bluuebunny/crossref_metadata_2025 huggingface dataset:
Thallic Ion Oxidation of Styrene: Kinetics of Decomposition of the Oxythallation Adduct C6H5—CH(OCH3)—CH2Tl(OAc)2
Authors: Nadon Louise , Zador Miklos
Published: May 2006

The kinetics of decomposition of the organo-thallic adduct formed in methanol between styrene and Tl(OAc)3, (C6H5—CH(OCH3)—CH2—Tl(OAc)2) has been studied in a water–methanol solvent. The reaction follows a first order rate law. The organo-thallic compound, RTl(OAc)2, is shown to be dissociated at low concentrations yielding two reactive species, RTlOH+ and RTl2+. The influence of acidity on the rate of decomposition shows that RTl2+ is much more reactive than RTiOH+. The kinetic parameters have been determined. The implication of the results on the rate-determining step of Tl(III) oxidation of styrene is discussed.
Rearrangement Studies with 14C. XXXIX. 1,2-Phenyl Shifts in Solvolyses of Triphenylvinyl-2-14C Triflate
Authors: Lee Choi Chuck , Cessna Allan J. , Davis Bruce A. , Oka Mitsuo
Published: May 2006

Solvolysis of triphenylvinyl-2-14C triflate was carried out in HOAc, 97% HCOOH, or CF3COOH. The reaction products showed rearrangements of the 14C-label from C-2 to C-1 averaging about 6.7, 7.7, and 27.0%, respectively, for the acetolysis, formolysis, and trifluoroacetolysis. The presence of the conjugate base of the solvent, added as the sodium salt, did not affect the extent of rearrangement. It is suggested that the 1,2-phenyl shift across the double bond of the triphenylvinyl cation takes place during the ion-pair stage and that the extent of rearrangement is related to the lifetime of the ion-pair and the nucleophilicity of the solvent.
Biosynthesis of Corydaline and of Ochotensimine
Authors: Holland H. L. , Castillo M. , MacLean D. B. , Spenser Ian D.
Published: May 2006

Radioactivity from [3-14C]tyrosine and from [methyl-14C]methionine is incorporated nonrandomly into predicted positions of corydaline and ochotensimine in Corydalissolida and C. ochotensis, respectively. The methyl group of methionine supplies the C-methyl group of corydaline and the exocyclic methylene group of ochotensimine, as well as the "bridge" carbon atom and the exocyclic O- and N-attached one-carbon units of each alkaloid. Maintenance of the 3H/14C ratio of [methyl-3H,14C]methionine within these units of corydaline is consistent with incorporation of intact CH3 groups.Partial loss of 3H relative to 14C is observed in the course of a Schmidt reaction of [2-3H, 2-14C] acetate.
Study of the Reactions of Chromium(III) Halides and Heterocyclic Ligands Containing Group VA and VIA Donor Atoms
Authors: Preti C. , Tosi G.
Published: May 2006

Complexes of thiomorpholin-3-one, thiomorpholin-3-thione, thiazolidine-2-thione, and thiazolidine-2-selenone with CrX3•nH2O (X = Cl, Br, I) were prepared and characterized. On the basis of vibrational (conventional and far infrared) and electronic spectroscopy, magnetism and conductivity measurements, the structures of these complexes were identified. The bonding occurs through the oxygen in the complexes of thiomorpholin-3-one and through the nitrogen in all the remaining complexes. The complexes crL3x3 involve unidentate ligands, are neutral, monomeric, and hexacoordinate. Spectroscopic parameters for the complexes have been calculated and compared with similar chromophores containing CrN3X3, CrO3X3, and CrS3X3 chromophores.
Nouvelle voie d'accès aux β-cétophosphonates γ,δ-éthyléniques
Authors: Peiffer Gilbert , Courbis Pierre
Published: May 2006

The addition of enynic phosphonates[Formula: see text] to alcohols in the presence of boron trifluoride, leads to γ,δ-ethylenic β-ketophosphonates.[Formula: see text]Yields of 70% have been obtained. Whether Z or E enynic derivates are starting materials the E ketophosphonate is obtained in both cases. The dipole moments of both families of compounds have been measured.
On the Reaction of p-Cresol with 4-Aminoantipyrine
Authors: Dave Vinod , Stothers J. B. , Warnhoff E. W.
Published: May 2006

The structure of the yellow product from the ferricyanide oxidation of p-cresol and 4-aminoantipyrine is shown to be 1 and not 3. Borohydride reduction of the imine 1 gave 2 which underwent elimination to 5a. Ferricyanide oxidation of 5a regenerated 1.
Crystal and Molecular Structure of Benzylidenimine Disulfide
Authors: Barrick James C. , Calvo Crispin , Olsen Fredric P.
Published: May 2006

The crystal and molecular structure of benzylidenimine disulfide has been determined. Crystals are monoclinic with space group P21/c, Z = 4, a = 12.93(2), b = 5.554(9), c = 20.46(3) Å, and β = 112.5(2)°. A full matrix least squares refinement on 2304 unique reflections of positive intensity measure collected on a [Formula: see text] Automatic diffractometer produced a conventional R of 0.029. The molecular geometry is very similar to that in the corresponding tetra- and trisulfides with a fairly short sulfur–sulfur bond length of 2.033(2) Å and a fairly long sulphur–nitrogen bond length of 1.690(3) Å.
Photolyse du chlorure d'éthyle gazeux en-dessous et au-dessus du potentiel d'ionisation
Authors: Cremieux Lionel , Herman Jan A.
Published: May 2006

Photolysis of gaseous ethyl chloride was performed at λ = 123.6 and 106.7–104.8 nm. There is no ionisation at 123.6 nm, while at 106.7–104.8 nm 40% of the absorbed light lead to ions. The identified products are the following: H2, CH4, C2H2, C2H4, C2H6, C3H6, C3H8, C4H10, CH3Cl, C2H3Cl, 2-C4H9Cl, 2,3-C4H8Cl2, and 1,3-C4H8Cl2. The effect of radical and electron scavengers on the product formation was studied. Charge neutralization reactions increase yields of H2, C2H2, and C2H4.
Dimetallation of β-Lactams. Introduction of 3-Substituents in N-Unsubstituted β-Lactams
Authors: Durst T. , Elzen R. Van Den , Legault R.
Published: May 2006

