bluuebunny/crossref_metadata_2025 huggingface dataset:
Configuration of pyruvic acid ketals, 4,6-O-linked to d-galactose units, in bacterial and algal polysaccharides
Authors: Gorin P. A. J. , Ishikawa T.
Published: May 2006

Methyl 4,6-O-(hydroxyisopropylidene)-α-d-glucopyranosides (X and XI) were synthesized and the ketal configuration of X was established by a Smith degradation to 1,3-O-(hydroxyiso-propylidene)-l-erythritol (XIII), which was prepared from 2,8-anhydro-1-deoxy-d-glycero-β-d-gulo-octulopyranose (XVI). Methyl 4,6-O-(hydroxyisopropylidene)-α-d-galactopyranosides (II and V) were prepared and their ketal configurations determined by comparison of molecular rotations. Methyl 4,6-O-(1-carbomethoxyethylidene)-α-d-galactopyranosides (IX and XII) from II and V and methyl 4,6-O-(1-carbomethoxyethylidene)-α-d-glucopyranosides (XIV and XV) from X and XI were utilized for this purpose. Also, the hydrogen-bonding characteristics of methyl 4,6-O-(hydroxyisopropylidene)-2,3-di-O-methyl-α-d-galactopyranosides (III and VI) from II and V were compared with those of methyl 4,6-O-(hydroxyisopropylidene)-2,3-di-O-methyl-α-d-glucopyranosides (VII and VIII) from X and XI. Based on the finding that X contains an axial C-methyl group, the results from the two approaches show that methyl 4,6-O-(hydroxyisopropylidene)-α-d-galactopyranoside (II) contains an axial C-methyl group in the conformations depicted. The stereoisomer of this compound was prepared from 4,6-O-(1-carboxyethylidene)-d-galactose (IV), a partial hydrolysis product of Corynebacterium insidiosum polysaccharide and Difco agar and establishes that the natural products contain equatorial C-methyl ketal groups.
Studies on metal hydroxy compounds. I. Thermal analyses of zinc derivatives ϵ-Zn(OH)2, Zn5(OH)8Cl2.H2O, β-ZnOHCl, and ZnOHF
Authors: Srivastava O. K. , Secco E. A.
Published: May 2006

Thermogravimetric (t.g.a.) and differential thermal analyses (d.t.a.) of ϵ-Zn(OH)2, Zn5(OH)8Cl2.H2O, β-ZnOHCl, and ZnOHF are reported and discussed. The results show that the replacement of a hydroxyl group by a halogen group contributes to greater thermal stability of the hydroxy compound. The thermal stability increases in the order ϵ-Zn(OH)2 < Zn5(OH)8Cl2 < β-ZnOHCl < ZnOHF.The hydroxy compounds decompose via dehydration in the initial step followed by hydrolysis of the zinc halide and (or) volatilization of the zinc halide yielding an ultimate residue of zinc oxide and trace quantities of the zinc halide.
Studies on metal hydroxy compounds. II. Infrared spectra of zinc derivatives ϵ-Zn(OH)2, β-ZnOHCl, ZnOHF, Zn5(OH)8Cl2, and Zn5(OH)8Cl2·H2O
Authors: Srivastava O. K. , Secco E. A.
Published: May 2006

Infrared spectra of ϵ-Zn(OH)2, β-ZnOHCl, ZnOHF, Zn5(OH)8Cl2, and Zn5(OH)8Cl2·H2O and their deuterated analogues in the range 2.5–16 μ are reported for the first time. The effects of substituting a halogen for an OH group in Zn(OH)2 are (i) sharper OH stretching absorption bands, (ii) splitting of bands involving OH to give distinct doublets in ZnOHF and Zn5(OH)8Cl2, indicating strong intermolecular coupling, and (iii) shift of the OH stretching vibration to a higher frequency. Strong absorption bands are observed in the region of 695–780 cm−1 for all compounds and also near 1 020 ± 30 cm−1 in all cases except ZnOHCl. All the observed bands are displaced to lower frequencies by the deuterated analogues, with vH/vD ratios in the range 1.30–1.36. A cursory interpretation of the spectra of ZnOHCl and ZnOHF is given in terms of a planar molecule of Cs symmetry, but the unambiguous assignment of the bands must await a site group or group factor analysis.
Quantum chemistry of nitrogen compounds. V. L.c.a.o.–m.o.–s.c.f. calculations on HCN using a basis set of Gaussian orbitals
Authors: Moffat J. B. , Collens R. J.
Published: May 2006

Linear combination atomic orbital – molecular orbital – self-consistent field (l.c.a.o.–m.o.–s.c.f.) calculations with a basis set of Gaussian orbitals have been applied to hydrogen cyanide. Basis sets ranging from 11 to 42 functions have been examined. The effect of variation of the exponent values for a 20 function basis set has been investigated and the "best" exponents have been employed in the larger sets. The basis set consisting of 39 Gaussian-type functions yielded an energy of −116.5760 atomic units (a.u.). Sigma orbital energies appear to be relatively insensitive to the size of the basis set. Properties such as first ionization potential, sigma–pi gap, and pi–pi* gap appear to be reasonably well reproduced with basis sets as small as 22, 26, and 28 basis functions. The internuclear distances calculated with the 39 function set are in good agreement with the experimental results. Examination of the coefficients of the pi orbitals on carbon and nitrogen reveals that the pi structure is very little perturbed by a change in the sigma core.
Absolute rate constants for hydrocarbon autoxidation. V. The hydroperoxy radical in chain propagation and termination
Authors: Howard J. A. , Ingold K. U.
Published: May 2006

The hydroperoxy radical (HOO·) is the main chain propagating and terminating radical in the autoxidation of dilute solutions of 1,4-cyclohexadiene and 1,4-dihydronaphthalene in chlorobenzene at 30 °C. The absolute rate constant for the self-reaction of hydroperoxy radicals (chain termination) in nonpolar solvents is very much higher than previously reported values in aqueous media.
Absolute rate constants for hydrocarbon autoxidation. VI. Alkyl aromatic and olefinic hydrocarbons
Authors: Howard J. A. , Ingold K. U.
Published: May 2006

