bluuebunny/crossref_metadata_2025 huggingface dataset:
STEREOCHEMISTRY AND SEVEN COORDINATION
Authors: Claxton T. A. , Benson G. C.
Published: May 2006

A method is described to calculate the equilibrium configuration of any number of identical particles restricted to a spherical surface and interacting with forces derivable from an inter-particle potential of the form r−n. It is shown that distributions of symmetry C2 are expected for seven particles when n is small. In certain cases, the model can be used to explain the shape of molecules of the type MXm. The importance of directed valence in these molecules is considered and the structure of IF7 discussed.
THE OXIDATION OF PHENOLS: I. THE OXIDATION OF 2,6-DI-t-BUTYL-4-METHYLPHENOL, 2,6-DI-t-BUTYLPHENOL, AND 2,6-DIMETHYLPHENOL WITH PEROXY RADICALS
Authors: Horswill E. C. , Ingold K. U.
Published: May 2006

Previous work on the oxidation of alkyl phenols with peroxy radicals is summarized. The yields of the peroxy-cyclohexadienones formed from 2,6-di-t-butyl-4-methylphenol in the α,α′-azo-bis-isobutyronitrile-initiated oxidation of tetralin at 40 °C have been measured quantitatively. The results suggest that not all the oxidation chains are initiated by isobutyronitrile peroxy radicals.The products from the oxidation of 2,6-di-t-butylphenol and 2,6-dimethyiphenol with (butyl peroxy radicals are found to be mainly dialkyl-p-benzoquinones and tetraalkyl diphenoquinones.
THE OXIDATION OF PHENOLS: II. THE OXIDATION OF 2,4-DI-t-BUTYLPHENOL WITH PEROXY RADICALS
Authors: Horswill E. C. , Ingold K. U.
Published: May 2006

Ten products from the oxidation of 2,4-di-t-butylpheuol with t-butyl peroxy radicals have been identified. They can be subdivided into three groups, depending on the type of radical–radical coupling reaction by which they are produced or in which their precursors are formed: (i) phenoxy–peroxy coupling, (ii) phenoxy–phenoxy coupling at the 6 positions, and (iii) phenoxy–phenoxy coupling through the oxygen atom of one radical and the 6 position of the second radical. Products resulting from still other phenoxy–phenoxy coupling reactions are undoubtedly formed in minor amounts.
STEREOCHEMICAL STUDIES: V. REARRANGEMENTS ACCOMPANYING ATTEMPTS TO EPIMERIZE 4-OXA-3-OXO-5α-CHOLESTANE AND 4-OXA-3-OXO-5β-CHOLESTANE BY BREWSTER AND KUCERA'S METHOD
Authors: Lunn W. H. , Edward J. T. , Meyerson Seymour
Published: May 2006

Epimerization of 4-oxa-3-oxo-5α-cholestane by Brewster and Kucera's method gave only a 23% yield of the 5β-lactone; several other compounds were formed, apparently via skeletal rearrangement during hydrolysis of the tosylate. The attempted epimerization of 4-oxa-3-oxo-5β-cholestane gave mainly unsaturated acids, but no 5α-lactone (a small amount of skeletal rearrangement also occurred). Both epimers undergo rearrangement to γ-lactones when treated with trifluoroacetic acid.Mass spectra, used in conjunction with infrared and nuclear magnetic resonance spectra and other data to make structural assignments, were found to be highly sensitive to certain structural features. In particular, they can usually distinguish sharply between molecules that contain a pendant ring structure and those that do not.
SULFONATE ESTERS OF α-CHLOROALDOXIMES, ALDOXIMES, AND AMIDOXIMES VIA "SULFENE" ADDITION
Authors: Truce W. E. , Naik A. R.
Published: May 2006

Reaction of aromatic nitrile oxides with methanesulfonyl and benzylsulfonyl chlorides in the presence of triethylamine yielded sulfonate esters of α-chloroaldoximes [Formula: see text]. Under the same reaction conditions, aldoximes yielded sulfonate esters, which decomposed to nitriles, and amidoximes yielded amidoxime O-sulfonates, which were also prepared by the action of ammonium hydroxide on [Formula: see text]. Chemical as well as nuclear magnetic resonance spectroscopic evidence confirms the formula [Formula: see text] for amidoximes.
A GENERAL METHOD FOR SELECTIVE N-METHYLATION OF SUBSTITUTED TRYPTAMINES
Authors: Horner J. Kenneth , Skinner W. A.
Published: May 2006

A general method for selective N-methylation of substituted tryptamines is described. The method involves the lithium aluminium hydride reduction of an intermediate carbamate. Eleven new tryptamines and 11 new carbamoyltryptamines are described.
KINETIC SULFUR ISOTOPE EFFECTS IN AROMATIC BROMODESULFONATION
Authors: Baliga B. T. , Bourns A. N.
Published: May 2006

Both bromodeprotonation and bromodesulfonation occur during aqueous bromination of sodium p-methoxybenzenesulfonate, A, and potassium 1-methylnaphthalene-4-sulfonate, B. Whereas for A the bromodeprotonation increases appreciably in amount as the bromide ion concentration is raised, this reaction takes place to a relatively small extent for the less reactive B. A reinvestigation of the kinetics of bromination and a determination of sulfate yields for both of these compounds over a range of bromide ion concentration of 0 to 0.5 M have been made to evaluate the individual rates of these two competing reactions. The kinetic data for the bromodesulfonation of A favor a two-step mechanism with Br2 as the brominating species, but are not considered to eliminate completely a one- or two-step process involving Br+ (or H2OBr+). For B, the kinetics allow either a one- or two-step mechanism with molecular bromine as the brominating agent.Kinetic sulfur isotope effects (k32/k34) have been measured for the bromodesulfonation of A at different bromide ion concentrations. The observed effects are: at [Br−] = 0, 0.3%; at [Br−] = 0.03 M, 1.3%; at [Br−] = 0.5 M, 1.7%. These results confirm the two-step mechanism favored by kinetics and allow the rejection of the alternate mechanism with Br+ (or H2OBr+) as the brominating species. A similar study of B gave the following results: at [Br−] = 0, 0.2%; at [Br−] = 0.25 M, 0.3%; at [Br−] = 0.5 M, 0.4%; at [Br−] = 2.0 M, 0.8%. These results establish the two-step mechanism for this compound and completely eliminate the alternate one-step process.
KINETIC HYDROGEN ISOTOPE EFFECTS IN AROMATIC BROMODEPROTONATION
Authors: Baliga B. T. , Bourns A. N.
Published: May 2006

