bluuebunny/crossref_metadata_2025 huggingface dataset:
Sur la réduction par LiAlH4 de quelques dérivés du méthylène-3 camphre
Authors: Richer Jean–Claude , Pépin Yvon
Published: May 2006

not available
Reactions of nitro sugars. XVII. Koenigs–Knorr syntheses
Authors: Baer Hans H. , Rank Werner , Kienzle Frank
Published: May 2006

Starting from methyl 3-deoxy-3-nitro-β-D-glucopyranoside (1), the free sugar 3-deoxy-3-nitro-α-D-glucopyranose (2), its tetraacetate (3), and 2,4,6-tri-O-acetyl-3-deoxy-3-nitro-α-D-glucopyranosyl bromide (4) were prepared. Another sequence of reactions commencing with 1 gave the 6-O-trityl (6), the 2,4-di-O-acetyl-6-O-trityl (7), the 2,4,6-tri-O-acetyl (8), and the 2,6-di-O-acetyl (10) derivatives of 1, whereas the 2,4-di-O-acetyl derivative (9) could not be isolated in pure form because of acetyl group migration. Reaction of the bromide 4 with water, methanol, and benzyl alcohol, respectively, led to 2,4,6-tri-O-acetyl-3-deoxy-3-nitro-β-D-glucopyranose (5) and the corresponding methyl and benzyl β-D-glycosides (8 and 11). Condensation of 4 with 1,2,3,4-tetra-O-acetyl-β-D-glucopyranose (12), and condensation of tetra-O-acetyl-α-D-glucopyranosyl bromide (14) with the trityl compound 6, furnished derivatives of gentiobiose having a deoxynitro function at C-3′ (13) and C-3 (15), respectively.
Effect of the structure of phosphylating agents on their reaction with ethanolamine, an ambident nucleophile
Authors: Greenhalgh R. , Heggie R. M. , Weinberger M. A.
Published: May 2006

The reactions of a series of phosphylating agents (RR′P(O)X) with ethanolamine have been examined, and relative yields of the products from the nucleophilic amino and hydroxyl moieties determined. In general the amount of O-phosphylation increased as R and R′ were changed from dimethylamino through alkoxy to methyl and as the leaving group (X) was changed from OP(O)RR′ to CN. The only exceptions occurred when R was dimethylamino and X was Cl. When X was F, only O-phosphylation was observed. Thus, a wide range of essentially continuously varying selectivities was found.The results are discussed in terms of the amount of charge transfer involved in the formation of the transition state which is assumed to be determined by the electrophile. When the charge transfer is small, the contributions to the activation energy of such factors as solvation and ionization potential of the nucleophile are most important, resulting in N-phosphylation. As the amount of charge transfer increases, the energy of bond formation becomes the dominant factor and O-phosphylation is preferred.
Reactions of norbornen-7-one with Grignard reagents
Authors: Warkentin J.
Published: May 2006

The relative importance of addition and reduction, as well as the syn:anti selectivity of those processes, were determined for the reactions of five Grignard reagents with norbornen-7-one. Reduction is important or dominant in the reactions of Grignard reagents having β-hydrogen and there is a strong preference for the hydride transfer to occur from the syn face of the carbonyl group. Addition shows the analogous stereochemical preference with higher selectivity than reduction.
Free-radical reaction of cyanogen bromide with alkanes
Authors: Tanner Dennis D. , Lycan G. , Bunce N. J.
Published: May 2006

The photolysis of cyanogen bromide with cyclohexane yielded cyclohexyl bromide, hydrogen cyanide, and small amounts of cyanogen, while the benzoyl-peroxide-promoted reactions of cyanogen bromide with various alkanes yielded approximately equal amounts of alkyl bromides and alkyl cyanides, often in high yields. Both hydrogen cyanide and hydrogen bromide were shown to react with benzoyl peroxide and an added hydrocarbon to yield the corresponding alkyl cyanide and alkyl bromide. Possible reaction mechanisms for these reactions are discussed.
Photochemistry of nitroso compounds in solution. XV. Configuration and conformation of the enone oximes obtained from photoaddition of N-nitrosopiperidine to conjugated dienes
Authors: Chow Y. L. , Colón C. J. , Chang D. W. L.
Published: May 2006

In the presence of an acid, N-nitrosopiperidine photolytically adds to conjugated dienes to give 1:1 adducts in excellent yield. While the major products are the syn- and anti-isomers of piperidino α,β-unsaturated oxime derived from 1,4-addition, similar types of oximes derived from 1,2-addition are also obtained. The ratio of syn- and anti-oximes is determined by the relative configurational and the conformational stabilities of the two forms. The nuclear magnetic resonance (n.m.r.) chemical shifts and coupling constants provide useful information for the determination of the configuration and conformation of the oximes. A comparison of the n.m.r. data from α,β-unsaturated oximes indicates that the α-proton generally resonates at a lower field than the β-proton in contrast to the chemical shifts of α,β-unsaturated carbonyl compounds. The photoaddition of nitrosopiperidine to cycloheptatriene gave tropone oxime, probably through the elimination of piperidine from the 1:1 adduct.
2-Aminomethyl-benzhydrols
Authors: Freter Kurt , Götz Manfred
Published: May 2006

A series of 2-aminomethyl-benzhydrols (3) was prepared by-different methods; starting with substituted isoindolines (1), phthalides (4), or cyanobenzophenones (7).
Electron spin resonance studies of irradiated nitrous oxide
Authors: Smith D. R. , Seddon W. A.
Published: May 2006

The γ-radiolysis of N2O at 77 °K, or vapor phase irradiation with 1 MeV He+ ions followed by condensation at 77 °K, results in the formation and trapping of at least 4 paramagnetic species. Using isotopically labelled N2O these are identified as N2O+, NO2, NO3, and N. The latter assignment is reasonable on spectroscopic grounds but since this species arises exclusively from the central nitrogen of N2O it is difficult to describe its formation from established chemical reactions. The addition of H2O to the vapor phase experiments resulted in the trapping of O2−, while the addition of tetranitromethane or NO indicated the existence of O2− and O atoms, respectively. Possible reaction mechanisms are indicated.
Asymmetric syntheses of optically active α-amino acids by hydrocyanic acid addition to the optically active Schiff base
Authors: Patel Mahendra S. , Worsley Michael
Published: May 2006

