bluuebunny/crossref_metadata_2025 huggingface dataset:
The Pulse Radiolysis of Penicillamine and Penicillamine Disulfide in Aqueous Solution
Authors: Purdie John W. , Gillis Hugh A. , Klassen Norman V.
Published: May 2006

Aqueous solutions of penicillamine (RSH) and penicillamine disulfide (RSSR) have been pulse irradiated at several pH's and the ensuing reactions studied. The rate constant for the reaction of solvated electrons with penicillamine disulfide decreases from 7.3 × 10−9 M−1 s−1 at pH 7 to 0.8 × 109 M−1 s−1 at pH 10. The first-order rate constant for the decomposition of the resulting radical anion, RSSR−, increases from 1.77 × 106 s−1 at pH 7 to 6.5 × 106 s−1 at pH 10. Both of these pH effects are attributed to deprotonation of the two amino groups of the disulfide which have microscopic pK values of 7.9 and 8.5. The equilibrium constant for the reaction[Formula: see text]is (2.31 ± 0.2) × 102 M−1 at pH 8 but increases to 3.04 × 102 M−1 at pH 7 and decreases to 0.96 × 102 M−1 at pH 9. Measured from the kinetics of the build-up of RSSR−, k−2 = 1.83 × 106 s−1 at pH 8.Decay of RSSR− in the presence of RSH follows second-order kinetics at high dose rates and first-order kinetics at low dose rates. At high dose rates two second-order reactions[Formula: see text]appear to be involved with rate constants of 1.7 × 109 M−1 s−1 and 6.4 × 109 M−1 s−1 respectively at pH 8, At low dose rates the decay appears to be due to a pseudo first-order reaction between RSSR− and H2O, k ~ 2 × 103 s−1, with valine (RH) and penicillamine trisulfide (RSSR) as principal products. These products are obtained in similar yields by gamma radiolysis of penicillamine solutions. At pH 5, the thiyl radical decays by second-order kinetics, 2k = (2.85 ± 0.15) × 109 M−1 s−1.Studies of solutions containing penicillamine and methanol showed that penicillamine repairs methanol radicals very efficiently by hydrogen transfer. k = (1.1 ± 0.1) × 108M−1 s−1. The implications of the results for chemical radioprotection are discussed.
Carbon-13 Resonance Spectroscopic Studies on the Formation of Borate and Diphenylborinate Complexes of Polyhydroxy Compounds
Authors: Gorin Philip A. J. , Mazurek Mytosk
Published: May 2006

On complexing with sodium tetraborate the 13C magnetic resonance (c.m.r.) spectra of certain sugars contain considerably broadened signals. Replacement of the reagent with sodium diphenylborinate resulted in spectra with sharp singlets corresponding to the diphenylborinate complex, indicating that 13C-11B coupling likely does not occur. Most of the broadening is due rather to either the presence of more than one conformer of the borate complex or the rapid interconversion of the compound with borate complexes of types II and III. In one group of experiments the complexing of diphenylborinate with several low molecular weight sugars and polysaccharides was followed through c.m.r. spectroscopy. In another, complexing was observed with pyranosides having 1,3-hydroxyl groups with orientations that were almost diaxial. In the equilibrium reactions the approximate extent of complexing was estimated and with compounds that can form more than one complex, such as glycerol, the number and structures of the complexes were determined.
Identification by Combined Gas–Liquid Chromatography – Mass Spectrometry of Sterols Isolated from Scenedesmus obliquus Grown in Light and Heavy Water
Authors: Bélanger P. , Zintel J. A. , Heuvel W. J. A. Vanden , Smith J. L.
Published: May 2006

The sterol fraction from Scenedesmus obliquus, grown in heavy water, has been shown by combined g.l.c. – mass spectrometry to contain Δ7,22-ergostadiene-3β-ol, Δ7-ergostenol, chondrillasterol, and Δ7-chondrillastenol. The same algae, grown in light water, contain these four sterols and, in addition, ergosterol and corbisterol.
Pyrolyses and Mass Spectra of 2-Benzoxazolinone, 2-Benzimidazolinone, and 2-Benzothiazolinone
Authors: Thomson Michael L. , DeJongh Don C.
Published: May 2006

The electron-impact and chemical-ionization mass spectra of 2-benzoxazolinone (5), 2-benzimidazolinone (6), and 2-benzothiazolinone (7) have been compared with their pyrolysis products and parallels have been found. In each case, loss of CO occurs from [Formula: see text] followed by loss of CO for 5 and by HCN for 6 and 7. At 950° in a stream of N2, 5 gave 17% of C5H5N isomers, related to the loss of 2CO, along with 5.6% of quinoline. Compound 6 gave 14% of C6H4N2 isomers, related to the loss of CO. At 950°, 7 gave 2-thiophenecarbonitrile (1.1%), cyanonaphthalenes (4.5%), aniline (3%), cyanobenzene (2.5%), naphthalene (1.5%), and phenylisocyanate (2.5%). From 5–720–70% of the starting material was recovered or accounted for by isolation and identification of products in each case. G.c./m.s. was used to study pyrolysis mixtures.
Ternary Coordination Complexes Between Copper(II) and Amino Acids, and an Appraisal of the Enhancement of Ternary Complex Stability
Authors: Kruck Theo P. A. , Sarkar Bibudhendra
Published: May 2006

