Showing papers in "Canadian Journal of Chemistry in 1971"
TL;DR: The number and relative energies of nitrate combination frequencies in the 1700-1800 cm−1 region of the infrared spectrum may be used as an aid to distinguish the various coordination modes of the... as discussed by the authors.
Abstract: The number and relative energies of nitrate combination frequencies in the 1700–1800 cm−1 region of the infrared spectrum may be used as an aid to distinguish the various coordination modes of the ...
484 citations
TL;DR: In this paper, it was shown that when cellulose is heated it undergoes two competitive reactions and the actual sequence of these is clarified, being different from that previously postulate.
Abstract: Further evidence is presented to show that when cellulose is heated it undergoes two competitive reactions. The actual sequence of these is clarified, being different from that previously postulate...
228 citations
TL;DR: In this paper, a study has been made of the infrared O-H bands for CH3OH, DOH, and H2O in solution and of their correlation with hydrogen bonding and solvent basicity.
Abstract: A study has been made of the infrared O—H bands for CH3OH, DOH, and H2O in solution and of their correlation with hydrogen bonding and solvent basicity. Infrared bands for the three fundamentals an...
144 citations
TL;DR: In this paper, the pattern of component removal for black spruce during delignification by acidified sodium chlorite at 70 °C was studied and the determination of the acid soluble component was carried out.
Abstract: The pattern of component removal has been studied for black spruce during delignification by acidified sodium chlorite at 70 °C. Special emphasis was placed on the determination of the acid soluble...
139 citations
TL;DR: The decomposition temperature of the structure II clathrate hydrate of tetrahydrofuran has been followed to pressures above 3 kbars, where the hydrate is found to decompose incongruently in the reg...
Abstract: The decomposition temperature of the structure II clathrate hydrate of tetrahydrofuran has been followed to pressures above 3 kbars, where the hydrate is found to decompose incongruently in the reg...
135 citations
TL;DR: Using an energy-resolved electron beam, ionization potentials for the following free radicals have been measured: vinyl 8.95 V, allyl 8.07 V, benzyl 7.27 V as mentioned in this paper.
Abstract: Using an energy-resolved electron beam, ionization potentials for the following free radicals have been measured: vinyl 8.95 V, allyl 8.07 V, benzyl 7.27 V. For vinyl and allyl ions new measurements of thresholds for dissociative ionization give ΔHf(C2H3+) = 266 kcal/mol and ΔHf(C3H5+) = 226 kcal/mol, leading to neutral radical heats of formation ΔHf(C2H3) = 59.6 kcal/mol and ΔHf(C3H5) = 40 kcal/mol. The data for benzyl radical and ion give ΔHf(benzyl cation) = 213 kcal/mol.
121 citations
TL;DR: In this paper, the authors measured the A−(H2O)n−1−1 + H2O n−1+ H 2O n −1−H 2O = A−H n−n− 1 + H 2 O n− 1 −1 −H 2 O−n −1+H 2 N−1
Abstract: By measuring the A−(H2O)n−1 + H2O = A−(H2O)n equilibria in the gas phase and their temperature dependence, the equilibrium constants and ΔHn, n–1 and ΔSn, n–1 for some of the hydrates of NO2−, NO3−, CN−, and OH− were determined. Available thermochemical data are used for the evaluation of the total heats of hydration of the above ions. The total heats of hydration were then compared with the ΔH1,0. Relative to the total hydration energies the ΔH1,0 of the above ions were found larger than the ΔH1,0 of the halide ions.An approximate linear correlation was found to exist between ΔH1,0 of negative ions and the heterolytic bond dissociation energy D(A−–H+). With this relationship independent estimates for the electron affinities of NO2 and NO3 could be obtained.The ΔHn, n–1 of OH− were found in essential agreement with earlier measurements from this laboratory and in disagreements with recent measurements (Friedman) which gave much higher values.
116 citations
TL;DR: Magnesium orthovanadate crystallizes in the orthorhombic space group Cmca with a = 6.053(3), b = 11.442(6), c = 8.330(3) A, and Z = 4.4 as mentioned in this paper.
Abstract: Magnesium orthovanadate crystallizes in the orthorhombic space group Cmca with a = 6.053(3), b = 11.442(6), c = 8.330(3) A, and Z = 4. The structure was refined by full matrix least square methods ...
113 citations
TL;DR: In this paper, an arabinan and the previously characterized arabinogalactan and acidic polysaccharide complex have been isolated by extraction of defatted and deproteinized soybean cotyledon meal with water.