The bromodeprotonation of sodium p-methoxybenzenesulfonate is an ordinary halogenation reaction in which a hydrogen ortho to the methoxy group is replaced by bromine. The kinetic data for this reaction do not distinguish between a one- and a two-step mechanism with Br2 as the brominating species. The two-step mechanism was confirmed by the observation of a variation in the kinetic hydrogen isotope effect, kH/kD, with changing bromide ion concentration. The observed isotope effects are 1.01, 1.07, 1.18, and 1.31 at bromide ion concentrations 0, 0.5, 1, and 2 M, respectively.The isotope effect study strongly establishes that in this reaction the small depression in rate produced by bromide ion, beyond that due to Br3− formation, arises mainly from a salt effect, and only a small amount of this depression is caused by return of the intermediate to reactants.
THE CHEMISTRY OF EPISULFIDES: I. THE REACTIVITIES OF PROPYLENE SULFIDE AND PROPYLENE OXIDE TOWARDS ANILINE
Authors: Isaacs Neil S.
Published: May 2006

The rates of reaction of propylene sulfide and propylene oxide with aniline have been measured at three temperatures between 30° and 50°. The episulfide is found to be the less reactive and has the higher activation energy. The results are interpreted as indicating a considerable degree of ring opening in the transition state, with the strain energy of the ring providing a considerable portion of the activation energy.
PARAMAGNETIC CENTERS IN IRRADIATED POTASSIUM SULFATE
Authors: Gromov V. V. , Morton J. R.
Published: May 2006

not available
THE ALKALOIDS OF FUMARIACEOUS PLANTS: LV. THE STRUCTURE OF CULARIDINE
Authors: Manske Richard H. F.
Published: May 2006

Cularidine, which on O-methylation yields cularine, has one phenolic hydroxyl group. It was O-ethylated with diazoethane, and the resultant O-ethylcularidine was degraded to asaronic and 4-ethoxyphthalic acids via sodium – liquid ammonia fission, O-methylation, double Hofmann degradation, and oxidation. These fragments prove the structure of cularidine to be that shown by III.
THE CORRELATION OF CHASMANINE WITH BROWNIINE
Authors: Edwards O. E. , Fonzes L. , Marion Léo
Published: May 2006

By means of oxidative and reductive fission, respectively, of the 7,15-bridge, the alkaloids browniine and chasmanine were converted into 7,15-seco-7,10-diketones. After epimerization of its C-6 methoxyl the diketone derived from chasmanine was identical with that obtained from browniine. This correlation confirms the structure previously tentatively assigned to chasmanine, and establishes its stereochemistry since browniine and lycoctonine have been interrelated.
REACTION OF THIOLS WITH EPOXIDES OF CONJUGATED 1,4-DIKETONES
Authors: Wilgus III H. S. , Frauenglass E. , Chiesa P. P. , Nawn G. H. , Evans F. J. , Gates Jr. J. W.
Published: May 2006

The reaction of thiols with 2,3-epoxides of bicyclo, conjugated 1,4-diketones was found to proceed readily to give the dehydrated thio-substituted enediones or their enolized isomers, depending upon the reaction conditions and the bicyclic bridging of the starting materials. In no case was a mixture of these isomers observed. Enediones generally resulted from these reactions with and without triethylamine catalysis, whereas the use of an equimolar amount of triethylamine generally gave hydroquinones. The ease of rearrangement of enedione to hydroquinone followed the order: 2,3-dimethylbutadiene adduct [Formula: see text] reduced cyclopentadiene adduct > cyclopentadiene adduct = 1,3-cyclohexadiene adduct.
LYCOPODIUM ALKALOIDS: XVII. MASS SPECTRA OF ANNOTINE AND SOME ANNOTINE DERIVATIVES
Authors: MacLean D. B. , Curcumelli-Rodostamo M.
Published: May 2006

The mass spectra of annotine and some of its derivatives are recorded and discussed. Fragmentation mechanisms are proposed to account for the formation of the major peaks in the spectra. The composition of the ions has been verified by measurement of the high-resolution spectra of four of the five compounds. The results lend support to the structure previously proposed for this alkaloid.
UTILIZATION OF SULFUR: SYNTHESIS OF SYMMETRICAL THIIRANES FROM KETOHYDRAZONES
Authors: Latif N. , Fathy I. , Mishriky N. , Haggag B.
Published: May 2006

Dispiro (xanthene-9,2′-thiirane-3′,9″-xanthene), dispiro(thioxanthene-9,2′-thiirane-3′,9″-thioxanthene), epithiobidiphenyleneethane, epithiotetraphenylethane, epithiotetra-p-anisylethane, and epithiotetra-p-tolylethane are directly synthesized by the base-catalyzed interaction of the corresponding ketohydrazones, elemental sulfur, and yellow mercuric oxide. The reaction mechanism is discussed. Epithiotetra-p-tolylethane is also obtained by the uncatalyzed reaction of sulfur with the corresponding diazoalkane.
THE ABSOLUTE CONFIGURATION OF THE IBOGA ALKALOIDS
Authors: Kutney James P. , Brown Richard T. , Piers Edward
Published: May 2006

not available
EFFECT OF α-METHYLATION ON THE PARAMETERS CHARACTERIZING HYDROLYSIS IN WATER FOR A SERIES OF HALIDES AND SULFONATES
Authors: Heppolette R. L. , Robertson R. E.
Published: May 2006

The aim of this work was to explore the effect of α-methylation on the reactivity and detailed mechanism of hydrolysis. Accordingly, rate data and derived parameters are given for the hydrolysis of a series of halides and sulfonates in water. From the differences in kinetic parameters, an attempt is made to infer further information relating structure and mechanism.
THE HYDROLYSIS OF SUBSTITUTED METHYL BENZENESULFONATES IN WATER
Authors: Robertson R. E. , Stein A. , Sugamori S. E.
Published: May 2006

Rate data and derived parameters for the hydrolysis of a series of para-substituted methyl benzenesulfonates are given. The introduction of such substituents has negligible effect on ΔCp≠, and the difference in rate is largely reflected in δXΔS≠.
THE PHOTOCHEMICAL DECOMPOSITION OF SODIUM AZIDE
Authors: Jacobs P. W. M. , Kureishy A. R. Tariq
Published: May 2006