The equilibria involved in the ternary systems Cu(II)–A–B′ and Cu(II)–A–B″ (A = L-histidine, B′ = L-serine, B″ = L-glutamine) have been investigated by potentiometry in aqueous solution (0.15 M NaCl, 25°). In the ternary system Cu(II)–A–B′, three mixed complexes (MHAB′, MAB′, and MH−1AB′) were detected in addition to the binary complex species (MHA, MA, MH2A2, MHA2, MA2, MH−1A2, MB′, MB′2). The results observed in the Cu(II)–A–B″ system were quite similar to the system Cu(II)–A–B′ except that it did not show the presence of the species MH−1AB″. The stability constants were refined with a general least squares treatment. In the case of an equimolecular mixture of the constituents, a maximum of about 75% of Cu(II) is present as MAB′ at pH 5.5–9 and about 60% of Cu(II) as MAB″ at pH 5–10 when the concentration of each constituent is set equal to 10−2 M. A theoretical analysis and derivations of the expected stability constants of the complexes are presented on the basis of successive formation constants of the individual complexes carrying identical ligands. In each case an enhancement of the stability was observed with the ternary coordination complexes. Attempts have been made to explain the enhanced stability of the ternary coordination complexes.
The Electronic Spectra of Tetragonal Chromium(III) Complexes
Authors: Keeton M. , Chou B. Fa-Chun , Lever A. B. P.
Published: May 2006

not available
Etude par resonance magnetique des mouvements moléculaires dans l'acrylonitrile solide
Authors: Ban Buu , CHACHATY C.
Published: May 2006

Phase transitions and molecular motions in solid acrylonitrile and its deuterated homologue CH2=CDCN, have been studied between 100 and 191 °K (m.p.) by wide line n.m.r. and by T1 relaxation time measurements. Phase I (164 °K < T < 191 °K) is trapped and becomes metastable by quick cooling of acrylonitrile at 77 °K. It changes into the phase II, stable between 113 °K and 164 °K by a long duration annealing at 155–160 °K. The phase II → phase III transition occurs at 113 °K. It may be assumed that phase III, stable below this temperature, is rigid at T < 105 °K. Phase II may be characterized by a rotational oscillation of molecules around an axis defined by the N atom and the middle of the vinyl double bond. In phase I, acrylonitrile molecules undergo a binary reorientation motion around this axis with an activation energy of 4.2 kcal mol−1. The motion of peroxy radicals, trapped in acrylonitrile has been also studied by e.s.r. These radicals were produced by oxygen addition to free radicals previously formed by γ irradiation of acrylonitrile at 77 °K. The g anisotropy variation with temperature, shows no discontinuities at phase transitions, the activation of reorientation of peroxy radicals being 0.65 kcal mol−1. This result suggests that we are dealing in fact with macroradicals, the internal rotation of which is only observable in a solid matrix.
The Interaction of Sulfite Ion with 2,4,6-Trinitrobenzaldehyde: Kinetic, Equilibrium, and Proton Magnetic Resonance Studies
Authors: Marendic Neven , Norris Albert Richard
Published: May 2006

Sulfite ion reacts with 2,4,6-trinitrobenzaldehyde in aqueous solution of ionic strength 0.14 M to yield a 1:1 σ-complex at low sulfite concentrations and a 2:1 σ-complex at high sulfite concentrations. The visible absorption characteristics of these two σ-complexes as well as equilibrium constants and relevant thermodynamic parameters for their formation have been determined. P.m.r. studies demonstrate that two isomeric forms of the 1:1 σ-complex occur in aqueous dimethylsulfoxide solution and two isomeric forms of the 2:1 σ-complex occur in water. In both the 1:1 and the 2:1 complexes isomers are found which contain sulfite ion attached to the C-1 carbon and one of the isomeric 2:1 σ-complexes is postulated to exist in cis and trans forms. Observations are presented concerning the kinetics of the very rapid formation of the 1:1 σ-complex in water.
Alkyl Inductive Effects on Molecular Ionization Potentials. XVI. Esters
Authors: Levitt Leonard S. , Widing Harry F. , Levitt Barbara W.
Published: May 2006

Correlation of molecular ionization potentials, E1, with Taft's alkyl inductive substituent constants, σ1(R), has now been extended to include the esters. It is found that three series of esters, the formates, acetates, and methyl alkanoates, fall on three separate straight lines in accord with the general equation E1 = E0 + a1σ1(R), where E0 is the intercept and a1 the slope. The average standard error for the three lines is 0.024 eV with an average correlation coefficient of 0.992, showing that the alkyl substituent exerts an inductive influence on the electron density at the site suffering the electron loss: a lone pair on either the carbonyl or alkoxy oxygen atom. Evidence is deduced for the site of electron expulsion and a prediction is made concerning the site of vapor phase protonation of esters and carboxylic acids. E1 values presently not available experimentally are predicted for several esters.
Lanthanide Induced Shifts in the Proton Magnetic Resonance Spectra of Cyclic Amines
Authors: Hooper Donald L. , Kardos Alzbeta
Published: May 2006

Complex formation between europium tris(dipivalatomethane), Eu(DPM)3, and cyclic amines is not accompanied by inversion of the amine configuration, even for 2-alkyl and 2,6-dialkylpiperidines, where inversion of the amine configuration accompanies formation of the usual amine derivatives. There is, however, a steric effect of C-2 or C-6 substitution, in that the magnitude of the lanthanide induced shifts is sharply reduced.
Synthèse de méthyl-3 furoquinones
Authors: Huot Richard , Brassard Paul
Published: May 2006

The authors propose two new solutions to the problem of the synthesis of 3-methylfuranquinones. The methods have the advantage of requiring readily accessible substrates and reagents. A new synthesis of tanshinone I(26) illustrates one of the processes which in principle should also be applicable to the preparation of isotanshinones. Several novel transformations have been observed in the course of this study.
Identification of Intermediates in the Photolysis of Mercaptans in Dilute Glass Matrices. II
Authors: Elliot Allen John , Adam Frank Cuthbert
Published: May 2006

Dilute solutions of aliphatic thiols have been prepared and photolyzed at 253.7 nm in 3-methylpentane glasses at 77°K. The major products formed initially are thiyl radicals RS• and hydrogen atoms. Both of these are hot and yield solvent radicals by abstraction reactions, and relatively small amounts of RS2•, RS•, and possibly R1R2C=S. Thermal annealing of the matrices is accompanied by loss of hydrocarbon radicals through cage reactions and concommitant increase in the RS• concentration. An intermediate radical of the type R1R2ĊSH may also be produced in the annealing process. The photometric and spin resonance characteristics of RS•, RS2•and R1ĊH—SH are discussed and related to other systems in which these intermediates are observed. RS• is characterized in the amorphous phase by an absorption at 405 nm and a broad asymmetrical e.p.r. resonance near [Formula: see text] RS2• has a non-axial g-tensor with principal values of about 2.06, 2.02, and 2.00 and has no detectable absorptions between 350 and 1200 nm.The photolytic behavior of these metastable radical species is also investigated.
Aziridine Induced Isomerization of Isomaleimides to Maleimides
Authors: Joseph-Nathan P. , Mendoza V. , G. E. García
Published: May 2006

