Showing papers in "Canadian Journal of Chemistry in 1983"
TL;DR: In this article, a solution of spiroindolinonaphthoxazine in a common organic solvent shows profound photochromic effect, and the colorless form in ethanol displays three absorption bands (~320, 235, 203 nm) in the ult...
Abstract: A solution of spiroindolinonaphthoxazine in a common organic solvent shows profound photochromic effect. The colorless form in ethanol displays three absorption bands (~320, 235, 203 nm) in the ult...
191 citations
TL;DR: A general synthesis of 3-hydroxy homophthalates was developed and applied to the synthesis of sclerin (24), a compound possessing plant-growth activity.
Abstract: A general synthesis of 3-hydroxyhomophthalates is developed and applied to the synthesis of sclerin (24), a compound possessing plant-growth activity; the critical step in the synthesis of 24 can b...
124 citations
TL;DR: The subject of acidity functions is reviewed in this article, with emphasis on modern developments, using the Hammett cancellation assumption (zero-threshold order approximatatation).
Abstract: The subject of acidity functions is reviewed, with emphasis on modern developments. H0 and other scales determined in acid media, using the Hammett cancellation assumption (zero'th order approximat...
122 citations
TL;DR: In this article, the authors studied the kinetics of thermally initiated autoxidations of unsaturated lipids, linoleic acid, and methyl linoleate in micelles.
Abstract: The kinetics of thermally (30 °C) initiated autoxidations of unsaturated lipids, linoleic acid, and methyl linoleate are studied in 0.50 M sodium dodecyl sulfate (SDS) micelles. The rate of chain initiation, R1, was controlled by using known amounts of the thermal initiator, di-tert-butylhyponitrite (DBHN). The initiator efficiency, e, determined by the induction period method with x-tocopherol, was 0.30 for linoleic acid and varied (0.30 to 0.36) for methyl linoleate autoxiation as the concentration of the ester increased. The rate of autoxidation of linoleic acid follows the classical rate law since it is proportional to the substrate concentration and to the square root of chain initiation. The oxidizability of linoleic acid measured in micelles is 4.09 × 10−2 M−1/2 s−1/2. The oxidizability of methyl linoleate varied from 2.37 × 10−2 to 6.92 × 10−2 M−1/2 s−1/2 as the amount of solubilized ester increased. The latter results are indicative of pooling of the ester in the micellar phase. Additions of aque...
99 citations
TL;DR: In this paper, four basic lead carbonates were prepared and identified by X-ray powder diffractometry, including hydrocerussite, plumbonacrite, and two adducts MOH•2PbCO3.
Abstract: Four basic lead carbonates were prepared and identified by X-ray powder diffractometry. These were hydrocerussite (Pb3(OH)2(CO3)2), plumbonacrite (Pb10O(OH)6(CO3)6), and the two adducts MOH•2PbCO3 ...
92 citations
TL;DR: In this paper, the authors measured the heats of [CH2NH3]+• and [CH3XH]+• ions and showed that they do not interconvert with their conventional isomer at internal energies below the threshold for their fragmentation of lowest energy requirement.
Abstract: The title ions have been generated by dissociative ionisation of appropriate precursor molecules and have been unequivocally identified by collisional activation and collisional ionisation mass spectrometry. Their heats of formation, , have been measured and were found to be similar to those for their ionic isomer of conventional structure, [CH3X]+•. The exception is [CH2NH3]+• whose , is ca. 30 kcal mol−1 higher than that of [CH3NH2]+•. The shapes and appearance energies of metastable peaks in conjunction with isotopic labelling experiments, show that these novel ions do not interconvert with their conventional isomer at internal energies below the threshold for their fragmentation of lowest energy requirement, namely, loss of H•. However, unimolecular H• loss from all [CH2XH]+• ions is preceded by a rate determining isomerisation to [CH3X]+•, followed by fast dissociation. The results are generally in good agreement with recent abinitio calculations. Also described are the properties of the homologous i...
77 citations
TL;DR: In this paper, a simple banded absorption spectrum was detected by photochemical modulation spectroscopy in Hg-photosensitized reactions forming vinyl radicals, starting at 499.5nm and reaching maximum intensities at 1.5 µm.
Abstract: A simple, banded absorption spectrum has been detected by photochemical modulation spectroscopy in Hg-photosensitized reactions forming vinyl radicals. It starts at 499.5 nm, reaches maximum intens...
71 citations
TL;DR: In this article, the dynamic mechanical properties of Nafion precursor were determined as a function of the degree of conversion to the sodium ionomer, and those of the acid as an function of conversio...
Abstract: The dynamic mechanical properties of Nafion precursor were determined as a function of the degree of conversion to the sodium ionomer, and those of the acid as a function of the degree of conversio...
