Carbon tetrachloride, effective molar

Modified spectrophotometric procedures are described for the quantitative determination of cobalt and molybdenum as the 2-nitrosonaphth-l-olate and toluene-3,4-dithiolate complexes in carbon tetrachloride. The extraction, chelation and phase separation steps permitted rapid sample handling, controlled interferences more effectively and provided accurate assays. The molar absorptivities for cobalt and molybdenum were 5.1 x 104 and 2.5 xl04mol/lcm, respectively, and the detection limits for both elements were 4 ng/g. 

If the molar fractions of mononuclear complexes formed in stepwise processes are plotted as a function of the free ligand concentration, in general a single extreme is observed. Exceptions from this fairly general regularity occur in systems where the ratio of the components of the solvent mixture varies during the equilibrium measurement. For example, Vertes et al [Ve 73] employed Mossbauer examinations to follow the interaction of tin tetraiodide and dimethylformamide in rapidly frozen solutions in carbon tetrachloride as inert solvent, and showed that a plot of the sum of the molar fractions of the species SnI and Sn(DMF) J as a function of the dimethylformamide concentration exhibited two extremes. The phenomenon was explained by Nagypal and Beck [Na 75] in that a double effect occurs in the solution with an increase in the dimethylformamide concentration ... 

Styrene, a powerful quencher for the trichloromethy1 radical, showed no measurable effect on the selective carboxylation using B-CyD at the initial molar ratio 0.04 to carbon tetrachloride. Consequently, the selective carboxylation using 3-CyD as catalyst probably proceeds with trichloromethyl cations, formed in situ from carbon tetrachloride by the catalysis of copper powder, as the active species. 

The most simple methods for preparation of hafnium carbide and its composites are the follows. The powder of HfO was thermally treated with Mg in molar ratio 5 4 under a CH flow ranging from 800 to 950 °C [4]. The effective high temperature coating for carbon fiber reinforced carbon and carbon fibre reinforced silicon carbide was prepared with use of HfC [5]. For this purpose hafnium carbide layers were obtained in a thermally simulated chemical vapor deposition (CVD) reactor on nonporous substrates by reaction of hafnium tetrachloride, methane and addition of hydrogen (Eq. 10.1) ... 

---