The syntheses of L(+) and D(−) enantiomers of α-amino acids, norvaline, norleucine, and leucine, as their hydrochloride salts have been achieved in almost 100% optical purity and 40–60% overall yield.
Synthesis and polarographic studies of beta-substituted phenylcystine derivatives
Authors: Thibert R. J. , Patel C.
Published: May 2006

The synthesis of N-benzoyl-threo-β-p-substituted phenylcystine ethyl esters via azlactone intermediates is reported. A polarographic method for their determination using 0.1 M sodium acetate in anhydrous methanol as the supporting electrolyte was investigated. The relationship between the half-wave potential and the Taft polar substituent constant, σ*, was studied.
Phase relationships in lead sulfide – alkali chloride quasi-binary systems
Authors: Pelton A. D. , Flengas S. N.
Published: May 2006

Phase relationships in PbS–ACl (where A = Na, K, Rb, Cs) quasi-binary systems have been determined. These systems all show very large regions of liquid–liquid immiscibility. Cryoscopic calculations in PbS-rich solutions suggest that the alkali chloride dissolves in PbS partially as dissociated ions and partially as associated ion pairs.
Conformational interconversion of 3,3,5,5-tetramethylmethylenecyclohexane and related compounds
Authors: St-Jacques Maurice , Bernard Michel , Vaziri Cambyse
Published: May 2006

The proton magnetic resonance spectra of compounds 1 to 4 have been studied at various temperatures. The spectral changes observed for 2, 3, and 4 are interpreted in terms of interconverting chair conformations.
Rate of addition of bromine atoms to ethylene
Authors: Wong K. T. , Armstrong D. A.
Published: May 2006

The rate of combination of bromine atoms in the photosensitized hydrobromination of ethylene has been determined by the rotating sector technique. From this and kinetic data reported previously the rate constant for the addition of bromine atoms to ethylene in the presence of 380 Torr of propane as deactivating gas has been calculated to be 1.5 ± 0.3 × 10−14 cm3 molecule−1 s−1, independent of temperature in the range 15 to 35 °C. This result is discussed and compared with rate constants for other addition reactions to ethylene.
Coordination compounds of olefins with anhydrous silver tetrafluoroborate V. Complexes with some cyclic di- and oligo-olefins
Authors: Quinn H. W. , Vangilder R. L.
Published: May 2006

The following complexes of di- and oligo-olefins have been prepared and characterized: 2AgBF4•3-cyclopentadiene, AgBF4•cyclohexa-1,4-diene, AgBF4•cyclohexene-1,3-diene, 2AgBF4•3cyclohexa-1,3-diene, AgBF4•cyclohepta-1,3,5-triene hydrate, AgBF4•2cyclohepta-1,3,5-triene, AgBF4•2cycloocta-1,3,5-triene, AgBF4•2cycloocta-1,5-diene, AgBF4•cyclooctatetraene, and AgBF4•dicyclopentadiene.
Oxidative addition of substituted benzenethiols to trans-chlorocarbonylbis(triphenyl phosphine)iridium(I)
Authors: Senoff C. V.
Published: May 2006

A series of para-substituted benzenethiols have been shown to react with trans-IrCl(CO)(Ph3P)2 to form IrHCl(SC6H1Y)(CO)(Ph3P)2 where Y = NO2, Br, Cl, F, H, CH3, and CH3O. A good correlation between the νCO vibration in the infrared spectra of these complexes and the Hammett substituent parameter, σp, was observed indicating that the νCO vibration may be used to provide a measure of the transmission of the para-substituent's electronic effect to the central iridium atom.
Organic sulfur compounds. VI. Reduction of three α-(o-nitrophenylthio)ketones with sodium borohydride
Authors: Coutts R. T. , Matthias Sharon J. , Peel H. W.
Published: May 2006

Reduction of three α-(o-nitrophenylthio)ketones with sodium borohydride and palladium–charcoal gave mainly α-(o-nitrophenylthio)alcohols and, as minor products, α-(o-aminophenylthio)alcohols. Only two benzothiazines were formed. Bis[2-(3-phenyl-2H-1,4-benzothiazine)] was a minor product of the catalyzed reduction of ω-(o-nitrophenylthio)acetophenone whereas 1-(3,4-dihydro-4-hydroxy-3-oxo-2H-1,4-benzothiazin-2-yl)benzyl alcohol was the main product of the catalyzed reduction of α-benzoyl-α-(o-nitrophenylthio)acetate.
Pyrone studies. Photochemistry of triacetic acid lactone
Authors: Bedford C. T. , Forrester J. M. , Money T.
Published: May 2006

The irradiation of triacetic acid lactone in various solvents results in novel rearrangement to β-methyl-glutaconic acid derivatives. In benzene solution an efficient conversion to β-methylglutaconic acid anhydride occurs while in methanol solution a mixture of products is obtained whose structures represent retention and rearrangement of the original carbon skeleton. Results obtained from irradiation of the corresponding methyl ether of triacetic acid lactone in methanol solution are also described.
Studies of carbohydrate derivatives by nuclear magnetic double resonance. Part V. Some 1H–{1H} INDOR experiments
Authors: Burton R. , Hall L. D. , Steiner P. R.
Published: May 2006

A simple modification is described which enables a Varian HA-100 spectrometer to be used routinely for 1H–{1H} internuclear double resonance experiments. Several examples are given to illustrate the results which may be obtained via this technique, with particular emphasis on carbohydrate derivatives.
Electron spin resonance studies of radiation damage. Part III. Gamma irradiated acetonitrile
Authors: Sargent F. P.
Published: May 2006

not available
Pyranosiduloses. II. The synthesis and properties of some alkyl 2,3-dideoxy-2-enopyranosid-4-uloses
Authors: Fraser–Reid Bert , McLean Angus , Usherwood E. W. , Yunker Mark
Published: May 2006