69 citations
TL;DR: Ullmann condensation using Cu or copper oxide as the reactant and using no base has been studied in this paper, where reactions of active N-H, O-H and C-H compounds, RZH (imides, amides and amines, phenol, benzoic acid,...
Abstract: Ullmann condensation using Cu or copper oxide as the reactant and using no base has been studied. Reactions of active N—H, O—H, and C—H compounds, RZH (imides, amides, amines, phenol, benzoic acid,...
68 citations
TL;DR: Optically active phosphonic analogues of alanine, valine, leucine, phenylalanine, and phenylglycine were obtained by resolution of diphenyl 1-aminoalkanephosphonates with dibenzoyl-L-tartaric acid as discussed by the authors.
Abstract: Optically active phosphonic analogues of alanine, valine, leucine, phenylalanine, and phenylglycine were obtained by resolution of diphenyl 1-aminoalkanephosphonates with dibenzoyl-L-tartaric acid ...
65 citations
TL;DR: In this paper, the skeletal isomerization of cyclohexene in a microcatalytic pulse reactor was investigated by using aluminium orthophosphates (Al/P = 1) as catalysts.
Abstract: The skeletal isomerization of cyclohexene, in a microcatalytic pulse reactor, was investigated by using aluminium orthophosphates (Al/P = 1) as catalysts. An attempt has been made to correlate the ...
TL;DR: An investigation based on X-ray fiber diffraetion and conformational analysis methods has provided a proposed chain conformation and crystalline structure for lichenan, a poly β(1'→'3) cellotriose.
Abstract: An investigation based on X-ray fiber diffraetion and conformational analysis methods has provided a proposed chain conformation and crystalline structure for lichenan, a poly β(1 → 3) cellotriose....
TL;DR: Partial molar volumes of the Fe2+, Ni2+, Fe3, Cr3+, Cr3, Rh3+, and M(NH3)5OH3+ (M =Cr, Co, Rh, Ir) aqueous ions have been obtained by extrapolation from density measurements at 29815 K on the perchlo
Abstract: Partial molar volumes of the Fe2+, Ni2+, Fe3+, Cr3+, Rh3+, and M(NH3)5OH3+ (M = Cr, Co, Rh, Ir) aqueous ions have been obtained by extrapolation from density measurements at 29815 K on the perchlo
TL;DR: The potentially bidentate ligands Ph2P(CH2)nSPh (n = 1, 2) form complexes of rhodium, iridium, palladium, or platinum(II) in which ligands are coordinated to a metal center either by the...
Abstract: The potentially bidentate ligands Ph2P(CH2)nSPh (n = 1, 2) form complexes of rhodium(I), iridium(I), palladium(II), or platinum(II) in which ligands are coordinated to a metal centre either by the ...
TL;DR: In this article, the first reported laboratory observation of gas phase emission from vibrational levels greater than zero for this state was reported, and the absolute rate constants for quenching of the lowest vibrational level by O(3P), O2(a1Δg),, CO2, CO 2, SF6, HE, and Ar are given.
Abstract: Spectroscopic and kinetic results for the quenching of are presented, including the first reported laboratory observation of gas phase emission from vibrational levels greater than zero for this state. In addition, the absolute rate constants for quenching of the lowest vibrational level by O(3P), O2(a1Δg), , CO2, SF6, HE, and Ar are given. These results are compared with the results of atmospheric modeling studies. Qualitative evidence is presented for the formation of O2(a1Δg) and in the quenching of this state.
TL;DR: In this article, a flow microcalorimeter and vibrating tube densimeter were used at 25 °C to obtain apparent molar heat capacities and volumes of aqueous NaHCO3, KHCO3 and NaHSO3, from 0.1 to 1.0
Abstract: A flow microcalorimeter and vibrating tube densimeter were used at 25 °C to obtain apparent molar heat capacities and volumes of aqueous NaHCO3, KHCO3, NaHSO3, and KHSO3, from 0.1 to 1.0 mol kg−1, ...
TL;DR: A theoretical study of the magnitude and origin of deviations in the photostationary state relation, has been carried out by computer simulation as mentioned in this paper, and various homogeneous tropospheric mixtures were chosen with initial pollutant concentrations varied from those of highly polluted to very clean atmospheres.
Abstract: A theoretical study of the magnitude and origin of deviations in the photostationary state relation, has been carried out by computer simulation. Various homogeneous tropospheric mixtures were chosen with initial pollutant concentrations varied from those of highly polluted to very clean atmospheres. Even for the homogeneous conditions assumed here, strong negative deviations were observed ([O3]t[NO]t/[NO2]t < (k1/k3)t for many of the conditions chosen. Failure of [I] in many cases resulted largely from the non-zero value of d[O3]/dt. Many other factors, including significant rates of O3 reaction with NO2, alkene, HO2, HO, and ozone photolysis, contribute significantly to the deviations seen in several cases considered.