When sodium azide is irradiated with ultraviolet light the rate of photolysis at first decreases and then becomes constant. Two reaction mechanisms are involved: the first occurs only in salt which has not previously been irradiated, whereas the second requires the presence of metallic sodium. These two reactions are interpreted as the formation and linear growth of nuclei in the dislocation network of the salt and an equation developed from this model gives good agreement with the experimental results. Incorporation of Fe3+ ions in NaN3 leads to a greater number of nucleus-forming sites.
THE RADIOLYSIS OF ALKALINE AQUEOUS SOLUTIONS CONTAINING HYDROGEN AND OXYGEN
Authors: Armstrong W. A.
Published: May 2006

The initial yields of H2O2 in aerated water, [Formula: see text] and in water containing H2 and O2, [Formula: see text] have been measured for alkaline solutions irradiated with 60Co γ-rays. [Formula: see text] decreases with increasing pH from a value of 1.22 in neutral solution to 0.63 in solutions of pH 13.92 and the relationship[Formula: see text]is valid over the pH range 7 to 14.[Formula: see text] decreases from 3.30 in neutral solution to a minimum of 2.00 at pH 11.35 and then increases to 2.65 at pH 13.92. The equation[Formula: see text]which is applicable for neutral solutions, is not valid for basic solutions.A reaction mechanism in accordance with the observed results and the literature values of the rate constants of likely radical reactions has been developed. It is assumed that in the alkaline solutions investigated OH radicals react with OH− ions to form O− radicals which react preferentially with O2 to form O3− radicals which then react either with H2 or H2O2. The increase in [Formula: see text] at PH > 12 is attributed to a difference in the rate of reaction of O3− with H2O2 and HO2−, k(O3− + H2O2)/k(O3− + HO2−) = 2.45.
DIMETHYLBERYLLIUM BIS(TRIMETHYLAMINE) AND DIMETHYLBERYLLIUM TETRAMETHYL-o-PHENYLENEDIAMINE
Authors: Bell N. A. , Coates G. E.
Published: May 2006

not available
THE NUMERICAL ANALYSIS OF ELECTRON SPIN RESONANCE SPECTRA WITH HYPERFINE STRUCTURE
Authors: Newton R. , Schulz K. F. , Elofson R. M.
Published: May 2006

not available
CYCLOHEXANE COMPOUNDS: VI. NUCLEAR MAGNETIC RESONANCE SPECTRA OF SOME DERIVATIVES OF THE STEREOISOMERIC 3-BROMO-1,2-CYCLOHEXANEDIOLS AND THE 2-BROMO-1,3-CYCLOHEXANEDIOLS
Authors: Bannard R. A. B.
Published: May 2006

First-order analysis of the 60 Mc.p.s. proton magnetic resonance spectra of 1α-methoxy-2β-acetoxy-3α-bromocyclohexane, 1α-methoxy-2α-acetoxy-3β-bromocyclohexane, 1α-methoxy-2β-bromo-3α-acetoxycyclohexane, 1α-methoxy-2α-bromo-3β-acetoxycyclohexane, and the corresponding diol diacetates confirmed the stereochemical interrelationships of substituents which were assigned previously on chemical grounds, and demonstrated that the compounds exist in chair conformations. The chemical shifts of the methoxy methyl and acetoxy methyl protons did not provide reliable criteria for the assignment of conformations to these substituents in this series. The coupling constants of the methine protons followed, in general, the pattern predicted by the Karplus equation, and the smaller J2,3 values observed in the cis,trans compounds relative to those in the trans,trans compounds are interpreted mainly on the basis of conformational equilibration, upon which is superimposed a small dihedral angular distortion or a remote substituent orientational effect.
MASS SPECTRA OF OXYGENATED QUINOLINES
Authors: Clugston D. M. , MacLean D. B.
Published: May 2006

The mass spectra of the monohydroxyquinolines, the monomethoxyquinolines, N-methyl-2-quinolone, and N-methyl-4-quinolone have been recorded. The isomeric hydroxy compounds vary somewhat in the stability of the molecular ion, but all show the same fragmentation mechanism. Two general fragmentation patterns are discernible in the spectrum of each of the monomethoxyquinolines, but there is considerable variation among the isomers in the extent to which the two patterns occur. In addition, 8-methoxyquinoline undergoes a peculiar fragmentation wherein all three methyl hydrogens are lost. The 3-methoxy compound is unusual in that loss of 43 mass units from the molecular ion occurs in one step. Deuterium- and 13C-labelling experiments have proved to be useful in interpreting the fragmentation pathways. The spectra of the two N-methylquinolones prove that O to N methyl rearrangement does not occur to any significant extent upon electron impact.
SYNTHESIS OF POSSIBLE ACTINOMYCIN D PRECURSORS
Authors: Marsh Jr. John P. , Goodman Leon
Published: May 2006

The preparation of a number of polypeptides whose sequences are found in the actinomycin D molecule is described. The 4-methyl-3-hydroxyanthranoyl derivatives cf these peptides were also prepared as possible substrates for an enzyme that forms the phenoxazinone system of the antibiotic.
THE SYNTHESIS OF SUBSTITUTED BIURETS
Authors: Stollar H. , Ranz R. J. , Chubb Francis L.
Published: May 2006

not available
NUCLEAR RECOIL REACTIONS IN CYCLOPENTADIENYLMANGANESE TRICARBONYL
Authors: Costea T. , Negoescu Irina , Vasudev P. , Wiles D. R.
Published: May 2006

The first stages in an intensive study of Szilard–Chalmers recoil reactions in a covalent metal-organic compound are described. The radioactive manganese-56 is found, as expected, as inorganic manganese (75–80%), as the parent compound (12–20%), and as one or other of two hitherto unidentified, unstable compounds depending on whether anhydrous paper chromatography or paper ionography is used as the separation method (5–7%). Some data are given showing the effect of room-temperature annealing following irradiation at −196 °C. In particular, the yield of one of the unidentified compounds increases markedly (to ~15%) while that of the other compound remains nearly unaffected.Thin-layer chromatography in anhydrous benzene was used as separation method in thermal annealing studies. They show two hitherto unreported phenomena: The apparent retention increases considerably and then decreases again as annealing continues, and the annealing reaction at two temperatures in the liquid and one in the solid phase are qualitatively very similar. These results are interpreted as indicating the presence of another species, the "pseudoparent", which is not distinguished chromatographically from the parent. Some discussion is given as to possible mechanisms.
ABSORPTION SPECTRA AND CONFIGURATION OF SOME AMINE COMPLEXES OF COPPER (II) ACETATE
Authors: Narain Gopal
Published: May 2006