Ethyl 2,3-dideoxy-α-D-erythro-hex-2-enopyranoside (9a) an accessible and highly crystalline substance is selectively oxidized at the allylic position to ethyl 2,3-dideoxy-α-D-glycero-hex-2-enopyranosid-4-ulose (10a) in 80% yield. This hydroxyketone can be benzoylated, acetylated, and tosylated, and the resulting esters are all highly crystalline, as is the parent ketone. 3,4-Di-O-acetyl-D-xylal reacts with ethanol under boron trifluoride catalysis to give the anomeric mixture of ethyl 4-O-acetyl 2,3-dideoxy-D-glycero-pent-2-enopyranosides which may be separated after deacetylation. The deacetylated α-D anomer (14α) is readily oxidized by manganese dioxide to give an ethyl 2,3-dideoxy pent-2-enopyranosid-4-ulose (6-ethoxy-2,6-dihydropyran-3-one) (12); however, the corresponding β-D (14β) anomer resists oxidation. All of these ketones display a diagnostic nuclear magnetic resonance pattern consisting of clean doublets for H-1 and -3, and a doublet of doublets for H-2. Reduction of 10a with lithium aluminum hydride gives back the parent D-erythro alcohol exclusively, and catalytic hydrogenation saturates the olefinic double bond. These α,β-unsaturated ketones (10) in the hexose series are all levorotatory although their parent D-erythro alcohols (9) are strongly dextrorotatory; the saturated ketones derived from them are also strongly dextrorotatory. The epimeric D-threo alcohols which should also be oxidizable to 10 are however strongly levorotatory.
The radiation chemistry of carbon monoxide at very high dose rates
Authors: Willis C. , Miller O. A.
Published: May 2006

Carbon monoxide has been irradiated with single intense pulses from an electron accelerator at a dose rate of ~ 2 × 1027 eV g−1 s−1. The yield of carbon dioxide obtained was G(CO2) = 0.7 ± 0.1 with a very small yield of carbon suboxide, G(C3O2) ≤ 0.02.Addition of propene reduces the carbon dioxide yield to almost zero while addition of propane has no effect. This suggests that propene is acting as an oxygen atom scavenger rather than as a quencher of an excited state of carbon monoxide. However, rate constant data do not support this suggestion and it is concluded that the residual yield of carbon dioxide observed at high dose rates arises from reaction 9[Formula: see text]where CO+ is in an A2Π or B2Σ+ state.
Cinétique de relaxation des complexes Ce(IV).alcool
Authors: Boivin G. , Zador M.
Published: May 2006

Relaxation kinetics of Ce(IV). alcohol complexes has been studied. The rate constants of formation and dissociation have been determined and are found to depend on the nature of the alcohol: primary > secondary > tertiary. In addition, there is an increase in the rate with acidity; a mechanism is proposed to explain this.
New preparation of benzo-2,1,3-oxadiazoles (benzofurazans)
Authors: Prokipcak J. M. , Forte P. A.
Published: May 2006

A new procedure for the synthesis of substituted benzo-2,1,3-oxadiazoles (benzofurazans) has been established. The method involved the pyrolysis of substituted methyl N-(o-nitrophenyl)carbamates. A possible mechanism for the reaction is outlined.
Potassium fluoride catalyzed reactions between malononitrile and α, β-unsaturated ketones
Authors: ApSimon J. W. , Hooper J. W. , Laishes B. A.
Published: May 2006

The preparation and structure elucidation of the condensation products between malononitrile and a variety of α,β-unsaturated ketones using potassium fluoride as catalyst is described. If the carbonyl group of the α,β-unsaturated ketone is hindered, then Michael addition occurs. If, however, the carbonyl group is unencumbered, a Knoevenagel reaction appears to occur first which, in many cases, is then followed by conjugate addition and intramolecular condensation to yield compounds of unusual structure.
Kinetics of the pyrolysis of propylene. Part II
Authors: Simon M. , Back M. H.
Published: May 2006

Analysis of the products of the pyrolysis of propylene in the initial stages shows that products of molecular weight up to C9 are primary products of major significance below about 850 °K and above about 200 Torr. As these products accumulate in the system, their dissociation causes secondary initiation and a rapid increase in pressure. Measurements of the initial rate of decrease in pressure and of the final maximum rate of increase in pressure of the reaction are consistent with this interpretation of the mechanism.
Bicyclo[2,2,1]heptylphosphonates II. Stéréochimie de l'addition de Diels–Alder du vinylphosphonate de diméthyle sur quelques cyclopentadiènes; étude par r.m.n.
Authors: Callot Henry J. , Benezra Claude
Published: May 2006

The stereochemistry of the Diels–Alder addition of the vinylphosphonate (1) to cyclopentadiene, hexachlorocyclopentadiene (6), dimethoxytetrachlorocyclopentadiene (8), and pentachlorocyclopentadiene (10) has been studied. The configuration of the compounds has been proved by chemical correlation and essentially by n.m.r. spectroscopy. The study of the n.m.r. spectra confirms the 31P,1H vicinal coupling dihedral angular dependence and suggests an electronegativity range for the —P(O)(OCH3)2 group.
Studies on pyrylium and thiopyrylium salts
Authors: McKinnon D. M.
Published: May 2006

2H-Thiopyran-2-ones, 4H-thiopyran-4-ones, and 4H-pyran-4-ones may be reduced by lithium aluminum hydride to the corresponding thiopyranols or pyranols, which on treatment with perchloric acid are converted to pyrylium or thiopyrylium salts. The reaction fails with 2H-pyran-2-ones. Peracetate oxidation of 2H-thiopyran-2-thiones affords thiopyrylium salts, but with other pyran-2- and 4-thiones yields the corresponding ketones. The rearrangement of an acetylenic thiolester to thioflavone is described.
1,3-Dipolar cycloaddition reactions of 2-(2′-thienyl)aziridines
Authors: Lown J. W. , Matsumoto K.
Published: May 2006

