bluuebunny/crossref_metadata_2025 huggingface dataset:
The Absorption Spectra of Sugars in the Near Infra-Red
Authors: Barr E. S. , Chrisman C. H.
Published: January 2005

The infra-red absorption spectra of aqueous solutions of nine monosaccharides and four disaccharides have been observed in the region between 1.7 and 4.6μ. A special technique of evaporation was used in the preparation of samples, so as to minimize the effect of the solvent upon the transmission curves. It was found that all thirteen materials gave very similar spectra; band locations were very nearly identical, although there was some degree of variation in intensities. Bands not previously reported were found at 2.16 and 2.35μ, and the intense absorption in the region of 3.3μ was partially resolved into component bands.
Infra-Red and Raman Spectra of Polyatomic Molecules X. C2D2, C2DH, and C2H2
Authors: Stitt Fred
Published: January 2005

The infra-red spectra of acetylene and its deuterium isotopes have been studied on a prism spectrometer from 450 to 4000 cm—1. All but two of thirty observed bands have been assigned as fundamentals, first and second overtones, and one-one combination or difference bands. Most of the bands of these types which are infra-red active according to the selection rules are either observed or occur in a region where they may be masked by the presence of super-imposed bands.
Investigations on the High Temperature Photolysis of Acetaldehyde
Authors: Grahame David C. , Rollefson Gerhard K.
Published: January 2005

A detailed investigation of the high temperature photolysis of acetaldehyde vapor has given results differing in certain details from those of previous investigators. The heat of activation found for the over-all reaction (8.6±0.3 kcal.) leads with one assumption to a value of 75 kcal. for the energy of the C–C bond in acetaldehyde. The reaction between methyl radicals is rather accurately bimolecular. Values are given for the relative quantum efficiencies for the production of free radicals in acetone and acetaldehyde at elevated temperatures at two wave-lengths.
The Ultraviolet Absorption of NO2
Authors: Harris Louis , King G. W. , Benedict W. S. , Pearse R. W. B.
Published: January 2005

A system of eight discrete and several diffuse bands in the ultraviolet absorption spectrum of NO2 has been analyzed. From the positions of the bands and their temperature coefficient of absorption the upper state intervals have been determined as 523 and 714 cm—1, those of the lower state as 749 and 1319 cm—1. The latter are not the same as the fundamentals deduced from infra-red data. Different possibilities of reconciling these intervals are discussed.
The Absorption Spectra of Gaseous Methylamine and Dimethylamine in the Photographic Infra-Red
Authors: Cleaves A. P. , Sponer H. , Bonner L. G.
Published: January 2005

The absorption spectra of gaseous methylamine and dimethylamine have been measured in the region from 6000 to 12,000A using a 105-foot stainless steel absorption tube and a 3-m grating spectrograph. Absorption bands were observed at 7940, 9100, 9940, 10,070, 10,330 and 11,800A in methylamine and at 7940, 8045, 9100, 10,360, 10,625 and 11,800A in dimethylamine. The only band showing resolvable fine structure was that at 9940A in methylamine. Wherever possible the observed bands have been assigned to overtones and combinations of the fundamental N–H and C–H valence vibrations.
The Rate of Solution of Metals in Acids as a Function of Overvoltage II. The Solution of Cadmium in Sulfuric Acid
Authors: Kimball George E. , Glassner Alvin
Published: January 2005

The rate of solution of cadmium in sulfuric acid has been measured as a function of the hydrogen overvoltage at the electrode surface. The rate was found to be constant at a given potential, independent of the concentration of sulfuric acid used. The rate increases with the electrode potential in accordance with the theory of Kimball. From the dependence of the rate on the speed of stirring, and also from the behavior on varying the potential, it is concluded that the solution process is diffusion controlled. The effect of surface inhomogeneities was too great to permit an evaluation of the absolute rate.
Solvent Action on Optical Rotatory Power III. The Influence of Liquid Structure on the Interaction of Dipoles
Authors: Beckmann Charles O. , Marks Henry C.
Published: January 2005

By taking into account the London ``dispersion'' forces and the structural characteristics of a liquid system, an equation for the change of rotivity per mole of dipole solvent in unit volume for liquid solutions is obtained which has the same form as the equation obtained by Beckmann and Cohen for a mixture of gases that are perfect except for dipole interaction, namely, S=G(α,β,γ)+KγPγ.This is due to the fact that the polarization term arises from the integration over the angles of orientation alone. The constants, G(α, β, γ) and Kγ have, of course, a new significance in the present work.
Lattice Vibrations of Crystals and the Corresponding Vibrations of Their Solutions. II
Authors: Freed Simon , Weissman S. I.
Published: January 2005