Absolute rate constants have been measured for the autoxidation of a large number of hydrocarbons at 30 °C. The chain-propagating and chain-terminating rate constants depend on the structure of the hydrocarbon and also on the structure of the chain-carrying peroxy radical. With certain notable exceptions which are mainly due to steric hindrance, the rate constants for hydrogen-atom abstraction increase in the order primary < secondary < tertiary; and, for compounds losing a secondary hydrogen atom, the rate constants increase in the order unactivated < acyclic activated by a single π-electron system < cyclic activated by a single Π-system < acyclic activated by two π-systems < cyclic activated by two π-systems. The rate constants for chain termination by the self-reaction of two peroxy radicals generally increase in the order tertiary peroxy radicals < acyclic allylic secondary 

[Formula: see text] cyclic secondary 

[Formula: see text] acyclic benzylic secondary < primary peroxy radicals < hydroperoxy radicals.
Ricci's sixth type of solid solution. A study of the systems Li2SO4–LiBrO3–H2O and LiBrO3–NaBrO3–H2O at 25°
Authors: Campbell A. N. , Kartzmark E. M. , Musbally G. M.
Published: May 2006

The equilibrium diagrams of the systems Li2SO4–LiBrO3–H2O and NaBrO3–LiBrO3–H2O have been determined at 25°. The system NaBrO3–LiBrO3–H2O is simple, neither compound nor solid solution being formed. In both systems the stable solid form of lithium bromate is the monohydrate and the X-ray powder picture of this monohydrate has been obtained.In the system Li2SO4–LiBrO3–H2O, a solid solution of LiBrO3.H2O in Li2SO4.H2O, having the Li2SO4.H2O lattice, extends from Li2SO4.H2O up to a solid solution of composition 42 wt.% Li2SO4, 45 wt.% LiBrO3, 13 wt.% H2O. No corresponding solid solution of Li2SO4.H2O in LiBrO3.H2O exists. No intermediate phase corresponding to a stoichiometric compound, or at least to another lattice pattern, exists.
Activity coefficients in the system H2O–NaCl–MgSO4 at 25°C
Authors: Platford R. F.
Published: May 2006

The system H2O–NaCl–MgSO4 was studied by both the isopiestic and the electromotive force (e.m.f.) methods, and mean activity coefficients of NaCl and MgSO4 were measured at 25 °C at ionic strengths up to 0.72. Difficulty was encountered in extrapolating the isopiestic results to infinite dilution and an extrapolation was chosen which made the isopiestic results consistent with e.m.f. results on the same system. Harned's rule was not obeyed for either salt.
1H and 19F nuclear magnetic resonance spectra of the adduct BF3.H2O
Authors: Gillespie R. J. , Hartman J. S.
Published: May 2006

It is shown by low-temperature 1H and 19F nuclear magnetic resonance (n.m.r.) spectroscopy that boron trifluoride monohydrate is formed in dilute solutions in acetone containing both water and BF3. In solutions in which [H2O] < [BF3], proton–fluorine coupling is observed which definitely establishes that in acetone solution at low temperatures the monohydrate is the simple donor–acceptor complex H2O → BF3. In solutions in which [H2O] > [BF3], no proton–fluorine coupling was observed because of rapid proton exchange.
Spontaneous decarboxylation of oxalacetic acid
Authors: Tsai C. S.
Published: May 2006

The kinetic study at different pH values indicates that the monoanion of oxalacetic acid is the major active species which decarboxylates spontaneously. The decarboxylation of the monoanion is favored by nonpolar solvents. Solvent and isotopic effects suggest that the reaction may proceed via an intramolecular hydrogen-bonded intermediate as an activated complex. Infrared spectra which show the formation of an intramolecular hydrogen bond of oxalacetate in solution are obtained. A plausible mechanism consistent with experimental results is proposed for the spontaneous decarboxylation of oxalacetic acid.
Strongly basic systems. VIII. The H− function for dimethyl sulfoxide – water – tetramethylammonium hydroxide
Authors: Dolman Douglas , Stewart Ross
Published: May 2006

An H− acidity function based on the ionization of 24 substituted anilines and diphenylamines has been established in the system dimethyl sulfoxide – water – tetramethylammonium hydroxide. The H− of a 0.011 M solution of tetramethylammonium hydroxide ranges from 12 in water to 26.2 in 99.6 mole % dimethyl sulfoxide – water, an increase in basicity of 14 powers of 10. The increase in basicity is due to the increased activity of the hydroxide ion brought about by the reduction in its solvation in the poor anion-solvating solvent dimethyl sulfoxide, and indicates the extensive solvation enjoyed by the hydroxide ion in water.The pKHA values of the indicator acids vary from 13.9 for 2,4-dinitrodiphenylamine to 25.6 for 3-chloroaniline. From a plot of log KHA versus the Hammett substituent constants (σ) for six monosubstituted diphenylamines, a ρ value of 4.07 is found. Similar results are obtained for the anilines. The acidities of all the substituted diphenylamines do not follow the above-mentioned correlation with the Hammett σ constants; the pKHA values of 4-amino-, 4-methoxy-, 4-methylsulfonyl-, and 4-nitro-diphenylamine are all less than expected from the Hammett σ constants for the substituents in these compounds. The 4-nitro substituent exerts a particularly large acid-strengthening effect on the acidities of aniline and diphenylamine, the decreases in pKHA being approximately 8.4 and 6.8 pK units, respectively. An exalted substituent constant of +1.65 for p-NO2 is needed to account for the acidity of p-nitro-diphenylamine.
The alkaloids of Aconitum septentrionale Koelle
Authors: Marion Léo , Fonzes L. , Wilkins Jr. C. K. , Boca J. P. , Sandberg F. , Thorsén R. , Lindén E.
Published: May 2006