β-Lactams, unsubstituted in the 1 and 3 position react with 2 equiv. of n-butyllithium in THF at 0° within 1 h to form 1,3-dilithio salts. The dilithio salts react with various electrophiles (ketones, alkyl halides, I2) to give β-lactams substituted in the 3 position.
Primary Bond Formation in the Addition of Cyclopentenone to Chloroethylenes
Authors: Loutfy R. O. , Mayo P. de
Published: May 2006

not available
Palladium(II) Complexes with Dithiomalonamide and N,N′-Diphenyldithiomalonamide
Authors: Pellacani Gian Carlo
Published: May 2006

Dithiomalonamide (Hdtma) and N,N′-diphenyldithiomalonamide (Hdpma) form diamagnetic square-planar complexes PdL2 and PdL2•2DMF. For these complexes a [PdS4] coordination was suggested by their electronic and i.r. spectra. The splitting orbital parameters, Δ1, indicates that these anionic ligands assume an intermediate position in the spectrochemical series of sulfur donors. These ligands also form Pd(HL)2X2 (X = Cl, Br, I, ClO4) and PdHLX2 (X = Cl, Br, I) complexes in which spectroscopic evidence suggests an S,N bidentate ligand coordination, forming six-membered rings. ν(PdN) and ν(PdS) are tentatively assigned. For Pd(Hdpma)2X2 complexes from the far i.r. and electronic spectra we propose a cis-PdN2S2 configuration. The Δ1 parameters in the six-membered ring Pd(HL)2X2 complexes indicate a ligand strength greater than in the analogous S,N coordinated five-membered ring complexes of dithiooxamides and show an inversion of the order found in Ni(HL)2X2 (HL = Hdtma, Hdpma) complexes. In PdHLX2 complexes the presence of two bands assignable to Vasym(PdX) and Vsym(PdX) supports a cis-halogen configuration.
The Dipole Polarizability of the Hydrogen Molecular Ion: A Variational Two-Center Calculation
Authors: McEachran R. P. , Smith Sharon , Cohen M.
Published: May 2006

The electric dipole polarizability tensor of the hydrogen molecule-ion has been calculated variationally over a wide range of internuclear separations, using the accurate two center James (ref. 3) orbital as the unperturbed wavefunction. Our most accurate values, obtained with first order functions containing between three and five variational parameters, are in good agreement with some recent moment function values calculated by Bates (ref. 7).
Photolysis of Thietane–Cyclopentadiene Mixtures. Reactions of Monomeric Thioformaldehyde
Authors: Dice David R. , Steer Ronald P.
Published: May 2006

The 313 nm photolysis of thietane–cyclopentadiene mixtures in the vapor phase at temperatures between 25 and 235 °C has been studied. 2-Thiabicyclo[2.2.1]hept-5-ene (TBH) results from the concerted, thermal, 1,4-Diels–Alder cycloaddition of thioformaldehyde to cyclopentadiene. Other products arise via nonconcerted processes involving biradical intermediates. Thioformaldehyde is scavenged quantitatively with high added pressures of cyclopentadiene and thus the yield of TBH may be used as a measure of the amount of monomeric CH2S produced in the system.
An Electron Spin Resonance Study of the Spin Adducts of OH and HO2 Radicals with Nitrones in the Ultraviolet Photolysis of Aqueous Hydrogen Peroxide Solutions
Authors: Harbour John R. , Chow Vivian , Bolton James R.
Published: May 2006

The photolysis of H2O2 in aqueous solution has been used to study and characterize electron spin resonance (e.s.r.) spectra of the •OH and •HO2 radical spin adducts with the spin traps 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) and phenyl-t-butyl nitrone (PBN). At high concentrations of spin trap and low concentrations of H2O2 an e.s.r. spectrum is obtained which we assign to the •OH radical adduct (for DMPO, aN = 15.3 G, aβH = 15.3 G, [Formula: see text] and g = 2.0060; for PBN, aN = 15.3 G, aβH = 2.75 G, and g = 2.0057). At low concentrations of spin trap and high concentrations of H2O2• a second spin adduct spectrum is obtained which we assign to the spin adduct of the HO2 radical (for DMPO, aN = 14.3 G, aβH = 11.7 G, aγH = 1.25 G, g = 2.0061; for PBN, aN = 14.8 G, aβH = 2.75 G, and g = 2.0057).
The Addition of Arylselenium Trichlorides vs. Areneselenenyl Chlorides to cis- and trans-1-Phenylpropene
Authors: Garratt Dennis G. , Schmid George H.
Published: May 2006

2,4-Dinitrophenylselenium trichloride has been found to add to cis- and trans-1-phenylpropene in an anti stereospecific manner to yield threo-dl-and erythro-dl-β-chloroalkyl 2,4-dinitrophenyl selenide dichlorides, respectively. Comparison is made with the adducts from the addition of 2,4-dinitrobenzeneselenenyl chlorides. β-Chloroalkyl 2,4-dinitrophenyl selenides react with chlorine or sulfuryl chloride to yield β-chloroalkyl 2,4-dinitrophenyl selenide dichlorides. β-Chloroalkyl selenide dichlorides were observed to decompose into 1,2-dichloro adducts and areneselenenyl chloride. 2,4-Dinitrobenzeneselenenyl acetate was shown to add to alkenes in an anti stereospecific manner.
Cleavage of the Methylenedioxy Ring in the Grignard Reaction of 3,4-Methylenedioxybenzonitrile
Authors: Forrest Janet E. , Heacock Ronald A. , Forrest Thomas P.
Published: May 2006

The reaction of 3,4-methylenedioxybenzonitrile (2) with ethyl magnesium bromide gives products resulting from opening of the methylenedioxy ring, namely 4-hydroxy-3-n-propoxypropiophenone (3) and 3-hydroxy-4-n-propoxypropiophenone (4) in addition to the expected product 3,4-methylenedioxypropiophenone (1). The isomeric hydroxy-n-propoxy ketones were differentiated on the basis of their spectroscopic properties.
Synthesis of 3β,14β,19-Oxygenated Cardenolides
Authors: Kruger G.
Published: May 2006