Treatment of N-phenylisomaleimide with aziridine gave 3-(N′-aziridinyl)-N-phenylsuccinimide identical with the adduct formed between N-phenylmaleimide and ethylenimine. The isomerization proceeded through the intermediate 2 whose decomposition in solution to a mixture of 3, 4, and 5 is also described.
Long-range Proton–Proton Coupling Constants in the Vinylpyridines. Conformational Preferences of the Vinyl Group and Molecular Orbital Calculations
Authors: Rowbotham J. Brian , Schaefer Ted
Published: May 2006

The p.m.r. spectra of 2-vinylpyridine, 2-methyl-5-vinylpyridine, and 4-vinylpyridine are examined for long-range coupling constants between the vinylic and ring protons. Those over six, seven, and eight bonds from the vinyl group to ring or methyl protons in the para position are dominated by a π electron mechanism. Those over five bonds between the α proton and a ring proton in the meta position indicate that the vinyl group prefers to lie cis to the nitrogen in 2-vinylpyridine but trans in the 5-vinylpyridine. INDO-MO-FPT calculations of coupling constants between vinyl protons and ring protons, carbon-13, and nitrogen-14 nuclei are presented in graphical form.
Influence of Lewis Acids on the Diels–Alder Reaction. VI. Reaction of 2,5-Dimethyl- and 2,5-Diphenylfuran with Ethyl Propiolate
Authors: McCulloch A. W. , McInnes A. G.
Published: May 2006

The AlCl3-promoted reactions of 2,5-dimethyl- and of 2,5-diphenylfuran with ethyl propiolate afford as major products ethyl 2,6-dimethyl-3-hydroxybenzoate (6a) and ethyl 3,5-diphenyl-2-hydroxybenzoate (8b), respectively. Also isolated from these reactions were ethyl 2,4-dimethyl-5-hydroxybenzoate (7a), ethyl 3,5-dimethyl-2-hydroxybenzoate (8a), ethyl 2,4-diphenyl-5-hydroxybenzoate (7b), and ethyl 2,6-diphenyl-3-hydroxybenzoate (6b). Minor by-products were trans ethyl 3-(2,5-dimethyl-3-furyl-acrylate (10) and ethyl 3-acetyl-2-(2,5-dimethyl-3-furyl)-5-methyl-cyclopenta-2,5-dienecarboxylate (11).
o-Nitrophenylethylene Glycol: a Photosensitive Protecting Group for Aldehydes and Ketones
Authors: Hébert Jacques , Gravel Denis
Published: May 2006

o-Nitrophenylethylene glycol (1) was synthesized and found to be useful as a photochemically labile blocking group for aldehydes and ketones. The acetals obtained are cleaved smoothly upon irradiation at 3500 Å, regenerating the parent carbonyl compound in very good yield.
Synthèse d'α-L-Fucopyrannosides
Authors: Rafestin Marie-Edith , Delay Didier , Monsigny Michel
Published: May 2006

The β-L-fucopyranosyl chloride 2,3,4-tri(chlorosulfate) (1) has been prepared by reaction of sulfuryl chloride with L-fucose at low temperature (yield, 47%). This β-L-fucopyranosyl chloride (1) gave high yields of the α-L-fucoside by reaction with alcohols. The p-nitrobenzyl α-L-fucoside has been prepared (yield, 35%). From L-fucose, the α-L-fucoside is obtained in three steps.
Infrared Chemiluminescence from the Reactions of Oxygen Atoms with Halomethanes
Authors: Arnold S. J. , Kimbell G. H. , Snelling D. R.
Published: May 2006

Infrared chemiluminescence from vibrationally excited CO was observed when CH3Cl, CH2Cl2, CHCl3, or CH2Br2 was introduced into a stream of oxygen atoms. Emission from vibrationally excited HCl was also observed from CH2Cl2 and CHCl3. The mechanisms describing the reactions of oxygen atoms with these molecules are discussed in detail. The reaction step responsible for the formation of CO† is postulated to be[Formula: see text]and for HCl†[Formula: see text]
Synthesis of 3,4,6-Tri-O-methyl-D-glucose, -D-galactose, and -D-mannose
Authors: Berry Joffre M. , Choy Yuen-Min , Dutton Guy G. S.
Published: May 2006

Reaction of 1,3,4,6-tetra-O-acetyl-D-glucose, -D-mannose, and -D-galactose with dihydropyran and p-toluenesulfonic acid in dichloromethane gave the corresponding 2-tetrahydropyranyl ethers. Deacetylation, methylation, and hydrolysis gave 3,4,6-tri-O-methyl-D-glucose, 3,4,6-tri-O-methyl-D-mannose, and 3,4,6-tri-O-methyl-D-galactose in 60, 28, and 25% overall yields, respectively. A small amount of 3,5,6-tri-O-methyl-D-galactose was also obtained.
Vibrational Spectra and Structures of the Solid Phases of Germane
Authors: The Nguyen Dinh , Gagnon J.-M. , Belzile R. , Cabana A.
Published: May 2006

This paper reports the i.r. and Raman spectra of the four solid phases of GeH4. Pure and mixed isotopic crystals have been examined. Marked spectral changes are observed at every transition. The interpretation of the spectra, based upon the Halford–Hornig approach, provides information on the crystal structure of each form. Phase I is plastic and molecules probably lie at sites of symmetry T or Td. The spectra of the two intermediate phases are consistent with site symmetries of either D2d, S4, C3v or C3 but the two former are favored. The stable phase below 63 °K is of lower symmetry, the molecules lying at sites of either D2, C2v, C2, C5, or C1, symmetry. Possible factor groups are proposed for phases II, III, and IV. The molecules are found to occupy only one set of equivalent sites in each of the phases.
The Synthesis of Some Analogs of the Hallucinogen 1-(2,5-Dimethoxy-4-methyl-phenyl)-2-aminopropane (DOM). III. Some Derivatives of 3-phenylalanine
Authors: Coutts Ronald T. , Malicky Jerry L.
Published: May 2006

