bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of ΔHf2980(C6F5I,g) from Studies of the Combustion of Iodopentafluorobenzene in Oxygen and Calculation of D(C6F5—X) Bond Dissociation Energies
Authors: Krech Michael J. , Price Stanley James W. , Yared Wayne F.
Published: May 2006

The heat of formation of iodopentafluorobenzene has been determined using the direct combustion method previously developed and used for hexafluorobenzene and octafluorotoluene. The combustion with oxygen yields CO2, CF4, F2, I2, and IF5. With a tenfold excess of oxygen the average CO2 to CF4 molar ratio is 11.08 ± 0.028. A material balance was obtained for carbon and fluorine. An apparent shortfall of about 30% in iodine has been related to the formation of IO2(OH) during analysis. The value of ΔHf2980 (C6F5I,g) = −133.2 ± 3.0 kcal mol−1 has been combined with D(C6F5—I) and ΔHf2980(I, g) to obtain ΔHf2980(C6F5,g) = −92.6 kcal mol−1 Using this value and the appropriate values of ΔHf2980 (C6F5X,g) and ΔHf2980(X, g), values of D(C6F5—X) have been calculated for X = OH, H, F, Cl, I, CH3, and CF3.
Kinetics and Mechanism of the Thermal Decomposition of Hexaamminecobalt(III) and Aquopentaamminecobalt(III) Ions in Acidic Aqueous Solution
Authors: Newton Anthony Martin , Swaddle Thomas Wilson
Published: May 2006

The initial step in the thermal decomposition of Co(NH3)63+ in acidic aqueous solution is the replacement of NH3 by H2O, which occurs by a hydrogen-ion independent path, first order in complex, with rate coefficient k1 = 7.9 × 10−5 s−1 (140.4°), ΔH* = 36.6 kcal mol−1 and ΔS* = 10.7 cal deg−1 mol−1 in 0.1 M HClO4. For Co(NH3)5OH23+, there is a similar initial aquation path with k1 = 12.6 × 10−5 s−1 (140.6°), ΔH* = 41.9 kcal mol−1 and ΔS* = 24 cal deg−1 mol−1 and also a path first order in complex but inverse first order in [H+] with k2′ = 6.2 × 10−1 M s−1 (140.6°), ΔH* = 43.5 kcal mol−1 and ΔS* = 26.7 cal deg−1 mol−1 in perchlorate media of ionic strength 1.0 M. The effects of electrolyte type and concentration on the rates of these reactions have been examined. Subsequent aquation steps are relatively rapid because of the predominance of inversely [H+]-dependent pathways and are followed by redox to Co(H2O)62+, NH4+, N2, N2O, and a minor amount of O2. A mechanism involving OH and NH2 radicals is proposed for the redox step.
Distributions de charges et effets chimiques. VI. Etude PCILO des répartitions de charges dans les hydrocarbures éthyléniques
Authors: Grignon Jacques , Fliszár Sándor
Published: May 2006

Analyses of the electron density distribution for some series of alkyl-substituted ethylenes reflects clearly the transfer of charge from the substituents in the normal inductive order. The accumulation of charge occurs preferentially on the sp2 atom in the β position with respect to the substituent but does not follow exactly the inductive order because of the effect of a charge alternation which opposes in part the inductive effect. [Journal Translation]
Some Metal Halide – Phosphorus Halide – Alkyl Halide Complexes. Part III. The µ-Trihalohexahalodimetallate Ions of Titanium and Zirconium
Authors: Bullock Joseph I. , Parrett Frederick W. , Taylor Nicholas J.
Published: May 2006

Titanium tetrachloride reacts rapidly with trichloro-, tribromo- and methyldichlorophosphine in the presence of t-butyl chloride to give compounds containing a phosphonium cation R1R2PX2+ (R1 = t-butyl, R2 = chloride, bromide, or methyl, X = chloride or bromide) and the principal metal-containing anion, Ti2Cl9−. For tribromophosphine and t-butyl chloride a stoichiometric product, [ButPBr3][Ti2Cl9] was obtained which was characterized using vibrational spectroscopy. The other reactions gave non-stoichiometric materials, the sublimates of which may contain higher polymeric anions whilst the residues contained TiCl5− along with the parent dimeric anion.Zirconium tetrachloride and titanium tetrabromide reacted in a similar way to give the new ions Zr2Cl9− and Ti2Br9− in stoichiometric reactions.
Thermodynamics of Ionization of Benzoic Acid and Substituted Benzoic Acids in Relation to the Hammett Equation
Authors: Matsui Takeki , Ko Hon Chung , Hepler Loren G.
Published: May 2006

We have made both ampoule and titration calorimetric measurements leading to ΔH0 of ionization of aqueous benzoic acid at 298 K, and have considered our results in relation to those from several earlier investigations in an effort to select the "best" value for this important quantity. We have also made calorimetric measurements leading to ΔH0 values for ionization of several substituted benzoic acids, and have selected "best" ΔH0 values for 15 meta- and para-substituted benzoic acids. It is found that there are good linear relationships between ΔG0, ΔH0, and ΔS0 values for most of these substituted benzoic acids. It is also found that the Hammett equation accounts well for ionization constants over the temperature range 278–318 K for all of these acids and accounts very well for ionization constants of those acids with positive σ substituent parameters.
13C Nuclear Magnetic Resonance Studies. 32. The 13C Spectra of Several Norbornyl Derivatives
Authors: Stothers J. B. , Tan C. T. , Teo K. C.
Published: May 2006

not available
Photo-CIDNP Studies of 2-Butanone and 3-Pentanone in Solution
Authors: Vaish Shiv P. , McAlpine Robert D. , Cocivera Michael
Published: May 2006

The results of photolysis of 2-butanone and 3-pentanone as studied by chemically induced dynamic nuclear polarization (CIDNP) and electron spin resonance spectroscopy (e.s.r.) are reported. In aqueous solutions and t-butanol only the ethyl radical is detected by means of e.s.r., indicating α cleavage to be a major path involving excited states. This observation is further supported by the n.m.r. spectra which are obtained during irradiation of these ketones in D2O and a mixture of CD3CN–D2O (1:1 by volume) containing carbon tetrachloride. Several compounds are detected with their protons spin polarized. A mechanism involving radical reactions is proposed which is consistent with the experimental results.
Determination of Trace Cadmium in Biological Materials by Neutron and Photon Activation Analyses
Authors: Jervis Robert E. , Tiefenbach Bella , Chattopadhyay Amares
Published: May 2006