Because vibrations have been found in liquids which closely resemble what have been regarded as lattice vibrations in crystals, we examine whether the vibrations in crystals are to be ascribed to local complexes rather than to an extended lattice. Our experiments confirm the appropriateness of the term ``lattice vibrations'' and analogous vibrations must, it seems, be accepted as taking place in solutions. Alcohol with a more regular arrangement within the liquid than water gives rise to greater sharpness in the quasi-lattice vibrations of the solution. Correspondingly, a mixed solvent gives a greater spread and diffuseness to the vibrations even though the electric fields immediately surrounding the positive ions in such a solution are as sharp in their effect on the electronic levels as in the pure solvents separately. With absolute alcohol, europium chloride and europium nitrate form solutions which show different quasi-lattice vibrations in their spectra; but when these salts are dissolved in water, the vibrations of the solutions appear about the same. The hydrated crystals of europium chloride exhibit lattice vibrations which are different from those of the hydrated mixed magnesium europium nitrate. In the ionic crystals of anhydrous europium fluoride, a lattice frequency appears; this is considerably greater than any yet measured. A discussion concerning the nature of the systems partaking in the quasi-lattice vibrations is included.
Photosensitization and Fluorescence by Aromatic Hydrocarbons
Authors: West W. , Miller W. E.
Published: January 2005

Benzene, naphthalene, related hydrocarbons and some of their derivatives act as optical sensitizers towards the decomposition of alkyl iodides in hexane solution. Within this group, the sensitizing power of a substance towards an acceptor runs parallel with the ability of the acceptor to quench the fluorescence of the sensitizer; this is demonstrated quantitatively and in detail. The quantum yield of the naphthalene-sensitized decomposition of ethyl iodide follows an equation of the form 1/φ=a+b(1/[EtI]), and detailed analysis of the quenching and sensitization shows that while sensitization and fluorescence are alternative processes, they are not completely reciprocal, in that more molecules may sensitize than may potentially fluoresce. All of the observed features of the sensitization are consistent with its being the result of a resonative transfer of energy at collision from the excited sensitizer to the acceptor.
On the Kinetics of the Order-Disorder Transformation in Cu3Au
Authors: Siegel Sidney
Published: January 2005

Using the elastic modulus S11 as an indicator, the rate of the order-disorder transformation of Cu3Au has been investigated in the region near the critical temperature. The variation of S11 with time, at constant temperature, of a [100] single crystal of the alloy has been measured, and all the data for the transformation from disorder to order can be represented in one curve by plotting the fraction of untransformed material against the ``reduced'' time, t/τ. The relaxation time τ decreases rapidly with increasing amount of undercooling below the critical temperature, and combined with the data of Sykes and Evans on the resistivity vs. time curves, points to a minimum in τ about 20°C below the critical temperature. The critical temperature for the ordering process was found to be 386.8°C, for the disordering process 388.0°C. The observed data on the variation of τ with temperature are discussed in terms of a mechanism of nucleation and growth for the transformation.
Raman Spectrum of 1-Bromo-Dodecane
Authors: Cleveland Forrest F. , Murray M. J.
Published: January 2005

Raman displacements, estimated intensities and depolarization factors have been measured for 1-bromo-dodecane in the liquid state. The strong, polarized frequencies 563 and 647, characteristic of the —CH2Br group, have the same constant values as do other members of the series from n-propyl to n-heptyl bromide inclusive. The weak, depolarized frequency 3009 is also probably associated with this group. Five of the observed frequencies agree rather well with values of infra-red active chain and end frequencies recently calculated by Whitcomb, Nielsen and Thomas for undecane, the mean deviation being 30 cm—1. The intense, highly polarized frequencies 2850 and 2930 and the less intense, depolarized frequency 2961 appear in the bromide spectrum as well as in the spectra of many other compounds containing alkyl radicals.
Dielectric Polarization in Solution II. The Polarization of Some Alcohols as a Function of Concentration and Temperature
Authors: Rodebush W. H. , Eddy C. R. , Eubank L. D.
Published: January 2005

Curves showing the apparent molal polarization as calculated by the Debye-Clausius-Mosotti procedure are compared with the molal polarizability calculated as proposed in the introductory paper of this series. It is possible to give a satisfactory explanation of the latter curves in terms of association whereas the former curves show a behavior so complex that it is difficult to interpret. In the first paper of this series the authors showed that the behavior of the apparent molal polarization as calculated by the Debye-Clausius-Mosotti procedure was such as to lead to dubious conclusions even for the simplest type of polar substances. A procedure of applying the equation of Onsager was outlined which promises to make possible the interpretation of data on polarization in a realistic manner. The first paper was inspired by an attempt to apply the Debye-Clausius-Mosotti procedure to the alcohols in solution where it leads to results that are puzzling indeed. In this paper these data are published and discussed from the standpoint of the Onsager theory. When some additional data on alcohols in very dilute solution are obtained, it is hoped that an exact value can be obtained for the moments of the alcohols.
Ozone in Silent Electric Discharge
Authors: Otto William H. , Bennett Willard H.
Published: January 2005

Ozone is produced in silent discharges in air by collisions intermediate between ionizing energies and attaching energies, due to the dissociation of oxygen molecules into atoms by electrons. A more detailed mechanism for the silent discharge is given.
The Normal Vibrations of Molecules of the Tetramethylmethane Type
Authors: Silver Samuel
Published: January 2005