Coordination complexes of copper(II) acetate, ammonia, aliphatic amines, and pyridine have been prepared. Molecular formulae on the basis of percentage of constituent elements were found to be Cu(OAc)2(am)2, where OAc represents acetate ion and am any amine used. Conductivity measurements in nitrobenzene and formamide indicate that the complexes are nonelectrolytes and thus it is suggested that acetate ions are also coordinated. Molecular weight measurements in the same solvents confirm this. Visible absorption measurements in formamide show a single band at about 635 mμ.
THE OXIDATION OF PHENOLS: III. THE STOICHIOMETRIES FOR THE OXIDATION OF SOME SUBSTITUTED PHENOLS WITH PEROXY RADICALS
Authors: Horswill E. C. , Howard J. A. , Ingold K. U.
Published: May 2006

The stoichiometries for the oxidation of some substituted phenols with cumyl peroxy radicals at 65 °C have been measured. The results can be correlated generally with the expected phenolic oxidation products. Phenols with one or two unsubstituted ortho positions can react with more than 2 peroxy radicals per molecule. A maximum stoichiometry of 2.6 peroxy radicals was obtained with 2,4-dimethylphenol. 2,4,6-Tri-substituted phenols generally have stoichiometric factors of 2.0 or less.
PREPARATION AND REACTIONS OF SOME PYRRYLTHIOL ESTERS
Authors: Bullock E. , Chen T.-S. , Loader C. E.
Published: May 2006

Two syntheses and some reactions of pyrrylthiol esters are described. The value of the thiol ester residue as a protecting group in the synthesis of complex pyrroles and their derivatives is considered. A simplified synthesis of a pyrrole related to the uroporphyrins is reported.
A GENERAL METHOD OF PREPARATION OF SUBSTITUTED 2-HYDROXY-1.4-QUINONES
Authors: Kasturi T. R. , Arunachalam T.
Published: May 2006

not available
THERMAL ISOMERIZATION OF HEXACHLOROCYCLOPROPANE
Authors: Hale W. F.
Published: May 2006

not available
ABSOLUTE RATE CONSTANTS FOR HYDROCARBON AUTOXIDATION: III. α-METHYLSTYRENE, β-METHYLSTYRENE, AND INDENE
Authors: Howard J. A. , Ingold K. U.
Published: May 2006

Absolute rate constants for the copolymerization of α-methylstyrene and oxygen have been measured from 13 to 50 °C. The propagation and termination rate constants can be represented by[Formula: see text]Experiments with 2,6-di-t-butyl-4-methylphenol at 65 °C have shown that C6H5C(CH3):CH2 and C6H5C(CD3):CD2 have the same propagation rate constant but that chain termination involves a deuterium isotope effect (kt)H/(kt)D ≈ 1.5.Absolute rate constants for the copolymerization of oxygen with β-methylstyrene and with indene at 30 °C showed that a significant fraction of the oxidation chains were terminated by a kinetically first order process (rate constant kx). The rate constants for β-methylstyrene and indene at 30 °C are kp = 51 and 142 l mole−1 s−1, kt = 1.6 × 107 and 2.5 × 107 l mole−1 s−1, and kx = 0.61 and 1.2 s−1, respectively. The propagation rate constant for indene can be separated into a rate constant for the copolymerization with oxygen (kadd = 128 l mole−1 s−1) and a rate constant for hydrogen atom abstraction (kabstr = 14 l mole−1 s−1). In the presence of heavy water the first order process for indene had a deuterium isotope effect (kx)/(kx)D2O ≈ 3.
ABSOLUTE RATE CONSTANTS FOR HYDROCARBON AUTOXIDATION: IV. TETRALIN, CYCLOHEXENE, DIPHENYLMETHANE, ETHYLBENZENE, AND ALLYLBENZENE
Authors: Howard J. A. , Ingold K. U.
Published: May 2006

Absolute rate constants have been measured for the autoxidation of five hydrocarbons under a variety of conditions. The propagation (kp) and termination (kt) rate constants at 30 °C (in l mole−1 s−1) are: tetralin in chlorobenzene 6.3 and 3.8 × 106 respectively, cyclohexene in chlorobenzene 6.1 and 2.8 × 106, diphenylmethane 4.8 and 8.0 × 107, ethylbenzene 0.11 and 2.0 × 107, and allylbenzene 10 and 2.2 × 108. Measurements on tetralin, α-methylstyrene, and allylbenzene in different solvents indicate that the effect of solvents on oxidation rates is mainly connected with changes in the rate of termination rather than propagation. Experiments with α,α-d2-diphenylmethane gave isotope effects kH/kD ~5.1 for kp and ~1.4 for kt. The rate constant for hydrogen atom abstraction from 2,6-di-t-butyl-4-methylphenol by peroxy radicals decreases in the order expected if steric effects are important, i.e., primary peroxy > secondary peroxy > tertiary peroxy radical.The co-oxidation method of estimating chain termination constants is criticized on the grounds that it can only be used to distinguish the fairly large changes in kt commonly encountered between hydrocarbons giving tertiary peroxy radicals and those giving secondary or primary radicals.The effect of hydrocarbon structure on bimolecular chain termination rate constants is reviewed. There is a gradation in kt from ~2 × 108] mole−1 s−1 for primary peroxy radicals, through the range 8 × 107 to 1 × 106 for secondary radicals, to the range from 3 × 105 to 3 × 102 for tertiary peroxy radicals.
A CRITIQUE OF PAULI REPULSIONS AND MOLECULAR GEOMETRY
Authors: Bader R. F. W. , Preston H. J. T.
Published: May 2006

A theoretical method, which allows one to determine the effect of the Pauli exclusion principle on the electron density distribution, is used to test the concepts underlying the electron pair repulsion theory of molecular geometry. It is shown that pictures of overlapping orbitals frequently do not correspond to the actual effect which the Pauli principle has on the three-dimensional charge density. An alternative electrostatic approach, involving the concept of a binding region for a polyatomic molecule, is proposed to account for the observed molecular geometries.
THE KINETICS OF THE THERMAL DECOMPOSITION OF PYRITE
Authors: Coats A. W. , Bright Norman F. H.
Published: May 2006

