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Leptosperols A and B (1 and 2), two cinnamoylphloroglucinol–sesquiterpenoid hybrids featuring unprecedented 1-benzyl-2-(2-phenylethyl) cyclodecane and 2-benzyl-3-phenylethyl decahydronaphthalene ba...

We report the formation of aliphatic organosulfates (OSs) in secondary organic aerosol (SOA) from the photooxidation of C10–C12 alkanes. The results complement those from our laboratories reporting the formation of OSs and sulfonates from gas-phase oxidation of polycyclic aromatic hydrocarbons (PAHs). Both studies strongly support the formation of OSs from the gas-phase oxidation of anthropogenic precursors, as hypothesized on the basis of recent field studies in which aromatic and aliphatic OSs were detected in fine aerosol collected from several major urban locations. In this study, dodecane, cyclodecane and decalin, considered to be important SOA precursors in urban areas, were photochemically oxidized in an outdoor smog chamber in the presence of either non-acidified or acidified ammonium sulfate seed aerosol. Effects of acidity and relative humidity on OS formation were examined. Aerosols collected from all experiments were characterized by ultra performance liquid chromatography coupled to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS). Most of the OSs identified could be explained by formation of gaseous epoxide precursors with subsequent acid-catalyzed reactive uptake onto sulfate aerosol and/or heterogeneous reactions of hydroperoxides. The OSs identified here were also observed and quantified in fine urban aerosol samples collected in Lahore, Pakistan, and Pasadena, CA, USA. Several OSs identified from the photooxidation of decalin and cyclodecane are isobars of known monoterpene organosulfates, and thus care must be taken in the analysis of alkane-derived organosulfates in urban aerosol.

Vapor–liquid equilibria at 298.15 K have been determined for binary mixtures of tetrachloromethane or heptane plus a cyclic hydrocarbon (cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, cis-decalin, norbornane, octahydro-4,7-methano-1H-indene, adamantane), using a head-space gas chromatographic technique. Excess molar Gibbs energies and activity coefficients for the systems investigated have been obtained by a least-squares treatment of the equilibrium results. All mixtures exhibit positive deviations from ideality, increasing with the cycloalkane size. The Gibbs energies of solvation, Δsolv G°, for cyclic hydrocarbons in the two solvents have been evaluated and compared with those of linear and branched alkanes. The effect of cyclization upon Δsolv G° has been discussed.

Based on structural studies already available for the cocrystals of a sterically-rigidified tetraarylpyrene (TP) host substituted at the periphery by flexible methoxymethyl (MM) groups, i.e., TPMM, with aliphatic guests, formation of ternary or three-component cocrystals was targeted by replacing one of the guest species in the binary cocrystals with a different guest. Ternary cocrystals of TPMM with cyclododecene + cyclodecane, cyclododecene + cyclooctane and cyclododecene + decalin pairs were indeed successfully isolated and characterized by single-crystal X-ray structure determination. The ternary cocrystals, in principle, constitute ‘isomorphous pseudopolymorphs’ of binary cocrystals of TPMM with cyclododecene.

The structure of a molecule and its concentration can strongly influence diffusional properties for transport in nanoporous materials. We study mass transfer of alkanes in BPL activated carbon using the concentration-swing frequency response method, which can easily discriminate among mass transfer mechanisms. We measure concentration-dependent diffusion rates for n-hexane, n-octane, n-decane, 2,7-dimethyloctane, and cyclodecane, which have different carbon numbers and geometries: straight chain, branched chain, and cyclic. Micropore diffusion is determined to be the controlling mass transfer resistance except at low relative saturation for n-decane, where an external mass transfer resistance also becomes important, showing that the controlling mass transfer mechanism can change with system concentration. Micropore diffusion coefficients are found to be strongly concentration dependent. Adsorption isotherm slopes obtained from measured isotherms, the concentration-swing frequency response method, and a predictive method show reasonably good agreement.