The root of A. septentrionale Koelle has been found to contain a number of alkaloids, seven of which have been isolated and characterized. The major alkaloid is the previously known lappaconitine. The minor bases, except alkaloid D, appear to be new. Of these, the main one, alkaloid A (C43H59O12N3), is a double ester, since it consists of an alkamine esterified with a methyl ester of N-succinoylanthranilic acid. The other minor bases are alkaloid B (C17H25O2N), alkaloid C (C19H27O3N), alkaloid D (C30H42O7N2) which is deacetyllappaconitine, alkaloid E (C37H54O7N) containing no ester group, and alkaloid F (C19H29O6N). No trace of the previously reported cynoctonine and septentrionaline was found.
Organic sulfur compounds. V. The preparation of some benzothiazine hydroxamic acids
Authors: Coutts R. T. , Smith Elizabeth M.
Published: May 2006

2-Arylidene-3,4-dihydro-4-hydroxy-3-oxo-2H-1,4-benzothiazine hydroxamic acids (VI) were best prepared by the reduction of α-(o-nitrophenylthio)cinnamates and related compounds of general structure V with sodium borohydride and palladium–charcoal. These precursors (V) were obtained by reacting methyl (o-nitrophenylthio)acetate and its simple derivatives with a variety of aryl aldehydes, in the presence of piperidine. Attempts to prepare the sulfones of V in a similar manner from methyl or ethyl (o-nitrobenzenesulfonyl)acetate were successful in two instances when absolute methanol or ethanol was the solvent. The alternative reaction, in which one molecule of the aldehyde condensed with two molecules of the (o-nitrobenzenesulfonyl)acetate, also occurred.Methyl and ethyl (2-nitrobenzenesulfonyl)acetate and their simple ring-substituted derivatives were smoothly hydrolyzed and decarboxylated by heating a solution of the acetate in aqueous alcohol containing piperidine. Methyl p-nitrophenylsulfone is similarly obtained in an excellent yield from methyl (p-nitrobenzenesulfonyl)acetate. Neither methyl (o-nitrophenylthio) acetate nor methyl α-(4-trifluoromethyl-2-nitrobenzenesulfonyl)propionate is affected by this treatment.
Influence des effets inductifs et stériques sur la basicité des amines tertiaires
Authors: Perrault Guy
Published: May 2006

not available
Dipole moments of some ethylene derivatives
Authors: Bock E. , Dojack E. F.
Published: May 2006

The dipole moments of the ethylene derivatives acrylonitrile, chloroacrylonitrile, methyl vinyl ketone, vinyl bromide, 1,1-dichloroethylene, and tribromoethylene were determined in benzene solution at 20 °C. The measured dipole moments were corrected for the solvent effect by the method of Looyenga. In addition the applicability of the Looyenga equation for the solvent effect was tested on earlier reported data for 20 different molecules, whose dipole moments were derived from dilute benzene and carbon tetrachloride solutions, respectively. The corrected dipole moment values were compared with earlier corrected values calculated according to the method of Le Fevre and Le Fevre and with reported gas values. It was found that for most compounds both methods of correction yielded dipole moment values which differed by 0–10% from the gas values.
Conformational effect in the stannous chloride debromination of sym-tetrabromoethane
Authors: Kwok W. K. , Miller Sidney I.
Published: May 2006

The initial ratios of cis- to trans-dibromoethene product in the stannous chloride reduction of sym-tetrabromoethane in dimethylformamide were 1.51 ± 0.04 at 25°, 1.36 ± 0.03 at 50°, and 1.20 ± 0.03 at 75°. Transition state energy differences in the trans–gauche tetrabromoethane rotamers are estimated as (Ht≠ – Hg≠) = 480 and (Ft≠ – Fg≠) = 244 cal/mole at 25°. A conformational energy analysis was performed. We have shown how a rate-equilibrium parallelism can be adapted to a conformational analysis for systems of this type, and how α, a constant between zero and unity, can be used to characterize the transition state relative to reactants and products (eq. [8]). In the present system, however, there is no rate-equilibrium parallelism and α cannot be defined.
Allene chemistry. VIII. Diaddition of thiol compounds to allene
Authors: Oswald Alexis A. , Griesbaum Karl , Hall Daniel N. , Naegele Walter
Published: May 2006

The radical-type diaddition of simple aliphatic and aromatic thiols, thiolacetic acid, dialkyldithiophosphoric (phosphorodithioic) acids, 2-mercaptoethanol, mercaptoacetic acid, 2-mercaptopropionic acid, and their esters to allene was studied. In general, such diadditions were found to be better than known metathetical reactions for the large-scale synthesis of trimethylene bis-sulfide compounds, the products of terminal diaddition. The various types of thiol compounds differ widely in their reactivity towards allene. A comparison of the data for t-butane- and benzene-thiol addition suggests that, in general, the amount of branched diadducts from monoadditions is directly proportional to the hydrogen-donor ability of the thiol, and that the amount of the allylic monoadduct formed is proportional to the stability of the thiyl radical.
Carbonyl-bridged and related compounds. Structural assignments by nuclear magnetic resonance spectroscopy
Authors: Allen C. F. H.
Published: May 2006

The spectral data, predominantly nuclear magnetic resonance spectra, of a number of carbonyl-bridged and related compounds have been examined. In most instances they confirm the structures arrived at by classical procedures, but in some instances revisions have been made.
Dinitrophenyl peptides. II. Further studies on the preparation and properties of 2,4-dinitrophenyl glycyl peptides
Authors: Loudfoot J. H. , Chan Y. M.
Published: May 2006

The study of 2,4-dinitrophenyl peptides has been extended to include the preparation and properties of some further dinitrophenyl dipeptides, namely, the glycyl-l-tryptophan, glycyl-l-proline, glycyl-l-phenylalanine, and glycyl-l-glutamic acid derivatives. Electrophoresis gave a good separation of products, and thin-layer chromatography proved to be a good means of purifying and separating the products. The molar absorbancy varies somewhat in the 350–360, 260–270, and 210–235 mμ, ranges in aqueous sodium bicarbonate solution, is more consistent in 95% ethanol at 344 mμ, and shows some variation in the 255–265 mμ region in 95% ethanol; the infrared absorption spectra have been obtained. The characterization of two dinitrophenyl amino acyl chlorides by conversion into the amides, anilides, and p-toluidides is also reported.
Mercury-photosensitized reactions in the presence of CO: decomposition of ethylenimine
Authors: Jones A. , Lossing F. P.
Published: May 2006