The synthesis of 3β,14β,19-oxygenated and of 3β,19-oxygenated-14-dehydro cardenolides from the bulk steroid pregnenolone acetate 1a is reported. The 19-oxygenated cardenolides which have been prepared include coroglaucigenin esters 4e and 4f and corotoxigenin acetate 4g. Coroglaucigenin and corotoxigenin occur in nature as glycosides in a number of plant species. In the synthetic scheme developed, successive transformations of the 3β-acetoxy-10β-methyl-5-ene moiety of 1a afford 19-hydroxy- or acyloxy-14-enes via 19-hydroxy-8(14)-enes and 8,19-oxido-14-enes.
Ring C Functionalized Diterpenoids. Part IV. Minor Products from the Cleavage of the Cyclopropane Ring in Methyl ent-Trachyloban-19-oate with Thallic Acetate
Authors: Campbell Helen Margaret , Gunn Patrick Alistair , McAlees Alan James , McCrindle Robert
Published: May 2006

Structures are assigned to seven minor products (6b, 9, 11b, 12b, 13b, 16, and 25b) obtained from treatment of methyl ent-trachyloban-19-oate (1) with thallic oxide in acetic acid. The mechanism of the oxidative cleavage is discussed. Formation of the major products, described earlier, and all but one (25b) of the minor products may be rationalized in terms of initial scission of the C13—C16 bond.
Biosynthesis of Lycopodine. The Question of the Intermediacy of Piperidine-2-acetic Acid
Authors: Marshall W. D. , Nguyen T. T. , MacLean D. B. , Spenser Ian D.
Published: May 2006

In Lycopodiumtristachyum lycopodine is derived from L-lysine whereas pipecolic acid is derived from D-lysine. Malonic acid serves as a specific precurser of the non-lysine derived segments of lycopodine. Piperidine-2-acetic acid is not incorporated into the alkaloid.
Pyrophosphates of Tetravalent Elements and a Mössbauer Study of SnP2O7
Authors: Huang Chung-Hsi , Knop Osvald , Othen David A. , Woodhams Frank W. D. , Howie R. Allan
Published: May 2006

Cubic M4+P2O7 pyrophosphates of Ti, Zr, Hf, Sn, and Pb have been examined by X-ray powder diffractometry and by infrared, Raman, and Mössbauer 119Sn spectroscopy. The tin compound appeared to be of Chaunac's type I (with P2O7 groups oriented at random) and could be converted to type II (with ordered P2O7 groups) by heating to high temperatures. All the other preparations were of Chaunac's type II. Evidence from lattice parameters and intensity features of the Raman spectra suggests that the cubic MP2O7 pyrophosphates fall in two groups, one containing the compounds of the typical elements (Ge, Sn, Pb) and the other, the compounds of the transition elements. No support has been found for the view that the P—O—P groupings of the pyrophosphate anion in these compounds are linear. The 119Sn chemical shift in SnP2O7 is only slightly less negative than the shift in CuSnF6.4H2O, which makes SnP2O7 one of the most ionic compounds of tetravalent tin known. The observed quadrupole splitting in the Mössbauer spectrum of SnP2O7 arises largely from the contribution of the valence term to the electric field gradient at the Sn atom.
A 2-Azapentadienyl Carbanion: a Nonstereospecific Electrocyclization
Authors: Hunter D. H. , Steiner R. P.
Published: May 2006

Treatment of 1,3,5-triphenyl-4-aza-1,3-pentadiene under selected basic conditions leads to either isomerization among the azapentadienes or to cyclization. Analysis of the products from reaction under aprotic conditions (LiTMP in THF) suggested that the open-chain delocalized carbanion exists in both the W and sickle forms. The open-chain anions were observed to electrocyclize in a nonstereospecific manner to produce a 1:1 mixture of cis- and trans-2,4,5-triphenyl-1-pyrrolines. Reaction in protic media (methanol and tert-butyl alcohol) produced a 1,5-proton transfer as well as cyclization. The details of the 1,5-proton transfer reaction were elucidated using methanol-O-d and the collapse preferences and intramolecularity in this medium were determined.
Determination of 3 × 3 Harmonic Force Field of Planar X2YZ Molecules
Authors: Brand J. C. D. , Rao Ch. V. S. Ramachandra
Published: May 2006

The problem of multiple solutions encountered during the determination of a 3 × 3 General Harmonic Force Field is analyzed. The A1 force fields of the planar molecules COCl2, NO2F, and H2CO, are considered and formaldehyde is treated in some detail as illustration.
Thermodynamic Properties of Aqueous Organic Solutes in Relation to their Structure. Part II. Apparent Molal Volumes and Heat Capacities of c-Alkylamine Hydrobromides in Water
Authors: Jolicoeur Carmel , Boileau Jeanine , Bazinet Serge , Picker Patrick
Published: May 2006

The density and specific heat of aqueous solutions of various c-alkylamine hydrobromides, and of n-dodecylammonium bromide, have been measured at 25 °C. The limiting apparent molal volumes [Formula: see text] and heat capacities [Formula: see text] derived from these data, are compared to the corresponding quantities for n-alkylammonium and immonium salts. The methylene group contribution to[Formula: see text] and [Formula: see text] of the cyclic compounds is generally lower than that of the linear homologs; this group contribution is also found to depend markedly on ring size, in contrast to monotonous variations found in the series of the linear compounds. The difference is suggested to originate in solvation effects in which geometrical factors (solvent structure and solute geometry) play a significant role.
Crystal and Molecular Structure of a Novel Polycyclic Ga, O, N Cage Compound: (GaH)6(GaH2)2(μ3-O)2(μ3-NCH2CH2NMe2)4(μ-NHCH2CH2NMe2)2
Authors: Rettig Steven J. , Storr Alan , Trotter James
Published: May 2006