The kinetics of the thermal decomposition of purified pyrite to pyrrhotite and sulfur in a dynamic argon atmosphere have been studied over the temperature range 600 to 653 °C. The reaction was followed by the rate of weight loss as indicated by a quartz spring balance and also by the rate of progression of the pyrite/pyrrhotite interface into a cylindrical, compressed, polycrystalline pellet. The temperature coefficient of the reaction was found to be 69.5 ± 5.9, 64.7 ± 3.3, and 66.9 ± 5.1 kcal mole−1, when the results were processed in three different ways. The pyrite/pyrrhotite interface was found to progress at a linear rate into the pellet at a given temperature; equations were derived to express the variation of reaction rate with temperature. Attempts to follow the early nucleation stage of the decomposition, using massive mineral crystals, proved unsuccessful.
THE REACTION OF HYDROGEN AND ETHYLENE IN THE GAS PHASE
Authors: Lin M. C.
Published: May 2006

not available
CHEMISTRY AND SYNTHESIS OF SOME DIHYDRO-2H-l,4-BENZOTHIAZINE DERIVATIVES
Authors: Prasad Raj Nandan , Tietje Karin
Published: May 2006

The formation of 3-oxo-3,4-dihydro-2H-1,4-benzothiazine (IIIa) by cyclization of alkyl 2-haloacetamidophenyl sulfides (I) was investigated; it is proposed that the reaction proceeds via a six-membered sulfonium halide. The preparation of 4-alkyl derivatives of IIIa and of 4-alkyl and 4-acyl derivatives of its reduction product 3,4-dihydro-2H-1,4-benzothiazine (Va) is described. Acylation of Va was shown to proceed without opening of the thiazine ring. Preparation of the O-benzoyl, N-benzoyl, and O,N-dibenzoyl derivatives of 2-(β-hydroxyethyl-mercapto)aniline (VIII) has permitted clarification of the confusion in the literature with respect to the derivatives of Va and VIII. Compound XVIII, the 1,1-dioxide of IIIa, undergoes C-alkylation at the 2-position when treated with alkyl halides, rather than O-alkylation as previously suggested.
STEROIDS AND RELATED NATURAL PRODUCTS: XXX. SELECTIVE REDUCTION OF ESTERS. PART A. BENZOATES
Authors: Pettit George R. , Green Brian , Dunn George L. , Hofer Peter , Evers William J.
Published: May 2006

Previously, reagents such as sodium borohydride – boron trifluoride were shown to be capable of reducing typical aliphatic esters and lactones to the corresponding ether derivatives. Under the same reaction conditions, a variety of benzoate esters (Ib, IIb, III, and V) were essentially unaffected. Resistance to attack was illustrated by conversion, with sodium borohydride – boron trifluoride, of 3-oxo-17β-benzoyloxy-5α-androstane (III) into 3β-hydroxy-17β-benzoyloxy-5α-androstane (IV) and of reserpine (V) into alcohol VI. With aryl–carbon–oxygen bonds of the ketone VII or alcohol IXa type, reaction with sodium borohydride– boron trifluoride was shown, in general, to cause reductive fission of the benzyl–oxygen linkage (e.g. X → XI). An exception was noted in the case of tertiary benzyl alcohols containing an available β-hydrogen (e.g. IXc). Here, dehydration to yield, for example, olefin XIIb appears to be the more favorable reaction course. The marked difference in the reactivity of sodium borohydride – boron trifluoride toward benzoyl–oxygen vs. benzyl–oxygen bonds has been demonstrated.
STEROIDS AND RELATED NATURAL PRODUCTS: XXXI. SELECTIVE REDUCTION OF ESTERS. PART B. CARBONATES
Authors: Pettit George R. , Evers William J.
Published: May 2006

Direct reduction of several pivalate esters to neopentyl ethers has been accomplished with boron trifluoride – sodium borohydride. The utility of the reduction reaction was illustrated with esters Ic, IIb, and IVa. Under the same conditions, a selection (Id, IId, and IVa) of carbonate esters was found to be relatively resistant to reduction. In this respect, the carbonate esters resembled benzoate esters, and selective reduction of a ketone (IId) or another ester (IVa → IVb) in their presence was possible. For comparison, one xanthate ester (Ie) was allowed to react with boron trifluoride – sodium borohydride, and only the corresponding alcohol (Ia) was isolated. Raney nickel desulfurization of xanthate Ia was shown to provide alcohol Ia and hydrocarbon If as principal products.
STEREOCHEMISTRY OF o-SUBSTITUTED FORMANILIDES
Authors: Rae Ian D.
Published: May 2006

not available
A METHOD FOR THE DETERMINATION OF WATER IN NONPOLAR LIQUIDS; THE SOLUBILITY OF WATER IN BENZENE
Authors: Moule D. C. , Thurston W. M.
Published: May 2006

A new method is described for the analysis of water in nonpolar organic liquids. It is based on an isotope dilution procedure and involves the exchange of the water present in the sample with D2O. The change in isotopic composition of the D2O is determined by infrared difference spectroscopy. The method appears to be accurate to ± 0.8%.The principal advantage of this method is that the difficult problem of calibration with organic–water standards is avoided. It is restricted, however, to solvents which have a low solubility in water and do not have exchangeable hydrogens.A series of solubility measurements were carried out for H2O in C6H6 from 10 to 60 °C. The data were fitted to the usual interpolation equation In (f/x) = −A/T + B ln T + C, and the thermodynamic functions of solution, ΔG, ΔH, ΔCP, and ΔS, were computed for the transfer of 1 mole of water from the benzene phase to the vapor phase.
STUDIES OF METAL COMPLEXES OF PYRIDINE DERIVATIVES: THE EFFECTS OF COORDINATION UPON INFRARED INTENSITY OF THE FUNCTIONAL GROUP IN β-CYANOPYRIDINE
Authors: Brewer D. G. , Wong Patrick T. T.
Published: May 2006

The infrared intensity of the C≡N group in β-cyanopyridine complexes with some first-row transition metal ions (Zn(II), Cu(II), Ni(II), Co(II), Fe(II), and Mn(II)) in aqueous solution has been measured. The coordination between the nitrogen atom on the pyridine ring and these metal ions exerts a marked change in the magnitude of the band intensity of the functional group. This can be interpreted in terms of a simple molecular orbital model and the relative magnitudes of σ-bonding and π-bonding involved in the complexes. A "coordination constant" is introduced for this system, and a linear correlation between these constants and the C≡N band intensities of the metal complexes is obtained from both the experimental data and theoretical considerations.
THE COLLISION RATE IN A DILUTE CLASSICAL GAS
Authors: Brown R. J. C.
Published: May 2006