The 1,3-dipolar cycloaddition of 2-(2′-thienyl)aziridines to a series of acetylenic and heteromultiple dipolarophiles leading to a series of new linked heterocycles is described. The versatility of these reactions suggests a general synthetic route to linked heterocycles.
The reaction of acetic acid and nitrogen dioxide
Authors: Pandey R. N. , Barton Donald
Published: May 2006

Nitric oxide was found to be an autocatalyst in the reaction of acetic acid and nitrogen dioxide at 470 and 527 °K in the vapor phase. The observed products, in addition to NO, were CO, CO2, and CH3NO2.
Pyrolysis of bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylic anhydride
Authors: Mamer O. A. , Lossing F. P. , Hedaya E. , Kent M. E.
Published: May 2006

The pyrolysis of the titled anhydride at low pressures and short contact times was found by both mass spectral and chemical experiments to involve an unusual decarboxylation to benzocyclobutenone. The latter subsequently decarbonylates to give a triad of C7H6 isomers: 5-vinylidenecyclopentadiene, ethynylcyclopentadiene, and benzocyclopropene. No evidence was found for dehydronorbornadiene, which would be expected on the basis of the pyrolysis of maleic anhydride or phthalic anhydride.
Preparation and properties of 5-nitro-, 7-nitro-, and 5,7-dinitrooxindole
Authors: Coutts R. T. , Hindmarsh K. W. , Mah E.
Published: May 2006

The preparation and the mass spectra of the title compounds are discussed.
The thermal decomposition of benzoic acid
Authors: Winter Keith , Barton Donald
Published: May 2006

The thermal decomposition of benzoic acid has been studied in a Pyrex reaction vessel at 475, 486, and 499 °C over the pressure range 5 to 40 Torr. The main products, CO2 and C6H6, were accompanied by smaller quantities of CO, H2, and biphenyl. The percentage of conversion varied from less than 1% for initial rate experiments to over 90 % in attempts to obtain a material balance. Moderately reproducible initial rates of formation of CO2 were obtained after the vessel had been conditioned by pyrolysis of benzoic acid. The order for the initial rate of formation of CO2, 1.20 ± 0.03 at 475 °C and 1.28 ± 0.04 at 499 °C, is discussed in terms of a combination of first and three-halves order reactions. Formation of both C6H5D and C6H6 in the presence of C6D5CD3 is accepted tentatively as evidence of formation of benzene by both molecular and radical processes.
Molar excess volumes in binary systems of n-hexadecane and 1-n-chloroalkanes at 25 °C
Authors: Heric E. L. , Coursey B. M.
Published: May 2006

The molar excess volumes at 25 °C in nine binary systems of n-hexadecane with 1-n-chloroalkanes from 4 through 18 carbons have been calculated from density measurements. The applicability of Brønsted and Koefoed's congruence principle to the excess volumes was investigated.
Fluorinated carbohydrates. Part VI. Studies of derivatives of 3-deoxy-3-fluoro-D-galactose
Authors: Brimacombe J. S. , Foster A. B. , Hems R. , Westwood J. H. , Hall L. D.
Published: May 2006

A synthesis of 3-deoxy-3-fluoro-D-galactose from 1,2:5,6-di-O-isopropylidene-α-D-gulofuranose is described. The 1H and 19F n.m.r. spectra of several derivatives of D-galactose and of its 3-deoxy-3-fluoro derivative have been assigned in accord with previously established stereospecific dependencies.
Reactions of Alkyl Halides in Fused Salt Media
Authors: Bailey R. A. , Prest S. F.
Published: May 2006

Passage of C1 to C5 haloalkanes through SnCl2–KCl melts results in halide exchange reactions, alkene formation, and rearrangement (including cyclization) reactions of the organic molecules. Relative reactivities, product distributions and melt composition effects are consistent with a carbonium ion mechanism in which the melt functions as a halide ion acceptor. Some control of product distribution by choice of Lewis acid character of the melt seems possible.
Nuclear Magnetic Resonance Study of Several Derivatives of 1,3,5,7-Tetramethyltricyclo[5.1.0.03,5]octane. Stereochemical Assignments by Nuclear Overhauser Enhancements
Authors: Gordon M. , Howell W. C. , Jackson C. H. , Stothers J. B.
Published: May 2006

Measurements of the nuclear Overhauser enhancements in the title series permit unequivocal assignments of the 6-substituent in a series of 1,3,5,7-tetramethyltricyclo[5.1.0.03,5]octan-2-ones and derivatives. Supporting evidence provided by long-range coupling interactions through four σ-bonds is also presented. The proton shifts in these systems appear to depend primarily on the degree of steric hindrance; this aspect is discussed.
Structure of the Acetone–Indanedione Adduct
Authors: Kuhn Stephen J. , Rae Ian D.
Published: May 2006

A compound formed by condensation of 2 mol of indanedione and 2 of acetone is shown to have structure 2. This reinterpretation, largely based on p.m.r. and i.r. evidence, is supported by the structures assigned to an enol acetate and a dihydro derivative of 2.
Extractive-photometric Investigation of Cadmium Chelates of 4-(2-Thiazolylazo)-resorcinol (TAR)
Authors: Navratil O. , Frei R. W.
Published: May 2006

A quantitative interpretation of the extractive distribution of cadmium chelates of TAR (= H2A) between liquid organic and water phases has been made and two groups of extractable species have been determined: (a) uncharged complexes of the type CdA in which co-ordinated water is replaced by suitable uncharged organic base (2,9-dimethyl-1,10-phenanthroline) and (b) charged complexes CdA22− which are extracted as ionic pairs in the presence of charged organic bases.The evaluation of the character of the bases and the effect of pH and the nature and concentration of other inorganic anions are presented.
The Heats of Solution and Related Thermodynamic Properties of Sodium Chlorate in Water and Water–Dioxane Mixtures
Authors: Campbell A. N. , Bhatnagar O.
Published: May 2006