The normal modes of a tetrahedral A(CH3)4 molecule have been investigated. For fixed orientations of the methyl groups, there are two configurations in which the molecule as a whole possesses the symmetry group Td. The group theory analysis has been applied to one of these configurations, referred to as the eclipsed form, and on the basis of Redlich's theorem a set of symmetry coordinates has been derived for each set of equivalent points. Every symmetry coordinate is associated with an irreducible representation of the group, and, as a consequence, the secular determinant is factored to the maximum extent possible on symmetry considerations alone. Using a simple valence potential, the secular equations for the totally symmetric and doubly degenerate modes have been developed. Calculations have been made for tetramethylmethane, C(CH3)4, tetramethylsilane, Si(CH3)4, and the tetramethylammonium ion, N+(CH3)4, assuming in every case that the force constants associated with the methyl groups are the same as in ethane. The results are in reasonable agreement with frequencies observed in the Raman spectra and a tentative assignment of the latter is suggested.
The Entropy of Dilution of Strong Electrolytes in Aqueous Solutions
Authors: Frank H. S. , Robinson A. L.
Published: January 2005

The relative partial molal entropy of water, S̄1–S10, in aqueous electrolyte solutions is calculated from existing data. An attempt is made to correlate these values with changes in the structure of water in the solutions. It is found that cations of small radii and ions capable of forming hydrogen bonds with the water, such as H3O+, OH— and NH+4, help to stabilize the water structure, while large ions and ions of nonspherical and nontetrahedral shapes have an effect in the opposite direction. In dilute solutions the entropy of dilution depends largely on the ionic strength. In all cases deviations from the Debye-Hückel limiting law are positive.
Effect of Gravitational Field on the Thermal Diffusion Separation Method
Authors: Farber Milton , Libby W. F.
Published: January 2005

A test of the effect of gravitational field on the operation of the Clusius-Dickel thermal diffusion method for gas separation has been made by use of a hollow disk with one hot surface, the whole disk spinning at various speeds. Linear increases in both the equilibrium separations and the rates of separation with increasing centrifugal force were obtained for speeds below a certain maximum value. Above this both the rate and equilibrium separations fell rapidly. He–CO2 mixtures were used. The results indicate that the standard column would be improved if it were placed in a larger field up to ten times that caused by gravity. Theories for the action of the thermal diffusion column should show this. The apparatus cannot compete with the standard column type for isotopic separations but may have some application to industrial separation problems.
The Low Temperature Gaseous Heat Capacities of Certain C3 Hydrocarbons
Authors: Kistiakowsky G. B. , Lacher J. R. , Ransom W. W.
Published: January 2005

The low pressure thermal conductivities of allene, propylene, propane, methyl acetylene and cyclopropane have been measured over the temperature range 150 to 340°K. The heat capacities derived from these measurements are compared with those from other sources. Data are presented in support of the bracketing method for deriving heat capacities from heat conductances. Heats of certain hydrogenation reactions, when calculated to 0°K and to the nonvibrating state, are found to exhibit the same regularities as the experimental values determined at 335°K.
Statistical Theory of Duplex Films
Authors: Feng Lawrence S. K. , Band William
Published: January 2005

The dissociation treatment of condensing systems is applied to duplex films. Complete agreement with the data on the saturated state of the films of myristic acid published by Adam and by Harkins is obtained on the following assumptions: (i) the momentum of each entire molecule contributes to the monolayer gas pressure; (ii) the interaction potential between the ``liquid ends'' of the molecules is equivalent to an ``intrinsic pressure'' which has the effect of increasing the surface tension at the interface between parent liquid and monolayer; (iii) this intrinsic pressure is derivable from a Lennard-Jones type of interaction potential depending on mean molecular area: W=W0+α/A4.5—β/A3; (iv) the tails of the molecules can form clusters, thus forming micelles in the duplex film, in which there are six bonds per molecule, each with interaction energy ε=—8.8×10—14 erg per molecule. The field constants α, β seem to depend slightly on the nature of the parent liquid, but the energy ε is independent of this. The duplex film therefore appears to have its liquid layer in contact with the parent liquid, the free tails forming the gas layer. More data on different parent liquids are needed before a definite decision on this point can be made.
The Infra-Red Absorption Spectrum of Methylphenylacetylene
Authors: Murray M. J. , Cleveland Forrest F.
Published: January 2005

The infra-red spectrum of methylphenylacetylene between 500 and 2300 cm—1 has been measured with the aid of a prism spectrometer. The results are compared with the Raman spectrum of this compound, previously measured by the authors. The results are inconclusive as regards the assignment of the fundamental whose overtone, according to Badger's hypothesis, is responsible for the resonance splitting of the frequency near 2230 cm—1.
The Rotational Structure of the Hydrazoic Acid Bands in the Photographic Infra-Red
Authors: Eyster Eugene H.
Published: January 2005

The third and fourth harmonics of the N–H stretching frequency in hydrazoic acid, at 9547.31 and 12,412.19 cm—1, respectively, have been studied photographically under high dispersion. The rotational structure has been well resolved and completely analyzed, to yield the rotational constants in the ground and excited states. The effective moments of inertia in the ground state have been combined with other information to determine the structure of the molecule; the best values of the molecular parameters are: N1–H=1.012AN2–N3=1.128AN1–N2=1.241AΔHN1N2=110∘52′.
Normal Vibrations of Chains of Similar and Similarly Situated Dynamical Systems and the Infra-Red Spectrum of Undecane
Authors: Whitcomb S. E. , Nielsen H. H. , Thomas L. H.
Published: January 2005

Theory indicates that the normal modes of vibration of chain molecules fall into two classes; end vibrations in which the amplitude falls off exponentially from the ends towards the middle, and chain vibrations in which it varies harmonically as in a standing wave. The transition from one class to the other takes place via chain vibrations with a small number of nodes of amplitude along the chain. For a long chain we expect only those chain vibrations to show up in the infra-red spectrum for which the phase of the electric moment is constant along the chain.