The effect of CO addition on a number of Hg(3P1) photosensitized decompositions, under conditions of incomplete quenching, has been investigated. Compounds having large quenching cross sections (i.e. those presumably decomposing through formation of triplet excited states) have enhanced rates of decomposition in the presence of CO. Those having small cross sections (i.e. those for which the primary interaction is presumably the direct attack of Hg(3P1) atom on a C—H bond) show no enhancement. This difference in behavior, which is interpreted in terms of activation by a HgCO* complex, suggests that CO addition under the appropriate conditions can be used to decide whether or not certain decomposition products aries from an electronically excited precursor. For example, the effect of CO on the sensitized decomposition of ethylenimine indicates that the major dissociation process to form C2H4and the NH radical proceeds by way of an electronically excited precursor, while a minor process (5%) to form

[Formula: see text] radical and a H-atom does not. Some results on the sensitized decomposition of formaldehyde are also discussed.
Effect of intramolecular hydrogen bonding on the relative acidities of substituted salicylic acids in benzene solution
Authors: Dunn G. E. , Penner Thomas L.
Published: May 2006

The relative acidities of fifteen 4- and 5-substituted salicylic acids were determined in benzene solution by potentiometric titration. The potentials at half neutralization (h.n.p.) relative to that of salicylic acid were considered to measure the acidities of the substituted acids relative to the parent acid. These potentials, designated by Δhnp, gave a significantly better correlation with Hammett's sigma constants in an equation of the form proposed by Jaffe, Δhnp = ρ1σ1 + ρ2σ2, than in a simple Hammett equation, Δhnp = ρ1σ1. In these equations the subscripts 1 and 2 refer to the position of a substituent relative to the carboxyl group and to the phenolic group respectively. The value of ρ2/ρ1 was found to be 0.4, indicating that the electronic effect of a substituent on the acid strength via the phenolic hydrogen-bonded path is almost half as large as the direct effect through the carboxyl group. These results, together with the fact that in aqueous solution there is very little if any transmission via the phenolic group, are discussed in terms of intramolecular hydrogen bonding of salicylic acids in benzene and in water.
Reductive cleavage with metal in liquid ammonia. III. Olefin formation from the reaction of sodium metal with methyl 4,6-O-ethylidene-3-O,S-dimethyl-2-thio-α-d-altropyranoside dissolved in 1,2-dimethoxyethane
Authors: Nayak U. G. , Sharma M. , Brown R. K.
Published: May 2006

Methyl 4,6-O-ethylidene-3-O,S-dimethyl-2-thio-α-d-altropyranoside, when heated in refluxing 1,2-dimethoxyethane with an equimolar quantity of metallic sodium, gave approximately a 75% yield of a mixture of the three olefins, methyl 2,3-didehydro-3-deoxy-4,6-O-ethylidene-S-methyl-2-thio-α-d-altropyranoside (XI), l,2-didehydro-l-deoxy-4,6-O-ethylidene-3-O,S-dimethyl-2-thio-d-ribo-hexopyranose (XII), and methyl 3,4-didehydro-3-deoxy-4,6-O-ethylidene-S-methyl-2-thio-α-d-erythro(or threo)-hexopyranoside (XIII) (tentative). Only compounds XI and XII could be separated and characterized. The structural assignments were based on a comparison with authentic samples and on nuclear magnetic resonance and infrared data, as well as on a comparison with the characteristics of analogous 4,6-O-benzylidene compounds previously reported (2).
The alkali metal adducts of acetophenone anil
Authors: Smith James G. , Veach C. Doreen
Published: May 2006

Contrary to previous reports, the reaction between acetophenone anil and sodium produces a product containing one atom of sodium per mole of anil. In its chemical behavior, this adduct appears to consist of equal parts of N-sodio-N,1-diphenylethylamine and α-sodioacetophenone anil. Thus, treatment with an alkyl halide results in products derived by alkylation of the nitrogen atom of N,1-diphenylethylamine and alkylation of the methyl group of acetophenone anil.The behavior of acetophenone anil towards lithium is quite different and very solvent dependent. In ether, hydrolysis of the lithium adduct produces a dimer, N,N′,2,3-tetraphenyl-2,3-butanediamine. In tetrahydrofuran with either lithium or potassium, another dimer, N,N′,l,4-tetraphenyl-1,4-butanediamine, is formed by dimerization through the methyl group of acetophenone anil. The structure of this new dimer was established by separation of the diastereomers and cyclization of each to the corresponding 1,2,5-triphenylpyrrolidine.The mechanism by which these products are formed is discussed.
Solvent and substituent effects on the H–19F coupling constants of some substituted fluorobenzenes
Authors: Hutton H. M. , Richardson B. , Schaefer T.
Published: May 2006

JoHF and (JoHF + JmHF) in some substituted flurobenzenes increase algebrically as the dielectric constant of the medium increases. Benzene solvent also causes a substantial increase in these parameters. JpHH, JpHF, JmHH, and (probably) JmFF are independent of solvent. Because (JoHF – JmHF) normally lies between 2 and 3 c/s, deceptively simple spectra often occur because of the magnitudes of the other coupling constants involved. A substituent X, whose electronegativity (EX) is greater than EH, reduces (JoHF + JmHF) if it is para to F, but increases (JoHF + JmHF) if it is ortho or meta to F. There is a need for accurate studies under controlled solvent conditions if patterns in substituent effects are to be observable.
Electrolysis of α-bromocarboxylic acids
Authors: Woolford R. G. , Soong Judy , Lin W. S.
Published: May 2006