The result given by Maxwell and by Boltzmann for the collision rate in a dilute classical gas has been widely accepted. Investigation of a stochastic model for the collisions indicates that the collision rate averaged over a macroscopic period of time is about 3% lower than the original result.
ORGANIC COMPOUNDS OF URANIUM. PART I. REACTIONS OF URANIUM PENTAETHOXIDE WITH β-KETOESTERS
Authors: Bhandari A. M. , Kapoor R. N.
Published: May 2006

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AN IMPROVED PREPARATION, ANALYSIS, AND SOME PROPERTIES OF TETRAOXYGEN DIFLUORIDE
Authors: Streng A. G.
Published: May 2006

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ORGANIC AND BIOLOGICAL SPECTROCHEMICAL STUDIES: XXIII. CONFORMATION OF THE p-DIMETHOXYBENZENE CATION RADICAL IN CONCENTRATED SULFURIC ACID
Authors: Forbes W. F. , Sullivan P. D.
Published: May 2006

The electron spin resonance spectrum of the p-dimethoxybenzene cation radical in concentrated sulfuric acid is interpreted in terms of cis–trans isomerism. Empirical molecular orbital calculations support these assignments. The two isomers are found to possess slightly different "g" values, Δg (cis – trans) being ca. 1.8 × 10−5.Nuclear magnetic resonance and ultraviolet data show that the radical exists in equilibrium with the neutral non-radical species at room temperature, but that sulfonation occurs at higher temperatures. Nuclear magnetic resonance and electron spin resonance data of solutions of p-dimethoxybenzene in D2SO4 show that rapid exchange of the ring protons occurs.
RÉACTIONS DE L'ÉPOXYSTYRÈNE AVEC LA GLYCINE ET SES DÉRIVÉS
Authors: Berse Casimir , Jankowski Krzysztof
Published: May 2006

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STUDIES ON PLANTS: XI. ALKALOIDS OF ASPIDOSPERMA SPEGAZZINII
Authors: Orazi Orfeo O. , Corral Renée A. , Stoichevich Marta E.
Published: May 2006

Extraction of the trunk bark of Aspidospermaspegazzinii Molf. ex Meyer yielded ajmaline and two quaternary alkaloids. One of the latter, characterized as the tetraphenylboride salt, was found to be identical with the Nb-metho derivative of akuammidine. Methylation of the phenolic group of the second quaternary alkaloid (named spegatrine) followed by thermal degradation led to the corresponding nor-base, which was identified as lochnerine; therefore, the structure and absolute stereochemistry of spegatrine are given by formula I. A confirmation was provided by Nb-methylation of sarpagine to spegatrine.
CHOLLA GUM: II. STRUCTURE OF THE UNDEGRADED CHOLLA GUM
Authors: Parikh V. M. , Jones J. K. N.
Published: May 2006

Cholla gum (Opuntiafulgida) has partially been degraded to yield several oligosaccharides and a degraded polymer. The structure of the degraded polymer was reported in an earlier paper. Six of the oligosaccharides formed have been isolated in a pure state and identified. They are (i) 6-O-β-D-galactopyranosyl-D-galactose, (ii) 3-O-β-D-galactopyranosyl-D-galactose, (iii) 3-O-α-L-arabinofuranosyl-L-arabinose, (iv) 5-O-β-D-xylopyranosyl-L-arabinose, (v) 3-O-β-D-galactopyranosyl-L-arabinose (?), and (vi) a new trisaccharide O-β-D-xylopyranosyl-(1 → 5)-O-α-L-arabinofuranosyl-(1 → 3)-L-arabinose. The purified gum was subjected to Smith-type degradation, and the results of this experiment are compared with the methylation studies carried out earlier. On the basis of all this information plus the suggested structure for the degraded gum, it is proposed that the repeating unit of the polysaccharide consists of a total of 36 sugar residues with a backbone of 1 → 6 linked galactose residues.
THE SYNTHESIS OF SOME IODOPHTHALAZINES AND PHTHALAZINECARBONITRILES
Authors: Hirsch Arthur , Orphanos Demetrius G.
Published: May 2006

1-Iodo- and 1,4-diiodo-phthalazines were obtained by treating the corresponding chloro compounds with a solution of sodium (or potassium) iodide in acetone containing hydrogen iodide. These iodophthalazines, on reaction with copper cyanide in pyridine, gave the relevant phthalazinecarbonitriles.
A 5-PHOSPHAFULVENE WITTIG REAGENT
Authors: Hocking M. B.
Published: May 2006

1,2,5-Triphenyl-1-carbethoxymethylenephosphole (I), a fairly stable isolable phosphorane, has been shown to undergo Wittig reactions with cyclohexanone, benzaldehyde, and acetaldehyde under a variety of conditions. Both the reactivity and stereoselectivity of I are less than the corresponding properties of triphenylcarbethoxymethylenephosphorane (II); these properties may be useful in certain applications.
FACILE METHYLATION OF HUMIC ACIDS FROM ORGANIC SOILS
Authors: Morita Hirokazu
Published: May 2006

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SELECTIVE REDUCTION OF SUBSTITUTED ALDONOLACTONES TO ALDOSE DERIVATIVES
Authors: Hulyalkar R. K.
Published: May 2006

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NUCLEAR MAGNETIC RESONANCE STUDY OF 2,3-QUINOXALINEDICARBOXALDEHYDE AND ITS CYCLIC MONOHYDRATE
Authors: Moriconi Emil J. , Young James W. , Brady Thomas E. , Fritsch Albert J.
Published: May 2006

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ENERGETICS OF FORMATION OF SOME OXYGENATED IONS AND THE PROTON AFFINITIES OF CARBONYL COMPOUNDS
Authors: Harrison A. G. , Ivko A. , Raalte D. Van
Published: May 2006

The energetics and mechanism of formation of ions of m/e 31, 45, and 59 from a number of alcohols, ethers, and esters have been studied. The following ionic heats of formation have been obtained: CH2=OH+, 176 kcal/mole; CH3O+, 213 kcal/mole; CH3CH=OH+, 145 kcal/mole; CH2=OCH3+, 170 kcal/mole; (CH3)2C=OH+, 125 kcal/mole; CH3CH2CH=OH+, 131 kcal/mole; CH3CH=OCH3+, 135 kcal/mole; CH2=OC2H5+, 144 kcal/mole. It is concluded that with the exception of CH3O+ the alkoxy ions probably are not formed by electron impact processes. The gas-phase proton affinities of a number of carbonyl compounds are estimated.
A SPECTROPHOTOMETRIC STUDY OF HEXA-, PENTA-, AND TETRA- COORDINATED HALOGENOCOPPER(II) COMPLEXES IN ACETONE – HYDROHALIC ACID MIXTURES
Authors: Faye G. H.
Published: May 2006

