Range Of Molar Ratios Research Articles

Conductivity and Viscosity of the Tetrabutylammonium Bromide – Carbon Tetrachloride System

Conductivity and viscosity measurements have been made on tetra-n-butylammonium bromide – carbon tetrachloride solutions for the mole ratio range 1:40 to 1:2 at temperatures from 25 to 40 °C. At any individual concentration, both conductivity and viscosity follow an Arrhenius type temperature dependence. Viscosity increases exponentially with tetrabutylammonium bromide concentration while conductivity has a maximum at approximately 1:5 mole ratio R4NBr–CCl4.

A spectrophotometric investigation of iron(III) chlorine in pyridine

The incorporation of the solvent pyridine into the Coordination Model for non-aqueous solvents is most illuminating with regards to the importance of non-specific solvation. This is a strongly coordinating solvent with poor solvating properties. The species formed when FeCl 3 is dissolved in pyridine have been investigated in both dilute and concentrated solutions over a mole ratio range of 0 to 10 moles of chloride per mole of iron(III). It has been shown that the three species formed which can be detected by ultraviolet-visible spectroscopy and molar conductance techniques are FeCl 4 −, (FeCl 3.nC 5H 5N) and a metastable species of low Cl −/Fe III ratio.

Copolymerization of Vinyl Chloride with Ethylene by the VO(OEt)3-Alkylaluminum Catalyst Systems

Abstract The copolymerization of vinyl chloride with ethylene was carried out in n-heptane by using the catalyst systems consisting of VO(OEt)3 and AlEt3, AlEt2Cl, or AlEtCl2 at 50°C. It was found that each of the above catalyst systems produces a random copolymer at Al/V molar ratios below 1.5; however, polyethylene is mainly obtained above the ratio of 1.5. With the VO(OEt)3/AlEt3 catalyst system, its good catalyst activity being in contrast with the inactivity of the Ti(O-n-Bu)4/AlEt3 catalyst system, the maximum catalyst activity was observed at the Al/V molar ratio of 0.5. The copolymerization rate decreased with an increase in the ethylene fraction in the monomer mixture, reaching a minimum value at a 80 mol% ethylene feed; however, the rate increased above this feed ratio with a further increase in the ethylene feed. The contamination of a copolymer with polyethylene which has been observed in the copolymerization by the Ti(O-n-Bu)4/AlEt2Cl or AlEtCl2 catalyst system was not observed in the present case. The monomer reactivity ratios for the copolymerization by the VO(OEt)3/AlEt3 catalyst system were found to be r1(vinyl chloride)=2.48 and r2(ethylene)=0.02. The reaction between VO(OEt)3 and AlEt3 was investigated by means of infrared spectroscopy and gasometry, and it was found that the average valency states of the V of the catalyst system is higher than four at the Al/V molar ratio range where a random copolymer is exclusively obtained.

Simultaneous determination of thiamine and pyrithiamine

1. (1) Alkaline potassium ferricyanide oxidation of thiamine and pyrithiamine yields two different products as judged by excitation and emission characteristics. The former oxidation produces thiochrome and the latter pyrichrome. 2. (2) The differences in spectral characteristics of thiochrome and pyrichrome have been utilized to determine quantitatively thiamine and pyrithiamine concentration in a mixture of the two. 3. (3) Two generalized equations were derived to determine the concentration of thiamine and pyrithiamine in the presence of biological material: T = d ad − bc E 435 385 − b ad − bc E 480 385 = mνmoles thiamine/asay P = a ad − bc E 480 385 − c ad − bc E 480 385 = mνmoles pyrithiamine/asay where E = emission, P = pyrithiamine, T = thiamine, the numerator of the subscripts the emission wavelength, and the denominator the excitation wavelength. Constants a and b represent the relative molar fluorescence of thiochrome and pyrichrome when excited at 385 mμ and emitting at 435 mμ. Constants c and d represent the relative molar fluorescence of the same two respective compounds with the emission measured at 480 mμ and excitation at 385 mμ. 4. (4) The limit of detection for both thiamine and pyrithiamine is determined both by their absolute amounts and by the molar ratio of the two. When the molar ratio of pyrithiamine to thiamine was between 40 and 8, 12 mμmoles of pyrithiamine could be detected with recoveries ranging from 90 to 115%. With a similar range of molar ratios, 1.5 mμmoles of thiamine per assay could be detected with recoveries ranging from 90 to 100%. The limitations of this approach have been considered.

Studies on the low pressure polymerization of ethylene using catalysts containing sodium alkyls

AbstractThe low pressure polymerization of ethylene with the use of catalysts prepared from various sodium alkyls and titanium tetrachloride was studied. Catalysts prepared from amylsodium were very active over a wide range of molar ratios of amylsodium to titanium tetrachloride (2–50); the activity decreased sharply with lower molar ratios. Rate of polymerization was found to decrease sharply, probably as a result of fusing of polyethylene particles to the catalyst surface during polymerization. Up to a pressure of about three atmospheres, the polymerization gave better yields with increase in pressure, but no increase in rate was observed on using higher pressures. Yields increased also with lowering of temperature; 0°C. gave the best yields. Molecular weight determinations showed that the polyethylenes produced had high molecular weights which did not vary over a wide range. With butylsodium, catalysts similar to those with amylsodium were formed; they showed a smaller optimum range (5–9) of molar ratios of alkyl sodium to titanium tetrachloride. Catalysts prepared from phenylsodium were much weaker, and the optimum molar ratio of phenylsodium to titanium tetrachloride, contrary to the other sodium alkyls, was found to lie at much lower molar ratios of alkyl sodium to titanium tetrachloride. Polymerizations were, in the case of phenylsodium, accompanied by an induction effect. Preliminary studies on the preparation of catalysts for the low pressure polymerization of ethylene in the presence of cyclopentadienylsodium and titanium tetrachloride were as yet not successful.

Equilibrium of the CO2-NH3-Urea-H2O System under High Temperature and Pressure. III. Effect of Water Added on Liquid-Vapor Equilibrium

Abstract (1) The effect of water added to ammonium carbamate on liquid-vapor equilibrium of the CO2-NH3-Urea-H2O system was investigated at 160 °C. and a loading density of ammonium carbamate 0.60 g./cc. and over the range of mole ratio from 0.20 to 1.00 of water added to ammonium carbamate. (2) The equilibrium pressure is approximately constant independent of the amount of water added within the range of the experimental conditions. Both the vapor- and the liquid-compositions become richer in carbon dioxide, and the equilibrium yield of urea decreases with an increase of the amount of water added. (3) The results of calculation of the compositions and densities of the liquid- and the vapor-phases in the equilibrium state when water ranging from 0.20 to 1.00 mole was added to one mole of ammonium carbamate have been shown.