Crystals of 11H,22H-10,10,21,21-tetramethyl-3,5,14,16-tetra(N,N-dimethyl-2-aminoethyl)-1,12-dioxonia-3,5,7,10,14,16,18,21 -octaazonia-2,4,6,11,13,15,17,22-octagallanata-nonacyclo-[13.7.0.02,7.03,22.04,12.07,11.011,14.013,18.018,22]docosane are triclinic, a = 13.358(1), b = 9.300(1), c = 9.545(1) Å, α = 92.16(2), β = 107.49(1), γ = 89.23(2)°, Z = 1, space group [Formula: see text]. The structure was solved by Patterson and Fourier syntheses and was refined by full-matrix least-squares procedures to a final R of 0.038 for 3393 reflections with I ≥ 4σ(I). The bond lengths involving nonhydrogen atoms have been corrected for thermal motion. The molecular structure features a novel Ga, O, N cage structure which includes the first crystallographic examples of four-membered Ga2NO and six-membered Ga3N2O rings. Three of the four crystallographically independent gallium atoms are tetrahedrally four-coordinate with bond lengths: Ga—O, 1.869 and 1.879(2), Ga—N, 1.945–2.001 (3), and Ga—H, 1.40–1.52(4–5) Å. The remaining gallium atom is five-coordinate with distorted trigonal bipyramidal geometry (Ga—O(ax), 1.960(3), Ga—N(ax), 2.779(3), Ga—N(eq), 1.949 and 1.999(3), and Ga—H(eq), 1.49(5)Å). Other bond lengths in the molecule are: N—C, 1.449–1.493(4–10), C—C, 1.486–1.528(6–7), N—H, 0.85(5), and mean C—H, 1.03 Å. The errors quoted above are those arising from the least-squares analysis and do not reflect uncertainties introduced by the thermal analysis.
Photocyclization Reactions of Aryl Polyenes. IX. The Photocyclization of Stilbenecarboxaldehydes and 1-Formylphenyl-4-phenyl-1,3-butadienes
Authors: Manning Carl , Leznoff Clifford C.
Published: May 2006

The photocyclization–oxidation reaction of 4-stilbenecarboxaldehyde gave 3-phenanthrenecarboxaldehyde. Similarly, irradiation of 3-stilbenecarboxaldehyde gave a mixture of 2-and 4-phenanthrenecarboxaldehyde. Irradiation of 1-(p-formylphenyl)-4-phenyl-1,3-butadiene gave a mixture of 1-(p-formylphenyl)naphthalene and 8-phenyl-2-naphthaldehyde. Photocyclization of 1-(m-formylphenyl)-4-phenyl-1,3-butadiene yielded 1-(m-formylphenyl)naphthalene, 5-phenyl-2-naphthaldehyde, and 8-phenyl-1-naphthaldehyde. The surprising nature of the photocyclization–oxidation reactions of stilbenes and 1,4-diphenyl-1,3-butadienes containing formyl substituents is discussed.
The Mechanism of The Microbial Hydroxylation of Steroids. Part 1. The C-21 Hydroxylation of Progesterone by Aspergillusniger ATCC 9142
Authors: Holland Herbert L. , Auret Barbara J.
Published: May 2006

The mechanism of the C-21 hydroxylation of progesterone (1a) by Aspergillusniger ATCC 9142 to give 11-deoxycorticosterone (1b) has been studied by the use of progesterone derivatives and of C-21 deuterium labelled progesterones. The requirement of the C-21 hydroxylase system for a C-20 carbonyl group is demonstrated and the possibility of the involvement of this group, in the C-20,21 enol form, in the C-21 hydroxylation reaction has been discussed. However, on the basis of the observed deuterium isotope effect (KH/KD = 1.25), a mechanism for the microbial C-21 hydroxylation reaction is proposed in which the rate-determining step is the direct insertion of oxygen into a C-21 carbon–hydrogen bond and not one involving enolization of the C-20 carbonyl.In addition, C-11α and C-15β hydroxylation of both 20α- and 20β-hydroxypregn-4-ene-3-one (2a and 2b) by A. niger has been observed.
Azole Chemistry, IX. A New Synthesis of Fused Pyrimidines: Tetrahydropyrimido[1,2-a]benzimidazoles
Authors: Alper Howard , Pepper Lawrence
Published: May 2006

2-Aminobenzimidazole and 2-amino-5,6-dimethylbenzimidazole react with various epoxy bromides in hot 2-butanone to give, after basification, 3-hydroxy-1,2,3,4-tetrahydropyrimido[1,2a]benzimidazoles. The spectral properties of these heterocycles are discussed.
Reactions of Alkyl Azidoformates with Norbornylene
Authors: Edwards Oliver E. , Elder John W. , Lesage Maurice , Retallack Robert W.
Published: May 2006

Evidence is presented that the reactions of alkyl azidoformates with norbornylene induced by direct irradiation do not involve intermediate triazolines. The products of this, and acetophenone-photosenzitized reaction of the mixtures in cyclohexane, are described and contrasted with those from the direct photolysis of the corresponding N-alkoxycarbonyl triazolines. The action of aqueous dioxane at 170° converted 2,3-iminonorbornane (3-azatricylo[3.2.1.02,4]octane) into 3-aminonortricyclene and syn-7-amino-2-exo-hydroxynorbornane. Three preparations of derivatives of 2-exo-aminonorbornan-3-one are described. The trimethylsilyl ether of the enol of norbornan-2-one (2-trimethylsilyloxynorborn-2-ene) was prepared.
Structure électronique de dérivés sulfures. XI. Thiétanne et dérivés
Authors: Guimon Claude , Liotard Daniel , Pfister-Guillouzo Geneviève
Published: May 2006

The conformations of thietane, thietane sulfoxide, and their 3-chloro derivatives were obtained theoretically by minimization of the energy with respect to geometric parameters using the semi-empirical CNDO/2 method extended to the third period. The results agree well with known experimental data. The respective stabilities of the different conformers are explained by partial energy results obtained by a bicentric partition of the total potential energy of the molecules. [Journal translation]
The Vibrational Spectra and Structure of Dimethyl Carbonate and its Conformational Behavior
Authors: Katon J. E. , Cohen M. D.
Published: May 2006

The infrared spectra of dimethyl carbonate in the liquid and solid phases and the Raman spectrum of the liquid phase are reported. The evidence suggests that dimethyl carbonate exists as an equilibrium mixture of at least two conformers in the liquid state. An experimental value for the enthalpy difference of the two conformers of 2.6 ± 0.5 kcal/mol is obtained from the temperature dependency of the infrared spectrum.Dimethyl carbonate crystallizes as an oriented polycrystalline film and polarized infrared spectra of the solid have been obtained. These have been utilized, along with the liquid phase data to obtain an improved vibrational assignment. There appears to be a solid–solid phase change in dimethyl carbonate in the vicinity of 140 K, but the details of this change are not known.
Reactions of OH, CH2OH, Br2−, and (CNS)2− Free Radicals with Cysteine at pH 5.3
Authors: Goyal Greesh Chand , Armstrong David Anthony
Published: May 2006

