The radio-frequency and microwave spectrum of Ar35ClF has been measured by molecular beam electric resonance spectroscopy. The molecular constants are: Ar35ClF¯Ar37ClF¯B1327.113(5)MHz1319.650(5)MHzDJ4.66(20)kHz4.72(20)kHzμa1.053(3)DeqQa−140.869(15)MHz−111.053(15)MHzThe atomic arrangement is Ar–Cl–F and the vibrationally averaged argon-chlorine distances are 3.3301(1) and 3.3290(1) Å in Ar35ClF and Ar37ClF, respectively. The Ar–ClF bond stretching frequency is 47 cm−1. From the value of eqQa the equilibrium structure is linear with an angle bending frequency of 41 cm−1. The linear structure is striking evidence against the validity of an additive pair potential for an atom and a diatomic molecule. The observed structure is well predicted by Walsh's rule for triatomic molecules.
Electric-deflection studies on molecular beams of the lanthanide trifluorides have been carried out in the temperature range 1000–1200°C. Substantial refocussing, indicative of polar distortions, has been observed for LaF3, GdF3, and LuF3. Weaker refocussing was present in TmF3. CeF3 and ErF3 showed refocussing barely above the noise level. Defocussing was observed in PrF3, NdF3, TbF3, DyF3, and HoF3. Observations on SmF3, EuF3, and YbF3 were inconclusive due to sample reduction in the oven but showed no refocussing attributable to the respective trifluorides. ScF3 and YF3 showed refocussing of a magnitude similar to the trifluorides of La, Gd, and Lu. Deflection studies on the three known lanthanide difluorides revealed that SmF2, EuF2, and YbF2 are strongly polar molecules in the vapor phase and must, therefore, have highly bent structures.
The orientation of addition of H atoms to the asymmetric olefins propylene, butene-I, and isobutene has been determined as a function of atom concentration, olefin concentration, hydrogen pressure, total pressure, and olefin conversion. Conditions have been determined for which complicating secondary processes are believed to be unimportant. The percentage of nonterminal addition is 5.7, 5.7, and 0.48 for propylene, butene-I, and isobutene, respectively. From these data activation energy differences between nonterminal and terminal addition of 1.7 and 3.2 kcal/mole for the linear olefins and isobutene, respectively, may be calculated. For D atom addition to propylene, a small isotope effect was observed, nonterminal addition being 5.4%. These observations are consistent with a predominantly free radical or electroneutral character for H atoms.
The systems: nicorine-water and nicotine-methylethyl ketone were investigated by ther~nal analysis but the cutcctic points were not obtainecl due to tlic estrclne \riscosity and consequent supercooling of solutio~is of hiqh nicotine content.The densities, viscosities, ant1 refractive;ndices were determined for the nicotille -methylethyl Icetone -water sysleni a t 25.0' C.'I'he mutual solubilities of nicotine, methylethyl Icetone, a11d water were deterlnined ovef the entire temperature range. -A ternary critical point was found a t 67.3' C, the critical composition being 27 weight per cent nicotine; 14 weight per cent methylethyl ketone. The methylcthyl ketone -water and nicotine-water solubility cl~rves were redetermined. The existing data for the former syste111 were confirmed but the data for the classical syste~u ~~icotil~e-water \yere found to be seriously in error a t the higher critical solution temperature.Thus the lower critical solutiol~ temperature was found to be 61.5" C, i r l good agreeruerlt with previous figures, but the upper critical solution temperature lies a t 233.0' C, some twenty degrees higher than had been obtained by previous worlcers; the corresponding critical compositions are 36% a n d 409; nicoti~le respectively.The system nicotine-water presents the lvell-known egg-shaped diagram to be found in almost every testbool; of physical c11emist1-y. In othel-words this system is the classical example of a taro-liquid system with both maximum and minimum critical solution temperatures. The system methylethyl lcetoile -water is similar in character, although the lower critical solutioll temperature is cut off by the occurrence of the solid phase, ice. I t was thought that it would be of interest to investigate the three-component system: nicotine -methylethyl kctoile -water, in order to determine the influence of one closed partial miscible region on another of the same type. There existed two main possibilities; either the third component nrould so increase mutual solubility that the volume of heterogeneity would shrinl< to a point before meeting the other volume of heterogeneity and thus t~iro volumes of heterogeneity mould exist in the solid model, or the two volumes would meet forming a tunnel. A further question was whether, in the latter case, the ternary critical s o l u t i o~~ temperatures would lie above or below those of the binary systems.The system methylethyl ketone -water has been investigated by Rothmund (1) and by hlIarshall (2) but the most recent data are issued by the Shell Chemical Corporation (3). Rothnlund fou~ld an upper critical solution temperature and he observed the te~ldellcy to a lower critical solutio~l temperature but he could not realize it because of the occurrence of ice. Ra~ldall and McI
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