Two nuclear activation techniques have been applied for the determination of trace cadmium residues in a variety of Canadian foodstuffs, soils, and other biological materials. A neutron activation procedure based on radiochemical isolation of 115Cd has been used for p.p.b. concentrations in foods, vegetables, and scalp hair whereas an instrumental photon activation method employing assay of 111mCd with a solid state Ge(Li) detector has been useful for soil, fertilizer, and a few vegetation samples at p.p.m. levels. For the latter technique, bombardment at either 15 or 35 MeV has been used, the higher energy bombardment gave a slightly higher sensitivity. However, in samples containing appreciable amounts of indium and tin, interference is minimized by irradiating at the lower energy.The cadmium content of most Canadian foods ranged from 2–70 p.p.b.; agricultural soils studied contained 0.5–2 p.p.m., some of which could be attributed to fertilizers containing up to 5 p.p.m. of cadmium, whereas vegetable crops grown on such soils generally contained 0.1–0.2 p.p.m. For scalp hair, cadmium concentrations ranged from 0.25–2.0 p.p.m.The accuracy of the nuclear activation techniques was assessed with standard reference materials and by comparison with atomic absorption and the agreement was generally in the range of 2–7%.
The Oxidation of Heterocyclic Thiones
Authors: Charlton James L. , Loosmore Sheena M. , McKinnon David M.
Published: May 2006

The treatment of a variety of heterocyclic thiones with hydrogen peroxide in acetic acid produces either heteroaromatic cations or the corresponding "oxo" compound. The results may be correlated with structural and electronic features. Benzo substitution or the presence of strongly electron withdrawing groups in the molecule favors the latter product, whereas the presence of a σ trivalent nitrogen atom in the molecule favors the former.
The Barrier to Rotation About the N—N Bond in N-Nitrosamines as Determined by Nuclear Magnetic Resonance Total Line Shape Analysis
Authors: Cooney J. D. , Brownstein S. K. , ApSimon J. W.
Published: May 2006

The energy barrier to internal N—N bond rotation in five cyclic and two bicyclic N-nitrosamines [Formula: see text]has been determined using high temperature 100 MHz n.m.r. spectroscopy. A substantial contribution from the ionic resonance structure of [Formula: see text] produces considerable double bond character in the nitrogen–nitrogen bond and a concomitant increase in the rotational barrier about the N—N bond. The molecules were examined in the[Formula: see text]liquid state and had ring sizes varying from five to nine atoms. The Arrhenius and Eyring activation parameters for the energy barrier were determined using total line shape analysis and the intensity ratio approximation method. The energy barrier to N—N bond rotation was found to range from 23–29 kcal/mol depending on the molecular structure and the solvent.
A Synthesis of Specifically Substituted Pyrenes: 2,7-Dimethylpyrene
Authors: Mitchell Reginald H. , Carruthers Robert J.
Published: May 2006

The synthesis of 2,7-dimethylpyrene (1a) from mesitylene is described as an example of a general synthesis applicable to many substituted pyrenes. Intermediates in the synthesis are 2,11-dithia[3,3]metacyclophanes (4) and [2,2]metacyclophane-1,9-dienes (6).
The Kinetics of the Water–Gas Shift Reaction on Nickel(II) Oxide Catalysts in the Néel Temperature Region
Authors: Krupay Bordan Walter , Ross Robert Anderson
Published: May 2006

The water–gas shift reaction has been studied from 200 to 300 °C at atmospheric pressure on both black and green forms of nickel(II) oxide which contrast in their magnetic properties and stoichiometry. Whereas black oxide samples, prepared in various ways, exhibited activation energies of 23 ± 1 kcal mol−1 throughout the temperature interval, the green oxides were characterized by a change in activation energy from 20 ± 1 kcal mol−1 above 250 °C to between 10 and 15 kcal mol−1 below this temperature. These values were obtained with a standard water–gas mixture of 40 Torr carbon monoxide and 40 Torr water vapor. With a carbon monoxide partial pressure of 80 Torr the green oxide gave a monotonic value of 21 ± 1 kcal mol−1.Rate order data suggest that the rate-limiting process does not change on the black oxides in this temperature interval, whereas on the green oxides rate control is probably associated with the surface reactivity of carbon monoxide above 250 °C and water vapour below this temperature. These effects may be related to different forms of active surface oxygen species that are present on the green oxide samples above and below the Néel temperature region.
Protonation of Methyl Substituted Phenols in Super Acids
Authors: Childs R. F. , Parrington B.D.
Published: May 2006

The protonation of a series of methyl substituted phenols and anisoles in FSO3H has been examined. When the para position of the phenol is unsubstituted, protonation was found to take place exclusively at this site. A methyl group on C-4 reduces the basicity of this carbon such that protonation on C-2, C-6 or oxygen can now compete with para protonation. Despite claims to the contrary, in FSO3H no significant amount of meta protonation was observed for any of the phenols. In FSO3H–SbF5, 2,4,6-trimethylphenol is protonated on C-3 or C-5; however, it would appear that this meta protonation is accompanied by a modification of the hydroxy group by either further protonation or reaction with the Lewis acid SbF5.
Phototropic Products from the Reactions of Aril Monoazines with Bases
Authors: Yates Peter , Levi E. M. , Shapiro B. L.
Published: May 2006

Treatment of benzil monoazine with sodium methoxide gives 5-methoxy-1,2,5-triphenyl-3,4-diaza-2,4-pentadien-1-one (2), 5-benzoyl-4,5-dihydro-3,4,5-triphenylpyrazol-4-ol (3), and simple cleavage products. Compound 3 is hydrolyzed to 3,4,5-triphenylpyrazole and benzoic acid. It is phototropic, being reversibly converted on exposure to sunlight to a red product, which is readily autoxidized to benzil monoazine. Analogous phototropic products are formed on reaction of p-anisil monoazine and p-tolil monoazine with sodium methoxide. Reduction of the azines to the phototropic products may occur by cleavage to α-keto imine anions followed by their dimerization; such a pathway can also account for the formation of the cleavage products. Alternatively, reduction may proceed by hydride or electron transfer; that hydride transfer need not necessarily be involved is established by the observation that treatment of p-tolil monoazine with potassium t-butoxide also gives the corresponding phototropic product. It is proposed that the phototropic transformations involve intramolecular hydrogen abstraction to give enolic isomers of 3 and its analogs in which the heterocyclic ring has been cleaved.
Proton Magnetic Resonance Studies of 2′-Deoxythymidine, its 3′- and 5′-Monophosphates and 2′-Deoxythymidylyl-(3′, 5′)-2′ -deoxythymidine in Aqueous Solution
Authors: Wood Donald J. , Hruska Frank E. , Ogilvie Kelvin K.
Published: May 2006