Syntheses of the hydrochlorides of 3-(2,5-dimethoxyphenyl)alanine, 3-(2,5-dimethoxy-4-methylphenyl) alanine, and 3-(4-bromo-2,5-dimethoxyphenyl)alanine are described. A phenol, C10H14ClNO4, related to the second of these three compounds was also prepared and is concluded to be a monohydrate of the lactone, 3-amino-6-hydroxy-7-methyl hydrocoumarin hydrochloride.
Etude de l'effet des cations alcalins sur la structure du succinate de cuivre
Authors: Sharrock P. , Theophanides T.
Published: May 2006

New complex-salts of copper of the general formula M2Cu(succinate)2.xH2O, where M = Li, Na, K, and NH4; 0 ≤ x ≤ 51/2 were synthesized. The complexes were studied by infrared and visible spectroscopy, thermogravimetry, X-ray powder patterns, and magnetic susceptibility measurements.
Thermodynamics and Spectroscopy of the Hydrogen Bonded Complex Formed between Hydrogen (Deuterium) Chloride and Dimethyl Ether in the Gas Phase by Raman Scattering
Authors: Gilbert A. S. , Bernstein H. J.
Published: May 2006

The equilibrium constant Kp has been obtained for the complex [Formula: see text] over a range of temperatures between 22 and 132 °C by monitoring the integrated intensity of the Raman scattered band from unassociated DCl in a mixture with dimethyl ether. By applying the relation In KP = −ΔH/RT + ΔS/R the quantities ΔH, ΔG, and ΔS have been evaluated.Broad νCl–H and νCl–D complex bands have been observed and are found to be polarized.
Ring C Functionalized Diterpenoids. Part III. 12-Substituted ent-Beyeranes
Authors: Fairlie John Cairns , McAlees Alan James , McCrindle Robert , Neidert Eli
Published: May 2006

On treatment with hot formic acid ent-16-kaurene (4a) and the related ester 4b give a mixture containing 12-, 15- and 16-ent-beyerane derivatives (10a, 1a; 7a, 12a; 9a, 11a) in which the last predominates, while ent-15-beyerene (5a) gives mainly the C-15 formate 7a. In keeping with the anticipated longer lifetimes of the intermediate ions 2 and 3 in trifluoroacetic acid as compared with formic acid, reaction of 4b in the former medium at room temperature affords a mixture containing 1c, 11c, and 12c, in which the relative yield of the 12-substituted derivative (1c) is markedly increased. Treatment of methyl ent-trachyloban-19-oate (14) or methyl ent-15-atisen-19-oate (6b) under the same conditions gives a mixture similar to that obtained from 4b.
A Selective Determination of the Proton Nuclear Relaxation Times of the Alkaloid Vindoline: An Extension via Fourier Transform Measurements
Authors: Hall L. D. , Preston Caroline M.
Published: May 2006

A Fourier Transform method has been used to measure the spin–lattice relaxation times of essentially all the protons of the alkaloid, vindoline. It is shown that even for a molecule of this size substantial and potentially useful differences exist in the experimental relaxation times which reflect the degree of crowding of each proton by other protons.
The Ion Kinetic Energy Spectra of Benzyl Fluoride and the Isomeric Fluorotoluenes
Authors: Safe S. , Jamieson W. D. , Embree D. J.
Published: May 2006

One of the classical problems in mass spectrometry is the structure and formation of the C7H7+ and XC7H6+ ions which are generated in the mass spectra of alkylbenzenes and many other aromatic compounds. The intermediacy of both symmetrical tropylium ion structures and unsymmetrical benzyl ions has been postulated using a number of different approaches. We have investigated this problem using ion kinetic energy spectroscopy, a relatively new technique, with the isomeric fluorobenzenes and benzyl fluoride as model compounds. Our results indicated incomplete substituent (i.e. fluorine) scrambling in the first field-free region of the mass spectrometer and thus incomplete equilibration in the decomposing FC7H6+ ions and these conclusions are in contrast to results obtained using other techniques.
Etude comparée des spectres d'absorption dans le proche infrarouge des complexes 1–1 entre l'eau et les bases, en mélanges ternaires'
Authors: Burneau André , Corset Jacques
Published: May 2006

The spectra of the complexes involving a water molecule and a proton acceptor molecule are obtained by using ternary mixtures water – base – carbon tetrachloride. The vibrational assignment of these spectra is performed through a prior calculation and by examining the shape of the absorptions and their frequencies according to the base. With the complexes HOH … B, it is observed that the bands related to the v(011) combinations, which involve the free OH group, are narrower than v(110) and have always a larger extinction coefficient. In the 7000–7300 cm−1 region, the most intense absorption is the v(101) combination with the weak bases, but the &([a-z]+);(002) overtone with the strong ones.
Base Catalyzed Isomerization of Epoxides to Bicyclic Allylic Alcohols, Potential Intermediates for the Total Synthesis of the DL-Aldohexoses
Authors: Ranganayakulu Kurupati , Singh Udai P. , Murray Thomas P. , Brown Robert K.
Published: May 2006

Treatment of the epoxide 2-deoxy-1,6:3,4-dianhydro-β-DL-ribo-hexopyranose (3) with n-butyllithium, and the epoxides 2-deoxy-1,6:3,4-dianhydro-β-DL-lyxo-hexopyranose (5) and 4-deoxy-1, 6:2,3-dianhydro-β-DL-lyxo-hexopyranose (7) with lithium diethylamide has provided 1,6-anhydro-2,3-dideoxy-β-DL-erythro-hex-2-enopyranose (4), 1,6-anhydro-2,3-dideoxy-β-DL-threo-hex-2-enopyranose (6), and 1,6-anhydro-3,4-dideoxy-β-DL-threo-hex-3-enopyranose (8) in yields of 65, 50, and 20%, respectively. These allylic alcohols are potential intermediates for the synthesis of the various DL-aldohexoses.
Structure of Radicals Produced by γ-Radiolysis. Part 3. Radicals Derived from Adamantane, Adamantyl Derivatives, and Diamantane
Authors: Hyfantis Jr. George J. , Ling A. Campbell
Published: May 2006