Rate constants for the reactions of Cl atoms with cycloheptane, cyclooctane, cyclodecane, cyclohexanone, cycloheptanone, cyclooctanone, and cyclodecanone have been measured at 297 ± 2 K and atmospheric pressure of air using a relative rate method. n-Butane, with a rate constant of 2.05 × 10−10 cm3 molecule−1 s−1, was used as the reference compound, and the rate constants obtained (in units of 10−10 cm3 molecule−1 s−1) were cycloheptane, 4.22 ± 0.15; cyclooctane, 4.57 ± 0.15; cyclodecane, 5.13 ± 0.15; cyclohexanone, 1.79 ± 0.06; cycloheptanone, 2.46 ± 0.07; cyclooctanone, 2.97 ± 0.09; and cyclodecanone, 3.65 ± 0.15, where the indicated errors are two least-squares standard deviations and do not include uncertainties in the rate constant for the reference compound n-butane. Room temperature rate constants for the C5–C10 cycloketones indicate that the CH2 groups adjacent to the carbonyl group are almost totally deactivated toward H-atom abstraction by Cl atoms, and this also applies to acyclic ketones. A previous structure–reactivity relationship for Cl + alkanes has been extended to include acyclic and cyclic ketones. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: 52–58, 2013

This paper uses DFT and G3(MP2) calculations to examine whether unbridged 10-membered rings can be made by (pi)6 + (pi)4 cycloadditions to (Z)- and (E)-hexatrienes, hexa-1,5-dien-3-ynes, (Z)-hexa-1,3-dien-5-ynes, hexa-1,2,3,5-tetraenes, and (Z)-hexa-3-ene-1,5-diynes. Cycloadditions to four 4pi reactants, buta-1,3-diene, butenyne, butatriene, and butadiyne, are explored. Thirty different basic cycloadditions are identified, and all are shown to be exothermic according to G3(MP2) calculations; strain energies in the products are comparable with that of cyclodecane itself, despite the presence of trans-alkene, alkyne, allene, cumulene, and s-trans diene moieties. The major obstacles to the isolation of 6 + 4 cycloaddition products are competing (pi)4 + (pi)2 cycloadditions and, especially, rapid Cope rearrangement of the products, but, in many cases, the judicious introduction of substituents can overcome these problems so that practical syntheses should be possible. Reactions between (E)-hexa-1,3,5-triene and s-trans-buta-1,3-diene are shown to have substantially lower activation energies than those involving (Z)-hexa-1,3,5-triene reacting with either s-cis- or s-trans-buta-1,3-diene. Conformationally locked derivatives of s-cis,s-cis (E)-hexa-1,3,5-trienes can lead to derivatives of (Z,Z,E)-cyclodeca-1,3,7-triene that are stable to Cope rearrangement, and reactions should proceed at close to ambient temperatures with suitable activating groups. We predict that it should be possible to prepare suitably substituted derivatives of at least 11 more highly unsaturated ring systems: (5Z,7Z)-cyclodeca-1,2,5,7-tetraene, (1Z,3Z)-cyclodeca-1,3-dien-7-yne, (2Z,7E)-cyclodeca-1,2,3,7-tetraene, (Z)-cyclodeca-1,2,3-trien-7-yne, (4Z,8E)-cyclodeca-1,2,4,8-tetraene, (Z)-cyclodeca-1,2,4,5,7-pentaene, (Z)-cyclodeca-1,2,4-trien-8-yne, (1Z,7E)-cyclodeca-1,7-dien-3-yne, (R,S,E)-cyclodeca-1,2,4,5,8-pentaene, cyclodeca-1,2,4,5,8,9-hexaene, and (R,S)-cyclodeca-1,2,4,5-tetraen-8-yne. In three other cases, we predict that cycloaddition will be followed by unusual and intriguing rearrangements. Cycloadditions can be accelerated by the presence of electron-withdrawing groups in either the 6pi or 4pi reactants. Transannular cyclizations of some products may lead to interesting stereocontrolled routes to 6,6- and/or 5,7-bicyclic structures.

金沢大学薬学部, 金沢大学大学院自然科学研究科生理活性物質科学, Photolysis of 2-phenylcyclododecanone (2PCDD, ring size: C12) has been investigated in an air-saturated solution. The ﾎｱ-photocleavage of 2PCDD (Norrish type I) has led to the formation of triplet acyl-benzyl biradical (3BR) which reacts with O2 to produce a peroxyester intermediate. A major photoproduct of 2-phenyl-1-oxacyclododecane is formed by a stepwise decarboxylation from the peroxyester intermediate. The peroxyester is also a common intermediate for minor products of benzaldehyde, cyclodecane, and acetophenone. 1-Phenylcycloundecane is produced from decarbonylation of 3BR. On the other hand, 3BR undergoes intersystem crossing to the singlet biradical which in turn recombines to form the parent 2PCDD or to afford a cage product of cyclophane. The recombination yield to the starting species is estimated to be 0.5 by measuring a time evolution of enantiomer concentration of 2PCDD starting from one optically pure enantiomer. Photolysis mechanism of 2PCDD in the presence of molecular oxygen has been proposed and discussed. © 2006 Elsevier B.V. All rights reserved.