The electrolysis of α-bromovaleric, α-bromocaproic, α-bromodiethylacetic, and α-bromoisobutyric acids in both methanol and water has been studied. This represents the first detailed study of the behavior of α-halocarboxylic acids during Kolbe electrolysis.Under the experimental conditions, Kolbe dimer of the α-bromoacid is not produced, even in small amounts, in either solvent. In methanol, hydrogen ester and bromoester were the major electrolysis products. In water, straight-chain acids gave alkyl halide, 1,1-dibromoalkane, and Kolbe dimer of hydrogen acid, whereas branched-chain acids gave ketone and other products from bromination of the ketone. In both solvents, considerable free bromine was produced.
Ionization of acetylene and its electronic energy levels
Authors: Collin Jacques E. , Delwiche Jacques
Published: May 2006

The ionization processes in acetylene under photon, electron, ion, and metastable atom impact, including new results, are critically discussed in relation with the electronic structure of acetylene and with the known spectroscopic information. It is shown that the first ionization potential at 11.409 eV corresponds to a 1 πu electron removal and that Franck–Condon processes yield an adiabatic ionization potential in this particular case. The new production of ions around 13.25 eV and 14.5–15 eV is due to pre-ionized states probably optically forbidden. From the discussion it is suggested that these might be excited linear σg πu4 πg* or σg πu4 πu* states. The second ionization potential of acetylene, related to the removal of a 3 σg electron, is shown to be around 16.5 eV.
The four trans chlorohydrins of 3-methoxycyclohexene
Authors: Langstaff E. J. , Hamanaka E. , Neville G. A. , Moir R. Y.
Published: May 2006

trans-3-Methoxycyclohexene oxide (II), when treated with ethereal hydrogen chloride, gives the chlorohydrin dl-1α-chloro-2β-hydroxy-3α-methoxycyclohexane (IVa), and the cis oxide III gives dl-1β-chloro-2α-hydroxy-3α-methoxycyclohexane (Va). The point of scission of the oxide ring (remote from the methoxyl) is therefore the same as in other reactions observed by ourselves and others. The reaction of 3-methoxycyclohexene (I) with N-chlorosuccinimide and water at 100° gives three chlorohydrins: dl-1β-chloro-2α-hydroxy-3α-methoxycyclohexane (VI), dl-2β-chloro-1α-hydroxy-3α-methoxycyclohexane (VIa), and dl-2α-chloro-1β-hydroxy-3α-methoxycyclohexene (VIIa) (approximately in the ratio 10:38:50, respectively). Two of the chlorohydrins were solids, and the homogeneity of the liquid isomers was demonstrated in several ways. The structures were proven by the nuclear magnetic resonance spectra of the p-nitrobenzoates, and by chemical methods. The results are of considerable interest with regard to the theory of addition and substitution reactions. There is a close parallel with the results in the bromohydrin series.
Biosynthesis of dictamnine. The origin of the quinoline nucleus
Authors: Monković Ivo , Spenser Ian D. , Plunkett A. O.
Published: May 2006

The biosynthesis of dictamnine, a furoquinoline alkaloid, was studied in intact Dictamnus albus plants. The quinoline ring system is derived from anthranilic acid and acetate. Tryptophan is not a precursor. Anthranilic acid concentration appears to control the rate of dictamnine biosynthesis in intact D. albus.
Gas chromatographic studies of isotopically labelled ethylenes
Authors: Atkinson J. G. , Russell A. A. , Stuart R. S.
Published: May 2006

The use of long, silver nitrate – ethylene glycol gas chromatographic columns has permitted a near base line separation to be achieved for deuterated olefins differing by only one deuterium atom. All of the six deuterated ethylenes and two deuterated butenes have been studied, and good separations have been obtained between the different isotopic species. The isotope effects (KD/KH) on the retention times have been calculated. Evidence of a difference in the relative retention times of two of the ethylene-d2 isomers is presented for the first time. It has been demonstrated that the isotopic content of deuterated olefins can be determined by quantitative analysis with the same accuracy as by mass spectral analysis. A careful study of ethylene-13C failed to reveal an observable isotope effect on its retention time relative to light ethylene.
Rapeseed meal autolysis. Formation of diastereomeric (2R)-1-cyano-2-hydroxy-3,4-epithiobutanes from progoitrin
Authors: Daxenbichler M. E. , VanEtten C. H. , Tallent W. H. , Wolff I. A.
Published: May 2006

When defatted seed from Brassica napus L. var. Regina II (a rapeseed) was autolyzed, its major thioglucoside (progoitrin) underwent degradation analogous to that for epiprogoitrin in Crambe abyssinica seed meal. Depending on the conditions, (R)-1-cyano-2-hydroxy-3-butene and the diastereomeric forms of (2R)-1-cyano-2-hydroxy-3,4-epithiobutane were formed in autolyzed B. napus meal instead of (S)-goitrin. The configuration at the chiral center containing the hydroxyl is assigned on the basis of known data. The configuration at carbon 3 of the episulfides is predicted on the basis of the optical rotatory dispersion data.
Molecular orbital calculations for conjugated molecules containing boron and nitrogen
Authors: Baird N. C. , Whitehead M. A.
Published: May 2006

The Π-electron networks in boron–nitrogen chains and rings have been treated by l.c.a.o.–m.o. techniques. The results for B—N chains predict a very weak alternation of bond order, smaller charges on the terminal atoms than on the internal atoms, and very little conjugation across B—B and N—N linkages. The calculations for the B—N rings predict an absence of a "4n + 2" pi-electron rule for aromaticity and a predominance of exocyclic over endocyclic Π bonding in the substituted rings. These results are compared with the properties of known B—N chains and rings and are contrasted with l.c.a.o.–m.o. calculations for the analogous carbon–carbon systems.
Constraints on the determination of stability constants for metal complexes. I. Bipyridyl and phenanthroline complexes
Authors: McBryde W. A. E.
Published: May 2006

A discrepancy is known to exist between stability constants for nickel and copper(II) complexes with 2,2′-bipyridyl and 1,10-phenanthroline determined on the one hand by a partition method and on the other by the method of hydrogen-ion balance. The latter method is shown to be incapable of precisely defining pL above a certain value, namely about pKa + 2. Part of the formation curves of the complexes whose stability constants are in dispute are beyond these critical values of pL, and so cannot be determined from pH measurements. Additional data support the accessibility of higher pL values through partition measurements. Values of pKa for bipyridyl are given for various concentrations of sodium perchlorate background at 25 °C.
Constantes de stabilité de thiocomplexes et produits de solubilité de sulfures de métaux. II Sulfure de zinc
Authors: Gubeli A. O. , Ste-Marie J.
Published: May 2006

