACLEOD ELOFSON. Can. J . Chem. 60, 2852Chem. 60, (1982. Benzenediazonium tetrafluoroborate, C6HsN2+.BF,-, crystallizes in space group P2, In with unit cell dimensions n = 17.347(2), b = 8.396(1), c = 5.685(1) A, P = 92.14(1)", Z = 4. The structure was solved by direct phasing methods using the program SHELX 76.The parameters were refined by full-matrix least-squares to a final R = 0.063 for 1346 observed reflections. The bond lengths and angles agree very well with those of Rplmming for benzenediazonium chloride. The C-N and N=N bond lengths are 1.415(3) and 1.083(3) A, respectively, and the bonds of the benzene ring do not show any significant differences as they vary from 1.371 (5)

The polarographic behavior of 1,1′-dimethyl- and 1,1′-dibenzyl-4,4′-bipyridinium dichloride has been investigated over the pH range of 1 to 13. Reversible reduction waves are obtained for the first single-electron step for both compounds. The second step is electrochemically irreversible but evidence is presented to indicate that the second step is fleetingly reversible at the dropping mercury electrode for methyl viologen but not benzyl viologen. Minor waves due to adsorption of the reduced viologen on the surface of the mercury have been observed.

No abstract

The reduction of diazotized aromatic amines has been observed to occur at the dropping mercury electrode. The reduction is irreversible and the polarographic waves are too complex to treat with electrochemical equations. Nevertheless distinct waves whose heights vary directly with concentration are obtained. One wave of the reduction occurs at a potential well below that of the azo or nitro groups or nitrite ion. Therefore, it is possible to use the dropping mercury electrode with an applied potential of 0.3 volt vs. the saturated calomel electrode as an indicator for the measurement of the concentration of diazotized amines. In this manner, amperometric coupling titrations, diazotization rates, coupling rates, etc., may be studied. The new technique is more generally applicable than either the gasometric or colorimetric methods of measuring the concentration of diazotized amines. In certain cases, such as measuring the rapid formation of an insoluble azo compound, the polarographic technique is the only practical method available.

with water. The ether layer was separated, dried, and concentrated in vacuo yielding a crystalline solid which after recrystallization from benzene gave 0.04 g of pure material, mp 171-173°, whose spectral and physical properties were indistinguishable from those of tetramethylphthalyldiol prepared by another route (vide supra).