Interconversion of carbon sites in boat-chair-boat (BCB) cyclodecane occurs by way of the twist-boat-chair (TBC) conformation, which predicts that C-1 exchanges with C-4, etc. The previously obtained low-temperature 13C spectra could be matched by assuming (1,4) or (1,3) exchange, but not (1,2) exchange. A free-energy barrier of 5.54 kcal/mol was obtained for conversion of BCB to TBC at -137.4 degrees C. The major conformation of chlorocyclodecane and cyclodecyl acetate is assigned to the IIIe BCB.

The low-molecular-weight semicrystalline isotactic poly(1-butenes) were synthesized using metallocene catalyst. Molecular weight was determined using GPC. Chemical structure was verified using differential scanning calorimetry. Recent work presents SLE phase diagrams for two samples of iPBu-1 ( M n ― = 16 812 Da and M n ― = 18 708 Da ) in many organic solvents (n-octadecane, 3-methylpentane, 2,2-dimethylbutane, cyclodecane, toluene and ethylbenzene) being the model representatives of gasoline and motor oils. Solubilities were studied using dynamic method. Performing these experiments over a large concentration range allowed the construction of the T–x phase diagram of the polymer/diluent systems. It was found that the solubility of iPBu-1 decreases with an increase of the hydrocarbon's carbon atoms number. The lower-molecular-weight iPBu-1 shows better solubility than the higher-molecular-weight iPBu-1. Moreover, the excess Gibbs energy models were used to describe the nonideal behaviour of the liquid phase and to estimate the solubility of iPBu-1 in the whole range of mole fraction. Activity coefficients at infinite dilution for polymer and solvent were determined from the solubility measurements and were predicted by the UNIFAC-FV model and molecular Monte Carlo simulation.

Calcined vanadium phosphorus oxide (VPO) prepared by an organic route is found to be an active and effective catalyst for the oxidation of various alkanes such as cyclopentane, cyclohexane, n-hexane, cycloheptane, cyclooctane, cyclodecane and adamantane in acetonitrile solvent using the environmentally benign oxidant, hydrogen peroxide, where the oxidation mechanism is believed to involve a reversible V4+/V5+ redox cycle.

The skeletal isomerization of cycloalkanes with the number of carbons greater than six, cycloheptane, cyclooctane, cyclodecane, and cyclododecane, was performed over sulfated zirconia in liquid phase at 50°C. A main product of methylcyclohexane was formed from cycloheptane via a protonated cyclopropane intermediate, protonated [4.1.0]bicycloheptane, together with small amounts of trans-1,2-dimethylcyclopentane, cis- and trans-1,3-dimethylcyclopentanes, 1,1-dimethylcyclopentane, and ethylcyclopentane. A major product from cyclooctane was ethylcyclohexane via a protonated cyclobutane intermediate, protonated [4.2.0]bicyclooctane, followed by cis-1,3-dimethylcyclohexane in addition to small amounts of trans-1,2-, -1,3-, -1,4-dimethylcyclohexanes, 1,1-dimethylcyclohexane, and methylcycloheptane. The detailed reaction-paths for cycloheptane and cyclooctane were shown after additional examinations in reactions of methylcyclohexane, ethylcyclopentane, ethylcyclohexane, and 1,2-dimethylcyclohexane. Cyclodecane was dehydrogenated into cis- or trans-decaline with the evolution of a dihydrogen. Cyclododecane was converted into lots of products, more than 30 species.

Based on the most general concepts of the translational mobility and geometry of a porous medium, an expression is derived for the self-diffusion coefficient of liquid molecules in such a medium. An analytical relation between the self-diffusion coefficient and the effective geometric parameters of the pores, as well as the sizes of diffusant molecules, is proposed. The derived expression agrees well with experimental results.

A minimal enriched P450 BM3 library was screened for the ability to oxidize inert cyclic and acyclic alkanes. The F87A/A328V mutant was found to effectively hydroxylate cyclooctane, cyclodecane and cyclododecane. F87V/A328F with high activity towards cyclooctane hydroxylated acyclic n-octane to 2-(R)-octanol (46% ee) with high regioselectivity (92%).