A mathematical treatment of solubility curves of sulfides is introduced for the determination of formation constants of complexes in solution. As an example, this theoretical method is used in the determination of the species in equilibrium in solution with a precipitate of zinc sulfide (β-ZnS). The excess of sulfide in solution varies from 0.0004 M to 0.01 M. The presence of Zn2+ is noted in acidic solution, followed by the presence of ZnS.H2O or Zn(HS)(OH) for the rest of the pH scale. The solubility product of ZnS and the formation constant of Zn(HS)(OH) are given for an ionic strength 1.0 (NaClO4) at 25 °C.
A non-stereospecific alkene hydroxylation. Stereochemistry of the ring opening of dl-cis- and dl-trans-N,N-dimethyl-3-phenylglycidamide by acids
Authors: Chan S.O. , Wells E. J.
Published: May 2006

Attempts to prepare dl-erythro-N,N-dimethyl-2,3-dihydroxy-3-phenylpropionamide by the usual organic peracid hydroxylation of dl-trans-N,N-dimethylcinnamamide gave unexpectedly a 40:60 mixture of both diastereomers, the threo form being predominant. The anomaly prompted a closer investigation of each of the intermediate stages in the overall hydroxylation process. Epoxidation of dl-trans-N,N-dimethylcinnamamide by monoperphthalic acid gave only dl-trans-N,N-dimethyl-3-phenylglycidamide. Opening of the epoxide ring by acids gave a mixture of dl-erythro and dl-threo diols in a ratio of 40:60. cis-N,N- Dimethyl-3-phenylglycidamide, when subjected to the same ring-opening processes, also gave a mixture, but in a ratio of 75:25.
Cyclodehydration of certain β-hydroxyketones to substituted aromatic hydrocarbons
Authors: Canonne P. , Holm P. , Leitch L. C.
Published: May 2006

A series of β-hydroxyketones, CH3CR(OH)CH2COCH3, has been converted into substituted aromatic hydrocarbons in 80–90% yields by a double dehydration with cyclization in the presence of acids. The nuclear magnetic resonance spectra of the compounds, several of which are new, have been measured.
Novel oxidations of methyl glycopyranosides by periodic acid in dimethyl sulfoxide
Authors: Yu R. J. , Bishop C. T.
Published: May 2006

The following methyl glycopyranosides reduced only 1 mole of oxidant when oxidized by periodic acid in dimethyl sulfoxide: methyl β-l-arabinopyranoside, methyl α-d-lyxopyranoside, methyl β-d-ribopyranoside, methyl β-d-xylopyranoside, methyl α-d-galactopyranoside, methyl α-d-glucopyranoside, methyl α-d-mannopyranoside, and methyl α-l-rhamnopyranoside. A polysaccharide, Dextran 500 (an α, 1 → 6 linked glucan), also reduced only 1 mole of oxidant per anhydrohexose unit when oxidized under the same conditions. Selective cleavage of the C2—C3 bond was observed in the oxidations of the lyxoside, riboside, xyloside, and rhamnoside. The C3—C4 bond was oxidized specifically in the arabinoside and galactoside. Nonselective oxidation occurred in the glucoside, mannoside, and dextran. Rapid cyclization of the initial oxidation products to give an intramolecular hemiacetal is the probable explanation of the limited oxidations in dimethyl sulfoxide. The product of such a cyclization was isolated as a crystalline acetate from the oxidation of methyl β-l-arabinopyranoside, and its structure was established by nuclear magnetic resonance spectroscopy. Most of the stereoselective oxidations could be explained by assuming that vicinal glycol groups in an axial–equatorial orientation were oxidized faster than those in an equatorial–equatorial arrangement.
Preparation and characterization of Zn(II), Cu(II), and Fe(III) fluorosulfates
Authors: Goubeau J. , Milne J. B.
Published: May 2006

Zinc, cupric, and ferric fluorosulfates have been prepared. The Raman and infrared spectra of potassium fluorosulfate and the infrared spectra of calcium, zinc, cupric, and ferric fluorosulfates have been measured from 33 to 4 000 cm−1. Evidence for covalent bonding in the cupric and ferric fluorosulfates has been found. The magnetic properties of cupric and ferric fluorosulfates have been studied, and ferric fluorosulfate has been found to be magnetically concentrated. The thermal decomposition of zinc, cupric, and ferric fluorosulfates is reported.
The inhibited autoxidation of styrene. Part VII. Inhibition by nitroxides and hydroxylamines
Authors: Brownlie I. T. , Ingold K. U.
Published: May 2006

The inhibition of the oxidation of styrene by the stable aliphatic nitroxide radical, 2,2,6,6-tetramethyl-4-piperidone nitroxide (I), and two stable aromatic nitroxide radicals, 4,4′-dimethoxydiphenyl nitroxide (II) and 4,4′-dinitrodiphenyl nitroxide (III), has been studied. The aromatic nitroxides react with both alkyl (R·) and peroxy (RO2·) radicals, but the aliphatic nitroxide only reacts with alkyl radicals. The hydroxylamines derived from I and II react only with peroxy radicals. They are quite effective oxidation inhibitors, exhibiting a deuterium kinetic isotope effect kH/kD ~ 2−3. The hydroxylamine from III inhibits the oxidation of styrene for a short time and then becomes an extremely powerful oxidation catalyst. It is suggested that a product from this hydroxylamine undergoes a rapid chain-branching reaction with styrene.
Steroids. XI. The solvolysis of the epimeric 4-ethyl-4-methylcholesteryl methanesulfonates
Authors: Just George , Hall Norman D. , Richardson Keith St. C.
Published: May 2006