The effects of γ-radiolysis on adamantane, perdeuterated adamantane, diamantane, 1- and 2-chloroadamantane, 1- and 2-bromoadamantane, 1-cyanoadamantane, 1- and 2-adamantanol, 1- and 2-adamantylamine have been examined via electron spin resonance techniques, and the nature of the predominant species produced is discussed. Spin-scavenging experiments using 2-methyl-2-nitrosopropane have been used, together with previously reported Br2 scavenging experiments, to identify the nature of the predominant species produced when purified solid adamantane is subjected to radiolysis. Data indicate that this is the 1-adamantyl radical. A possible reason for the controversial nature of data on this subject reported previously by other investigators is given.
The Electron Pair in Chemistry
Authors: Daudel R. , Bader R. F. W. , Stephens M. E. , Borrett D. S.
Published: May 2006

The reality of the electron pair as a fundamental unit in the electronic structure of molecular systems is evidenced by calculations which show that the most probable partitioning of a system is the one which localizes pairs of electrons in well-defined spatial regions or loges. The loges in turn, correspond to those regions of space generally associated with core, bonded, and non-bonded electrons. In terms of information theory, they yield the maximum amount of information concerning the localizability of the electrons. The most probable three-loge partitioning of the six-electron BH(X1∑+) system, for example, is dominated by the event which places two electrons in each of three loges, the location and shape of the loges being such as to justify the labelling of the electron pairs they localize as core, bonded and nonbonded. Since the loges are defined in real space and are totally nonoverlapping, one may define the volume of space occupied by pairs of electrons. In BH, for example, the volume of space required to contain 95% of the nonbonded pair of electrons is over two times larger than that required to contain 95% of the bonded pair. It is possible to define core loges which exhibit pair occupation probabilities ranging in value from 95% in LiH+ to 85% in BH. Corresponding probabilities ranging in value from 75% to 90% are obtained for bonded and nonbonded loges. In the set of molecules studied here, the occurrence of events with such high probabilities is found only for loges which maximize the probability of a pair occupation.
Product Studies of the Mutual Termination Reactions of sec-Alkylperoxy Radicals: Evidence for Non-Cyclic Termination
Authors: Bennett John E. , Summers Raymond
Published: May 2006

The yields of alcohol and ketone from the mutual termination reaction of sec-butyl-, sec-hexyl-, cyclopentyl-, and cycloheptylperoxy radicals have been measured over the temperature range from −125 to +100 °C. The ratio of alcohol/ketone departs markedly from the value of unity predicted by the Russell mechanism, being greater (ca. 2.5) at +100 °C and considerably less (ca. 0.1) at −125 °C.
Observations of Stratospheric Aerosol Layers by Optical Radar
Authors: Hirono M. , Fujiwara M. , Uchino O. , Itabe T.
Published: May 2006

A ruby laser radar has been constructed at Fukuoka (33° N), south-west Japan, for the purpose of probing the upper atmosphere. Observations of stratospheric aerosol layers have been carried out since October 1972. Data obtained show that the layers of enhanced optical backscattering due to aerosols in the height range of 16–30 km were found throughout the period of observation. One of the layers always appeared at about 20 km height and varied to some extent in its height, structure, and peak value of scattering, day-to-day and month-to-month. Other layers appeared in the region above 25 km and seemed more variable. Height profiles of non-Rayleigh backscattering cross section βm are calculated for each night and each month of the observation and compared with the temperature, wind velocity, and ozone concentration in the stratosphere. The individual scattering profile is most likely controlled by the large scale structure of the temperature profile of the night. The mean value of βm in the region around 20 km has its minimum in January and increases from winter to summer. Comparison is also made with the geometrical cross section of the aerosols deduced from the small ion density data and the results show that a large fraction of the aerosol mass is in the range of Aitken particles.
The Determination and Statistical Mechanical Interpretation of the Solubility of Water in Benzene, Carbon Tetrachloride, and Cyclohexane
Authors: Goldman Saul
Published: May 2006

The solubility of water in each of benzene, carbon tetrachloride, and cyclohexane, was determined at 5° intervals over the range 10 to 40 °C. The solubilities were converted to Henry's law constants and these constants were interpreted by means of a statistical mechanical theory based on Zwanzig's perturbation theory of fluids. A fitting-parameter in the form of a correction factor to the water–solvent pairwise potential function was required. The values of this parameter for the benzene–water and cyclohexane–water systems could be rationalized on the basis of anisotropy of solvent polarizability. The values of the parameter for the carbon tetrachloride – water system were consistent with a hydrogen-bonding interaction between water and carbon tetrachloride.
Preparation and Nuclear Magnetic Resonance Study of Phosphorus Compounds Containing Alkenyl Functional Groups
Authors: Clark Peter W. , Curtis John L. S. , Garrou Philip E. , Hartwell George E.
Published: May 2006

The phosphines PPhn(CH2CH2CH=CH2)3−n, n = 2–0, PPhn(CH2CH2CH2CH=CH2)3−n, n = 1 or 2, and PPh2CH2CH = CH2 have been synthesized and studied by 1H and 31P magnetic resonance. The n.m.r. spectra of PPh2(OCH2CH=CH2), its oxide, O=PPh2(OCH2CH=CH2), and its Arbuzov rearrangement product, O=PPh2(CH2CH=CH2), have been investigated by 31P decoupling of the proton spectrum, selective proton decoupling of the 31P spectrum, and comparison with computer-simulated spectra to determine the spin–spin coupling constants. The n.m.r. spectra of the related oxides O=PPh2CH2CH2CH=CH2, O=P(CH2CH2CH=CH2)3, and O=P(OCH2CH=CH2)3 are also assigned. The data indicate that 3JPH > 2JPH for alkenylphosphines, 2JPH is larger for phosphine oxides than for phosphines, and 3JPH is little changed in comparing phosphorus(III) with phosphorus(V) compounds.
Nitrosation with Lithium Nitrite
Authors: Chen M. F. , MacDonald S. F.
Published: May 2006