The heats of solution of sodium chlorate in water, and in several water-dioxane mixtures, have been determined experimentally at concentrations of salt ranging from 0.01 molal to saturation. For the dilute region, a direct method was used but for the concentrated range the method was that of diluting the saturated solution. The free energy decreases due to dilution have been calculated from previously determined activity coefficients. Using these data, the entropy changes have been evaluated.The graph of heat of solution vs. concentration of sodium chlorate passes through a minimum for the solutions more concentrated in dioxane, but not for water and weak dioxane mixtures. A tentative explanation of this is offered.
Secondary Kinetic Isotope Effects in Bimolecular Nucleophilic Substitutions. IV. The Temperature Dependence of the Deuterium Effect for the Reaction of N,N-Dimethyl-d6-aniline and Methyl p-toluenesulfonate. Correlation of Isotope Effects on Activation Parameters
Authors: Leffek K. T. , Matheson A. F.
Published: May 2006

The temperature dependence of the isotope effect for the reaction of dimethylaniline and dimethyl-d6-aniline with methyl p-toluenesulfonate in nitrobenzene solvent has been measured, yielding the result, (ΔHD* − ΔHH*) = −134 ± 30 cal mole−1, (ΔSD* − ΔSH*) = −0.15 ± 0.09 cal mol–1 degree−1.This result has been compared with 15 other temperature dependence studies by plotting ΔΔH* per D atom vs. TΔΔS* per D atom. The points fall on two clearly separated straight lines. A similar correlation is found for a plot of ΔΔG* per D atom vs. ΔΔH* per D atom.The significance of the correlation is discussed and a possible rationalization, in terms of mechanism and particularly the role of the solvent is given.
Synthesis and Structure of 3-Methyl-1-phenyl-4-sulfhydrylbenzylidene-5-thiopyrazolone
Authors: Langler R. F.
Published: May 2006

The synthesis of 3-methyl-1-phenyl-4-sulfhydrylbenzylidene-5-thiopyrazolone (4) is reported. It is a potential sequestering agent as well as a new example of a β-dithiocarbonyl compound. The structure of 4 is unambiguously established by conversion to 4-benzoyl-3-methyl-1-phenyl-5-pyrazoIethiol (3).
Magnetic and Spectral Studies on Cobalt(II) Fluorosulfate
Authors: Taylor J. M. , Thompson R. C.
Published: May 2006

The magnetic moment of cobalt(II) fluorosulfate has been measured over the temperature range 312 to 120 °K and the results agree with theory for cobalt(II) in a regular octahedral ligand environment with λ equal to the free-ion value and no reduction in the magnetic moment due to electron delocalization. From its electronic spectrum, values of the ligand-field parameters Dq and B are estimated to be 765 and 860 cm−1, respectively. The infrared spectrum shows no distortion of the fluorosulfate groups from C3v symmetry.
X-Ray and Infrared Studies of Lead Apatites
Authors: Bhatnagar Vijay Mohan
Published: May 2006

The cell constants and infrared spectra of lead apatites have been investigated. The lowering of the molecular symmetry Td of the phosphate ion, and the nature and extent of changes in vibration frequencies of lead apatites with the ionic substitution of PO43− by AsO43− and VO43− are discussed.
Photolysis of 2,4,6-Tri-t-butylnitrobenzene
Authors: Barclay L. R. C. , McMaster I. T.
Published: May 2006

Photolysis of 2,4,6-tri-t-butylnitrobenzene gave 5,7-di-t-butyl-3,3-dimethyloxindole. The latter was synthesized by an unambiguous route from 3,3-dimethyloxindole. The mechanism of this intramolecular photocyclization is discussed.
Electrochemical Bifunctionalization of Olefins in the Presence of Halide Ions
Authors: Weinberg N. L. , Hoffman A. Kentaro
Published: May 2006

An electrochemical procedure has been developed for halofunctionalization of olefins, which allows for introduction of both nitrogen and oxygen containing substituents. The method obviates the need for silver salts or chemical oxidants, presently employed in analogous chemical routes. Thus 1-phenyl-2-butene on electrolysis in acetonitrile solution containing Et4NI, Et4NBr, or Et4NCl was converted to the corresponding haloamide derivative. In a related study, which extends the scope of electrochemical functionalization by nitrogen to negatively substituted olefins, dimorpholinization of trans-dibenzoylethylene was carried out by anodic oxidation of an acetonitrile solution of the olefin in presence of morpholine and Et4NI.
Synthesis of Paratose (3,6-Dideoxy-D-ribo-hexose) and Tyvelose (3,6-DiAeoxy-D-arabino-hexose)
Authors: Williams E. H. , Szarek W. A. , Jones J. K. N.
Published: May 2006

Convenient syntheses of the biologically important 3,6-dideoxyhexoses paratose (12) and tyvelose (8) from the readily available chlorodeoxy sugar methyl 4,6-O-benzylidene-3-chloro-3-deoxy-β-D-allopy-ranoside (1) are described.
Electronic Excited States of the Cyclic 1,4-Diaza-1,3-diene (Cyclic α-Diimine) System. Photochemical Reactions of 2H-Isoimidazole, 5,6-Dihydropyrazine, and 1,4-Diazepine Derivatives
Authors: Arnold D. R. , Abraitys V. Y. , Mcleod Jr. D.
Published: May 2006

The five-, six-, and seven-membered cyclic 1,4-diaza-1,3-dienes have been irradiated under a variety of conditions. The six-membered ring (dihydropyrazine) opens in a 6πe valence isomerization reaction. The resulting enediimine is stable at low temperatures and has been characterized (i.r.). Irradiation of 2,3,5,5-tetramethyl-5,6-dihydropyrazine (1b) results in formation of the enediimine 2b which reacts further to give the rearranged monomer 12 and/or dimers 13 depending upon the temperature. The five-and seven-membered systems are stable to irradiation in inert solvents. However, irradiation of 2,2-dimethyl-4,5-diphenylisoimidazole (10h) in isopropyl alcohol gives the dihydroderivative 19 and in tetramethylethylene the one-to-one adduct 25.The u.v. spectrum of the six-membered ring (5,6-dihydropyrazine) is very different from that of the five- and seven-membered rings. The long wavelength maximum (ca. 350 nm) of the six-membered ring is attributed to a transition directly into an excited state common to the enediimine 2 (i.e., the excited state has a node between C-5 and -6 of the dihydropyrazine).
Molecular Theory of Energy Conversion and of Initiation of Chemical Reactions in Solids
Authors: Melton Charles E.
Published: May 2006