The products of radiolysis of cysteine in nitrous oxide saturated solutions at pH 5.3 have been investigated both in the absence of other solutes and in the presence of 1 M methanol, 0.5 M KBr, and 0.2 M NaCNS. The results can be explained by a mechanism in which the free radicals •OH, •CH2OH, •Br2−, and •(CNS)2− all react with the cysteine (CysSH) sulfhydryl group to form CysS• as a major intermediate product. Minor yields (0.2 molecules per 100 eV) of ammonia observed in the case of attack by •Br2− may result from attack on the NH3+ group or α-hydrogen by this species. Cysteine trisulfide was observed in all systems with a yield 0.12 ± 0.03 molecules per 100 eV and is probably formed from minor secondary reactions of CysS• radicals. In agreement with previous conclusions based on the analysis of products from deaerated solutions the majority of CysS• radicals form CysSSCys.
Facile Synthesis of Thiols and Sulfides
Authors: Brindle Jean-Rock , Liard Jean-Louis
Published: May 2006

Sulfurated sodium borohydride reacts with benzylic halides to give high yields of α-toluenethiol or benzylic polysulfldes depending upon the experimental conditions and the mode of hydrolysis.Aliphatic halides and dibenzylic halides react in the same manner as benzylic halides for a given experimental condition whereas benzylic halides substituted with other groups can be totally or partially reduced depending on the stability of the substituent towards NaBH2S3.Halogens directly attached on the aromatic ring do not react with NaBH2S3.
Photoionization Cross Sections at 11.6–11.8 eV
Authors: Beran Jo Allan , Dhingra Anil Kumar , Liu Wu-Schyong , Mullica Donald Foster
Published: May 2006

The relative photoionization cross sections of a homologous series of alkanes, alkenes, alkyl chlorides, aldehydes, ethers, ketones, and alcohols have been determined at 11.6–11.8 eV using an argon resonance lamp. Correlations have been made between the photoionization cross sections and the molecular polarizability, the diamagnetic susceptibility, and the electron ionization cross sections of the molecules. No general correlation was found to exist but linear correlations were observed within each molecular class of compounds. These results are in general agreement with earlier studies on the electron ionization cross sections at 70 eV.
Alkylation of 1-Methyl-2-piperidones
Authors: Deslongchamps Pierre , Cheriyan Ukken O. , Patterson Dennis R.
Published: May 2006

The alkylation of 1-methyl- and 1,3-dimethyl-2-piperidone is reported in good yield.
Properties of Concentrated Solutions of Indium Chloride
Authors: Campbell Alan N.
Published: May 2006

Certain properties of concentrated solutions of indium trichloride, ranging in strength from 9.889 to 0.4070 m, have been investigated. These properties are: density, molar volume, specific and equivalent conductance, degree of ionization, ionization constant, relative viscosity, activities, and activity coefficients of solvent water and of solute. Two interesting results emerge, viz., the specific conductance passes through a maximum at 3.5 m, and, if the ionization of indium chloride is treated as that of a binary electrolyte, the expression α2c/(1 − α) is constant within 10% over the range 6.267 to 0.7363 m (13.90 to 2.122 N).
Horseradish Peroxidase. XVIII. The Arrhenius Activation Energy for the Formation of Compound I
Authors: Hewson W. D. , Dunford H. B.
Published: May 2006

The rate of formation of compound I from the reaction of native horseradish peroxidase with hydrogen peroxide was studied from 3.7–70.0 °C. The second-order rate constants were used to construct an Arrhenius plot from which the activation energy of this reaction was calculated to be 3.5 ± 1.0 kcal/mol. The irreversibility of the reaction at 25 °C was confirmed by comparing absolute absorbance changes as recorded by the stopped-flow apparatus with the known spectra of the native enzyme and compound I.
The Stereochemistry of the Reformatsky Reaction of Methyl 4-Bromo-3-methylbut-2-enoate with β-Cyclocitral and Related Compounds
Authors: Gedye R. N. , Arora Parkash , Khalil A. H.
Published: May 2006

Both methyl Z- and E-4-bromo-3-methylbut-2-enoate react with β-cyclocitral in the presence of zinc to give the δ-lactone of 5-hydroxy-3-methyl-5-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2-pentenoic acid as the main product, indicating an E to Z inversion during the Reformatsky reaction. Similar results were obtained in the Reformatsky reactions of the Z- and E-bromo-esters with benzaldehyde and cyclohexenecarboxaldehyde. Here hydrolysis of the Reformatsky product gave, in each case, the corresponding Z-2,E-4-acids as the main products, indicating the formation of the δ-lactone as an intermediate. The synthesis of Z- and E-β-ionylideneacetic acid and the corresponding ring demethyl analogs using a Wittig reaction is also described.
The Use of Magnesium and its Salts in the Reaction of α,β-Unsaturated Carbonyl Compounds with Sodium Acetylide
Authors: Gardner John Nicholson
Published: May 2006

Conditions are described for the preparation in anhydrous ammonia of a magnesium–acetylene complex. In the presence of this complex, the addition of sodium acetylide to the carbonyl groups of some α,β-unsaturated aldehydes and ketones is shown to be a much more efficient reaction than when sodium acetylide alone is employed.
Base-catalyzed Degradations of Carbohydrates. IX. β-Eliminations of 4-O-Substituted Hexopyranosiduronates
Authors: Aspinall Gerald O. , Krishnamurthy Thinnayam N. , Mitura Walter , Funabashi Masuo
Published: May 2006

Two methylated disaccharides, methyl [methyl 4-O-(2,3,4,6-tetra-O-methyl-α-D-glucopyranosyl)-2,3-di-O-methyl-β-D-glucopyranosid]uronate (9) and methyl 6-O-(methyl 2,3,4-tri-O-methyl-α-D-galactopyranosyluronate)-2,3,4-tri-O-methyl-β-D-glucopyranoside (15) have been synthesized and used as model compounds for the study of the base-catalyzed β-elimination of 4-O-substituted hexopyranosiduronates without degradation of exposed reducing sugars and of the selective acid hydrolysis of hex-4-enopyranosiduronates.
Crystal Structure of Adeninium Trichloromercurate(II),
Authors: Authier-Martin Monique , Beauchamp André L.
Published: May 2006