Proton magnetic resonance studies of 2′-deoxythymidine, its 3′ and 5′-monophosphates and the dideoxynucleoside monophosphate, 2′-deoxythymidylyl-(3′,5′)-2′-deoxythymidine are described. Assignment of the spectral bands are carried out and the derived chemical shift and coupling constant data are discussed in terms of the conformational properties of these molecules. The main conclusion reached is that 3′- and 5′-phosphorylation as well as incorporation into the dinucleoside monophosphate at either the 3′- or 5′-terminus has only slight effects on the conformation of thymidine under the experimental conditions employed.
A Study of Molecular Motion in cis- and trans-Dichlorodiamminepalladium(II)
Authors: Ulrich S. E. , Dunell B. A.
Published: May 2006

Spin–lattice relaxation 'null times' have been obtained for cis- and trans-Pd(NH3)2Cl2. The presence of a low temperature minimum for the trans complex has been interpreted in terms of inequivalent ammine groups. The second moment values are consistent with both ammine groups in both complexes reorienting with sufficient rate above 77 K to narrow the n.m.r. line. Although whole molecule rotation does not occur in either complex, it is believed that libration does.
Cationic Aryltetrazene Complexes of Iridium
Authors: Gilchrist Alan B. , Sutton Derek
Published: May 2006

The details of the synthesis and properties of a number of cationic iridium aryltetrazene complexes of general formula [Ir(CO){N4(C6H4R)2}(PPh3)2]+ where R = H or para-F, Cl, Br, CF3, or OCH3 are presented. The complexes are compared with a number of other compounds possessing tetrazene or tetraazadiene ligands. A possible mechanism of formation is presented, consistent with presently available evidence.
Application of Carbon-13 Nuclear Magnetic Resonance Spectroscopy to the Structural Determination of Chlorodeoxy Sugars
Authors: Szarek Walter A. , Vyas Dolatrai M. , Gero Stephan D. , Lukacs Gabor
Published: May 2006

The carbon-13 n.m.r. spectra of a series of chlorodeoxy sugars are reported. The results demonstrate the utility of this technique for the assignment of structure to this class of carbohydrate derivatives.
Photolysis of SO2 in the Presence of Foreign Gases. VI. Acetylene and Allene
Authors: Luria Menachem , Heicklen Julian
Published: May 2006

The photolysis of SO2 at 3130 Å and 25 °C in the presence of C2H2 leads to CO, and, in the presence of allene to CO and C2H4 as gas phase products. In the C2H2 system, the CO comes from the two non-emitting triplet states of SO2, 57% from SO2** and 43% from SO2≠. In the allene system, the two excited singlet states of SO2, and possibly the emitting triplet state, also participate. The relative importance of the contributions from each state can be estimated to be >35% from 1SO2, <16% from 3SO2, 8% from SO2*, 12% from SO2**, and 29% from SO2≠.
Cycloaddition Reactions of Silyldiazoalkanes Involving Rearrangements from Carbon to Nitrogen
Authors: Bassindale A. R. , Brook A. G.
Published: May 2006

The products obtained from the 1,3 cycloadditions of a variety of silyldiazoalkanes, R3SiCN2R′, to several alkenes were studied: the data are consistent with the initial formation of the expected Δ1-pyrazoline. However, when R′ = Ph, COOEt, but not Me, a thermal 1,3 rearrangement of the silyl group from carbon to nitrogen subsequently occurs. Base-catalyzed isomerizations of the Δ1 to Δ2-pyrazolines were noted, as was the desilylation of the Δ1-pyrazolines in refluxing methanol. Mechanisms are proposed for the various reactions.
Chlorine Nuclear Quadrupole Resonance Spectra of 1-Substituted 2-Chloropolyfluorocycloalkenes
Authors: Chia Lian Sai , Cullen William R. , Gerry Michael C. L. , Yiaw Poh Siew
Published: May 2006

Chlorine nuclear quadrupole resonance frequencies are reported for the compounds [Formula: see text] (n = 2,3,4; Y = H, CH3, C2H5, Si(CH3)3, F. OCH3, N3, NR2, Cl, SCH3, P(C6H5)2, As(CH3)2, Mn(CO)5, π-C5H5Fe(CO)2, but not all combinations). The values range from 38.999 MHz (n = 3; Y = F) to 34.668 MHz (n = 2; Y = π-C5H5Fe(CO)2) and are roughly related to the electronegativity of Y and to the ring size. The mean temperature coefficients of the frequencies lie in the range −0.9 × 10−4 to −8 × 10−4/°K.
Electric Field Induced Light Emission and Conductance-Loss Transients in Liquid Anthracene
Authors: Shinsaka Kyoji , Freeman Gordon R.
Published: May 2006

Liquid anthracene has an unusually high electrical conductivity for a hydrocarbon, being 2 × 10−1 mho cm−1 at 507 K. At electric field strengths above 3 kV/cm the conductance suffers transient decreases that last <3 μs and are irregularly spaced in time. The average frequency of occurrence and magnitude of the transients increase rapidly with increasing field above the threshold. The conductance loss transients are accompanied by emission of light. These phenomena may be related to that of semiconductor laser emission.
The Synthesis of Specifically Deuterated Phenanthrenes
Authors: Charlton J. L. , Kostyk B. , Lai H. K.
Published: May 2006

Synthetic methods for the preparation of phenanthrene-1,3-d2, -2,4-d2, -1,2,3,4-d4, -1,3,6,8-d4, and -2,4,5,7-d4 are described.
A New Chlorinated Cyclopentenone Produced by a Cryptosporiopsis Species
Authors: Strunz George M. , Kazinoti Pavle I. , Stillwell Merlyn A.
Published: May 2006