The gas phase carbon catalyzed microwave promoted conversion of methane to ethylene, ethane and acetylene and hydrogen is reported. A selection of C1-C4 hydrocarbons, hexadecane, and a cyclic hydrocarbon, cyclodecane, were also subjected to microwave conversion, resulting primarily in a-olefins, ethylene and hydrogen. For methane conversion, the products are reminiscent of those found in methane pyrolysis. Microwave induced cleavage of the liquid hydrocarbons provides conditions for the stabilization, by rapid thermal quenching in ambient temperature liquid reagent, of products such as terminal olefins that would be labile under conventional (thermal bath) pyrolysis reaction conditions. The reactions of long chain acyclic and cyclic hydrocarbons involve high temperatures in the region of the spark leading to a cascade of unimolecular scission reactions from initially formed biradicals from cycloalkanes or radical pairs from linear alkanes, largely to the exclusion of intermolecular radical-radical and radical-molecule reactions. The observed products are discussed in terms of the thermochemistry and dynamics of high temperature unimolecular biradical and radical decomposition reactions, and mechanisms involving reactive surface metal sites. The reaction rates of alkanes were found to increase with the molecular weight of the reactants. Mechanistic pathways consistent with these results are discussed.

Low-temperature 13C NMR spectra of cyclodecane (1) showed the presence of a minor conformation, assigned to the twist-boat-chair-chair (TBCC), in addition to the expected boat-chair-boat (BCB). If only the TBCC and BCB conformations were assumed to be appreciably populated, then a free-energy difference between the two conformations of 0.73 ± 0.3 kcal/mol could be obtained from the five area measurements over a temperature range of −148.6 to −131.0 °C, with populations of 5.2 and 94.8% for the TBCC and BCB conformations at −146.1 °C. However, an alternative description of the conformations of 1 was suggested by the ab initio calculations, which predicted that the twist-boat-chair (TBC) and TBCC conformations have comparable free energies and populations. Equal amounts of TBCC and TBC would give populations of 5.2, 5.2, and 89.6% and relative free energies of 0.72, 0.72, and 0.00 kcal/mol for the TBCC, TBC, and BCB conformations at −146.1 °C, based on the experimental areas at this temperature. The experim...

Multifield 2H relaxation has been used to quantify the effect of solubilization of alkanes on the size and shape of the micelles in aqueous solutions of hexadecyltrimethylammonium bromide, C16TABr. Information about aggregate size and shape was deduced from the reorientation rate of the aggregates. The surfactant concentration was chosen so that the solutions without solubilizate contained moderately long rodlike micelles (axial ratio ∼4). It was found that the change in aggregation behavior upon solubilization is substantially different for solubilizates of similar chemical composition but different structures. Solubilization of small amounts of cyclohexane, cyclooctane, cyclodecane, trans-decalin, n-hexane, 2,3-dimethylbutane, or adamantane causes growth of the micelles. Further addition of these solubilizates (except for adamantane, which has a lower solubility limit than the other solubilizates) causes a decrease in the aggregate size. On the other hand, solubilization of n-octane, n-decane, or n-dode...

A previous analysis of the pressure-volume-temperature behaviour showed that the linear dimethylsiloxanes conform to a phenomenological principle of corresponding states resembling but not identical to that of the normal alkanes. A similar analysis for tetramethylsilane-regarded as the first member of the dimethylsiloxane homologous series: two cyclic dimethylsiloxanes, octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane, and two polydimethylsiloxanes, one linear and one cyclic-confirms that they conform to a similar principle. The results are used to predict with fair success the excess volumes of mixing of a series of six related mixtures of cyclic substances-cyclohexane, cyclooctane and cyclodecane + either octamethylcyclotetrasiloxane or decamethylcyclopentasiloxane-and two linear + cyclic substance mixtures-either n-hexane or decamethyltetrasiloxane + octamethylcyclotetrasiloxane.

We present an automated conformational analysis program, CAMDAS (Conformational Analyzer with Molecular Dynamics And Sampling). CAMDAS performs molecular dynamics (MD) calculations for a target molecule and samples conformers from the trajectory of the MD. The program then evaluates the similarities between each of the sampled conformers in terms of the root-mean-square deviations of the atomic positions, clusters similar conformers, and finally prints out the clustered conformers. This MD-based conformational analysis is a broadly used method, and CAMDAS is intended to provide a convenient framework for the method. CAMDAS has the ability to find the representative conformers automatically from an arbitrarily given structure of the molecule. The accuracy of the program was examined using N-acetylalanine-N'-methylamide, and the obtained result was consistent with that of the systematic search method. In the test calculation of cyclodecane, CAMDAS could identify most of the known conformers and their conformational enantiomers by examining only 5000 conformers. In addition, the potential-scaled method, which we have developed previously as an accelerating technique for MD, could find two additional conformers of cyclodecane that have not been reported. CAMDAS presents a convenient way to find the energetically possible conformers of a molecule, which is needed especially in the early stage of drug design.