The title compound belongs to space group P21/c with a = 23.99(1), b = 4.245(2), c = 25.98(1) Å, β = 117.58(7)°, and Z = 8. The structure was solved by the heavy-atom method and refined by block-diagonal least squares on 2589 independent observed reflections. All non-hydrogen atoms were refined anisotropically and some of the hydrogen atoms were located but their parameters were not refined. The final values of R and Rw were 0.042 and 0.047, respectively.The two nonequivalent mercury atoms have very similar environments. Two short Hg—Cl bonds (2.34–2.38 Å) at ∼ 165° define a quasi-molecular HgCl2 unit. Overall octahedral coordination is completed with two chloride ions at 2.76–2.84 Å and two chlorine atoms at 3.19–3.26 Å on neighboring HgCl2 quasi-molecules. HgCl6 octahedra share edges to form twofold ribbons in the b direction. This pattern of octahedra is identical with the onereported for β-NH4HgCl3. The cations are pairs of N(1)-protonated adenine molecules linked by two N(10)—H(10)… N(7) hydrogen bonds and stacked in the b direction. Water molecules act as acceptors in moderately strong hydrogen bonds with acidic protons H(1) and H(9) of adeninium ions. Other generally weaker hydrogen bonds exist between the various parts of the structure.
Application of Carbon-13 Nuclear Magnetic Resonance to Conformational Analysis of Trimethylene Sulfites
Authors: Buchanan Gerald W. , Stothers J. B. , Wood Gordon
Published: May 2006

not available
The Crystal Structure of cis-Dichlorobis(dimethylsulfoxide)platinum(II)
Authors: Melanson Robert , Rochon Fernande D.
Published: May 2006

The molecular and crystal structure of cis-dichlorobis (dimethylsulfoxide) platinum(II), cis-[PtCl2(DMSO)2], has been studied by X-ray diffraction. The compound belongs to the mono-clinic P21/c space group and the cell parameters are: a = 8.653, b = 13.580, c = 10.914 Å, β = 123.43°, and Z = 4. The refinement of the positional and anisotropic thermal parameters, carried out by full matrix least-squares calculations, converged to R = 0.029 and Rw = 0.027.The coordination around the platinum atom is planar. As expected, the DMSO molecules are bonded to the platinum atom through sulfur. The bond distances found are: Pt—Cl = 2.306, 2.312 Å; Pt—S = 2.244, 2.229 Å; S—O = 1.469, 1.454 Å, and S—C = 1.77 to 1.79 Å. The crystal consists of layers of molecules parallel to the ac plane.
Cinétique de la formation de la métalloporphyrine Cu(II) – hématoporphyrine IX dans l'acide acétique aqueux
Authors: Paquette Guy , Zador Miklos
Published: May 2006

The kinetics of interaction of hematoporphyrin IX with Cu(II) has been studied in an acetic acid – water solvent (50%–50% v/v). The reaction is of first order with respect to the porphyrin whereas the order with respect to copper(II) perchlorate is smaller than one. This is explained by taking into account the interaction between Cu2+ and acetic acid. The reactive species are Cu2+, CuOAc+, and free porphyrin. The mechanism of the reaction is compared to those proposed for similar systems.
Studies of β-Diketone Complexes of Rhenium. VIII. The Reaction of β-Diketones with Chloropentacarbonylrhenium(I), and the Preparation of Complexes of the Type Re(CO)4(dik), Re2(CO)6(dik)2, Re2(CO)6Cl2(dikH)2, Re(CO)3L(dik), and Re(CO)2(dik)L2
Authors: Fredette Maurice Conrad , Lock Colin James Lyne
Published: May 2006

The reaction of β-diketones with Re(CO)5Cl gave compounds of stoichiometries Re2(CO)6dik2 or Re2Cl2(CO)6(dikH)2. Reaction of the former compounds with carbon monoxide at high pressure gave Re(CO)4.dik, while with donor ligands such as pyridine or triphenylphosphine they gave compounds of stoichiometry Re(CO)3dikL. With triphenylphosphine further reaction gave Re(CO)2dik[P(C6H5)3]2. Compounds were investigated by infrared spectroscopy and mass spectroscopy, and a Cotton–Kraihânzel analysis was made of the carbonyl vibrational spectra in order to get an estimate of the π-acceptor ability of the β-ketoenolate ligands.
Study of Chemically Induced Dynamic Nuclear Polarization of Aliphatic Aldehydes in D2O and other Solvents
Authors: Chen Holger E. , Cocivera Michael , Vaish Shiv P.
Published: May 2006

The chemically induced dynamic nuclear polarization arising from irradiation of aliphatic aldehydes in D2O and various other solvents is reported. The aldehydes included acetaldehyde, propionaldehyde, isobutyraldehyde, and pivalaldehyde, and the solvents were benzene, acetonitrile, cyclohexane, methylcyclohexane, perfluoromethylcyclohexane, D2O, and D2O/acetonitrile. For propionaldehyde, the variation of c.i.d.n.p. with solvent can be explained by a variation of the relative importance of α-cleavage vs. hydrogen abstraction which occur via an excited triplet state. In addition, when D2O is the solvent, the c.i.d.n.p. provides information about secondary radical reactions not observed in the other solvents. For the other aldehydes, the nature of the solvent does not seem to affect the relative importance of α-cleavage vs. hydrogen abstraction. Acetaldehyde undergoes hydrogen abstraction whereas isobutyraldehyde and pivalaldehyde undgero α-cleavage via an excited triplet state.
Mechanisms of Thioacylal Hydrolysis in Sulfuric Acid Solutions
Authors: McClelland Robert Allan
Published: May 2006

The acid-catalyzed hydrolysis (aqueous H2SO4) of thioacylalsCH3SCH2OAc and ArSCH2OAc is reported. The former is shown to react solely by an A-1 mechanism proceeding via an intermediate CH3SCH2+ cation. In the latter series hydrolysis in dilute acids involves both this A-1 mechanism and a normal AAc-2 ester hydrolysis mechanism occurring simultaneously; as the acidity is increased the proportion of A-1 reaction increases until it completely dominates. The A-1 reaction shows lesser importance with electron-withdrawing substituents. The 4-nitro compound in fact shows no A-1 mechanism until about 40% H2SO4. These hydrolyses are compared with those of the corresponding acylals, which show a similar mechanistic behavior. Relative A-1 reactivities for RXCH2OAc, RX = CH3O, CH3S, C6H5S, C6H5O are 81, 49, 1, 0.022, relative to C6H5SCH2OAc. Discussions pertaining to the effects of the oxygen and the sulfur in these systems are presented.
The Hydrolysis of Imidate Salts. Stereoelectronic Control in the Cleavage of the Hemiorthoamide Tetrahedral Intermediate
Authors: Deslongchamps Pierre , Dubé Serge , Lebreux Claude , Patterson Dennis R. , Taillefer Roland J.
Published: May 2006