Abstract: An arabinan and the previously characterized arabinogalactan and acidic polysaccharide complex have been isolated by extraction of defatted and deproteinized soybean cotyledon meal with water. Methylation analysis involving gas chromatography – mass spectrometry of methylated alditol acetates formed from the methylated arabinan has shown that the parent polysaccharide is highly branched and of the same structural type as other arabinans associated with pectins. Methylated derivatives of mustard seed and lemon-peel arabinans and of soybean arabinogalactan have been similarly analyzed.
92 citations
TL;DR: In this article, a modified Lennard-Jones potential energy calculation shows that the preferred positions of Cl2 lie off-center and close to the equatorial plane of the tetrakaidecahedral cage with the Cl atoms near the axial planes of symmetry.
Abstract: The reorientation of molecules encaged in hydrates of structures I and II is controlled mainly by the cage geometry and the electrostatic fields of the water molecules. Departure from spherical symmetry of the short-range interactions between the guest molecule and the water molecules which form the cages leads to preferred orientations which become increasingly occupied at low temperatures. A modified Lennard-Jones potential energy calculation shows the preferred positions of Cl2 to lie off-center and close to the equatorial plane of the tetrakaidecahedral cage with the Cl atoms near the axial planes of symmetry. In an attempt to account for the remarkable reorientational freedom of polar guest molecules, the electrostatic fields of the water molecules are treated in detail. It is shown that the geometry of the cages causes the sum of the fields of the cage water dipoles to almost vanish at points near the cage center, but that this is not true of the resultant quadrupolar fields. It is suggested that th...
89 citations
TL;DR: Fulvic acid, a water-soluble soil humic fraction, was extracted from a Podzol soil and exhaustively methylated so as to make it soluble in benzene.
Abstract: Fulvic acid, a water-soluble soil humic fraction, was extracted from a Podzol soil and exhaustively methylated so as to make it soluble in benzene. The resulting material was separated repeatedly b...
TL;DR: In this article, the low temperature form of α-Zn3(VO4)2 has been crystallized in the orthorhombic space group Cmca.
Abstract: α-Zn3(VO4)2, the low temperature form of this compound, crystallizes in the orthorhombic space group Cmca with a = 6.088(3), b = 11.489(3), and c = 8.280(3) A and Z = 4. A total of 726 unique refle...
TL;DR: Ozone reacts very smoothly with acetals to give the corresponding esters, such as Tetrahydropyranyl ethers, β-glycopyranosides, ethylidene, or benzylide derivatives as discussed by the authors.
Abstract: Ozone reacts very smoothly with acetals to give the corresponding esters. Tetrahydropyranyl ethers, β-glycopyranosides, ethylidene, or benzylidene derivatives are also oxidized whereas the α-glycopyranosides are inert.
TL;DR: In this paper, the solubility of hydrogen sulfide in water is compared to deuterium sulfide and hydrogen sulfides in deuteria oxide with a 0.1 % accuracy between 0 and 50 °C.
Abstract: A new apparatus is described in which the solubility of deuterium sulfide in deuterium oxide and of hydrogen sulfide in water have been determined with 0.1 % accuracy between 0 and 50 °C. Solubility equations are derived and the solubility standard thermodynamic function changes, together with their standard errors, are tabluated. Equal solubilities would occur at −1 °C. The solubility of hydrogen sulfide in water is greater than for deuterium sulfide in deuterium oxide, the solubility difference increases to a maximum at 40 °C and thence decreases at higher temperatures.
TL;DR: The synthesis and characterization of the new phosphino acetylenes (C6H5)2PC≡CCF3, CCH3, and CC(CH3)3 were discussed in this article.
Abstract: The synthesis and characterization of the new phosphino acetylenes (C6H5)2PC≡CCF3, (C6H5)2PC≡CC(CH3)3, (C6H5)2PC≡CP(C6F5)2, (C6F5)2PC≡CCH3, (C6F5)2PC≡CC6H5, (C6H5)2PC≡CP[N-(C2H5)2]2, the mixed arsi...
TL;DR: The n.m.r. spectral data for a number of tetrahydro-1,3-oxazines and derived salts are tabulated and discussed in this paper.
Abstract: By measurement of CH–NH coupling constants at low temperatures, the N–H axial conformation was shown to be the dominant, or sole, conformation for tetrahydro-1,3-oxazine, tetrahydro-2-methyl-1,3-oxazine, and 1-methyl-1,3-diazane. These results provide further experimental evidence for the generalized anomeric effect. Nuclear Overhauser experiments established the partial axial character of the N-methyl substituent in tetrahydro-3,4,4,6-tetramethyl-1,3-oxazine.The n.m.r. spectral data for a number of tetrahydro-1,3-oxazines and derived salts are tabulated and discussed.
TL;DR: The stereochemistry of dehydrogenation of the primary carbinol group of D-Galactose by D-galactose oxidase has been determined.