A new metabolite, isolated from cultures of a Cryptosporiopsis sp., is shown to be (1R,5S)-2-cyclopentene-1-carboxylic acid, 2-trans-allyl-3-chloro-1,5-dihydroxy-4-oxo methyl ester.
The Oxidation of Acetals by Ozone
Authors: Deslongchamps Pierre , Atlani Paul , Fréhel Daniel , Malaval Alain , Moreau Claude
Published: May 2006

Ozone reacts very smoothly with acetals to give the corresponding esters. There are six gauche conformations that are theoretically possible for an acetal function. It is shown that only three of them are reactive toward ozone. It is proposed that a reactive acetal function must take a conformation in which each oxygen must have an electron pair orbital oriented antiperiplanar to the C—H bond. The mechanism of this reaction is also discussed.
Synthesis of Lactose-Operator Gene Fragments by the Improved Triester Method
Authors: Itakura K. , Katagiri N. , Narang S. A.
Published: May 2006

The synthesis of lactose-operator gene fragments have been achieved by the improved triester methodology and new phosphorylating and condensing reagents.
The Crystal and Molecular Structure of a Nickel Complex of the Schiff Base, Bis(trifluroacetylacetone)triethylenetetraamine
Authors: Richardson Mary Frances
Published: May 2006

The Schiff base, bis(trifluoroacetylacetone)triethylenetetraamine (H2L), forms a nickel complex with the composition NiC16F6H22N4O2 (NiL). Crystals of NiL belong to the monoclinic space group P21/c with a = 10.040(2), b = 15.077(7), c = 13.943(7) Å, β = 111.88(5)°, Dc = 1.610 g/cc, Do = 1.61(2) g/cc, Z = 4. A total of 1686 independent reflections with F2 ≥ 2σ(F2), 2θ ≤ 42° were measured on a Picker 4-circle diffractometer by the θ–2θ scan technique with MoKα radiation. A full matrix least squares refinement of the structure yielded an unweighted R factor of 0.057. The structure confirms that condensation of triethylenetetraamine with trifluoroacetylacetone occurs through the acetyl group, not through the trifluoroacetyl group. The nickel atom is octahedrally coordinated by the four nitrogen and two oxygen atoms of the L2− ligand. The triethylenetetraamine moiety has the α-configuration, so that the oxygen atoms occupy cis positions on the octahedron. Distortions in the octahedral geometry are due to the three contiguous five-membered rings in the complex; the average N—Ni—N angle is 81.1°. The trifluoroacetylacetone fragments are essentially planar, with an average O—Ni—N angle of 90.6°. These rings are folded about the O—N lines, the folding angles being 17.1 and 8.0° for the two rings. The average Ni—O, Ni—N (trigonal), and Ni—N (tetrahedral) distances are 2.037, 2.044, and 2.128 Å, respectively.
Some Electrical and Thermodynamic Properties of the System: Indium Trichloride–Dioxane–Water
Authors: Campbell Alan N.
Published: May 2006

The following properties have been investigated: conductance in water and in water–dioxane, the solubility products of indium hydroxide and of indium iodate, e.m.f.'s of the cell: In(s)/InCl3(m)/sat. KCl/Hg2Cl2 in sat. KCl/Hg and resulting activity coefficients, heats of solution of indium trichloride in water, water–dioxane, and pure dioxane, freezing point diagram of dioxane–water, heats of mixing of dioxane–water, heats of mixing of indium chloride–water with dioxane–water, change in volume on mixing of water–dioxane, and of water–indium chloride with water–dioxane.
Photochemical and Thermal Decomposition of 1-Pyrazolines
Authors: Engel Paul S. , Shen Lan
Published: May 2006

Quantum yields for photochemical nitrogen extrusion from seven 1-pyrazolines were found to range from 0.12 to 0.88 but 4-oxo-3,3,5,5-tetramethyl-1-pyrazoline (8) proved to be photochemically and thermally remarkably stable. 4-Isopropylidene-3,3,5,5-tetramethyl-1-pyrazoline (7) decomposed thermally with Ea = 39.8 kcal mol−1 and ΔS≠ = 0.7 e.u. The high stability of this compound contrasts with 4-methylene-1-pyrazoline (17).
Conformational Studies on 1,3-Dioxepanes. Part V. The Effect of Introduction of an sp2-hybridized Carbon Atom
Authors: Grindley T. Bruce , Szarek Walter A.
Published: May 2006

It has been demonstrated, by a consideration of geminal and long-range coupling constants, that the introduction of an sp2-hybridized carbon atom into a 1,3-dioxepane ring markedly affects the conformational equilibrium.
The Preparation of Protio and Deuterio Derivatives of the Tetracyanoquinodimethane–Tetrathiofulvalene Complex
Authors: Dolphin D. , Pegg W. , Wirz P.
Published: May 2006

The preparation and purification of the protio and deuterio derivatives of tetracyanoquinodimethane and tetrathiofulvalene, and of the anisotropic organic conductors prepared from these compounds, are reported.
Unusual Reactions of Peroxides. II. Decomposition of Diphenylmethyl Peroxides
Authors: Hiatt R. , LeBlanc D. J. , Thankachan C.
Published: May 2006

Thermal decomposition of bisdiphenylmethyl peroxide at 110–130 °C in solution yields approximately 90% H2 + 2Ph2CO by a nonradical mechanism. In C2Cl4, toluene, or nitrobenzene log k (s−1) = 11.0 ± 0.5 − (27 000 ± 1000)/2.303RT. Photolytic decomposition of this peroxide in toluene yielded no H2.t-Butyl diphenylmethyl peroxide decomposed in toluene with log k (s−1) = 16.7 − 38 600/2.303RT, giving free radical products and no H2. There is some evidence for facile disproportionation of the initial alkoxy radicals in the solvent cage.
Etude des Succinates Simples et Complexes de Cobalt(II)
Authors: Sharrock Patrick , Theophanides Théophile
Published: May 2006

Cobalt(II) succinate tétrahydraté, CoC4H4O·4H2O and anhydrous (amorphous and crystalline) have been prepared and studied by i.r. and u.v.–visible spectroscopy, magnetic susceptibility, thermogravimetry, and by X-ray diffraction. The alkaline salts of cobalt succinate M2Co2(C4H4O4)3, where M = K+ and NH4+ have also been prepared for the first time. The staggered gauche and trans conformations of succinic acid have been found to be present in the complexes. The cage-like structure has not been found in any of the Co(II) carboxylates studied here.
The Kinetics and Mechanism of H2–D2 Exchange Catalyzed by Hydridochlorotris(triphenylphosphine)ruthenium(II)
Authors: Strathdee Graeme , Given Russell
Published: May 2006