The buffered hydrolysis of 4β-ethyl-4α-methylcholest-5-en-3β-yl mesylate and 4α-ethyl-4β-methylcholest-5-en-3β-yl mesylate has been studied. Both reactions resulted in a predominance of ring-contracted products accompanied by small, but significant, amounts of products derived from stereospecific alkyl shifts. A chair–boat equilibrium is postulated to explain these results.
The utility of the dehalogenation–deetherification sequence for the proof of structure of methoxyhalocyclohexanols and methoxyhalocyclopentanols. Synthesis of the cis- and trans-2- and -3-methoxy-cyclohexanols and -cyclopentanols
Authors: Bannard R. A. B. , Casselman A. A. , Langstaff E. J. , Moir R. Y.
Published: May 2006

An unequivocal proof of structure for the methoxychlorocyclopentanols (I′c–IV′c) was obtained by deetherification with 68% hydrobromic acid at 65–70°, followed by hydrogenolysis with Raney nickel and hydrogen, to the 1,2- and 1,3-cyclopentanediols, in the same manner as the methoxybromocyclohexanols (I–IV) were converted into the 1,2- and 1,3-cyclohexanediols. Hydrogenolysis of the methoxybromocyclohexanols and the methoxychlorocyclopentanols provided stereospeciflc syntheses for the cis- and trans-2- and -3-methoxycy-clohexanols and -cyclopentanols in 80–97% yields. Deetherification of the latter compounds with 68% hydrobromic acid gave the corresponding 1,2- and 1,3-cyclohexanediols and 1,2-cyclopentanediols in 70–90% yields, but only 5–7% yields of the 1,3-cyclopentanediols. For the proof of structure of methoxyhalocyclanols, deetherification should therefore precede, rather than follow, dehalogenation.
Vibration–rotation spectrum of germyl iodide-d3
Authors: Griffiths James E.
Published: May 2006

The vibration–rotation infrared absorption spectrum of germyl iodide-d3 has been recorded under medium resolution conditions. The fine structure in the doubly degenerate bands was resolved and analyzed.From an assumed B″ value of 0.051 cm−1, values for A″, A4′, A5′, A6′, ζ4′, ζ5, and ζ6 were calculated. The fundamental frequencies for GeD3I were found to be 1 509.9, 582.8, and 249.5 for the a1 species and 1 529.5, 614.5, and 405.6 cm−1 for the e species. Only the results for ν4 and ν5 differ appreciably from earlier estimates.
Concerning the existence of perchloratopentamminecobalt(III) perchlorate
Authors: Jones W. E. , Swaddle T. W.
Published: May 2006

Contrary to earlier reports, treatment of aqueous chloropentamminecobalt(III) ion with silver oxide and then with perchloric acid yields aquopentamminecobalt(III) perchlorate, and not perchloratopentamminecobalt(III) perchlorate. No detectable inner-sphere substitution of perchlorate for water in aquopentamminecobalt(III) ion takes place in aqueous perchloric acid of up to at least 5 M concentration at 25°. Solid aquopentamminecobalt(III) perchlorate is stable at 110°, but heating above 160° results in slow general decomposition to Co3O4 without the intermediate formation of perchloratopentamminecobalt(III) perchlorate; the solid explodes violently at 290°.
Rotational barrier in dithiocarbamate esters
Authors: Holloway C. E. , Gitlitz M. H.
Published: May 2006

Four N,N -dialkyldithiocarbamate esters have been prepared and examined by nuclear magnetic resonance. From the temperature variation of the N-alkyl resonances, estimates of the barriers to rotation about the C—N bond have been made. Activation energies of the order 10 to 12 kcal provide evidence for an appreciable amount of C—N double bonding; this lends support to the assignment of the "thioureide" band in present and earlier infrared studies.
Mercury-photosensitized decomposition of dimethyl ether. Part III. The combination of radicals
Authors: Loucks Leon F.
Published: May 2006

As part of the study of the mercury-photosensitized decomposition of dimethyl ether, the combination of methyl radicals has been investigated in the temperature range 200 to 300 °C and at pressures between 3 and 300 mm Hg. For pressures of less than 100 mm the second-order rate coefficient for the combination of methyl radicals shows a pressure dependence. The pressure dependence agrees qualitatively with that observed by others, but occurs at somewhat higher pressures. Calculations for the Kassel equation using the Arrhenius parameters for ethane decomposition and fitted to the pressure dependence of the methyl radical combination show that the number of effective modes for ethane decomposition is 8 or 9. Carbon dioxide was found to be a quite ineffective third body for energy transfer. The results for the mercury-photosensitized decomposition of dimethyl ether have also been analyzed to obtain information about the combination of methyl radicals with methoxymethyl radicals. The combination of these radicals becomes pressure dependent at pressures less than about 15 mm. Kassel integrations based on the rate constant

[Formula: see text]for the unimolecular decomposition of methyl ethyl ether at the C—C bond, and fitted to the observed pressure dependence of the combination reaction, lead to s = 10 for these reactions.The rate constant for the abstraction of a hydrogen atom by a methyl radical from dimethyl ether was found to be

[Formula: see text]
Spectrophotometric studies on surfactants. I. Interactions between cationic and anionic surfactants
Authors: Scowen R. V. , Leja J.
Published: May 2006

Interactions taking place in aqueous solutions when cationic surfactants, alkyl trimethyl ammonium bromides (CnTABs, dodecyl or octadecyl), are added to solutions of anionic surfactants, like alkyl dithiocarbonates (xanthates, hexyl or nonyl) and dodecyl sulfate or laurate ions, result either in the formation of 1:1 complexes or in mixed micelles. Infrared and ultraviolet spectra show that complexes are largely ionic, with some perturbations of bonds in anions and a limited hydrolysis in the case of laurate ions.
Use of a Grignard reagent to lengthen a triose carbon chain
Authors: Walton D. J.
Published: May 2006