Excess enthalpies HE at 298.15 K have been determined by flow microcalorimetry for binary mixtures of heptane or tetrachloromethane + a cyclic hydrocarbon (cycloheptane, cyclooctane, cyclodecane, 1,2,3,4-tetrahydronaphthalene, cis-decahydronaphthalene, trans-decahydronaphthalene, bicyclohexyl). With the exception of tetrahydronaphthalene + tetrachloromethane and of trans-decahydronaphtalene + heptane, all mixtures examined exhibit positive deviations. HEs have been analysed in terms of the DISQUAC model. Partial molar excess enthalpies at infinite dilution as well as standard enthalpies of solvation, ΔHo, have been evaluated for cycloalkanes in the two solvents and compared with those of linear and branched alkanes. The effect of cyclization upon ΔHo has been discussed and the contributions to ΔHo of the cavity and of the interaction terms have been estimated through the scaled particle theory.

Reactions of cycloheptane and cyclooctane were performed over the superacid of sulfated zirconia in liquid phase at 50 °C a main product was methylcyclohexane from cycloheptane through a protonated bicyclo[4.1.0]heptane and ethylcyclohexane from cyclooctane via a protonated bicyclo[4.2.0]octane. Cyclodecane was dehydrogenated into decalines; cyclododecane was converted into many products, more than 30 species.

We demonstrate that Casimir-Polder energies between noble gas atoms (dissolved in water) and oil-water interfaces are highly surface specific. Both repulsion (e.g. hexane) and attraction (e.g. glycerine and cyclodecane) is found with different oils. For several intermediate oils (e.g. hexadecane, decane, and cyclohexane) both attraction and repulsion can be found in the same system. Near these oil-water interfaces the interaction is repulsive in the non-retarded limit and turns attractive at larger distances as retardation becomes important. These highly surface specific interactions may have a role to play in biological systems where the surface may be more or less accessible to dissolved atoms., Comment: 5 pages, 6 figures

By means of a vibrating-tube densimeter, the densities at 25°C have been determined for binary mixtures of tetrachloromethane with a liquid (cyclodecane, cis-decahydronaphthalene, trans-decahydronaphthalene, bicyclohexyl, pentane) or a solid hydrocarbon (cyclododecane, cyclopentadecane, norbornane, adamantane, octahydro-4,7-methano-1H-indene). Excess molar volumes have been obtained in the whole mole fraction range for mixtures containing a liquid hydrocarbon. For solid cycloalkanes, apparent molar volumes have been evaluated in the whole range of miscibility. The partial molar volumes at infinite dilution\(\bar V^\circ \) have been calculated for all examined cycloalkanes and compared with those of n-alkanes. The dependence of\(\bar V^\circ \) upon the size and shape of the ring or cage structure of the solute is discussed. The capability of the Flory theory to reproduce VE for these mixtures is also tested.

With the aim of searching for conformational signatures and investigating the influence of cyclic connectivity in the valence XPS spectra of cycloalkane compounds ranging from C 5 H 10 to C 10 H 20 , the XPS spectra of optimized model structures are simulated by means of the direct Green's function approach. Calculations are performed using the minimal STO-3G basis set and a self-energy expansion derived at the level of the diagonal two-particle-hole Tamm-Dankoff approximation (2ph-TDA). A bent n-alkane chain is used to decouple roughly the combined effects of the cyclic connectivity and the torsional constraints imposed by such a connectivity

