A. A. Palko

Lithium isotope separation factors of some two-phase equilibrium systems

Isotope separation factors of seventeen two‐phase equilibrium systems for lithium isotope enrichment have been determined. In all cases, lithium amalgam was used as one of the lithium‐containing phases and was equilibrated with an aqueous or organic phase containing a lithium compound. In all systems examined, isotopic exchange was found to be extremely rapid, and 6Li was concentrated in the amalgam phase. The isotopic separation factor for the LiOH(aqueous) vs Li(amalgam) system has been studied as a function of temperature from −2 to 80 °C. The values obtained have been compared with the ’’electrolysis’’ and exchange separation factors given in the literature. The two‐phase systems, LiCl(ethylenediamine) vs Li(amalgam) and LiCl(propylenediamine) vs Li(amalgam), have been studied, and the isotopic separation factors have been determined as functions of the temperature. The factors for the two systems have been found to be substantially the same (within limits of the errors involved) over the temperature ...

Separation of Boron Isotopes. II. The BF3 Anisole System

A new gas‐liquid countercurrent system has been developed for the separation of boron isotopes. This system utilizes the exchange reaction between BF3 gas and the BF3·methyl phenyl ether (anisole) complex. Quantitative dissociation of the complex is attained by heating, and recombination by cooling. Half‐time for the isotopic exchange has been shown to be less than three seconds. The single‐stage separation factor [B10F3·anisole (liq.)/B11F3·anisole (liq.)/B10F3 (gas)/B11F3 (gas)] varies from 1.039 at 0°C to 1.028 at 30°C. Physical properties of the complex have been determined and solvent decomposition has been studied.

Separation of Boron Isotopes. I. Boron Trihalide Addition Compounds

Isotopic separation factors for several gas‐liquid systems for concentrating boron isotopes have been determined. Separation factors at 25°C are:         System(B10/B11) liq/(B10/B11) gasBF3(g) vs anisole·BF3 (liq.)1.032±0.011 (95% C.I.)BF3(g) vs di−n−butyl sulfide·BF3 (liq.)1.033±0.005 (95% C.I.)BF3(g) vs phenol·BF3 (liq.)1.027±0.014 (95% C.I.) Separation factors for a number of BCl3‐organic systems have also been studied, and a new compound (C6H5)2O·BCl3 has been prepared and characterized.

Raman and Infrared Spectra of BF3 Complexes with Diethyl Ether and Tetrahydrofuran, and the Isotopic Exchange of these Complexes with BF3

The Raman and infrared spectra of BF3·diethyl ether and BF3·tetrahydrofuran have been recorded for both the B10 and B11 compounds. The spectra have been compared to that of BF3·dimethyl ether and tentative assignments of the skeletal vibrations have been made. The isotopic data have been used to calculate theoretical equilibrium constants for isotopic exchange between the complexes and BF3. The calculated values are slightly higher but compare quite well with published values of experimentally determined separation factors.

Separation of Boron Isotopes. III. The n‐Butyl Sulfide‐BF3 System

The gas‐liquid isotopic exchange between BF3 and the n‐butyl sulfide‐BF3 complex was studied as a possible system for enriching boron isotopes. The single stage separation factor varied from 1.054 at —20°C to 1.033 at 26°C. B10 concentrated in the liquid phase. The heat of association of the n‐butyl sulfide‐boron trifluoride complex was determined to be —12.76±0.06 kcal/mole from a series of vapor pressure measurements of the complex made at several mole ratios of BF3 to sulfide.

Separation of Boron Isotopes. VI. Ethyl Ether, Ethyl Sulfide, and Triethylamine‐BF3 Systems

The BF3 complexes of ethyl ether, ethyl sulfide, and triethylamine were studied. Isotopic equilibrium constants for the reactions B10F3(g)+B11F3·donor(l)⇌B10F3(g)+B10F3·donor(l) were measured at several temperatures for each of the three systems. Vapor pressures of the ethyl sulfide complex, and rates of exchange of boron between BF3 and BF3·Et3N were also determined.

Equilibrium Constant for Boron Isotope Exchange between BF3 and BF3·O (CH3)2

The isotopic equilibrium constant for boron exchange between BF3 and BF3·O (CH3)2 has been measured at −8°, 4°, and 22°C. The measured values are compared with values calculated from infrared and Raman spectral data. The physical basis for boron isotope fractionation in systems of this type is discussed.

Separation of Boron Isotopes. V. The Phenol‐BF3 System

The exchange of boron between BF3(g) and BF3·phenol(l) was studied. The single‐stage isotopic fractionation factor varied according to the equation, logα= (10.315/T) —0.02423, over the temperature range —8°C to 37°C. B10 is concentrated in the liquid phase. Vapor‐pressure measurements of dilute and concentrated solutions of BF3 in phenol were made at various temperatures from —10°C to 40°C. The freezing point of the BF3·phenol complex was approximately —15°C; that for the BF3·2 phenol, —5°C.

Separation of Boron Isotopes. IV. The Methyl Sulfide‐BF3 System

The exchange of boron between BF3 (gas) and the dimethyl sulfide‐BF3 complex (liq.) was studied from —20°C to +26°C. The single stage separation factor changed from 1.056 to 1.031 over this temperature range with B10 concentrating in the liquid phase. Vapor pressures of dimethyl sulfide and of various mixtures of BF3 and dimethyl sulfide were determined. ΔH for the reaction BF3 (gas)+Me2S (liq.)→BF3·Me2S (liq.) was estimated to be —10.1 kcal/mole over the above temperature range. The melting point of the 1:1 complex was —19.6°C.

Separation of Boron Isotopes. VIII. BF3 Addition Compounds of Dimethyl Ether, Dimethyl Sulfide, Dimethyl Selenide, Dimethyl Telluride, Dibutyl Ether, and Ethyl Formate

Studies were made of the physical and chemical properties of molecular addition compounds formed by BF3 and Group VIb donors. The dimethyl telluride complex was too unstable to exist at temperatures above −30°C. The freezing point of the 1:1 dimethyl selenide·BF3 compound was −43°C. From room temperature to its freezing point, the saturation pressure of the 1:1 dimethyl selenide complex was given by log10 P=9.945— (1824/T). The 1:1 butyl ether and ethyl formate complexes formed at 25°C but deteriorated slowly with the formation of noncondensible gases. The freezing points of these complexes were −30° and −8°C, respectively. Between room temperature and their freezing point, the saturation pressures of freshly prepared Bu2O·BF3 and HCOOEt·BF3 were given by logP=5.65— (1010/T) and logP=5.70— (1330/T), respectively. For the same temperature range, the equilibrium constant for the isotopic exchange reaction 10BF3(g)+A·11BF3(l)=11BF3(g)+A·10BF3(l) was given by logKeq=(8.13/T) −0.0131, when A was dimethyl selen...