A spectrophotometric study of the Cu(II) – acetone – hydrochloric (hydrobromic) acid systems has revealed that at relatively high ratios of halide: copper there is a probable equilibrium between four-, five-, and six-coordinate halogenocopper(II) complexes. A distorted tetrahedral species is favored at the highest ratios. Ligand field bands of pseudo-octahedral monohalogenocopper(II) complexes and, in the visible region, a charge transfer band of the six-coordinate complex, [CuCl4(ac)2]2−, have been identified. The results of the present work point to the important role of the solvent in determining the geometries and absorption spectra of the complexes, a factor that seems to have been misinterpreted by some previous workers.
ION–MOLECULE REACTIONS IN METHYL ALCOHOL AND METHYL-d3 ALCOHOL
Authors: Thynne J. C. J. , Amenu-Kpodo F. K. , Harrison A. G.
Published: May 2006

The rate constants for the hydrogen-transfer ion-molecule reactions[Formula: see text]have been measured at thermal ion energies and found to be 12 × 10−10 cm3 molecule−1 s−1 and 8.0 × 10−10 cm3 molecule−1 s−1 respectively. The rate coefficients at higher ion energies (3.7 eV ion exit energy) show little change from these values. Reactions [a] and [b] have also been studied using CD3OH and it is found that in reaction [a] the hydroxyl hydrogen is transferred 2.5 times more readily at low ion energies and 1.8 times more readily at high ion energies than a methyl hydrogen. This rather small specificity would appear to preclude formation of a "locked-in" collision complex even at low ion energies.
THE POLYMERIZATION OF STYRENE BY ANHYDROUS PERCHLORIC ACID AND THE SPECTRA OF BENZYLIC CARBONIUM IONS
Authors: Bywater S. , Worsfold D. J.
Published: May 2006

A spectroscopic investigation of the reaction of anhydrous perchloric acid with styrene in methylene chloride solution has been carried out, together with a study of the spectra of styrene and its derivatives dissolved in sulfuric acid. From the results it was decided that the absorbing species formed at the end of the reaction in methylene chloride are derivatives formed from the cyclized end groups of the polymer chain, and not the polystyrylcarbouium ion. It is not thought possible to determine from spectroscopic studies whether the polymerization reaction goes via a true ionic intermediate or a perchlorate ester.
KINETICS OF THE OXIDATION OF GLYCOLLIC ACID BY VANADIUM (V)
Authors: Bakore G. V. , Shanker Rama
Published: May 2006

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LIFETIME OF THE PHOSPHORESCENCE OF HEXAFLUOROACETONE VAPOR
Authors: Gandini A. , Kutschke K. O.
Published: May 2006

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THE HIGH RESOLUTION NUCLEAR MAGNETIC RESONANCE SPECTRUM OF THE NONRIGID AB2X2 SYSTEM
Authors: Jones R. G.
Published: May 2006

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ADDENDUM: STEREOCHEMISTRY AND SEVEN COORDINATION
Authors: Claxton T. A. , Benson G. C.
Published: May 2006

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NUCLEAR MAGNETIC RESONANCE SPECTRA OF GLYCOL-CLEAVAGE OXIDATION PRODUCTS OF METHYL ALDOPENTOPYRANOSIDES
Authors: Perlin A. S.
Published: May 2006

The products obtained by the periodate oxidation of methyl α- and β-D-xylopyranosides have been examined by nuclear magnetic resonance spectroscopy. In deuterium oxide each product exists mainly in two forms, one of which is a hydrated dialdehyde and the other a hemialdal (1,4-dioxane derivative). In dimethyl sulfoxide the dialdehyde cyclizes slowly to yield the hemialdal which, at equilibrium, is found to be by far the most stable of the many isomeric forms possible. The spectrum of this hemialdal in both solvents provides an example of a degenerate ABX type of pattern. The spectra of the products prepared from 5-deuterated xylosides show that the 1-methoxyl group of each hemialdal is axial and the 4-hydroxyl group equatorial, and that the one derived from the β-anomer possesses an inverted chair conformation relative to that of the other hemialdal and of the glycoside itself. The 2-hydroxyl group of each hemialdal appears to be axially oriented. The data support the long-standing view that glycol scission of anomeric aldopentopyranosides leads to products that are mirror images.It has been found also that each product yields a mixture of several p-nitrobenzoates.
SUBSTITUTION OF ACYCLIC SUGAR ACETALS: RATE OF PERCHLORIC ACID CATALYZED ACETOLYSIS OF 2,3,4,5,6-PENTA-O-ACETYL-D-GLUCOSE DIETHYL DITHIOACETAL AND 1,2,3,4,5,6-HEXA-O-ACETYL-D-GLUCOSE S-ETHYL MONOTHIOACETAL
Authors: Kurihara Norman H. , Painter Edgar Page
Published: May 2006

The rate constants for the perchloric acid catalyzed substitution of one ethylthio group of 2,3,4,5,6-penta-O-acetyl-D-glucose diethyl dithioacetal (Va) and the acetoxy group bonded to C1 of 1,2,3,4,5,6-hexa-O-acetyl-D-glucose S-ethyl monothioacetal (VIa) have been measured when the substrates were dissolved in solutions of acetic acid and acetic anhydride. The rate-determining step is interpreted to be the dissociation of the substrate conjugate acid to give a carbonium–sulfonium cation. The rate constants indicate that acyclic sugar derivatives are substituted faster than cyclic (pyranose) derivatives, and that an acetoxy group is substituted faster than an ethylthio group.
ALKYLATION OF CYCLIC AMIDINES WITH MANNICH BASES
Authors: Podesva C. , Vagi K.
Published: May 2006

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THE ROLE OF β-ALANINE AND OF GLYCERATE IN THE BIOSYNTHESIS OF RICININE
Authors: Thomas P. R. , Barnes M. F. , Marion Léo
Published: May 2006