Rate constants have been measured for the reactions of OH radicals with a series of C(6)-C(10) cycloalkanes and cycloketones at 298 ± 2 K, by a relative rate technique. The measured rate constants (in units of 10(-12) cm(3) molecule(-1) s(-1)) were cycloheptane, 11.0 ± 0.4; cyclooctane, 13.5 ± 0.4; cyclodecane, 15.9 ± 0.5; cyclohexanone, 5.35 ± 0.10; cycloheptanone, 9.57 ± 0.41; cyclooctanone, 15.4 ± 0.7; and cyclodecanone, 20.4 ± 0.8, where the indicated errors are two least-squares standard deviations and do not include uncertainties in the rate constant for the reference compound n-octane. Formation yields of cycloheptanone from cycloheptane (4.2 ± 0.4%), cyclooctanone from cyclooctane (0.85 ± 0.2%), and cyclodecanone from cyclodecane (4.9 ± 0.5%) were also determined by gas chromatography, where the molar yields are in parentheses. Analyses of products by direct air sampling atmospheric pressure ionization mass spectrometry and by combined gas chromatography-mass spectrometry showed, in addition to the cycloketones, the presence of cycloalkyl nitrates, cyclic hydroxyketones, hydroxydicarbonyls, hydroxycarbonyl nitrates, and products attributed to carbonyl nitrates and/or cyclic hydroxynitrates. The observed formation of cyclic hydroxyketones from the cycloheptane, cyclooctane and cyclodecane reactions, with estimated molar yields of 46%, 28%, and 15%, respectively, indicates the occurrence of cycloalkoxy radical isomerization. Potential reaction mechanisms are presented, and rate constants for the various alkoxy radical reactions are derived.

Excess volumes at the temperature 298.15 K of (octamethylcyclotetrasiloxane + cyclodecane or hexane or decamethyltetrasiloxane) and of (decamethylcyclopentasiloxane + cyclodecane) were determined in a continuous-dilution dilatometer. The results were analysed using a phenomenological corresponding-states treatment based on the treatment of Patterson and Bardin. In that it correctly predicts the magnitude of the excess volumes and, for the mixtures containing only cyclic components, the dependence on ring size, this approach describes the experimental results better than does a simple two-parameter equation-of-state treatment based on the van der Waals one- or two-fluid models tested previously for mixtures of these kinds of molecules.

The acyclis ω-tosyloxy-α-phenylsulfenyl ketone 1 a, derived from R-(−)-carvone, underwent intramolecular alkylation to give the cyclodecenone derivative 2a in good yield. Oxidation of the sulfide to the sulfoxide and thermal elimination of phenylsulfinic acid gave the ketone 8, presumably resulting from Diels-Alder dimerization of the exomethylene ketone 9, as the major product and the endocyclic α,β-unsaturated ketone 7 as the minor product. Reduction of 7 with LAH and treatment of the allylic alcohol product 10 with the sulfur trioxide-pyridine complex followed by LAH gave the (Z),(Z)-1,6-cyclodecadiene 11 and three other minor products, possibly including the sesquiterpene, helminthogermacrene (3). In contrast to the keto sulfoxide 2b, which mainly underwent exo elimination of phenylsulfinic acid, the hydroxy sulfoxide 12b, prepared from ketone 2a, underwent largely endo elimination to give the allylic alcohol 13 containing a (Z),(Z)-1,5-cyclodecadiene system.

The fused-ring system of the title compound, C17H24O2, limits its conformational freedom. The five-membered cyclopentane and furan rings adopt envelope conformations, the tetrahydropyranone ring a boat conformation and the cyclodecanone ring a cyclodecane boat–chair–boat conformation.

The acyclis ω-tosyloxy-α-phenylsulfenyl ketone 1 a, derived from R-(−)-carvone, underwent intramolecular alkylation to give the cyclodecenone derivative 2a in good yield. Oxidation of the sulfide to the sulfoxide and thermal elimination of phenylsulfinic acid gave the ketone 8, presumably resulting from Diels-Alder dimerization of the exomethylene ketone 9, as the major product and the endocyclic α,β-unsaturated ketone 7 as the minor product. Reduction of 7 with LAH and treatment of the allylic alcohol product 10 with the sulfur trioxide-pyridine complex followed by LAH gave the (Z),(Z)-1,6-cyclodecadiene 11 and three other minor products, possibly including the sesquiterpene, helminthogermacrene (3). In contrast to the keto sulfoxide 2b, which mainly underwent exo elimination of phenylsulfinic acid, the hydroxy sulfoxide 12b, prepared from ketone 2a, underwent largely endo elimination to give the allylic alcohol 13 containing a (Z),(Z)-1,5-cyclodecadiene system.

The method of simulated annealing has been combined with an exact ring closure algorithm to locate the global minimum of hydrocarbon rings without energy minimization. A new program called ANNEAL-RING carries out simulated annealing by computation of the exact new positions of three or more atoms and then application of the Metropolis Monte Carlo accept-reject criterion [exp(-ΔE/RT)] with cooling. Cyclononane, cyclodecane, cycloundecane and cycloheptadecane were studied.