Alcoholic lithium nitrite and 1 mol of HCl may be used to nitrosate ketones. The yields are comparable to those obtained when alkyl nitrites are used with catalytic amounts of HCl.
Rearrangement Reactions in the Electron Impact Fragmentation of Isobutene
Authors: Lin Margaret S.-H. , Harrison Alex. G.
Published: May 2006

The detailed mass spectrum of isobutene has been examined using both D and 13C labelling. It is shown that at low average internal energies of the molecular ion complete randomization of hydrogens and of carbons occurs prior to fragmentation to form C3H5+. As the average internal energy of the molecular ion increases (by increasing the ionizing electron energy) the extent of both carbon and hydrogen randomization decreases. Carbon scrambling is complete in the molecular ion prior to fragmentation to form C2 ions under all conditions studied. The results are consistent with a skeletal isomerization of the isobutene molecular ion by a mechanism involving a series of 1,3 ring closures to form methylcyclopropane type ions.
The Crystal and Molecular Structure of the Antihistaminic Drug Triprolidine Hydrochloride Monohydrate [trans-1-(p-Tolyl)-1-(2-pyridyl)-3-(1-pyrrolidino)-prop-1-ene]
Authors: James M. N. G. , Williams G. J. B.
Published: May 2006

The title compound crystallizes from anisole with 4 molecules per unit cell. The space group of this cell is P21/c and the cell parameters are a = 14.777(2) Å, b = 9.5785(8) Å, c = 13.099(1) Å, and β = 90.48(2)°. Diffractometer data with CuKα radiation to 2θ = 129° were collected and the structure solved and refined to weighted and unweighted R factors of 0.077 and 0.051 respectively. The 2-pyridyl ring and the p-tolyl system make dihedral angles of 29.7 and 55.3° respectively with the plane of the double bond. The inter-aryl dihedral angle is 106.5°. The protonated tertiary nitrogen atom is hydrogen bonded to the chloride ion and two chloride ions are connected via hydrogen bonds in a distorted square planar arrangement by two water molecules. The pyridyl ring is involved in a π orbital overlap linkage with another pyridyl ring on the same side of the molecule as is the hydrogen bond from the nitrogen function. Brief characteristics of a flexible receptor protein which will bind antihistamine drugs are given.
A Synthesis of Muscalure, the Housefly Sex Attractant
Authors: Ho Tse-Lok , Wong Chiu Ming
Published: May 2006

A convenient synthesis of muscalure starting from oleic acid or oleonitrile by reaction with C5 organometaillic reagents followed by Huang–Minlon reduction is reported.
Reversible Inhibition of Carboxypeptidase A. II. Inhibition of Esterase Activity by Dicarboxylic Acid Anions
Authors: Bunting John W. , Myers Chester D.
Published: May 2006

Reversible inhibition of the hydrolysis of O-hippuryl-L-3-phenyllactic acid by carboxypeptidase A has been studied for a series of decarboxylic acids at 25°, pH 7.5, and ionic strength 0.2. All inhibitors studied displayed either strictly competitive or partially competitive inhibition kinetics. For the series CO2H(CH2)nCO2H, strictly competitive inhibition was observed for n = 1, 3, 4, 8, 10, whereas partially competitive inhibition occurs for n = 2, 5, 6, 7. A series of 11 alkyl- and aryl-substituted malonic acids were all strictly competitive inhibitors; for a series of six alkylmalonic acids the inhibition constants are correlated with the Hansch π-parameter by the equation –log K1 = 2.257π + 1.75; arylmalonic acids are poorer inhibitors than expected on the basis of their π-parameters, in accord with a similar observation for monocarboxylic acids. Phthalic acid is a strictly competitive inhibitor (K1 = 1.7 mM), whereas the isomeric isophthalic and terephthalic acids cause relatively little inhibition even at 0.1 M; maleic acid is a partially competitive inhibitor, whereas the isomeric fumaric acid gives only 15% inhibition at 0.1 M. Homophthalic acid and 2,2-dimethyl- and 3,3-dimethylglutaric acids were also investigated.The characteristics of partially competitive inhibition displayed by all dicarboxylic acids and also monomethyl succinate and succinamic acid are consistent with a scheme which assumes the formation of an E.I2 complex. The observed specificity of dicarboxylic acid binding is used to postulate a schematic diagram for binding of these species to the enzyme, and an interpretation of this diagram is suggested on the basis of the crystallographically determined structure of the enzyme.
Carbonyl Ylides and the Rearrangement of (+)-trans-2,3-Diisopropenyloxirane
Authors: Paladini Jean-Claude , Crawford R. J.
Published: May 2006

The kinetics of the gas phase racemization and rearrangement of 2,3-diisopropenyloxirane have been determined. Comparison with the kinetic data for 2,3-divinyloxirane allows us to exclude the mechanism for the formation of vinyldihydrofuran wherein an inward conrotatory ring opening comprises the first step. The mechanism proposed consists of an isomerization about the carbon–oxygen bond of the carbonyl ylide to form an isomeric intermediate which then undergoes a disrotatory five-centered ring closure to produce 2-isopropenyl-4-methyl-2,3-dihydrofuran.
Electric Field Gradients in Alkali Halide Molecules
Authors: Laplante Jean-Pierre , Bandrauk Andre D.
Published: May 2006

The electric field gradient q has been calculated from Hartree–Fock wavefunctions for the molecules LiF, LiCl, LiBr, NaF, NaCl, NaBr, KF, and KCl. It is found that σ and π electrons behave quite differently. Exchange distortions are of great importance for a proper understanding of σ contributions to q. Polarizations of π electrons into the bonding region are also considerable. These effects are responsible for failures of classical models and are further discussed using calculated density difference diagrams.
Homogeneous Catalysis of Hydrogen Isotope Exchange between D2 and Ethanol by Chlorotris(triphenylphosphine)rhodium(I). I. in Benzene–Ethanol
Authors: Strathdee Graeme , Given Russell
Published: May 2006