TL;DR: The modified Gorin model of recombination as a long range interaction of weakly bound radicals is rederived to give a collision impact parameter 11% larger than rmax, the separation at the centrifugal maximum, to resolve some of the earlier difficulties with secondary and tertiary radicals.
Abstract: The modified Gorin model of recombination as a long range interaction of weakly bound radicals, constrained only by steric forces, is rederived to give a collision impact parameter 11% larger than rmax, the separation at the centrifugal maximum. This larger impact parameter resolves some of the earlier difficulties with secondary and tertiary radicals. By imposing a new constraint, that the orientation of the radicals be such as to permit exchange forces to act, a new model is developed in which kr = 1/4 Zr α, where a represents the product of fractions of active surface areas of each radical available for bonding. Excellent agreement is obtained in estimating values of kr.Analysis of disproportionation is made to show that it cannot be described by the tight transition state but must also be governed by similar, long range exchange forces between the bond being attacked and the same "active surface" of the abstracting radical. Using an ad hoc radius for equal to 4 A it is possible to reproduce the data o...
TL;DR: In an effort to advance our understanding of the principles governing the structures of and the hydrogen bonding in alkylammonium hexachlorostannates (IV), (RnNH4−n)2SnCl6, the authors have determined the ro...
Abstract: In an effort to advance our understanding of the principles governing the structures of and the hydrogen bonding in alkylammonium hexachlorostannates(IV), (RnNH4−n)2SnCl6, we have determined the ro...
TL;DR: In this paper, the syntheses and characterization of octaethylporphyrin complexes of ruthenium(II) and ruthensium(III) are described.
Abstract: The syntheses and characterization of some new octaethylporphyrin complexes of ruthenium(II) and ruthenium(III) are described; the complexes are Ru(OEP)(P″Bu3)2, Ru(OEP)(CO)L (L = PPh3, P″Bu3), [Ru...
TL;DR: In this paper, the preparation of o-nitrophenylethylene glycol is described along with its application as a photolabile protective group for aldehydes and ketones.
Abstract: The preparation of o-nitrophenylethylene glycol is described along with its application as a photolabile protective group for aldehydes and ketones. Formation of the acetals and ketals is achieved in good to high yields in the usual manner and deprotection is carried out in fair to high yield, by photolysis at 350 nm in an inert solvent such as benzene. Because of the particular nature of the present protective group, its stability to basic and acidic conditions has been examined and is reported to complete the scope and limitations aspect. From a mechanistic point of view, the isolation and characterization of o-nitroso-α-hydroxyacetophenone as the spent reagent demonstrates a mechanistic link with the known o-nitrobenzaldehyde to o-nitrosobenzoic acid photorearrangement.
TL;DR: In this paper, the photochemical primary process consists of (1) the formation of o n o n, and (2) the extraction of light in the vacuum ultraviolet, respectively.
Abstract: Photochemical and fluorescence studies of acetylene initiated by absorption of light in the vacuum ultraviolet have been described. The photochemical primary process consists of (1) the formation o...
TL;DR: In this paper, the infrared spectra of n-nonadceanc and n-heneicosane on transition from the orthorhombic to the so-called "hexagonal" or "rotator" phase are reported.
Abstract: Detailed measurements of the changes in the infrared spectra of n-nonadceanc and n-heneicosane on transition from the orthorhombic to the so-called "hexagonal" or "rotator" phase are reported.
TL;DR: In this article, the arylation of peracetylated glycals catalyzed by palladium salts provides a new synthesis of C-glycosides, which is applied to several aromatic compounds, including fluoro and nitro...
Abstract: The arylation of peracetylated glycals catalyzed by palladium salts provides a new synthesis of C-glycosides. The title reaction is applied to several aromatic compounds, including fluoro and nitro...
TL;DR: In this paper, iterative multiple linear regression analysis of substituent-induced chemical shifts in 3 and 4-substituted styrene derivatives is used to redefine σF and substituents constants (with respective standard errors of 0.01 and 0.005).
Abstract: Iterative multiple linear regression analysis of substituent-induced chemical shifts in 3- and 4-substituted styrene derivatives is used to redefine σF and substituent constants (with respective standard errors of ca. 0.01 and 0.005). Correlations with the data for various model systems indicate that these substituent constants are applicable to data sets involving both chemical shift and acidity measurements in aprotic media. The approach we have used involving a homogeneous data set with a large number of variables is particularly suited for providing well-defined dual substituent parameter constants for the more common neutral substituents.Correlations for individual nuclei are entirely consistent with a previously proposed model of substituent effects involving field, resonance, and polarization effects. From these results and the results for other model systems, it is concluded that σF and are respectively pure field and resonance substituent constants. It is pointed out that a combination of detaile...