These considerations have been applied to predict the vibration spectra of the straight chain paraffins, assumed to consist of a zigzag chain of carbon atoms each carrying two hydrogen atoms in a plane perpendicular to the chain and alternately above and below it.

The infra-red spectrum of undecane has been measured from 1 to 15μ on a prism spectrometer, the positions of 31 bands being determined. Accepted values of the interatomic distances and angles were assumed and force constants were adjusted to fit four of the fundamental frequencies to observed bands. Bands were observed near all the other fundamental frequencies predicted certainly to occur (as chain vibrations) and near one out of three that should possibly occur (as end vibrations near chain vibrations with few nodes). All but three of the observed bands could be accounted for as fundamentals, harmonics, or simple combination frequencies.
The Determination of Internuclear Distances and of Dissociation Energies from Force Constants
Authors: Sutherland G. B. B. M.
Published: January 2005

With a view to obtaining the internuclear distances and dissociation energies of individual bonds in polyatomic molecules purely from a knowledge of force constants the consequences of assuming that the potential energy of any di-atom may be expressed in the form V=—α/rm+β/rn have been further investigated. In addition to giving a relation between internuclear distance and force constant of the form suggested empirically by Badger, this assumption leads to a relation between force constant (ke), internuclear distance (re) and dissociation energy (De) of the form De=(kere2)/mn. It is found that such a relation does exist between those quantities for series of diatomic molecules belonging to the same row in the periodic table, provided one uses an ``effective'' internuclear distance re—dij. This was also used by Badger in his relation of force constant to internuclear distance and the values of dij obtained by the two different methods are in reasonably good agreement. The values obtained for the product mn are 4, 6.2, 6.2 and 10.8 for the respective series LiH to FH, Li2 to F2, Na2 to Cl2 and K2 to Br2. For the hydrides it would seem that —α/r+β/r4 is the correct form with β varying along the series. It is also shown that this function leads to a relation between the shift in frequency δv and the change in bond energy δD in the formation of a hydrogen bond.
Spectroscopic Evidence for Hydrogen Bonds: Comparison of Proton-Attracting Properties of Liquids. II
Authors: Gordy Walter , Stanford Spencer C.
Published: January 2005

Forty-two different organic liquids are rated according to their proton-attracting power by comparing the strength of the hydrogen bonds which they form with heavy methyl alcohol. The classes of liquids studied are: aldehydes, ketones, esters, ethers and amines. The amount of perturbation which the different solvents cause in the OD vibrational band of the CH3OD is taken as a measure of the strength of the deuterium bridges formed with the CH3OD. The study is a continuation of a previous work in which twenty-six similar liquids were studied, and the results agree with those of the former study in showing that according to proton-attracting power the different classes are in the order: esters<aldehydes and ketones<ethers <amines. From the study it is possible to observe the effects of unsaturation, substitution, and other structural variations on the electron donor power of the O or N atom to which the OD group forms a bond. It is shown that the strength of the deuterium bonds formed with CH3OD bears a close relation to the basicities of the solvents, to their solubilities for other proton donor solutes, and to their reactivity with other compounds. There appears to be no correlation between the dipole moments of the solvents and the strengths of the bonds formed with the CH3OD.
Adsorption Isotherms for Mobile Monolayers
Authors: Band William
Published: January 2005

A three-dimensional gas is pictured in contact with a liquid, forming at the interface a mobile monolayer. The density of the monolayer is maintained in equilibrium with the pressure of the gas. An equation is deduced giving as a function of temperature, the gas pressure which is just sufficient to initiate condensation in the monolayer. The only physical parameters involved in the relationship are the mass of the molecule and the heat of evaporation per molecule from the completely clustered monolayer. The fatty acids which exhibit monolayers with negligible external gas pressures, must have heats of evaporation greater than about 100×10—14 erg. Molecules as small as 20 atomic mass units and heats of evaporation less than about 75×10—14 erg should require pressures of the order of 10—2 atmosphere. An adsorption isotherm equation is found for monolayer concentrations less than the saturation value. Its form is similar but not identical with Langmuir's isotherm for immobile monolayers.
Directed Valence
Authors: Kimball George E.
Published: January 2005

The problem of directed valence is treated from a group theory point of view. A method is developed by which the possibility of formation of covalent bonds in any spatial arrangement from a given electron configuration can be tested. The same method also determines the possibilities of double and triple bond formation. Previous results in the field of directed valence are extended to cover all possible configurations from two to eight s, p, or d electrons, and the possibilities of double bond formation in each case. A number of examples are discussed.
On the Heterogeneous Ortho- Paraconversion on Paramagnetic Crystals
Authors: Farkas L. , Sandler L.
Published: January 2005

The rate of conversion of parahydrogen and of orthodeuterium is measured on paramagnetic crystals, viz., CuSO4, NiCl2 and neodymium oxalate. In the last case, crystals of approximately uniform size were used so that the total converting area was known. The conversion rate has a maximum at 0°C and it is shown that below this temperature the desorption rate of the H2 and the D2 is rate-determining. Hence, the ratio of the rates for H2 and D2 is not far from unity. The rate of desorption increases with increasing temperature and at higher temperatures, the rate of conversion on the surface becomes the slow process. The ratio of the rates for H2 and D2 becomes nearly 11 in this region. The heat of adsorption of the hydrogen on neodymium oxalate is about 2.4 kcal./mole.
Vibration Spectra and Molecular Structure IX. Further Studies of the Vapors of the Fatty Acid Series
Authors: Herman Robert C.
Published: January 2005