A new stereoelectronic theory for the cleavage of the tetrahedral intermediate (hemiorthoamide) in the hydrolysis of amides is presented. In this new theory, the precise conformation of the tetrahedral intermediate controls the nature of the hydrolysis products. It is postulated that the breakdown of the tetrahedral intermediate depends upon the orientation of the lone pair orbitals of the heteroatoms. Specific cleavage of a carbon–oxygen or a carbon–nitrogen bond in any conformer is allowed only if the other heteroatoms (oxygen and nitrogen) each have an orbital oriented antiperiplanar to the leaving O-alkyl or N-alkyl group. Experimentally, a study of the basic hydrolysis of a variety of N,N-dialkylated imidate salts having either a syn or an anti conformation demonstrates clearly that there is a stereoelectronic control in the cleavage of the hemiorthoamide.
Synthesis of Methyl 12S- and 12R-Hydroxylabd-8(17)-en-19-oates
Authors: Bell Russell A. , Gravestock Michael B. , Taguchi Vincent Y.
Published: May 2006

A formal total synthesis using podocarpic acid as the relay of methyl 12S- and 12R-hydroxylabd-8(17)-en-19-oates, 7 and 8 respectively, has been achieved. Carbons 13 → 16 of the labdane side chain were formed by the nucleophilic addition of s-butyllithium to the bicyclic acid 5a or the aldehyde 4, and the configuration of the alcohols assigned from a consideration of product distributions and physical and spectroscopic properties. The spectroscopic properties of the synthetic alcohols were in agreement with those reported for two alcohols isolated from JuniperusphoeniceaL. and assigned structures 7 and 8.
Studies of Ternary Nematic Phases by Nuclear Magnetic Resonance. Alkali Metal Decyl Sulfates/Decanol/D2O
Authors: Radley Keith , Reeves Leonard Wallace
Published: May 2006

The nematic regions of the ternary phase diagram for alkali metal decyl sulfates/decanol/D2O have been investigated. The lithium detergent system has a very restricted region of type I nematic phase which orients parallel to the magnetic field with a long time constant. The sodium detergent also forms a rather restricted nematic region which may be type II, oriented perpendicular to the magnetic field or type I oriented parallel to the magnetic field, depending on the decanol content. The rubidium and potassium detergents were insufficiently soluble to form phases while the cesium detergent forms a very extensive type II nematic phase region with wide variations in water contents and with decanol between 2 and 7 wt.%. It is clear that the cesium decyl sulfate system has considerable advantage over the sodium detergent in forming nematic phases for use as orienting media for small molecules and ions in n.m.r. studies.The partially averaged nuclear quadrupole coupling constants of Li-7, Na-23, and Cs-133 in ions and D-2 in the D2O have been used as the primary tool in investigating the phase behavior. Quadrupole couplings have been reduced to unit quadrupole moment for the nucleus. The resultant quantity "Es" in Hz b−1 reflects the strongly increasing electric field gradient induced in the monatomic ions by the nematic medium in going from Li+ to Cs+. The partially averaged quadrupole splittings which appear for the alkali metal ions in these uniaxial media are the result of distortion of the spherical symmetry of the ion and should not be interpreted in terms of degrees of orientation of the ion.
Reaction of Xenon Difluoride. Part II. Oxidative-fluorination of Phosphorus and Iodine Compounds and Cleavage of Silicon–Sulfur and Silicon–Nitrogen Bonds
Authors: Gibson James Andrew , Marat Ronald Kirk , Janzen Alexander F.
Published: May 2006

Reaction of alkyl(aryl)phosphines with xenon difluoride gives alkyl(aryl)hydridofluorophosphoranes which were characterized by proton and fluorine n.m.r. spectroscopy. With phenylchlorophosphines, substitution of chlorine by fluorine accompanied oxidative-fluorination to give phenylfluorophosphoranes, (C6H5)nPF5−n. With tert-butylchlorophosphines, chlorination of the tert-butyl group accompanied oxidative-fluorination, and a mixture of products was obtained. Reaction of xenon difluoride with methyl iodide gives methyliodine(III) difluoride, characterized by proton and fluorine n.m.r. spectroscopy.Silicon–sulfur and silicon-nitrogen bonds are cleaved by xenon difluoride and an intermediate containing a xenon–nitrogen bond is postulated.Reaction of xenon difluoride with hexafluoroacetone, perfluoropinacol, or disodium perfluoropinacolate failed to give stable xenon esters.
The Selective Lithiation and InSitu Trimethylsilylation of Benzyldiphenylchlorosilane and its Methoxy Analog. Compounds Which Could Conceivably Lead to Stable Si=C Species on Pyrolysis
Authors: Rutherford K. G. , Seidewand R. J.
Published: May 2006

The selective lithiation and insitu trimethylsilylation of benzyldiphenylchlorosilane and its methoxy analog to give (α-trimethylsilylbenzyl)diphenylchlorosilane and (α-trimethylsilyl-benzyl)diphenylmethoxysilane in excellent yields is reported. These compounds exhibit much greater stability on pyrolysis than β-halocarbosilanes. A stable Si=C species was not obtained on pyrolysis of the compounds synthesized.
The Water-activity of Supersaturated Aqueous Solutions of NaCl, KCl, and K2SO4 at 25°C
Authors: Lenzi Fabio , Tran Tuong-Tu , Teng Tjoon-Tow
Published: May 2006