Abstract: The stereochemistry of dehydrogenation of the primary carbinol group of D-galactose by D-galactose oxidase has been determined. Using D-galactose-6-d and methyl β-D-galactopyranoside-6-d, it has been established that the reaction involves removal of the pro-S 6-hydrogen atom. This conclusion is based on product analysis, and on the relative impact of the deuterium isotope effect on oxidation rates of substrates having different R:S deuteration patterns. The absolute configurations at C-6 of these substrates have been determined by selective chemical transformations to products of known configuration. The rotational conformation of the 6-carbinol group of D-galactose and its possible relationship to the specificity of the enzyme are discussed, as well as the stereochemistry of reductive deuteration of aldehydo sugar derivatives.
TL;DR: In this paper, the synthesis of (dl)-4-demethoxy-7-O-methyl daunomycinone as part of a scheme toward the total synthesis of...
Abstract: Daunomycin is a new and very promising antitumor antibiotic. This communication reports the synthesis of (dl)-4-demethoxy-7-O-methyl daunomycinone as part of a scheme toward the total synthesis of ...
TL;DR: In this paper, a free radical chain mechanism is presented to describe the kinetics of the pyrolysis of acetylene over the temperature range 700-2400 °K. The mechanism is based on the following initiation reaction and subsequent addition, abstraction, and decomposition reactions of the radicals involved.
Abstract: A free radical chain mechanism is presented to describe the kinetics of the pyrolysis of acetylene over the temperature range 700–2400 °K. The mechanism is based on the following initiation reactionand subsequent addition, abstraction, and decomposition reactions of the radicals involved are shown to account for the products observed and for the kinetic characteristics of the reaction.
TL;DR: In this article, reaction of N-acetyl-, N-benzoyl-, and N-carbobenzoxy derivatives of aliphatic amino acids with sodium hydride/methyl iodide in tetrahydrofuran containing dimethylformamide at 80° gave the correspo...
Abstract: Reaction of N-acetyl-, N-benzoyl-, and N-carbobenzoxy derivatives of aliphatic amino acids with sodium hydride/methyl iodide in tetrahydrofuran containing dimethylformamide at 80° gave the correspo...
TL;DR: In this article, a method of assigning dihedral angles to hydrogens adjacent to a methylene function by using computer analyzed n.m.r. coupling constants in a modified Karplus equation is presented.
Abstract: A method of assigning dihedral angles to hydrogens adjacent to a methylene function by using computer analyzed n.m.r. coupling constants in a modified Karplus equation is presented. The "Dihedral Angle Estimation by the Ratio Method" (DAERM) is based on the assumption that, although the magnitudes of the Karplus constants, k1 and k2, vary, the ratio of k1 to k2 is a constant. Dihedral angles computed in this way seem not to be influenced by the effects of ring strain and substituent electronegativity. The conformational preferences of several four- to six-membered ring Systems, some containing oxygen and sulfur atoms, have been investigated by this method. Molecular features such as ring puckering and flattening are indicated by DAERM as are some subtle electrostatic influences.
TL;DR: In this article, a multi-site exchange theory was applied to three restricted rotation barriers in amido-type systems, including N, N-dimethyl trifluoroacetamide and dimethyl acetamide.
Abstract: The experimental application of a multi-site exchange theory developed recently has been made to three restricted rotation barriers in amido-type systems. Inclusion of 8 spin-sites in the analyses of the line shapes for spectra of N,N-dimethyl trifluoroacetamide and dimethyl acetamide leads to improved values for the activation parameters. Variation of chemical shifts with temperature is included in the iterative fitting procedure. The determination of the relative signs of long range couplings and the inclusion and measurement of unresolved couplings has been accomplished. The barrier for hindered rotation in N,N-dimethyl benzamide has been re-investigated including the effect of relatively large chemical shift changes with temperature. The internal consistency of the measurements from all aspects indicates that systematic errors common in the determination of energy barriers by steady-state nuclear magnetic resonance (n.m.r.) have been largely eliminated and hence the activation parameters obtained form...
TL;DR: In this article, a single crystal X-ray structure of nitratobis (tricyclohexylphosphine)copper(I) is reported, which is solved by the heavy atom method and refined with isotropic thermal parameters to an R of 0.14.