The monomer spectra of the vapors of C3H7COOH, C3H7COOD and C4H9COOH have been obtained in the near infra-red with a rocksalt spectrometer. The association of each of the following molecules: HCOOH, HCOOD and C3H7COOD has been studied in the vapor phase by measuring the variation with temperature and pressure of the intensity of some association band. The bond strengths obtained for these fatty acids are 6.2, 6.4 and 6.9 kcal. per mole per bond, respectively. The fact that the bond strengths for light and heavy formic acids agree within the experimental error although the determinations were carried out with different bands is further evidence that the spectroscopic method is satisfactory. The lower value obtained for the bond strength in formic acid by this method compared to the vapor density value is discussed. In addition, it is suggested from the experimental data available at the present time, that it does not seem possible to claim the existence of a simple linear relationship between the bond strength and Δv/v. Some results concerning v(CH) absorption in the first five members of the fatty acid series are given.
Reactions of Free Radicals with Organic Compounds Containing Atoms with Unshared Electron Pairs
Authors: Rice Francis Owen , Walters W. D. , Ruoff P. M.
Published: January 2005

An experimental test for the reaction CH3+CH3OCH2CH3→CH3OCH3+CH3CH2 was made by decomposing methyl ethyl ether both alone and in presence of azomethane, and examining the products for dimethyl ether; none was detected, and if this reaction occurs at all it is only to the extent of a very few percent. A similar test for the reaction CH3+CH3CH2CH2NH2→CH3NH2 +CH3CH2CH2 was made by decomposing pure n-propylamine in a flowing system, but this also gave a negative result. The products formed in the promoted decomposition of dimethyl ether were found to be essentially the same as those formed in the normal decomposition.
The Structure of Phosphine and Related Hydrides
Authors: Stevenson D. P.
Published: January 2005

It is shown that Badger's rule when applied to the frequencies of some hydrides gives values for the interatomic distances which are in agreement with values deduced from the moments of inertia of the hydrides and with values predicted from the covalent radius suggested for hydrogen, 0.315A. Using the value 1.415A. for the phosphorus-hydrogen distance in phosphine and a reliable spectroscopic value for one of the moments of inertia of the molecule one finds the bond angle to be 93°. Values are suggested for the bond angles and bond distances in a number of hydrides whose structures have not been experimentally determined.
Bond Strength and Potential Energy Relationships in Acetylene
Authors: Henkin Hyman , Burton Milton
Published: January 2005

The spectroscopic value for the heat of formation of free CH and Herzberg's value for the heat of sublimation of graphite lead to a value of ∼137.9 kcal. for the C≡C bond strength in acetylene. This value is employed in a study of the potential energy levels of that compound and is shown to be the only one consistent with the most recent studies of its absorption spectrum. The fact that the known energy levels of free CH fit into the scheme is further evidence for the 125.1 kcal. value for the heat of sublimation of graphite.
The Molecular Structure of Isobutane
Authors: Beach J. Y. , Walter John
Published: January 2005

The two published electron diffraction investigations of isobutane led to slightly conflicting results. We have repeated the calculation of the theoretical scattering curves using Z—F instead of Z for the atom form factor and including the temperature factor. The final results are: C–C distance, 1.54±0.02A; C–C–C angle 111° 30′±2°.
Errors in the Determination of the Dissociation Constant of a Weak Acid by the Extrapolation Method
Authors: Kilpatrick Mary L.
Published: January 2005

In the extrapolation method for determining the dissociation constant of a weak acid the value of the limiting equivalent conductance is not known from independent measurements, and both the limiting equivalent conductance Λ0 and the dissociation constant K are obtained from conductimetric measurements on solutions of the acid. While clearly convenient, the reliability of the method has been questioned. In the present paper equations are derived which express the effect on K and on Λ0 of errors in the experimental quantities. For water as solvent, tables are given showing the numerical values of the errors. The possibility of detecting constant errors is discussed.
Intensities in Molecular Electronic Spectra X. Calculations on Mixed-Halogen, Hydrogen Halide, Alkyl Halide, and Hydroxyl Spectra
Authors: Mulliken Robert S.
Published: January 2005