A theory has been developed to describe the initiation of chemical reactions in solids. Two basic assumptions are made to formulate the model. First, the initiation of chemical reactions in solids ultimately results from the vibrational excitation of the individual molecules in the solid, and second, the lattice vibrations in a solid can be treated as pseudocollisions between the individual molecules in the lattice. In effect, the solid is treated as an ordered dense gas. These assumptions permit us to describe chemical reactions in a solid within the framework of collision theory. The resultant rate constant, k, depends on molecular and lattice parameters and on the temperature. It is of the form [Formula: see text], where N is the number of nearest neighbor molecules, b is the lattice spacing, v is the mean velocity of the individual molecules, and [Formula: see text]is the probability of translational–vibrational energy conversion.Conclusions based on the present model are in accord with qualitative results from a hard sphere model. For example, energy conversion (translational to vibrational) is many orders of magnitude greater in the region of a defect. Consequently, the probability for initiation of chemical reactions is orders of magnitude greater in the region of a defect.
Application of Proton Magnetic Resonance to Rotational Isomerism in Halotoluenes. VII. Barriers to Rotation and Conformational Preferences in α,α,α′,α′,2,4,5,6-Octachloro-m-xylene
Authors: Peeling J. , Goodwin B. W. , Schaefer T. , Wong C.
Published: May 2006

At low temperatures α,α,α′,α′,2,4,5,6-octachloro-m-xylene exists as three conformers in solution and the proton resonance spectrum can be assigned by comparison to the spectrum of α,α,α′,α′,2,4,6-heptachloro-m-xylene. The temperature dependent spectra of the former in toluene-d8 solution are fitted to computed spectra based on a set of coupled Bloch equations. The activation parameters for the rotation about the sp2–sp3 carbon–carbon bonds are Ea = 14.93 ± 0.13 kcal/mol, log A = 12.45 ± 0.09, ΔH≠ = 14.30 ± 0.14 kcal/mol, ΔS≠ = −2.0 ± 0.5 e.u., ΔG≠ = 14.9 ± 0.05 kcal/mol at 298 °K. The quoted errors are standard deviations.
Ions and Aggregates of Tetra-n-butylammonium Picrate in Nonaqueous Solvents at 25 °C: A Solvent Extraction Study
Authors: Goldman Saul , Cave G. C. B.
Published: May 2006

The values of ΔG0 at 25 °C were determined for the ionization, dimerization, and trimerization of tetra-n-butylammonium picrate (1) in benzene, chlorobenzene, and o-dichlorobenzene by a solvent extraction method. Corrections were applied for the presence of hydrates in the organic phase, in order to report ΔG0 values for the anhydrous solvents. In chlorobenzene, hexamers of 1 were also indicated in measurable concentrations. The various values of ΔG0 are related in a simple way to the bulk dielectric constant of the solvent.
Preparation of β-Cyclocitral
Authors: Gedye R. N. , Arora Parkash C. , Deck K.
Published: May 2006

An improved method for the preparation of pure β-cyclocitral by cyclization of citral anil with 95% sulfuric acid is reported. By avoidance of steam distillation of the reaction product, the formation of the by-products p-cymene and 1-acetyl-4,4-dimethyl-1-cyclohexene was prevented. The formation of this ketone by treatment of α- or β-cyclocitral anil with dilute sulfuric acid followed by steam distillation supports the mechanism proposed by Henbest et al.
Quinodimethane Analogs in the Pleiadene and Acepleiadene Systems
Authors: Lown J. W. , Aidoo A. S. K.
Published: May 2006

5,10-Dimethylene-5,10-dihydroacepleiadene and 7,12-dimethylene-7,12-dihydropleiadene have been synthesized. Their facile hydration to bridged epoxide structures suggests a non-planar boat structure in which they react as dienes. Evidence is presented for the base-catalyzed tautomerization of the former to the 18π peripheral aromatic 5,10-dimethylacepleiadylene. The isoelectronic diketone and methylene ketones in the acepleiadene series similarly tautomerize with potassium t-butoxide in dimethyl sulfoxide giving rise to stable radical anions.
Sur quelques réactions acide–base dans les solvants fortement basiques anhydres. III. n-Butylamine
Authors: Heumann W. R. , Šafařík L.
Published: May 2006

Cesium is the only alkali metal to react with n-butylamine, even at higher temperature. The n-butylamides of Na and K were prepared by heating the amine with the respective alkali hydrides. The amides were obtained as crystalline greyish white powders, which are stable when kept under pure nitrogen. The neutralization of a series of monobasic acids of various strength in n-butylamine by these amides was studied potentiometrically using a platinum indicating electrode. Potential jumps ranging from 1550 mV for hydrochloric acid to about 110 mV for diphenylmethane were obtained. The latter compound was the least acidic [Formula: see text] to react with the bases, while toluene [Formula: see text] did not react. The [Formula: see text] value of n-butylamine should therefore be about 37 to 38. Several dibasic acids and mixtures of two acids were also neutralized. The power of differentiation of the n-butylamine/butylamide system is quite pronounced, but in many cases potentiometric measurements were difficult due to precipitation of the salts formed. The neutralization of triphenylmethane produces an intense reddish orange color, which could be used as an indicator in visual titrations of weak acids with the n-butylamides.
Etude par spectroscopie infrarouge de mélanges binaires de l'eau avec quelques accepteurs de protons dans la région des vibrations de valence OH
Authors: Narvor Anne Le , Gentric Emilie , Saumagne Pierre
Published: May 2006

The i.r. spectra of binary mixtures of water (HDO and H2O) and four non-electrolyte cosolvants: acetonitrile, dioxane, dimethylsulfoxide, and hexamethylphosphorotriamide have been recorded from 3700 to 3100 cm−1, the mole fractions of water varying from 0 to 1. The investigation of the OH stretching bands of water suggests the presence of various types of hydrogen bonded complexes and confirms the existence of well-defined I–II complexes (one molecule of water bonded to two molecules of cosolvent) when Xwater < 0.1. In the range 0.8 < Xwater < 1 the organic cosolvent has negligible effect on the spectrum of water.
Syntheses of 3,3-Disubstituted 2-Arylacrylic Acids
Authors: Raap R. , Chin C. G. , Micetich R. G.
Published: May 2006