The H2–D2 exchange reaction is catalyzed extremely efficiently by solutions of hydridochlorotris(triphenylphosphine)ruthenium(II) in benzene between 279 and 298 K. Rates of exchange were partly controlled by the mass transport of hydrogen. A mechanism involving formation of di- and tetrahydride ruthenium species has been employed to explain the rapid H–D exchange without the participation of the original Ru—H bond of RuHCl(PPh3)3. Nuclear magnetic resonance and infrared experiments showed that the rate of exchange of Ru—H with D2 was insignificant with respect to the rate of the H2–D2 equilibration process.
Reactions of Ketene Acetals. III. A New Synthesis of α-Pyrones. II
Authors: Bélanger Alain , Brassard Paul
Published: May 2006

The cycloaddition of chloroketene acetals to α, β-unsaturated aldehydes and ketones gives the corresponding 2,2-dialkoxy-3-chloro-3,4-dihydro-1,2-pyrans. Treatment of these compounds with alkoxides in dimethylsulfoxide or dimethylformamide yields α-pyrones directly. Some intermediates and by-products have been identified and the reaction conditions have been studied.
Reactions of Ketene Acetals. IV. A New Synthesis of α-Pyrones. III
Authors: Bélanger Alain , Brassard Paul
Published: May 2006

A simple one-step synthesis of α-pyrones and 3-chloro-α-pyrones from β-functionalized α, β-enones and ketene acetals has been devised. The method has also been adapted to the preparation of some 4-methoxy-α-pyrones. Finally the mechanism of the reaction has been investigated.
Investigations of Substituent Effects by Nuclear Magnetic Resonance Spectroscopy and All-valence Electron Molecular Orbital Calculations. IV. 4-Substituted Phenylacetylenes
Authors: Dawson Daniel A. , Reynolds William F.
Published: May 2006

13C and 1H spectra have been determined for 18 4-substituted phenylacetylenes and carbon charge densities have been estimated by CNDO/2 molecular orbital calculations. Correlations of these parameters with σ1, and σR0 indicate that the important mechanisms of transmission of substituent effects are field, resonance, and π polarization effects, as previously noted for 4-substituted styrenes. Evidence is presented that demonstrates that both 1H and 13C chemical shifts for these compounds reflect ground state charge densities. CNDO/2 calculations on a variety of aromatic derivatives suggest that the σ1, dependence of 19F chemical shifts in these derivatives may primarily be due to π polarization.
Mise en évidence des tautomères énoliques des hydroxypyridines dans la source du spectromètre de masse
Authors: Maquestiau A. , Haverbeke Y. van , Meyer C. de , Katritzky A. R. , Cook M. J. , Page A. D.
Published: May 2006

3- and 4-Hydroxypyridines exist in their enolic form, in the gas phase, as evidenced by the similarity of the deuterium isotope effects on the loss of CO, calculated on nearly equimolar mixtures of HO- and DO-pyridines. This is confirmed by analysis of metastable ratios evaluated on hydroxypyridine fragment ions and on the same ions produced by direct ionization. 2-Hydroxypyridine shows a weaker isotope effect for the same reaction and this is confirmed by the study of an equimolar mixture of 2-ethoxy- and 2-ethoxy-d5-pyridines. It is shown that 2-hydroxypyridine also exists as its enolic form, in the gas phase.
Sodium Borohydride Reduction of 1-Acyl-1,2(1H)-Diazepines and their Iron Tricarbonyl Complexes. Some Reactions of 2,3-Dihydro-1,2(1H)-Diazepines
Authors: Tsuchiya Takashi , Snieckus Victor
Published: May 2006

Sodium borohydride reduction of the 1,2(lH)-diazepines 1a-e and 7, and the 1,2(1H)-diazepine iron tricarbonyl complexes 4a–b provides the 2,3-dihydro-1,2(1H)-diazepines 2a–e and 8, and the (2,3-dihydro-1,2(1H)-diazepine)Fe(CO)3 derivatives 5a–b, respectively. Fe(CO)3 complexes 5a and 6a may be also directly obtained from the 1,2(1H)-diazepines 2a and 3a, respectively. A number of diacylated compounds (3a–c, 6a–b, and 9) are prepared some of which (2a, 3a, 8, and 9) are readily converted into their corresponding (4 + 2)π cycloadducts (14a–d). Treatment of the borohydride reduction products 2a–c with sodium methoxide in methanol gives the 3,4-dihydro-1,2(2H)-diazepines 15a–c. Acetylation of 15a affords the 2-acetyl derivative 16a which may also be prepared by sodium methoxide deacetylation of either 3a or 9. 2-Tosyl-3,4-dihydro-1,2(2H)-diazepine (18) is obtained from 2a by a similar tosylation and deacetylation sequence. When either 2a or 3a are subjected to sodium methoxide in methanol-O-d, compounds 15a and 16a, respectively, are produced which show high deuterium incorporation at C4 and C6 (n.m.r. analysis). Photolysis of the 2,3-dihydro-1,2(1H)-diazepines 2a, 3a, 8, and 9 and the 3,4-dihydro-1,2(2H)-diazepine 16a affords the unstable 2,3-diazabicyclo[3.2.0]hept-6-ene 23a, 23b, 25a, and 25b and 1,2-diazabicyclo[3.2.0]hept-6-ene 27 derivatives, respectively. Treatment of either 25a or25b with sodium methoxide results cleanly in N2-deacylation to give compound 26.
Electric Dipole Moments of a Series of Δ8(14) Cholestenyl Esters
Authors: Pochan J. M. , Kuder J. E. , Chu J. Y. C. , Wychick D. , Hinman D. F.
Published: May 2006

Dipole moments of a series of Δ8(14) cholestenyl esters have been measured. These are isomeric with the cholesteryl alkanoates. There appears to be a limited correlation between crystal melting point and dipole moment. No correlation of dipole moment and mesomorphic tendency is observed.
The Kinetics of the Catalyzed Reaction between Two Substrates in a Special Case
Authors: Rybicky Jaroslav
Published: May 2006