The dipole strengths for certain perpendicular-type transitions N→Q in the mixed halogens, the hydrogen and monovalent metal halides, and the alkyl halides, are calculated theoretically by the LCAO and by the AO approximations. The scanty experimental absorption coefficient data on these halides (particularly the hydrogen and alkyl bromides and iodides) are critically examined, and acceptable experimental dipole strengths are obtained for the bromides. These show, very gratifyingly, the same kind of agreement with the calculated values as was found in IX of this series for the N→Q transitions in F2, Cl2, and Br2. The iodides, however, just like I2, show anomalously low strengths for the true N→Q part of the intensity (N→3II1 and N→1II), together with high strength for N→3II0+. These anomalies are ascribed here, as in I2, to partial case c coupling (partial preservation of atomic J's). The comparison between theory and experiment confirms the interpretation of the ultraviolet continua of the hydrogen and alkyl halides as N→Q transitions. Dipole strength calculations for the well-known 2Σ→2II transition in OH have also been made. The agreement with Oldenberg and Rieke's experimental values for OH is of much the same kind as for the other molecules. A general equation for the N→Q dipole strength in AX or OH is obtained covering any degree of ionicity and of polarity. This includes the AO and LCAO approximations, with any degree of polarity, as special cases. It is found that the intensity is on the whole not especially sensitive to polarity. The magnitudes of overlapping and dipole strength integrals in relation to molecular stability and to principal quantum number of the valence orbital are discussed. The integrals are notably larger for molecules containing the heavier halogens (3p, 4p, 5p orbitals) than for those containing fluorine (2p orbital). They are also larger for hydrogen halides than for corresponding halogens.
The Reactions of Ethyl Radicals
Authors: Moore Walter J. , Taylor Hugh S.
Published: January 2005

The photochemical investigation of the decompositions of diethyl zinc and diethyl mercury has established that the products in each case consist principally of ethane, ethylene, and butane, with smaller amounts of hydrogen and butylene. The composition of the product varies with the alkyl, but does not change markedly with temperature from 45° to 250°. An examination of the effects of varying the concentration, intensity of radiation, packing of reaction vessel, and inert gas pressure leads to the conclusion that butane is formed by the combination of two ethyl radicals produced in the primary process, while ethane and ethylene arise from a reaction between ethyl radicals and metal alkyl molecules. The reaction between ethyl radicals and hydrogen becomes measurable at about 160°, and by analogy with the corresponding process with methyl radicals may be assigned an activation energy of 9±2 kcal. The reaction C2H5+H=2CH3 proceeds rapidly at 100°. The investigation of the photolysis of ethyl iodide in the presence of mercury vapor and the mercury photosensitized hydrogenation of ethylene supports the conclusions based on the metal alkyl studies.
Hindered Rotation I. The Configuration of the Cyclohexane Molecule
Authors: Langseth A. , Bak B.
Published: January 2005

A restriction of the free rotation about the carbon-carbon single bond will play an important role in the potential function of the cyclohexane molecule. Any force whose nature is such that it will produce a hindrance to the free rotation about the C–C bond must also give rise to different potential energies for the ``chair'' and ``tub'' forms of cyclohexane even if these forms are ``strainless'' in the Baeyer theory sense. According to the nature of the rotational restriction (stabilizing ``staggered'' or ``opposed'' configurations) either the ``chair,'' the ``tub,'' or even the hexagonally symmetrical form with a plane carbon ring could be the most stable form. From considerations of the obtained Raman spectra of cyclohexane, cyclohexane-d1, and cyclohexane-d12 it is shown that the only form present in measurable quantities is the form with a D6h symmetry, i.e., the form with the plane of the carbon ring as a reflection plane for the hydrogen atoms. The rotational restriction about the C–C single bond, therefore, is of such a nature that it stabilizes this D6h configuration, in which the H atoms are in ``opposed'' positions.
Hindered Rotation II. The Hindered Rotation About the C–C Single Bond in Tetrachloroethane
Authors: Langseth A. , Bernstein H. J.
Published: January 2005

Because of the restriction to internal rotation, tetrachloroethane might consist of several rotational isomers: a cis-(C2v) form, a trans-(C2h) form, or forms intermediate to cis and trans with C2 symmetry. From the Raman spectrum of C2D2Cl4 and the spectrum of C2H2Cl4 at different temperatures experimental evidence has been obtained which shows that the equilibrium mixture consists of two rotational isomers, the cis-C2v form and the C2 form. The C2v form was found to be the more stable, with a potential energy 1100 cal. per mole lower than the potential energy of the C2 form.
The Variation of the Transference Numbers of Potassium Chloride in Aqueous Solution with Temperature
Authors: Allgood R. W. , Le Roy D. J. , Gordon A. R.
Published: January 2005

The transference numbers of potassium chloride in aqueous solution have been determined for concentrations from 0.01N to 0.10N at temperatures from 15°C to 45°C by the moving boundary method. Both cation and anion boundaries were used. The results obtained by the two methods are in satisfactory agreement, the sum (t++t-) for a solution being unity within a few units in the fourth decimal place; the data reported here are also in close agreement with those reported by Longsworth for 25°C. For the whole range of temperature, the Longsworth function t+°′ is linear in the concentration. It is found, however, that the cation transference number decreases with rising temperature, in contradiction to the Kohlrausch generalization which predicts that transference numbers less than one-half should increase with rising temperature.
Calculation of Dipole Moments from Rates of Nitration of Substituted Benzenes and Its Significance for Organic Chemistry
Authors: Ri Taikei , Eyring Henry
Published: January 2005