TL;DR: In this article, the reactions of Pt(PPh3)4 with elemental sulfur in ratios S/Pt = 3, 4, 5, and 6 give a mixture of compounds identified as [PtS(Pph3)2]2 and [PS4(pPh3]2], but PtS2(P ph3)3 is not detected.
Abstract: The reactions of Pt(PPh3)4 with elemental sulfur in ratios S/Pt = 3, 4, 5, and 6 give a mixture of compounds identified as [PtS(PPh3)2]2 and PtS4(PPh3)2; PtS2(PPh3)2 is not detected. The dimeric co...
TL;DR: The binding of Cu2+ to soil-derived fulvic acid (SFA) measured by fluorescence quenching titration is much stronger than Co2+ and Mn2+ which are similar as mentioned in this paper.
Abstract: The binding of Cu2+ to soil-derived fulvic acid (SFA) measured by fluorescence quenching titration is much stronger than Co2+ and Mn2+ which are similar. The conditional stability constants from curve fitting at pH 6 are 1.1 × 105 for Cu2+, 5.1 × 103 for Co2+, and 4.2 × 103 for Mn2+. The slight advantage in strength for Co2+ over Mn2+ is also demonstrated by the binding curves at pH 6 and 7. These two metal ions not only tend to bind more weakly but also bind to fewer sites, giving complexing capacity values of about 1.5 × 10−6 M compared to 2.0 × 10−5 for Cu2+ at pH 6. This lower binding capacity may be due to outer sphere complexation that does not allow access to some sites complexed by inner sphere binding Cu2+. Scattering experiments demonstrate that Cu2+ is more effective at precipitating and aggregating SFA than Co2+ and Mn2+. Cu2+ probably neutralizes the negative charges on SFA molecules allowing larger hydrophobic aggregates to form and precipitate.
TL;DR: The 2-chloroethyl and 2-phenylsulfonylethyl moieties are versatile protecting groups for the pyrrole nitrogen atom as discussed by the authors, and they are easily attached under phase transfer conditions using 1,2-dichloroethane.
Abstract: The 2-chloroethyl and 2-phenylsulfonylethyl moieties are versatile protecting groups for the pyrrole nitrogen atom. The 2-chloroethyl group is easily attached under phase transfer conditions using 1,2-dichloroethane. The 2-phenylsulfonylethyl moiety is readily appended under both phase transfer and homogeneous solution conditions using 2-phenylsulfonylcthyl chloride 5. Deprotection of the N-(2-chloroethyl)pyrroles is accomplished by means of efficient three-step, one-pot sequences via the N-vinyl compounds 3 and subsequent degradation of the N-(1-hydroxyethyl) compounds 4 or the acctoxymercuration derivatives 5 obtained therefrom. The 2-phenylsulfonylethyl group is excised by a reverse Michael reaction using sodium hydride or DBN as the base.The utility of the 2-chloroethyl protecting group is exemplified in a synthesis of benzyl cyclopenta[b] |pyrrole-5-carboxylate 13 from 1-(2-chloroethyl)-4-oxotetrahydroindolc 2d.
TL;DR: In this article, a complete nmr study of 12 3-C-phosphonates, -phosphinates, and phosphine oxide derivatives of three-c-branched-chain pento-and hexo-furanoses is reported.
Abstract: A complete nmr study (1H, 13C, 31P) of twelve 3-C-phosphonates, -phosphinates, and -phosphine oxide derivatives of 3-C-branched-chain pento- and hexo-furanoses is reported. For all compounds the configuration at C3 is determined and, for oxaphospholanes 9 to 12, the configuration at the asymmetric phosphorus atom. The 3T2 conformation of the furanose ring of acyclic derivatives 1 to 8 and the conformationally rigid cis-fused oxaphospholane-furanose bicyclic systems of 9 to 12 have been used to study the 3JPCCH vs. θP.H and 3JPCCC vs. θP.C relationships which are specific to this series of compounds. The use of the ν P=O ir stretching frequency, δ 31P chemical shift, and 1JP.C coupling constant values in structural analysis of C-phosphorus-bearing sugars is also reported and discussed.
TL;DR: Guanosine-5′-monophosphate (5′GMP) reacts with Pt(II) and Mg (II) metal ions to give complexes of the type Pt(5′ GMP)nCl2•xH2O, cis- and trans-[Pt(NH3)2(5''-GMP]2]Cl2[H 2O]Cl
Abstract: Guanosine-5′-monophosphate (5′-GMP) reacts with Pt(II) and Mg(II) metal ions to give complexes of the type Pt(5′-GMP)nCl2•xH2O, cis- and trans-[Pt(NH3)2(5′-GMP)2]Cl2•xH2O and Mg(5'-GMP2)•xH2O, wher...