Reverse application of the Reilly–Wood-Robinson and Zdanovskii–Stokes–Robinson equations to the water-activity data of various ternary aqueous systems containing NaCl, KCl, K2SO4 as one of the components yields self-consistent estimates of the water-activity of binary aqueous supersaturated solutions of the individual salts; these can be further extended by curvilinear extrapolation to give: [Formula: see text] with A1 = −3.28806 × 10−2, A2 = 1.12512 × 10−4, A3 = −4.30034 × 10−4, A4 = 2.70506 × 10−5, A5 = 1.43435 × 10−6, A6 = 1.30209 ×10−7, A7 = −1.51941 × 10−8, A8 = 1.00520 × 10−9, A9 = −4.21593 × 10−10, A10 = 2.62532 × 10−11, valid to aw(NaCl) = 0.5422, [Formula: see text][Formula: see text]with B1 = −3.21884 × 10−2, B2 = 9.77773 × 10−4, B3 = −6.05349 × 10−4, B4 = 1.18422 × 10−4, B5 = −7.91572 × 10−6, B6 = −3.88125 × 10−8, B7 = 1.55125 × 10−8, valid to aw(KCl) = 0.7115, [Formula: see text][Formula: see text] with C1 = −4.16810 × 10−2, C2 = 1.16033 × 10−2, C3 = −4.80543 × 10−3, C4 = 7.15536 x 10−4, valid to [Formula: see text][Formula: see text]
Sterically Hindered Aromatic Compounds. VI. A Remote ε-Deuterium Kinetic Isotope Effect in the Solvolysis of Perdeutero-2,4,6-tri-tert-butylbenzyl Chloride
Authors: Barclay L. Ross C. , Mercer John R. , MacAulay Peter J.
Published: May 2006

2,4,6-Tri-tert-butylbenzyl chloride deuterated at the three tert-butyl groups was synthesized. Conductimetric solvolysis studies of the normal and perdeutero-2,4,6-tri-tert-butylbenzyl chloride at 30.06 °C in 80% ethanol–water provides evidence for an inverse remote ε-deuterium isotope effect, kH/kD = 0.873−0.874. Under the same conditions the α-deuterium isotope effect was kH/kαD = 1.166 per deuterium, indicative of limiting solvolytic behavior. The remote ε-deuterium isotope effect for the perdeutero compound is discussed in terms of the inductive effect of deuterium and steric effects on the transition state conformation.
Formation et stabilité de lyato-complexes de l'argent(I) en solution hydro-méthanolique
Authors: Piuze Jean , Gübeli A. Otto
Published: May 2006

The total solubility of silver oxide as a function of the nonaqueous pH* in a mixture containing 52.1 wt.% methanol in water was measured for a constant decimolar ionic strength (NaNO3) at 25 °C and at atmospheric pressure. After examination of the different equilibria involved in the hydro-methanolic medium, mathematical expressions were derived, leading to the identification of the complex species formed through solvolysis phenomena with the lyate ions, i.e. OH− and CH3O−, and to the calculation of the relevant molar stability constants. The correlation between these results and those from previous publications on the aqueous solubility of Ag2O(s) was investigated.
Vapor Pressures of Triethylamine + Chloroform and of Diethyl Ether + Chloroform at 298.15 K
Authors: Handa Yash Paul , Jones David Edward
Published: May 2006

Vapor pressures of triethylamine + chloroform and of diethyl ether + chloroform were measured at 298.15 K with a calibrated quartz spiral. The ideal associated solution model has been used to determine the equilibrium constants and standard enthalpies of formation of the complexes from the thermodynamic properties derived from the vapor pressure measurements and from earlier calorimetric measurements. These complex formation constants are compared with values obtained by calorimetric and spectroscopic methods.
Mechanism of Electron Capture and Hydrogen Formation by HBr Irradiated in Mixtures with C2F6, CO2, and Xe
Authors: Nagra Surjit S. , Armstrong David A.
Published: May 2006

The gas phase 60Co γ-radiolysis of HBr in mixtures with C2F6 and CO2 has been studied at room temperature, using doserates determined from ionization chamber measurements. A new value of [Formula: see text] is reported, but [Formula: see text] was in agreement with earlier work. Ionization yields and hydrogen yields in the mixtures followed a linear energy partitioning equation.The increase in the fraction of scavengable electrons with increasing pressure of buffer gas can be satisfactorily explained by enhanced moderation of the energies of subexcitation electrons. A study of the competition for thermal electrons between SF6 and HBr indicates that the rate of electron capture by HBr maintains a second order dependence on HBr pressure over the 50 to 600 Torr range both in the presence and absence of buffer gas. There was no evidence for the collisional stabilization of HBr−* by the buffer gases and it is pointed out that thermal electron capture may involve (HBr)2 dimers.
Rates of OH Radical Reactions. I. Reactions with H2, CH4, C2H6, and C3H8 at 295 K
Authors: Overend R. P. , Paraskevopoulos G. , Cvetanović R. J.
Published: May 2006

A fast flash photolysis kinetic spectrophotometer capable of measuring rates of up to 105 s−1 is described. The rates of hydrogen abstraction from H2, CH4, C2H6, and C3H8 by OH radicals at 295 ± 2 K, have been measured in the gas phase by hydroxyl resonance absorption spectrophotometry. The influence of secondary reactions on the measured rates and the derivation of the absolute rate constants is discussed in detail.The absolute rate constants in units of cm3 mol−1 s−1 were found to be: [Formula: see text][Formula: see text][Formula: see text] and [Formula: see text]
Synthesis and Spectral Properties of [Cr(en)2NH3X]n+ Compounds
Authors: Wong Carl F. C. , Kirk A. D.
Published: May 2006

Preparation of the compounds cis- and trans-[Cr(en)2NH3F](ClO4)2, [Cr(en)2NH3NO2]-BrClO4, cis- and trans-[Cr(en)2NH3Cl](ClO4)2, cis-[Cr(en)2NH3Br](ClO4)2, trans-[Cr(en)2-NH3H2O]Br3, trans-[Cr(en)2NH3H2O]Cl3•xH2O, and trans-[Cl(en)2CrOHCr(en)2Cl](ClO4)3 is described. The compounds have been characterized by analysis and u.v.–visible and i.r. spectral data. Spectral criteria for establishing cis and trans configuration are discussed.
Conformational Studies on Oligomethylene Glycol Derivatives III. Ethylene Glycol Diacetate
Authors: Sundararajan Pudupadi R. , Labrie Plerre , Marchessault Robert H.
Published: May 2006

Conformational energies were calculated for the molecule ethylene glycol diacetate, using semiempirical methods. Several conformations corresponding to the trans and gauche states of the C—O and C—C single bonds are preferred. The g± state of the C—O bond is shifted from ± 120° by 10 to 32°. The relative energies of the various preferred conformations are found to depend on the value of the valence angle C—O—C. Calculations with C—O—C ranging from 110 to 124° showed that a value of 115° would be preferred for this angle. The predicted values of the torsion angles and bond angles are found to be in agreement with the crystal structure data on the benzoate derivatives of ethylene glycol.