(1) From a set of assumptions which seem reasonable a priori, the authors calculate the charge distributions in the molecules of mono-substituted benzenes, and the dipole moments of the latter from reaction rate data alone. These coincide very well with the observed moments. (2) From the dipole moments of aromatic and aliphatic compounds, the ortho-, meta- and para-percentages during nitration were calculated. These also accord satisfactorily with the experimental values. (3) It is concluded that these two facts give a quantitative basis to the usual explanation about the orienting power of substituents of benzene. (4) The nitration of benzene is an ionic reaction : The nitrating agent X·NO2 dissociates into X— and NO2+ in the activated complex, and the latter ion interacts with the reacting carbon. The activation free energy is reduced by the amount of the electrostatic interaction, i.e., 4.80·10—10εy/(rD). Here εy is the charge on the reacting carbon, r, the distance between NO2+ and the reacting carbon in the activated complex, D, the dielectric constant of the medium between NO2+ and the reacting carbon. (5) The authors find that r=1.6A and D=1 approximately, independent of the nature of the reacting media. The consequences of this theory are outlined. (6) Further this interpretation of reaction rates provides, for the first time, a method of calculating the atomic charges in the molecules as distinguished from the usual dielectric measurements which lead only to dipole moments.
Note on the Ultraviolet Absorption Systems of Benzene Vapor
Authors: Nordheim G. , Sponer H. , Teller E.
Published: January 2005

An attempt has been made to give a coherent interpretation of the absorption systems of benzene vapor in the far ultraviolet including the Rydberg series. The following assignments are proposed: A forbidden transition of symmetry 1A1g→1B1u is suggested for the bands at 2050 to 1850A and an allowed 1A1g→1E—u transition for the much more intense bands at 1850 to 1650A. The continuous background in the latter region may possibly be due to a transition involving a C–H dissociation. The observed two Rydberg series can both be assigned to allowed transitions of symmetry 1A1g→1E—u.
Entropy of Vaporization and Restricted Molecular Rotation in Liquids
Authors: Halford R. S.
Published: January 2005

Deviations among entropies of vaporization to constant vapor volume are attributed to restricted rotation of molecules in the liquid. An arbitrary measure of the amount of restriction is defined and the deviations are shown to exhibit a remarkable regularity when compared on this basis. Deviations due to perturbation of vibrations in the liquid must either parallel those due to restricted rotation or be quite small.
An Experimental Study of the Near Ultraviolet Absorption Spectrum of Benzene
Authors: Radle W. F. , Beck C. A.
Published: January 2005

The wave numbers and relative intensities of 500 of the absorption bands of benzene vapor in the 2600A region have been determined. A detailed study has been made of the variation of intensity with temperature of the main band of the A, B, and D progressions. These three bands have been assigned to the ground state, the 606-cm—1 and 2×606-cm—1 vibrational states, respectively, by Sponer and collaborators. The experimental data are in good agreement with a statistical calculation of the population factors for these states.
The Absorption of Phenyl Mustard Oil in the 4.8μ Region
Authors: Williams Dudley
Published: January 2005

An intensive study of the 4.8μ band of phenyl mustard oil has shown this band to have three components. Although these components have not been completely resolved, the present work indicates the frequencies involved to be 2130, 2080, and 1950 cm—1. The two highest frequencies have counterparts in the Raman spectrum, but the frequency 1950 cm—1 has not been observed by Raman methods. Fermi resonance is discussed as a possible explanation of the observed spectrum. Re-investigation of the spectra of the methyl, ethyl, and phenyl nitriles and isonitriles failed to reveal complexities in the region of 2100 cm—1.
Raman Spectra of Amino Acids and Related Compounds V. Deuterium Substitution in the Amino Group
Authors: Edsall John T. , Scheinberg Herbert
Published: January 2005

Raman Spectra are reported for CH3·ND2, CH3·ND3+, +D3N·ND3+ and +D3N·ND2. Comparison with the spectra of the corresponding compounds containing no deuterium reveals three classes of frequencies: (1) Those arising from the methyl group are unchanged within the experimental error by deuterium substitution in the amino group. (2) The amino and ammonium group frequencies are higher in the H than in the D compounds by a factor of 1.33 to 1.36. Among these a characteristic —ND3+ valence vibration is found near 2180 cm—1, corresponding to an —NH3+ vibration near 2970. These frequencies are broad and rather faint, and are lower by several hundred wave numbers than the corresponding sharp intense lines arising from the uncharged —NH2 and —ND2 groups. The principal deformation frequency of the NH3+ and NH2 groups appear to be near 1620; the corresponding frequency of the —ND3+ and —ND2 groups is near 1200. (3) Other frequencies are changed by a factor of less than 1.3 when deuterium is substituted for hydrogen in the nitrogen. The most intense lines in this group are the C–N and N–N stretching frequencies near 1000 cm—1, which show a decrease of 20 to 50 cm—1 on deuterium substitution. Some calculations, based on a very simple model, were made for these frequencies, but they did not quantitatively explain the observed results.
The Concentration of C13
Authors: Hutchison Clyde A. , Stewart David W. , Urey Harold C.
Published: January 2005

The chemical exchange method has been applied to the separation of the isotopes of carbon. Various exchange reactions have been tested, using counter-current flow in packed fractionation columns, and of these, the exchange between hydrogen cyanide gas and a solution of sodium cyanide in water has been found to be most efficient. In this exchange, the isotope of carbon of atomic weight 13 (ordinarily present to the extent of 1.06 percent) is concentrated in the gas phase. Suitable conditions for the exchange have been determined, and a satisfactory apparatus has been devised. Using two fractionation units in a cascade arrangement, sodium cyanide, containing carbon of 25 atom percent C13, has been produced at a rate of 2.5 grams per day. This corresponds to a transport of 0.15 grams of C13 per day. In all, more than 20 grams of carbon, containing 25 percent of C13, and additional quantities of less concentrated material, have been obtained in this way.
Ultrasonic Velocity in Carbon Dioxide and Ethylene in the Critical Region
Authors: Herget Carl M.
Published: January 2005