The kinetics of the catalyzed reaction between two substrates is dealt with for the special case in which the product associated with the catalyst cannot be distinguished from the product dissociated from the catalyst. The rate equation in which the yield is a sum of products both associated with and dissociated from the catalyst is derived and its applicability is assessed with respect to the kinetic and concentration conditions. It was found that under steady-state conditions and fast preequilibrium condition a twenty-fold excess of the substrates over the catalyst is enough for the yield of reaction to be represented by the equation derived with less than 1% relative error, and even for a five-fold excess the equation remains a fairly good approximation. Under such conditions the rate equation can find practical utility.
The Chemistry of Cochliodinol, a Metabolite of Chaetomium spp.
Authors: Jerram W. A. , McInnes A. G. , Maass W. S. G. , Smith D. G. , Taylor A. , Walter J. A.
Published: May 2006

Chemical and spectroscopic (u.v., i.r., 1H and 13C n.m.r., and mass) data are reported which suggest that cochliodinol is 2,5-dihydroxy-3,6-di(5′-(2″-methylbut-Δ2″-ene)-indolyl-3′)-cyclo-hexadiene-1,4-dione (1a).
Crystal and Molecular Structure of (±)-7,7-(2′,2′-Dimethyl)pentamethylene-1-methyl-norbornane-2-oxime
Authors: Rettig Steven J. , Trotter James
Published: May 2006

Crystals of (±)-7,7-(2′,2′-dimethyl)pentamethylene-1-methyl-norbornane-2-oxime are monoclinic, a = 9.202(2), b = 12.852(3), c = 12.698(3) Å, β = 110.83(2)°, Z = 4, space group P21/c. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.048 for 1538 reflections with I ≥ 3σ(I). The crystal structure consists of pairs of molecules linked by N … H—O hydrogen bonds (N … O = 2.821(3) Å ) to form centrosymmetric dimers. Bond distances are as follows: C—N = 1.266(3), N—O = 1.426(3), mean C(sp3)—C(sp3) = 1.540, and mean C(sp3)—C(sp3) = 1.511 Å.
Crystal and Molecular Structure of 2,5-Bis(2′-hydroxyethylamino)-1,4-benzoquinone
Authors: Rettig Steven J. , Trotter James
Published: May 2006

Crystals of 2,5-bis(2′-hydroxyethylamino)-1,4-benzoquinone are monoclinic, a = 5.020(1), b = 19.238(3), c = 5.214(1) Å, β = 96.15(3)°, Z = 2, space group P21/n. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.045 for 646 reflections with I ≥ 3σ(I). The benzoquinone ring in the centrosymmetric molecule is slightly, but significantly, nonplanar. Bond distances in the compound (C—C, 1.247 (2) and 1.410 (3), C—N, 1.332 (3) and 1.457 (3), C—C, 1.384–1.514 (3), N—H, 0.89 (3), O—H, 1.07 (5), and C—H, 0.95–1.09 (3) Å) are similar to those in related compounds. The structure features an extensive network of N—H … O (N … O = 2.639 (3) and 3.033 (2) Å) and O—H … O(O … O = 2.757 (3) Å ) hydrogen bonds.
Carbon-13 Nuclear Magnetic Resonance Spectra of Isothiazole, 1,2-Dithiole, and 1,3-Dithiole Derivatives
Authors: Plavac N. , Still I. W. J. , Chauhan M. S. , McKinnon D. M.
Published: May 2006

Carbon-13 chemical shift data have been obtained for a number of isothiazole, benzo[c]isothiazole, 1,2-dithiole, and 1,3-dithiole derivatives. A number of these compounds are thiones and the chemical shifts of the C=S carbons are discussed in the light of recent attempts to predict such chemical shifts from those of the analogous carbonyl compounds. Comparisons of substituent chemical shift (s.c.s.) effects in these heterocyclic compounds with those in simpler aromatic or conjugated systems have been made and additivity correlations tested in a number of cases.
Uses of Sydnones for Heterocyclic Syntheses
Authors: Badami B. V. , Puranik G. S.
Published: May 2006

N-(4-Bromo-3-chlorophenyl)sydnone is prepared and subjected to chlorination and bromination. 1,3-Dipolar addition of these sydnones with dimethyl acetylenedicarboxylate produces the substituted pyrazoles which could serve as intermediates.
Commentaire: Sur la sensibilité differente du vibrateur carbonyle d'acétophénones méta et para substituées aux facteurs σm+ et σp+
Authors: Berthelot M. , Laurence C.
Published: May 2006

The conclusions of Laurence and Wojtkowiak concerning the need to treat separately meta and para substituents in correlations between the frequencies νco for substituted acetophenones and the factors σ+ are confirmed. From a sampling of substituents chosen to illustrate best the effect under consideration, we indeed find a significant difference between the coefficients ρp+ and ρm+ at a confidence level greater than 99.9%.[Journal translation]
Studies in Solvolysis. Part VI. An Examination of the Heat Capacity of Activation for the Hydrolysis of 4-Methoxybenzyl Trifluoroacetate
Authors: Winter June Gertrude , Barron John Patrick , Scott John Marshall William
Published: May 2006

The heat capacity of activation for the hydrolysis of 4-methoxybenzyl trifluoroacetate in water containing 9.05 × 10−2 mol fraction of acetone has been measured and shown to be positive. This unusual result is consistent with the notion that the ester reacts by two distinct routes: one involving acyl–oxygen fission, the other, alkyl–oxygen fission. The relative importance of the two paths for the 4-methoxy ester has been established quantitatively via a Hammett σ–ρ correlation for a series of 4-substituted-benzyl trifluoroacetates. Such an assessment allows the observed heat capacity, entropy, and enthalpy of activation to be factored into parts appropriate to each of the two reaction paths.
Effet de substituant et de solvant sur l'enthalpie de dimérisation de diméthyl-2,6 phénols. Etude par résonance magnétique nucléaire
Authors: Baron D. , Tanguy M. , Lumbroso-Bader N.
Published: May 2006