The addition of vinylmagnesium chloride to 2,3-O-isopropylidene-d-glyceraldehyde (I) gave a mixture of the epimeric pentene derivatives II and V, which were separated by preparative gas–liquid chromatography. Ozonolysis and subsequent deketalization of the individual epimers gave d-threose and d-erythrose, respectively, in yields of ca. 40%. This represents a method of lengthening an aldose carbon chain by one carbon atom.
Nuclear magnetic resonance studies. XV. Conformational free energy of the formyl group
Authors: Buchanan G. W. , Stothers J. B. , Wu Siu-Tzyy
Published: May 2006

Proton spectroscopy has been employed to determine the conformational free energy (− ΔG0) of a formyl group bonded to a cyclohexane ring. The cis- and trans-4-t-butyl derivatives were used as models for the axial and equatorial formyl groups in cyclohexanecarboxaldehyde and 1-methylcyclohexanecarboxaldehyde. The wiggle-beat technique was used to determine the spectral line positions and separations because of the relatively small differences involved. The − ΔG0 values were found to be relatively insensitive to solvent polarity and concentration over the range 10–50 mole %. For 10 mole % solutions the average value of − ΔG0CHO was found to be 1.38 kcal/mole.
Organotin sulfides
Authors: Midgal Shmuel , Gertner David , Zilkha Albert
Published: May 2006

"Interfacial" conditions were used for the preparation of organotin sulfides, tetraalkyl- or tetraaryl-dichlorodistanthianes, and similar compounds having a polysulfide linkage between two tin atoms. The compounds were prepared by reaction of sodium sulfide or sodium polysulfide in aqueous solution with various molar ratios of dialkyl- or diaryl-tin dichlorides dissolved in petroleum ether or methylene dichloride. The new compounds were found to be less stable than the corresponding distannoxanes.
Kinetic studies of a phenoxy radical intermediate using optical and electron spin resonance spectroscopy
Authors: Ayscough P. B. , Russell K. E.
Published: May 2006

The reaction between 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 4-isopropyl-2,6-di-t-butylphenol has been studied by optical and electron spin resonance methods. The concentration of the intermediate 4-isopropyl-2,6-di-t-butylphenoxy radical, determined by electron spin resonance spectroscopy, rises fairly rapidly to a maximum value and then decays relatively slowly. Addition of 2,2-diphenyl-1-picrylhydrazine (DPPH-H) reduces the maximum concentration of phenoxyl but does not significantly change the initial rate of production of the intermediate.The kinetic results are interpreted in terms of a reversible primary reaction between DPPH and the phenol to give DPPH-H and the phenoxy radical. The phenoxyl can disappear by reaction with itself or with a second molecule of DPPH. The rate constant for the primary step at 20 °C is 0.18 ± 0.02 l/(mole s) and for the reverse reaction is 1.34 ± 0.2 l/(mole s); the rate constant for the reaction between 4-isopropyl-2,6-di-t-butylphenoxyl and DPPH is 0.68 ± 0.2 l/(mole s) at 20 °C. The activation energies for the respective reactions are 6.8 ± 0.6, 6.0 ± 1.0, and 6.4 ± 1.5 kcal/mole.
Kinetics of acid dissolution of an orthochlorite mineral
Authors: Ross G. J.
Published: May 2006

Measurements were made of the effect of temperature on the rate at which Mg, Fe, and Al were dissolved from clinochlore, a Mg-rich orthochlorite mineral, by acid. The Mg, Fe, and Al were dissolved at the same rate with the same activation energy of 21 kcal/mole. The data indicated that the reaction proceeded from the particle edges inwards and was controlled by diffusion.
Mechanism of thermal decomposition of dibenzhydryl oxalates
Authors: Warkentin J. , Singleton D. M.
Published: May 2006

Dibenzhydryl oxalate and several of its para-substituted analogs were thermally decomposed in diphenylmethane, diphenyl ether, and in α-chloronaphthalene solution. Evolution of gas (mainly CO2) was approximately first order, both rate and stoichiometry being poorly reproducible. Rates are correlated with σ+-substituent parameters, with ρ = −1.6 at 230.2°. The 13C/12C and 18O/16O isotope effects involved in CO2 formation were measured. It is concluded that thermolysis is a radical process with considerable polar character at the transition state and that the slow step involves concerted formation of one CO2 molecule, a diarylmethyl radical, and a carbodiarylmethoxy radical. The fate of the latter is primarily decarboxylation, but there is some decarbonylation and some trapping by diarylmethyl radicals. Tetraaryl ethane and CO2 are major products, the yield of the latter approaching 2 moles at high temperatures.
Correlations of substituent effects on proton and fluorine chemical shifts with inverse ionization potentials
Authors: Schaefer T. , Hruska F. , Hutton H. M.
Published: May 2006

The fluorine and proton chemical shifts in some geminally disubstituted vinylidene fluorides and ethylenes are discussed. For these compounds, at least, there are difficulties with an interpretation based on intramolecular time-dependent electric fields. On the other hand, the shifts correlate with the inverse ionization potentials of the substituents, indicating a paramagnetic effect arising from the second term in Ramsey's expression. It is suggested that the effect operates via the bonds and not across space. Methyl proton shifts in a series of substituted methyl compounds of group IV, V, and VI elements show similar correlations. A practical application of the correlation to spectral analysis problems is given.
Medium dependence of the proton chemical shift and H—H, H—F, F—F coupling constants in 1,1-difluoroethylene
Authors: Macdonald C. J. , Schaefer T.
Published: May 2006

The solvent dependence of the proton chemical shift, the geminal proton–proton, the cis and trans proton–fluorine, and the geminal fluorine–fluorine coupling constants in 1,1-difluoroethylene is reported for 25 solvents. The shift and the couplings involving protons depend primarily on the dielectric constant of the medium, but the Onsager reaction field model is inadequate to describe the changes observed. The fluorine–fluorine coupling depends also on dispersion interactions with the solvent molecules. A comparison with the solvent behavior of the spectral parameters of vinyl fluoride, 1-chloro-1-fluoroethylene, and trifluoroethylene indicates the importance, in varying degrees, of reaction field effects, hydrogen bonding, dispersion interactions, the orientation of the solute dipole moments, and the polarizability of specific bonds in the solute molecule in determining their solvent-induced changes.