Measurements of the velocity of ultrasonic waves in carbon dioxide and ethylene are presented; the velocity was obtained while the gas was allowed to follow a p—v isothermal. For carbon dioxide the pressure range is 5 to 98 atmospheres at temperatures of 28.0°, 30.0°, 31.0°, 32.0°, 33.0°, 35.0° and 38.0°C. For ethylene the pressure range is 35 to 75 atmospheres at temperatures of 9.7°, 18.7° and 23.0°C. For both gases, as pressure increases, the velocity decreases, falls to a sharp minimum, and then rises steeply on the high pressure side of this minimum. The minima have a discontinuity of slope for isothermals below the critical isothermal, which persists for a limited temperature range above the critical temperature. Above this range the curves become continuous in slope through the minimum. The curve log p vs. 1/T for the minima is linear through the critical point and, below the critical point, coincides within experimental error with standard vapor pressure data. Some calculations of ratio of specific heats near the critical point are included.
A Chemical Detector for Molecular Beams
Authors: Simons J. H. , Glasser J.
Published: January 2005

A thin film of tellurium has been found satisfactory for a detector plate for atomic hydrogen, oxygen, chlorine, and bromine and offers promise for organic free radicals. By a method of intensification with the use of positive development a high sensitivity is obtained. The technique of the preparation, use, and development of this detector is given. A list of possible uses of this detector is included.
Mercury Photosensitized Reactions of Propane
Authors: Steacie E. W. R. , Dewar D. J.
Published: January 2005

An investigation has been made of the mercury photosensitized reactions of propane, alone and in the presence of hydrogen at temperatures from 25 to 323°C. The products of the reaction are predominantly hydrogen, hexanes (mainly 2,3-di-Me-butane and 2-Me-pentane), and a small amount of higher paraffins. The postulated mechanism is: Hg(3P1)+C3H8→Hg(1S0)+C3H7+HHg(3P1)+H2→Hg(1S0)+2HH+C3H8→C3H7+H22C3H7→C6H142H→H2C3H7+C3H8→C6H14+H.The quantum yield of hydrogen is approximately 0.15 at 25°C and rises somewhat with increasing temperature.
Gaseous Heat Capacities. II
Authors: Kistiakowsky G. B. , Rice W. W.
Published: January 2005

The present paper describes a continuation of the work on the heat capacities of lower hydrocarbons by the Lummer-Pringsheim adiabatic expansion method. The apparatus and the procedure described in the first paper of this series, henceforth to be denoted as Part I, was used in the present research without important modifications.
Statistical Mechanics of Cooperative Phenomena
Authors: Kirkwood John G.
Published: January 2005

A direct method of successive approximation to the configurational partition function, based on the use of local free energies, is described. The method serves to clarify the assumptions underlying the Bethe method of local configurations and the quasi-chemical method of Guggenheim and Fowler.
Studies of Equilibrium Solid Solutions in Ionic Lattices Systems: KMnO4–KClO4–H2O and NH4Cl–MnCl2–H2O
Authors: Greenberg Alexander L. , Walden George H.
Published: January 2005

1. The systems, potassium permanganate-potassium perchlorate-water and ammonium chloride-manganous chloride-water, have been studied at equilibrium conditions by phase rule and x-ray diffraction methods. 2. The system potassium permanganate-potassium perchlorate-water yields a continuous series of solid solutions having orthorhombic crystal symmetry. For these, the components of which are of similar crystal and chemical structure and of identical valence type, Vegard's additivity law is followed by the a0 and c0 lattice constants, but the b0 constant shows a definite deviation. 3. A method is described of obtaining homogeneous crystals with a particle size which gives excellent powder diffraction photograms in cases where heat annealing is not feasible. 4. A method of analyzing for ClO4— is given. 5. The danger of making serious errors is pointed out in the use of rapid precipitation by chemical reaction or from supersaturated solutions as a method of preparing solid solutions for the study of the relationship between their lattice constants and composition. 6. The system ammonium chloride-manganous chloride-water shows three solid solution series; the crystals obtained in the first series have cubic symmetry, while in the others the symmetry is tetragonal. 7. The mechanism of the formation of the ``anomalous'' solid solutions between ammonium chloride and manganous chloride is given. Experimental and other considerations verify it. 8. It is shown that Vegard's law is not followed by the first solid solution series in which the components are of dissimilar chemical and crystal structure and dissimilar valence types. The curve for the relationship between the lattice constants and composition rises to a maximum and then falls off. Reasons to explain why this law does not apply to these solid solutions are given. 9. The existence of a new ``compound,'' 6NH4Cl·MnCl2·2H2O, is demonstrated. This and the known compound, 2NH4Cl·MnCl2·-2H2O, are considered to be examples of ``compounds of variable composition.'' They are tetragonal with a0 = 15.256±0.004A, c0 = 16.008±0.007A and a0 = 7.5139±0.0005A, c0 = 8.245±0.003A, respectively. The structure of the latter is that of 2NH4Cl·CuCl2·2H2O which belongs to space group D414h or P4mnm.