Some precise values for the enthalpy of dimerization of substituted phenols were determined by n.m.r.: 4-chloro-2,6-dimethylphenol in CCl4 (−2.5 kcal/mol ); 2,4,6-trimethylphenolin CCl4 (−3.8 kcal/mol ); 2,6-dimethylphenol in C6H12 (−4.8 kcal/mol ) and in C6H6 (−2.3 kcal/mol ).By comparison with earlier (1, 2) results obtained, especially on nonsterically hindered phenols, the study of the p-substituted 2,6-dimethylphenols confirms the predominance of cyclic structures for the dimers of the latter. The variations of ΔH2 are thus due essentially to the influence of the substituent effect on the acid–base properties of the hydroxyl group (increase of ΔH2 with pK).In addition, the differences between the values of ΔH2 obtained in CCl4 and in C6H12 suggest that the acidic hydrogen is doubtlessly not the chief site of solvation in CCl4, and that the variation of ΔH2 with the substituent is thus certainly due to the variation of electronic charge on the phenolic oxygen.
Kinetics of Proton Transfer Reactions of Carbon Acids. V. Variation of Primary Deuterium Isotope Effect with Solvent Composition for the Reaction of Di-(4-nitrophenyl)methane with t-Butoxide in t- Butyl Alcohol–Toluene Mixtures
Authors: Jarczewski Arnold , Pruszynski Przemyslaw , Leffek Kenneth T.
Published: May 2006

The second-order rate constants, activation parameters, and primary deuterium isotope effects are reported for the proton transfer reaction from di-(4-nitrophenyl)methane to t-butoxide ion in a series of solvents containing varying amounts of toluene in t-butyl alcohol. Increasing toluene content in the solvent decreases the rate constant and increases the enthalpy of activation, while the entropy of activation becomes less negative. The isotope rate ratio kH/kD increases from 7.3 in 10% v/v toluene to 9.4 in 50% v/v toluene at 25 °C, corresponding to a change in (ΔHD≠ − ΔHH≠) from 0.46 to 1.0 kcal mol−1 and a change in (ΔSD≠ − ΔSH≠) from −2.4 to −1.1 cal mol−1 deg−1. It is suggested that the negative values for (ΔSD≠ − ΔSH≠) are due to a time lag for solvent reorganization relative to the proton transfer.
Raman Spectral Studies of Cadmium–Nitrite Interactions in Aqueous Solutions and Crystals
Authors: Irish Donald E. , Thorpe Roderick V.
Published: May 2006

Raman spectra of aqueous solutions containing Cd2+ and NO2− clearly reveal the presence of solvated nitrite ion and of complexes. A band at 861 cm−1 is characteristic of the latter. The free nitrite concentration was measured from the intensity of the 817 cm−1 line and the average ligand number was evaluated for solutions with composition prescribed by the mole-ratio method. Four cumulative formation constants were deduced: β1 = 61.6; β2 = 993; β3 = 2390; β4 = 1899. Evidence that nitrite chelates Cd2+ through the two oxygen atoms is presented. The diagnostic spectral evidence consists of a high intensity, high frequency deformation mode and low intensity N—O stretching Raman bands with frequencies almost identical to those of the solvated nitrite ion. Data are also presented for solid Cd(NO2)2 and Kx−2Cd(NO2)x(x = 3,4,5).
Synthesis of Substituted Hydrindanes. Part I. Products Arising from the Cyclization of Acetonyl Cyclohexanones and Acetonyl Cyclohexadiones
Authors: Beth André , Pelletier Jacques , Russo Robert , Soucy Marcel , Burnell Robert H.
Published: May 2006

The preparation and cyclizations of certain 1,4-diketones have been studied as a route to substituted hydrindan-2-one systems. Other types of products encountered are also described.
Reaction of 4,4′-Bis(dimethylamino) triphenylmethyl Tetrafluoroborate with Alkoxide Ions. I. Determination of Ion-pair Dissociation Constant for Sodium Alkoxides
Authors: Leffek Kenneth T. , Suszka Andrej
Published: May 2006

The second-order rate constants have been determined for the reaction of 4,4′-bis(dimethylamino)triphenylmethyl tetrafluoroborate carbonium ion with sodium methoxide in methanol and sodium ethoxide in ethanol. The results have been used to evaluate the ion-pair dissociation constants for the two alkoxides. The activation parameters for the two reactions with the free alkoxide ions are also reported.
Carbon-13 Nuclear Magnetic Resonance Spectra of Carcinogenic Polynuclear Hydrocarbons. II. Benzo[a]pyrene
Authors: Buchanan Gerald W. , Ozubko Richard S.
Published: May 2006

13C n.m.r. signal assignments are presented for the carcinogenic polynuclear hydrocarbon benzo[a]pyrene. In addition to selective 1H decoupling, valuable information is obtained from the magnitudes of the α-, β-, and "peri" deuterium isotope shifts in the 1,3,6-trideuterio analog. The applicability of the model compound approach to signal assignment is explored in detail.
Solubility of Indium Trichloride and Some Double Salts
Authors: Kartzmark Elinor M.
Published: May 2006

not available
Orientation Effects and the Sign of Two-bond 13C–1H Coupling
Authors: Schwarcz Joseph A. , Cyr Natsuko , Perlin Arthur S.
Published: May 2006

Signs of two bond (2J) 13C–1H coupling in 13C–enriched carbohydrates have been determined from proton spectra by the double irradiation technique. Instances of both positive and negative 2J values are given and are characterized in terms of the relative orientations of the coupled proton and of oxygen appended to the 13C nucleus; e.g., an oxygen anti to the proton appears to make a positive contribution to 2J and a gauche oxygen a negative one. Theoretical calculations, using ethanol and 1,1-ethanediol as model compounds, are in accord with these experimental observations.
Hydroboration du tert-butyl-4 diméthyl-2,2 méthylène-1 cyclohexane et du triméthyl-3,3,5 méthylène-1 cyclohexane. Préparation des tert-butyl-4 hydroxyméthyl-1 diméthyl-2,2 cyclohexanes et des hydroxyméthyl-1 triméthyl-3,3,5 cyclohexanes
Authors: Richer Jean-Claude , Lamarre Claude
Published: May 2006

The stereochemistry of the hydroborations of 4-tert-butyl-2,2-dimethyl-l-methylenecyclohexane and of 3,3,5-trimethyl-1-methylenecyclohexane has been studied for comparison with that of the hydroboration of 4-tert-butyl-1-methylenecyclohexane which also was examined. cis- and trans-4-tert-butyl-1-hydroxyrnethyl-2,2-dimethylcyclohexane as well as cis- and trans-1-hydroxymethyl-3,3,5-trimethylcyclohexane were obtained in a pure state and their configurations proved by means of the corresponding acids and esters. [Journal translation]
Reaction of 1,2-Dichlorohexafluorocyclopentene with Phenol and p-Nitrothiophenol
Authors: Stockel Richard F.
Published: May 2006