The syntheses of several 3,3-disubstituted 2-arylacrylic acids are described. The Wittig reaction between arylglyoxylic esters and isopropylidenetriphenylphosphorane provides an efficient route to 2-aryl-3-methylcrotonic esters. Bromination of these esters with N-bromosuccinimide gives a mixture of the 3-bromomethyl-2-arylcrotonic esters and -2-arylisocrotonic esters. The 3-bromomethylcrotonic esters upon heating cyclize to lactones. Also prepared were 2-aryl-3-azidomethylisocrotonic acids and 3-aminomethyl-2-phenylisocrotonic acid. A stereospecific route to 3-azidomethyl-2-phenylisocrotonic acid and cis-3-azidomethyl-2-phenyl-2-pentenoic acid has been developed starting from α-methyl- and α-ethylcinnamic esters.
The Number of Hydride Ions in AlH2Cl Available for Hydrogenolysis of 1,3-Dioxolanes
Authors: Davis H. A. , Brown R. K.
Published: May 2006

2-Methyl-1,3-dioxolane (1) in ether is hydrogenolyzed completely to 2-ethoxyethanol by an equimolar proportion of AlH2Cl, whereas a 1/2 mol of AlH2Cl hydrogenolyzes 1 mol of 1 only to the extent of 50%. In the latter case, the intermediate compound 2-ethoxyethoxyhydridoaluminum chloride (C2H5OCH2CH2OAlHCl) formed with half of the 2-methyl-1,3-dioxolane, even though it contains a hydride ion, fails to react with the remainder of the dioxolane. This is believed due to the preference of C2H5OCH2CH2OAlHCl to form an internal Lewis acid-base complex rather than form a similar complex with 1, a step essential to facilitate the hydrogenolysis of 1.
Mechanism of the Pyrolysis of Acetylene
Authors: Back M. H.
Published: May 2006

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[Formula: see text]and 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.
Ion–Molecule Reactions in Methyl Fluoride and Methyl Chloride
Authors: Herod A. A. , Harrison A. G. , McAskill N. A.
Published: May 2006

The reactions of the molecular ion have been studied as a function of the ion kinetic energy for methyl fluoride and methyl chloride. The following reactions are observed[Formula: see text]For methyl fluoride (X = F) reactions c and d have kinetic energy thresholds and become significant at high ion energies. For CH3Cl (X = Cl) reaction a is not observed and reactions c and d are of only minor importance at high ion energies. Rate coefficients for the molecular ions and a number of fragment ions as well as rate coefficients for further reaction of CH4X+ are reported.
The Pseudo Thermodynamics of Solvolysis. A Detailed Study of the Pressure and Temperature Dependence of Benzyl Chloride Solvolysis in t-Butyl Alcohol – Water Mixtures
Authors: Dickson S. J. , Hyne J. B.
Published: May 2006

The pseudo first order rate constants for the solvolysis of benzyl chloride in aqueous t-butyl alcohol (t-BuOH) are reported at 40.00, 50.25, and 60.50 °C at various pressures up to 4084 atm. From these data the first temperature derivatives (ΔH* and ΔS*), the first (ΔV*) and second pressure derivatives, ∂ΔV*/∂P, and the mixed second derivative, ∂ΔV0*/∂T, of the rate are evaluated. These activation parameters exhibit extremum behavior in the highly aqueous solvent region. This behavior is discussed in terms of solvent structure variation. The signs of the pressure dependence of ΔH* and ΔS* are shown to be consistent with those required by the Maxwell type relationships for classical thermodynamic systems.
Oxidative Degradation of a Podocarpic Acid Derivative
Authors: Ho Tse-Lok
Published: May 2006

The dichromate oxidation of methyl-7-methyl-6,8,11,13-podocarpatetraen-19-oate, (5), is reported.
Organobismuth Compounds. III. Preparation and Infrared Spectra of Triphenylbismuth(V) Derivatives of Dibasic Acids
Authors: Goel R. G. , Prasad H. S.
Published: May 2006

Triphenylbismuth carbonate, oxalate, sulfate, selenate, and chromate have been prepared and their solid state infrared (i.r.) spectra have been studied in the frequency region 4000 to 200 cm−1. The i.r. spectroscopic results indicate that, like the corresponding trimethyl- and triphenylantimony(V) derivatives, these compounds also have non-ionic polymeric structures containing bridging anion groups and five co-ordinate bismuth. The i.r. frequencies associated with the bismuth–anion stretching vibrations appear to occur at 300 cm−1 for the carbonate and below 300 cm−1 for the other compounds.
Fully Fluorinated Alkoxides. Part V. Derivatives of Tetrafluorocatechol
Authors: Macdonald Celia , Tomlinson A. J. , Willis C. J.
Published: May 2006

Tetrafluorocatechol (tetrafluoro-1,2-dihydroxybenzene) has been found to form isolable complexes with transition metals (Ni2+ Cu2+ and Fe3+, and with germanium, acting as a chelating, dinegative, ligand. These complexes are few in number and of limited stability, suggesting that tetrafluorocatechol has less applicability as a ligand than related highly halogenated organic molecules. Complexes of tetrabromocatechol with Ni2+ are also described.
Synthetic Studies of Hydronaphthacenic Antibiotics. I. The Synthesis of 4-Demethoxy-7-O-methyl Daunomycinone
Authors: Wong C. M. , Popien D. , Schwenk R. , Raa J. Te
Published: May 2006

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 daunomycin.
Structure of the Second Coordination Sphere of Transition Metal Complexes. III. Ion Pairing involving Cobalt Complexes
Authors: Eaton D. R. , Seville Linda , Jesson J. P.
Published: May 2006