Tandem dehydrogenation–olefin-metathesis catalyst systems, comprising a pincer-ligated iridium-based alkane dehydrogenation catalyst and a molybdenum-based olefin-metathesis catalyst, are reported to effect the metathesis-cyclooligomerization of cyclooctane and cyclodecane to give cycloalkanes with various carbon numbers, predominantly multiples of the substrate carbon number, and polymers.

In a search for alkane candidates for 193 nm immersion fluids, several alkanes and cycloalkanes were synthesized, purified and screened to ascertain their absorption at 193 nm, refractive index and temperature dispersion coefficient in the context of the actual application. In general, cycloalkanes, and more specifically polycycloalkanes, possess a higher refractive index than do linear alkanes. Decalin, cyclodecane, perhydrophenanthreme (PHP), perhydrofluorene (PHF) and perhydropyrene (PHPY) are examined as potential second and third generation immersion fluids. The use of perhydropyrene, which possesses a high refractive index of 1.7014 at 193 nm, may be limited as an immersion fluid because of high absorption at 193 nm. Mixtures of cycloalkanes can lead to a higher enhancement of the refractive index together with a decrease on the viscosity. Exhaustive purification of the fluids is a critical step in determining the real absorption of the different fluids at 193 nm. Two simple purification processes of these cycloalkanes were developed that led to low absorption fluids in the VUV region. The possibility of forming the oxygen complex in aerated fluids was reduced by purging samples with argon or nitrogen. This easy elimination of the oxygen complex shows the weak bonding nature of this complex.

The fused-ring system of the title compound, C17H24O2, limits its conformational freedom. The five-membered cyclopentane and furan rings adopt envelope conformations, the tetrahydropyranone ring a boat conformation and the cyclodecanone ring a cyclodecane boat–chair–boat conformation.

The p-methoxy-substituted pincer-ligated iridium complexes, (MeO-(tBu)PCP)IrH(4) ((R)PCP = kappa(3)-C(6)H(3)-2,6-(CH(2)PR(2))(2)) and (MeO-(iPr)PCP)IrH(4), are found to be highly effective catalysts for the dehydrogenation of alkanes (both with and without the use of sacrificial hydrogen acceptors). These complexes offer an interesting comparison with the recently reported bis-phosphinite "POCOP" ((R)POCOP = kappa(3)-C(6)H(3)-2,6-(OPR(2))(2)) pincer-ligated catalysts, which also show catalytic activity higher than unsubstituted PCP analogues (Gottker-Schnetmann, I.; White, P.; Brookhart, M. J. Am. Chem. Soc. 2004, 126, 1804). On the basis of nu(CO) values of the respective CO adducts, the MeO-PCP complexes appear to be more electron-rich than the parent PCP complexes, whereas the POCOP complexes appear to be more electron-poor. However, the MeO-PCP and POCOP ligands are calculated (DFT) to show effects in the same directions, relative to the parent PCP ligand, for the kinetics and thermodynamics of a broad range of reactions including the addition of C-H and H-H bonds and CO. In general, both ligands favor (relative to unsubstituted PCP) addition to the 14e (pincer)Ir fragments but disfavor addition to the 16e complexes (pincer)IrH(2) or (pincer)Ir(CO). These kinetic and thermodynamic effects are all largely attributable to the same electronic feature: O --C(aryl) pi-donation, from the methoxy or phosphinito groups of the respective ligands. DFT calculations also indicate that the kinetics (but not the thermodynamics) of C-H addition to (pincer)Ir are favored by sigma-withdrawal from the phosphorus atoms. The high nu(CO) value of (POCOP)Ir(CO) is attributable to electrostatic effects, rather than decreased Ir-CO pi-donation or increased OC-Ir sigma-donation.

The conformers of cycloheptane through cyclodecane have been examined at the B3LYP/6-311+G* and MP2/6-311+G* theoretical levels, with some additional calculations at the CCD/6-311+G* and CCSD(T)/6-311++G** levels. With cyclooctane, B3LYP predicts that the boat-chair and crown conformers have similar energies, whereas MP2 and CCSD(T) predict that the crown conformer is 2 kcal/mol higher in energy. The latter is in agreement with the electron diffraction data. With cyclononane, B3LYP predicts that two of the higher-energy conformers found in molecular mechanics calculations should convert to one of the lower-energy conformers. However, MP2/6-311+G* optimizations find them to be true minima on the potential energy surface. B3LYP systematically predicts larger C-C-C bond angles for these compounds than either MP2 or CCD. The results of molecular mechanics MM4 calculations are generally in good agreement with those obtained using MP2.