The reaction of phenol with 1,2-dichlorohexafluorocyclopentene gave two major components. These have been identified as 1-chloro-2-phenoxy-3,3,4,4,5,5-hexafluorocyclopentene (1) and l-chloro-3,3,4,4-tetrafluoro-2,5,5triphenoxycyclopentene (2). A third component was detected by g.c. and assumed to be 3.Withp-nitrothiophenol as the reactant only 1,2-bis(p-nitrophenylthio)-3,3,4,4,5,5-hexafluorocyclopentene (4) was isolated in excellent yields.
Iminosulfuranes (Sulfilimines) Infrared and Ultraviolet Spectroscopic Studies
Authors: Shah Jitendra J.
Published: May 2006

This paper reports the i.r. and u.v. spectra of several N-p-tolylsulfonylsulfilimines and several new N-p-ethylbenzenesulfonylsulfilimines have been examined.
A Photoelectron Investigation of Acyl Silanes: The Photoelectron Spectra of Trimethylsilyl Phenyl Ketone and Phenyl tert-Butyl Ketone
Authors: Brown R. S.
Published: May 2006

The photoelectron spectra of trimethylsilyl phenyl ketone and phenyl tert-butyl ketone are presented and analyzed in terms of their constituent orbitals. A hyperconjugative interpretation for the low energy ionization potentials of the acyl silanes is postulated. A combination of p.e. spectroscopy and u.v. data are used to infer the level of the LUMO in these systems and to construct a partial energy level diagram.
Alkaline Hydrolysis Products of N-Substituted Phthalimides
Authors: Hasan S. Khaqan , Abbas S. Ahmad
Published: May 2006

Products of alkaline hydrolysis of N-substituted phthalimides are described. Five isomeric compounds, 1,6-diketo-3,4,5,6-tetrahydro-1 H-2,5-benzoxazocine (1), 2-(o-carboxyphenyl)-Δ2 -oxazoline (7), 2-phthalimidoethanol (3), N-vinylphthalamic acid (8), and N-(o-carboxybenzoyl)-aziridine (9), are possible from the alkaline hydrolysis of 2-bromoethylphthalimide (2). Gabriel claimed in 1905 that 1 was formed on alkaline hydrolysis of 2 but later structure 7 was suggested for the product. The interest in the synthesis of 1 has led to a reinvestigation of this hydrolysis and structure 7 is confirmed for the initial product of the hydrolysis but it converts on warming during recrystallization into 1 which affords 3 on heating above melting point.Hydrolysis of 2-chloroethylphthalimide (4) and 2-phthalimidoethyl-p-toluenesulfonate (5) also afforded 7. Attempted preparation of 1 from intramolecular cyclization of 2-hydroxyethylphthalamic acid (11) was not successful and only 3 was obtained.Reaction of phthalic anhydride with 2-aminoethylsulfuric acid (14) at 150 ° afforded diphthalimidoethyl phthalate (13) instead of 2-phthalimidoethylsulfuric acid (6). Isolation of 13 indicates formation of 3 as an intermediate product in this reaction.
Synthetic Morphinans and Hasubanans. Part IV. Total Synthesis of 3,14-Dihydroxyisomorphinans, 3-Methoxy-Δ8,14-morphinans, and 9α-Hydroxy-3-methoxyhasubanan
Authors: Monković Ivo , Wong Henry , Belleau Bernard , Pachter Irwin J. , Perron Yvon G.
Published: May 2006

The synthesis of a versatile intermediate 4a-(2-aminoethyl)-l,2,3,4,4a,9-hexahydro-6-methoxyphenanthrene (3a) and its utilization in the synthesis of 9α-hydroxy-3-methoxy-17-methylhasubanan (10), 3,14-dimethoxy-17-methylisomorphinan (9l), various 14-hydroxyisomorphinans (9), and 3-methoxy-Δ8,14-morphinan (11b) is described. A number of 17-alkyl-3,14-dihydroxyisomorphinans were prepared and tested for narcotic antagonist and analgesic activities in laboratory animals. Some of these new compounds have exhibited significant activities.
Diazomethane-catalyzed Transesterification of Oxalic Acid Esters
Authors: Young J. Christopher
Published: May 2006

In the presence of an alcohol, oxalic acid esters undergo diazomethane-catalyzed transesterification. Under mild reaction conditions, esters of homologous dicarboxylic acids and other polycarboxylic acids are unaffected.
Synthesis and Ion-exchange Properties of Tantalum Arsenate
Authors: Rawat J. P. , Mujtaba S. Qasim
Published: May 2006

A new inorganic ion-exchanger, tantalum arsenate, has been prepared under varying conditions. The exchanger prepared by mixing 0.1 M tantalum pentoxide and 0.1 M sodium arsenate in the ratio of 1:4 at pH 0 has been studied in detail for its ion-exchange capacity, pH titrations, and Kd values. The material can be prepared reproducibly. Its analytical importance has been established by the following quantitative separations: Zr4+ from Tm3+, Zr4+ from Eu3+, Pr3+ from Eu3+, and Pr3+ from Tm3+.
Thiophene Isosters of Phenylethanolamines
Authors: Bagli Jehan F. , Ferdinandi E.
Published: May 2006

The reaction of a variety of substituted thiophenes, under Friedel–Craft conditions, leading to acetylthiophenes is described. Some of the by-products obtained are isolated and their mode of formation rationalized. The bromination, the reduction of the bromoketones, and their transformation to thienylethanolamines is reported. The degradation products of bromohydrin as well as isomeric amines obtained in the final substitution reaction are characterized and a possible mechanism for the formation of these compounds is proposed.
The Far Infrared Spectra of Partially Orientationally Ordered Water Molecules: Hexamethylenetetramine Hexahydrate at 95 K
Authors: Bertie John E. , Solinas Marco
Published: May 2006

The far infrared spectra of four isotopic modifications of the partially orientationally ordered clathrate hydrate hexamethylenetetramine hexahydrate at 95 K are reported. The spectra are assigned to absorption allowed under the diffraction factor group, and to disorder-allowed absorption, following the theory for absorption by translational vibrations in orientationally disordered solids. Three phases formed primarily by hydrogen-bonded water molecules are known to be significantly, but only partially, orientationally ordered, hexamethylenetetramine hexahydrate, ice V, and ice VI. Of these phases, only ice VI fails to show sharp absorption in its far infrared spectrum in addition to the broad, disorder-allowed absorption.