The structure of the ion pair formed between Co(II) bistripyrazolylmethane ions and PF6− ions in acetonitrile solution has been investigated. Isotropic shifts observed in the 19F nuclear magnetic resonance (n.m.r.) spectra of the anion have been used for this purpose. It is concluded that the preferred position of the anion lies close to the symmetry axis of the cobalt complex and that a contact ion pair is involved. This result is contrasted with previous studies of second sphere coordination involving neutral molecules.
Dehydration of Amides to Nitriles Initiated by Hexamethylphosphoric Triamide
Authors: Monson Richard S. , Priest Deggary N.
Published: May 2006

Aliphatic and aromatic carboxamides are found to undergo ready dehydration in hexamethylphosphoric triamide at 220–240° affording the corresponding nitriles in good yield.
The Vibrational Spectra of Silane and Germane Derivatives. Part IV. The Infrared and Raman Spectra of the Iodo(methyl)germanes
Authors: Anderson J. W. , Barker G. K. , And J. E. Drake , Hemmings R. T.
Published: May 2006

The infrared and Raman spectra of the series of iodo(methyl)germanes, CH3GeI3, (CH3)2GeI2, and (CH3)3GeI have been recorded. A normal coordinate analysis based on a modified valence force field confirms the a priori assignments for all of the fundamental frequencies except the torsional modes.
Mouvements moléculaires et transitions de phases dans le perfluorométhylcyclohexane solide
Authors: Ban Buu , Chachaty C. , Renaud M. , Fourme R.
Published: May 2006

Solid Perfluoromethlycyclohexane has been studied by X-ray diffraction, n.m.r., and e.s.r. The two former methods confirm the existence of several thermodynamically stable crystalline phases between 77 °k and the melting point (234 °K): phase I (227 < T < 234 °K), phase II (173 < T < 227 °K), phased III (T < 173 °K) and that of a metastable phase (II′) below 130 °K. When the temperature is raised, the n.m.r., indicates successively the rotation of CF3 (phases II′ and III), the reorientation (phase I). Similar information is obtained from e.s.r. concerning the motions of [Formula: see text] radicals trapped in PFMCH.The comparison between g anisotropy, measured from the position of the peaks of e.s.r. spectra and that deduced from their second moments suggests a wide distribution of reorientaion correlation times for radicals in the metastable phase.
Base-catalyzed Degradations of Carbohydrates. I. Synthesis and Alkaline Degradation of 2-O-β-D-Glucopyranosyl-3-O-methyl-D-glucose
Authors: Aspinall G. O. , Khan R. , Pawlak Zofia
Published: May 2006

2-O-β-D-Glucopyranosyl-3-O-methyl-D-glucose has been synthesized by two routes. Alkaline degradation of the disaccharide, followed by reduction, hydrolysis under extremely mild conditions, and further reduction, affords D-glucitol, and 3,4-dideoxy-trans-erythro- and -D-threo-hex-3-enitol.
Sur l'aptitude à l'extension du noyau pipéridique en fonction de la substitution de l'atome d'azote: réaction du diazométhane avec quelques pipéridones-4 et désamination nitreuse des aminométhyl-alcools correspondants
Authors: Favre H. , Hamlet Z. , Lanthier R. , Ménard M.
Published: May 2006

Aptitude to ring expansion in the piperidine series, measured by the ratio of ring expanded ketone to epoxide, varies considerably according to the nitrogen atom substituent. This ratio is essentially the same in the case of the reaction of diazomethane on 4-piperidones and the nitrous acid deamination of the corresponding aminoalcohols. The values of the ratio are 0.01–0.1 for a phenylsulfonyl group, of the order 0.3–0.6 for a benzoyl group and slightly greater than 1 for a benzyl group. Electronic effects (inductive and field effects) are the cause of these differences. Parallels between the two reactions indicate that nucleophilic attack of diazomethane on the carbonyl group can lead to the ring expanded ketone and the epoxide.
Alkaline Epoxidation of Carbohydrate Nitroolefins
Authors: Baer Hans H. , Rank Werner
Published: May 2006

Action of hydrogen peroxide in a weakly alkaline medium upon nitroolefinic sugar derivatives led to α-nitroepoxides in excellent yields. Thus, methyl 4,6-O-benzylidene-2,3-dideoxy-3-nitro-α-D-erythro-hex-2-enopyranoside (1), its β-anomer 2, and its α-D-threo epimer 3 stereospecifically gave methyl 2,3-anhydro-4,6-O-benzylidene-3-C-nitro-α-D-mannopyranoside (6), the β-D-allo isomer 7, and the α-D-talo isomer 8, respectively. The corresponding β-D-threo olefin 4 produced a mixture of the β-D-gulo (9) and β-D-talo (10) epoxides, with 9 strongly preponderating. The β-D-gulo (11) and β-D-talo (12) derivatives were made from the enantiomer 5 of 4. Another route to α-nitroepoxides, originating from 3-bromo-3-deoxy-3-nitro sugars, furnished the β-D-manno isomer 13.
Acetonation of 3-Deoxy-3-nitro-D-glucose and Formation of a Derivative of 3-Deoxy-3-nitro-D-allose
Authors: Kovář Jan , Baer Hans H.
Published: May 2006

Reaction of 3-deoxy-3-nitro-D-glucose (1) with acetone and triethyl orthoformate in the presence of hydrogen chloride gave crystalline 3-deoxy-1,2-O-isopropylidene-3-nitro-α-D-glucopyranose (2), 3-deoxy-1,2:4,6-di-O-isopropylidene-3-nitro-α-D-glucopyranose (3), and 3-deoxy-1,2:5,6-di-O-isopro-pylidene-3-nitro-α-D-glucofuranose (5) in proportions varying with the acid concentration. The furanose derivative 5 is thermodynamically favored. Partial acid hydrolysis of 5 gave 3-deoxy-1,2-O-isopropylidene-3-nitro-α-D-glucofuranose (4), whereas action of mild base caused epimerization to 3-deoxy-1,2:5,6-di-O-isopropylidene-3-nitro-α-D-allofuranose(6).
Stereochemistry of Dehydrogenation by D-Galactose Oxidase
Authors: Maradufu A. , Cree G. M. , Perlin A. S.
Published: May 2006

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.