β-Alanine-2-14C has been fed to young Ricinuscommunis L. plants and the radioactive ricinine isolated. The activity of each carbon in the alkaloid molecule was determined. Propionate-2-14C was also fed to young Ricinus plants and the radioactivity on carbons 2 and 3 of the isolated ricinine was determined. The pattern of labelling produced by β-alanine-2-14C was very similar to that produced by propionate-2-14C, but was quite distinct from that produced when succinate-2,3-14C or acetate-2-14C was fed to the plant. Whereas with the latter, carbons 2 and 3 of the pyridone ring of ricinine are approximately equally labelled, the ricinine obtained after propionate-2-14C or β-alanine-2-14C was fed contains on carbon 3 almost twice the activity contained on carbon 2.It has been found that acetate-2-14C is not incorporated into carbon 6 of ricinine. It has also been established that (±)-glycerate-1-14C is incorporated into ricinine only negligibly (0.12%), whereas labelled glycerol is incorporated to the extent of 2.7–3.9%. Glycerate-3-14C, however, is known to be incorporated into the pyridine ring of nicotine; therefore, glyceric acid must undergo decarboxylation before incorporation.
ÉTUDES SUR LA TRIMÉTHYL-2,4,4 CYCLOHEXANONE ET SES PRODUITS DE RÉDUCTION
Authors: Richer Jean-Claude , Perelman David
Published: May 2006

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GAS–LIQUID CHROMATOGRAPHY OF TERPENES: XV. THE VOLATILE OIL OF MENTHA ARVENSIS VAR. GLABRATA RAY
Authors: Rudloff E. von , Hefendehl F. W.
Published: May 2006

The volatile oil of the North American wild mint (Menthaarvensis L. var. glabrata) was found to consist mainly of d-pulegone (80–90%) and smaller amounts of α-pinene, β-pinene, sabinene, limonene, 1,8-cineole, 1-octen-3-ol, menthone, isomenthone, piperitone, cis- and trans-pulegone oxide, and piperitenone. Trace amounts of γ-terpinene, menthofuran, β-caryophyllene, and ε-, δ-, and γ-cadinene were also isolated, and camphene, p-cymene, terpinolene, sabinene hydrate, isopulegone or its stereoisomer, β-elemene, and α-terpineol were tentatively identified. A labile autoxidation product of pulegone was also detected.A study of the seasonal variations in the oil composition showed that significant changes in the quantitative composition occurred only in very young plants. The maximum yield of oil was obtained at the start of flowering. Practically no variation in the composition of the oil was recorded for plants from different localities.
STRUCTURAL BIOCHEMISTRY: II. SYNTHESIS OF 3β-HYDROXY-17β (L-PROLYL-L-PROLYL)AMINO-5α-ANDROSTANE
Authors: Pettit George R. , Das Gupta Arun K. , Smith Robert L.
Published: May 2006

A practical synthetic route to 3β-hydroxy-17β-amino-5α-androstane (III) was developed and the configuration of the amine substituent established by proton magnetic resonance studies. Condensing amine III with carbobenzoxy-L-proline by means of Woodward's reagent K led to proline derivative IVa. Steroidal peptide Vb was readily prepared by first removing the protecting group from amide IVa by palladium-catalyzed hydrogenolysis and then repeating the peptide-forming and hydrogenation steps. Protection of the 3β-hydroxy group proved to be unnecessary, and the presently reported approach to steroidal peptides proved to be reliable and useful.
SYNTHESIS OF QUINAZOLONE HYDRAZIDES AS MONOAMINE OXIDASE INHIBITORS
Authors: Parmar Surendra S. , Arora R. C.
Published: May 2006

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ON THE FORMATION OF A PEROXY PHTHALAZINE COMPOUND BY THE AUTOXIDATION OF 1-METHYL-1,2-DIHYDROPHTHALAZINE
Authors: Hirsch Arthur , Orphanos Demetrius G.
Published: May 2006

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THE SYNTHESIS OF 1,4-DICHLORO-1,4-DINITRO-1,3-BUTADIENE
Authors: Carroll F. I. , Kerbow Sandra C. , Wall Monroe E.
Published: May 2006

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ELECTROLYTIC REDUCTION AND ELLINGHAM DIAGRAMS FOR OXY-ANION SYSTEMS
Authors: Bartlftt H. E. , Johnson K. E.
Published: May 2006

Standard reversible decomposition voltages, E0, for various decomposition reactions of K2CO3, Na2CO3, Li2CO3, BaCO3, CaCO3, MgCO3, Na2SO4, NaNO3, and KNO3 are calculated from thermal data and the values obtained plotted against temperature. That reaction which has the lowest values of E0 is considered to be the most likely to occur when the particular salt is electrolyzed. The results obtained indicate that in the case of the carbonates metal deposition is possible only for K2CO2 and Na2CO3 above 870 °K. In all other cases metal oxide and carbon (or CO at higher temperatures) are the favored cathode products. For Na2SO4, Na2S and Na2O are the favored cathode products and for the nitrates, nitrite and oxide or nitrogen evolution and oxide formation appear equally feasible thermodynamically.Once the likely electrolytic decomposition products are known, a method is presented whereby the products formed by reduction of the oxy-anions by metals (and in the case of the carbonates, by carbon) may be predicted. This method involves drawing an appropriate redox line on an Ellingham diagram. Finally, a comparison is made between the thermodynamic predictions and the few experimental results available.
HEATS OF POTASSIUM–LITHIUM ION EXCHANGE ON SULFONATED POLYSTYRENE RESINS
Authors: Heumann W. R. , Patterson D.
Published: May 2006

A Tian–Calvet microcalorimeter has been used at 25 °C to measure the heats of the exchange between K+ and Li+ as a function of the ionic composition of commercial Dowex 50W exchange resins of the following divinylbenzene contents: 1, 4, 8, and 16%. The heats, which are exothermic for the forward reaction, where K+ replaces Li+ on the resin, and endothermic for the reverse direction, increase with the degree of cross-linking. A sharp variation in the heat with ionic composition of the resin is observed for the forward exchange at low K+, and for the reverse exchange at low Li+ content. These results are consistent with a non-uniformity of the resin.
THE THERMAL UNIMOLECULAR ISOMERIZATION OF 1,2-DICHLOROETHYLENE
Authors: Hawton L. D. , Semeluk G. P.
Published: May 2006

The thermal cis–trans isomerization of 1,2-dichloroethylene in a toluene carrier was found to follow first order kinetics at temperatures below 846 °K. Within the limits of detection, no decomposition was observed, but there was evidence of a surface contribution to the isomerization. The results, extrapolated to a surface to volume ratio of zero, give for the cis to trans conversion[Formula: see text]and for the reverse action[Formula: see text]It is concluded that previous investigations which did not use a radical scavenger most probably were observations of a mixture of radical chain, heterogeneous, and unimolecular contributions to the isomerization.