The kinetics and mechanism of D2–C2H5OH exchange catalyzed by chlorotris(triphenylphosphine)rhodium(I) have been studied in 50 volume percent benzene-ethanol. In this mixed solvent, the rate of exchange was low and was limited by the rate of transfer of deuterium from dideuteridochlorotris(triphenylphosphine)rhodium(III) to the solvent, and not by the rate of activation of D2. The activation energy for the overall process was relatively low, 35 kJ mol−1. In addition, new data have been presented for the catalysis of H2–D2 exchange in benzene by RhCl(PPh3)3. Analysis of the apparent HD:D2 isotope effect that is observed during D2–C2–H5OH exchange suggests that this effect originates with the relative stabilities of the D2, HD, and H2 adducts with RhCl(PPh3)3, or by control of the HD and H2 product distribution by the H2–D2 equilibration reaction.
Complex Fluoroanions in Solution. V. Vanadium Pentafluoride
Authors: Brownstein S. , Latremouille G.
Published: May 2006

Vanadium pentafluoride is associated at low temperature in solution. It reacts with NbF6− and TaF6− to give complex fluoroanions and with BF4−, PF6−, AsF6−, and SbF6− to possibly yield complex fluoroanions.
Radioisomerization and Photoisomerization of Liquid 2 -Butenes in the Presence of Sulfur Compounds
Authors: Collin Guy J. , Perrin Patrick M. , Garneau François X.
Published: May 2006

The liquid phase radiolysis and photolysis of cis- and trans-2-butenes were studied in the presence of various additives. A very efficient isomerization of 2-butenes was achieved by the addition of thiols of low molecular weight (hydrogen sulfide, methyl and isopropyl mercaptans). In the absence of molecular oxygen, we have observed G values (trans-2-butene) of the order of 90 000. On the other hand, little or no isomerization occurred in the presence of carbon disulfide, sulfur hexafluoride, and tert-dodecylmercaptan. Although the majority of the additives have no effect on the 2-butene:hydrogen sulfide system, conjugated diolefins block the isomerization reaction. These diolefins disappear from the reaction mixture.
The Reaction of Chlorine Monoxide with Cyclohexene. A Molecule Induced Homolysis Reaction
Authors: Tanner Dennis D. , Nychka Nestor , Ochiai Tameichi
Published: May 2006

The reaction of chlorine monoxide with cyclohexene at −20° in the dark was found to proceed by an addition reaction to yield trans-2-chlorocyclohexyl hypochlorite. Concomitant with the addition, a molecule induced homolysis reaction of the chlorine monoxide occurs with cyclohexene to produce a number of free radical substitution and addition products, as well as products possibly arising from ionic addition reactions. Induced halogenation was found with added cyclohexane.
The Hydride Reduction of Hemiaminals of Thiobinupharidine and the Structure of Thionupharoline
Authors: Martin T. I. , MacLean D. B. , Wróbel J. T. , Iwanow A. , Starzec W.
Published: May 2006

Thionupharoline has been shown to be identical with 6-hydroxythiobinupharidine. The hydride reduction of hemiaminals of thiobinupharidine has been examined in ethanol solution. The steric course of reduction at C-6 is not nearly as selective as it has been reported to be in solution in methanol.
Isomeric Mixture Analysis of Some Ring-opening Reactions of Styrene Oxide
Authors: Hocking M. B.
Published: May 2006

Mixtures of ring-opened and other products of reactions of acetic or benzoic acids, or ethanol, or phenol with styrene oxide under various conditions can be qualitatively and quantitatively analyzed without isolation of the components by the use of n.m.r. This method, in the case of the ester products, avoids confusing the initial ring-opening result with the results observed after subsequent acyl migrations which readily occur in this type of system.
Synthetic Morphinans and Hasubanans. II. On the Mechanism of Acid-catalyzed Transformations of 17-(N-Phenylthioamido)-3-methoxy-Δ8,14-morphinan
Authors: Saucier Michel , Monković Ivo
Published: May 2006

The acid-catalyzed rearrangement of 3-methoxy-17-(N-phenylthioamido)-Δ8,14-morphinan (1) to 3-methoxy-17-(N-phenylthioamido)- Δ9,10-hasubanan (2), and acid-catalyzed cyclization of 2 to thiazinohasubanan (3) are described. Both transformations are discussed in terms of intramolecular vs. intermolecular hydride (proton) transfers. The reduction of 3 afforded 3-methoxy-10β-thiohasubanan (4), which was further hydrogenolized to 3-methoxy-hasubanan (5).
Structure and Reactivity of Methyl Radical — Cyanide Ion Pairs in Crystal I and Crystal II of Acetonitrile
Authors: Sprague Estel Dean , Takeda Keiji , Wang Jih Tzong , Williams Ffrancon
Published: May 2006

The extent of interaction between methyl radicals and cyanide ions produced in pairs by dissociative electron capture in the two solid phases of acetonitrile has been studied by e.s.r. using CD313CN. Although no interaction is observed when the radical–anion pairs are generated by photobleaching the acetonitrile dimer radical anion in Crystal I, a very weak interaction as evidenced by an isotropic 13C hyperfine splitting of 3.4 G is found for the corresponding species produced from the acetonitrile monomer radical anion in Crystal II. The rate of hydrogen atom abstraction by the methyl radical in Crystal I is at least a factor of 10 greater than in Crystal II at the same temperature over the range 77–113 K. These results show that the weak perturbation of the methyl radical by the cyanide ion does not enhance methyl radical reactivity in hydrogen atom abstraction. Evidence from 13C hyperfine splitting measurements on [Formula: see text] indicates that the configuration of the methyl radical is planar in these radical–anion pairs. It is emphasized that quantum mechanical tunneling provides a satisfactory explanation for the low apparent activation energies, the curved Arrhenius plots, and the abnormally large deuterium isotope effects which characterize hydrogen atom abstraction reactions by methyl radicals in glassy and crystalline solids at low temperatures. Moreover, since the tunneling rate is extremely sensitive to the width of the barrier, methyl radical reactivity is expected to show a very strong dependence on the precise geometry of the reacting partners in the solid state.
Calorimetric Heats of Ionization of Aqueous Benzoic Acid from 5–100 °C and Derived Thermodynamic Quantities
Authors: Matsui Takeki , Ko Hon Chung , Hepler Loren G.
Published: May 2006