Abstract: Copper(I) nitrate complexes of the types L2CuNO3, L3CuNO3, and L4CuNO3 (L = tertiary phosphine) have been synthesized by reduction of copper(II) nitrate with tertiary phosphines. Infrared spectra and single crystal X-ray measurements indicate the presence of bidentate nitrate in L2CuNO3, monodentate nitrate in L3CuNO3, and ionic nitrate in L4CuNO3.The single crystal X-ray structure of nitratobis (tricyclohexylphosphine)copper(I) is reported. CuO3N(PC18H33)2 crystallizes in the monoclinic space group C2/c with a = 18.18(1) A, b = 9.240(6) A, c = 22.41(2) A, and β = 96.57(5)°. The structure was solved by the heavy atom method and refined with isotropic thermal parameters to an R of 0.14. The copper atom is tetrahedrally coordinated by two phosphorus atoms and two oxygen atoms of a bidentate nitrate group. The P—Cu—P angle (140(1)°) and Cu—P bond lengths (2.29(1) A) are the largest reported for tetrahedral copper complexes.A facile synthetic route to acetylacetonatobis(phosphine)copper(I) complexes is also d...
TL;DR: The effect of several oxidizing metal salts on the square planar iridium(I) complexes trans-[IrI(CO)-(PPh3)2X] has been investigated.
Abstract: The effect of several oxidizing metal salts on the square planar iridium(I) complexes trans-[IrI(CO)-(PPh3)2X] (where X− = Cl−, Br−, I−, N3−, NCO−, NCS−, and NO2−) has been investigated. With nitrate salts of Ce(IV), Fe(III), and Cu(II), several of the reactions gave products characterized by analysis and i.r. spectroscopy as [IrIII(CO)(PPh3)2X(NO3)2]. With CuCl2•2H2O and CuBr2 several of the same starting materials gave products, [IrIII(CO)(PPh3)2XY2] (where X− = NCO−, NCS−, NO2− and Y− = Cl−; and X− = NCO−, NCS−, Br−, NO2− and Y− = Br−). These have been similarly characterized. An iridium(III) complex, [IrIII(PPh3)2(NO3)2H] has also been characterized.
TL;DR: Preparations and various interconversion reactions are described in this paper for the complexes: [M2X2(PPh2O)2(pPh2OH2], [MX(Pph2O)(PPh 2OH)2], and [M(PPH2O), where M = palladium or...
Abstract: Preparations and various interconversion reactions are described for the complexes: [M2X2(PPh2O)2(PPh2OH2], [MX(PPh2O)(PPh2OH)2], [MX(PPh2O)(PPh2OH)(PEt3)], and [M(PPh2O)2]n where M = palladium or ...
TL;DR: The addition of N-bromosuccinimide (NBS) to a solution of diphenylacetylene in anhydrous dimethylsulfoxide (DMSO) leads to the formation of benzil in near-quantitative quantities.
Abstract: The addition of less than 2 mol equiv. of N-bromosuccinimide (NBS) to a solution of diphenylacetylene in anhydrous dimethylsulfoxide (DMSO) leads to the formation of benzil in near-quantitative yie...
TL;DR: In this paper, the infrared spectra of polycrystalline LiBH4 and LiBD4 have been recorded in the region 4000-50 cm−1 at 80 °K.
Abstract: The infrared spectra of polycrystalline LiBH4 and LiBD4 have been recorded in the region 4000–50 cm−1 at 80 °K. Raman spectra of polycrystalline samples were also recorded at this temperature. The spectra of the and lattice vibrations are consistent with symmetrically equivalent borohydride ions which lie on either general positions, two-fold axes or mirror-planes. Six lattice vibrations of translatory origin appear in the infrared spectrum of LiBH4 and a mode of libratory origin is inferred from an absorption tentatively assigned as a second overtone of a librational mode. Similar spectral results are obtained for LiBD4. The inferred librational frequencies are 418 cm–1 for the ions and 319 cm–1 for the ions.
TL;DR: In the presence of chiral environment compounds, C, optical rotation is induced in symmetric substrates, S, and may be detected as circular dichroism in the electronic spectra of the solutions as mentioned in this paper.
Abstract: In the presence of chiral environment compounds, C, optical rotation is induced in symmetric substrates, S, and may be detected as circular dichroism in the electronic spectra of the solutions. Thu...
TL;DR: In this article, precise analyses of the proton and some fluorine magnetic resonance spectra in acetone solution are reported for the three monofluorobenzaldehydes as well as for 2-chloro-6-fluorobensaldehyde and f...
Abstract: Precise analyses of the proton and some fluorine magnetic resonance spectra in acetone solution are reported for the three monofluorobenzaldehydes as well as for 2-chloro-6-fluorobenzaldehyde and f...
TL;DR: The solubility of mercury in water has been determined between 4 and 72 °C as mentioned in this paper, and standard thermodynamic functions have been evaluated for mercury transfer from the liquid metal to aqueous solution.
Abstract: The solubility of mercury in water has been determined between 4 and 72 °C. Standard thermodynamic functions have been evaluated for mercury transfer from the liquid metal to aqueous solution and from aqueous solution to the gas phase. Mercury in water exhibits large positive deviations from Raoult's Law and shows a high relative volatility of 15 400 at 25 °C.