A copper-mediated procedure for terminal alkynyl-propargyl coupling has been applied to "skipped" bis-terminal undecatetrayne and 1,4-bis(pseudo)halobut-2-ynes with the aim of preparing ring carbomers of representative strained and loose cycloalkanes, namely [N]pericyclynes. Two unprecedented, cyclic. "skipped" polyynes with CH2 vertices have been isolated as mixtures of diastereoisomers: an isomer 1b and a dimer 2a of [5]pericyclyne 1a. The isomer 1b is a cyclotetrayne with an exocyclic allene function resulting from a unique formal SN process. Its structure has been established by 1H/13C HMQC and HMBC two-dimensional NMR analysis. According to density functional theory calculations, it is about 6 kcalmol(-1) more stable than [5]pericyclyne (1a). Compound 1b can also be regarded as a C13-relaxed [4]pericyclyne, a long sought "skipped" C12 tetrayne. The dimer 2a is a C30 ring that results from a formal SN process. It is a stable ring carbomer of cyclodecane, that is, a [10]pericyclyne, with four CH2 vertices.

The oxygen atom of cyclodecanone, formed by oxidation of cyclodecane using FeCl3–H2O2 in pyridine–acetic acid, is largely derived from molecular oxygen: taken in conjunction with results of radical-trapping experiments, this supports a free-radical mechanism for the hydrocarbon activation.

The present study describes an ongoing assessment of hydrogen donor (H-donor) compounds and compounds with similar chemical characteristics (decahydroquinoline and cyclodecane) as thermal stabilizers in JP-8+100 fuel. Decalin (a mixture of stereo-isomers (cis- and tmns-) of bicyclo[4.4.0] decane) and 1,2,3,4-tetrahydroquinolme (THQ) were evaluated at various concentrations in JF-8+100 fuel and stressed to temperatures up to 600°C for six hours in a flowing reactor system. Additionally, cisdecalin and tram+decalin, are assessed individually to determine if their thermal stability activities in a static reactor’ are correlatable to a flowing system, and to compare with the performsnce of decslin. The thermal oxidative and pyrolytic deposition for all fuel/additives mixtures, the conversion percentages and composition of the stressed fuel’s gaseous and liquid products are reported.

We report the complexation of a series of n- and cycloalkanes by an anionic, metal−ligand cluster carrying a 12- charge. This host also encapsulates cyclodecane isomers such as adamantane, the dicy...

Cyclodecane and cyclohexane were converted to the corresponding cycloalkanones and cycloalkanols upon ozonation at acidic pH. Also some ring cleavage to dicarboxylic acids or aldehydoacids was observed.

(i–PrPCP)IrH2 is found to be a remarkably effective solution-phase catalyst for the ‘acceptorless’ thermochemical dehydrogenation of cycloalkanes (and isomerization in the case of cyclodecane), and the first such catalyst reported to effect the dehydrogenation of n-alkanes.

Cycloalkanes are candidates for immersion fluids because of their potential for low absorption in the 193-nm region and for a high refractive index RI. We have developed an empirical correlation be- tween refractive index and density of alkanes, which allows a prediction of the best candidates for immersion fluids based on the alkane struc- ture. In particular, the correlation reveals that polycycloalkanes such as perhydrophenanthrene PHPh and perhydrodropyrene PHPy, which have a higher RI than linear or cyclic alkanes, will be excellent candi- dates for immersion fluids at 193 nm. Therefore, PHPh and PHPy were synthesized by exhaustive hydrogenation of phenanthrene and pyrene. However, methods for the purification of the synthesized and commercial alkanes such as cyclodecane CYD, cyclohexane CYX, pentane PNT, and decalin DEC are required in order to determine the actual absorption of candidates at 193 nm. The presence of an absorbing im- purity at 193 nm can cause the premature elimination of otherwise ex- cellent potential candidates. A rather subtle impurity is molecular oxygen, which does not itself absorb at 193 nm, but which forms complexes with alkanes that do absorb at 193 nm. In this case, the "impurity" is readily eliminated by simple purging with nitrogen or argon gas. © 2007 Society of

1,5,9-Triphospha-1,5,9-tris(2-propyl)cyclodecane is liberated from the molybdenum template upon which it is formed by action of aqueous base and after oxidation of the metal with halogens.