We have made calorimetric measurements at 5.0, 12.5, 25.0, 40.0, 50.0, 65.0, 75.0, 85.0, and 100 &([a-z]+);C that lead to values of ΔH0 of ionization of aqueous benzoic acid at each of these temperatures. These ΔH0 values have been used with pK = 4.204 at 25.0 °C for calculation of pK values from 5 to 100 &([a-z]+);C and also ΔCp0 of ionization values over this range. Usefulness of various extrapolation functions for ΔH0, ΔCp0, and pK up to 225 °C has been investigated.
Structure cristalline et moléculaire du cis-dithiocyanatobis(phénanthroline-1,10)mercure(II), Hg(SCN)2(C12H8N2)2
Authors: Beauchamp André L. , Saperas Bernard , Rivest Roland
Published: May 2006

The compound cis-Hg(SCN)2(Phen)2 belongs to the triclinic space group [Formula: see text] with a = 13.252(5), b = 11.077(4), c = 8.443(3) Å, α = 105.20(3), β = 83.25 (3), γ = 90.92(3)°, and Z = 2. The structure was solved by the heavy atom method and refined on 1718 independent reflections to an R factor of 0.069. The crystal contains discrete molecules, in which mercury is coordinated to four nitrogen atoms from two phenanthroline molecules and to two sulfur atoms from thiocyanate groups. These donor atoms define a distorted octahedral geometry around mercury. The Hg—N bond lengths are in the range 2.42(2)–2.52(2) Å, whereas the Hg—S bonds are equal to 2.622(8) and 2.582(8) Å. The molecules are packed in layers parallel to the (110) planes and the layers are held together by normal van der Waals interactions. Within the layers, the packing of the complex is characterized by parallel stacking of phenanthroline ligands at distances of ∼3.4 Å. The terminal nitrogen atoms of the thiocyanate groups are uncoordinated.
Hydrogen–Water Deuterium Exchange over Unsupported Group VIII Noble Metals
Authors: Sagert Norman H. , Pouteau Rita M. L.
Published: May 2006

Specific activities of unsupported powders of all six Group VIII noble metals have been determined for hydrogen – water deuterium isotope exchange. The metal surface areas, which are required to calculate the specific activities were measured by hydrogen chemisorption and were checked by electron microscopy. Specific activities were measured as a function of temperature in the range 353 to 573 K and also as a function of the partial pressure of hydrogen and water at suitable temperatures and over a tenfold range of partial pressures.The variation in the specific activities was Pd < Ir ≤ Ru < Rh < Os < Pt, and these specific activities varied over a range of about 1000. The observed orders with respect to hydrogen and water are shown to be consistent with a mechanism in which chemisorbed hydrogen atoms exchange with physically adsorbed water.From the orders and the apparent activation energies, the chemical activation energies (E0) were calculated. These varied randomly within the range 61 ± 6 kJ mol−1 for all the metals studied. Previously we showed that there was a correlation of E0 with the work function of the metal when metals were supported on a highly graphitized carbon black, and suggested that electron donation from the carbon to the metal was responsible for the correlation. This suggestion is supported by the present results which show that E0 is relatively constant for all six metals in the absence of a support.
Kinetics of the Thermal Decomposition of β-Trifluoroethylsilanes and Hot Molecule Kinetics of (CF3CH2SiF3)
Authors: Bell T. N. , Berkley R. , Platt A. E. , Sherwood A. G.
Published: May 2006

The thermal decomposition of β-trifluoroethylsilanes (CF3CH2SiFx(CH3)3−x where x = 0–3) is described by the reaction[Formula: see text]The Arrhenius parameters for the series of silanes studied are as follows:[Formula: see text]Some results for the decomposition of the hot molecule CF3CH2SiF3* are reported.[Formula: see text]
Coordinating Properties of the Fluorosulfate Ion. Tetrakis(pyridine) Complexes of Zinc(II), Copper(II), and Nickel(II) Fluorosulfates
Authors: Alleyne Carl S. , Thompson Robert C.
Published: May 2006

Complexes of the type M(py)4(SO3F)2 (py = pyridine, M = Ni, Cu, Zn) have been prepared and characterized. Infrared spectra of all three complexes, electronic spectra and magnetic susceptibility studies of the copper and nickel complexes, and e.p.r. studies of the copper complex are reported. The complexes have tetragonally distorted octahedral structures with fluorosulfate groups coordinated to metal ions as unidentate ligands. To facilitate comparison of the coordinating action of the fluorosulfate ion with other polyatomic anions the complexes, Cu(py)4X2 (X = ClO4−, BF4−, NO3−, p-CH3C6H4SO3−, CF3CO2−) have been prepared and their electronic properties examined. The studies indicate that the coordinating strength of SO3F− towards metals is greater than ClO4−, BF4−, and NO3− but less than p-CH3C6H4SO3− and CF3CO2−. Electrical conductivity studies on solutions in acetonitrile indicate a correlation between the relative coordinating strength of the anion in a given complex and the extent to which the complex undergoes ionic dissociation in this solvent.
Phase Diagrams for the Sodium and Potassium Benzoate – Water Systems
Authors: Clarke E. Colin W. , Glew David N.
Published: May 2006

The low temperature phase diagrams have been determined for the potassium benzoate – water and the sodium benzoate – water systems. The ice eutectics with these anhydrous alkali benzoates were found at −11.8 °C with 34.89% potassium benzoate and at −14.5 °C with 39.7% sodium benzoate. Previously reported hydrates of potassium benzoate (3) were not observed. Concentrated sodium benzoate solutions below 0 °C were found to attain equilibrium with sodium benzoate only with the greatest difficulty.