Rate constants for the reactions of Cl atoms with a series of C6–C10 cycloalkanes and cycloketones at 297 ± 2 K

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     

The C7-C10 cycloalkanes revisited

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.     

Beyond the corey reaction: one-step diolefination of cyclic ketones

The reactivities of the cyclic ketones cycloheptanone, cyclodecanone, and cycloundecanone with dimethylsulfoxonium methylide generated from trimethylsulfoxonium iodide and base (NaH) were studied in diglyme at 130 degrees C. Oxiranes, which primarily form via the Corey reaction, lead to ring expansions to give oxetanes and oxacyclopentanes when an excess of dimethylsulfoxonium methylide is used. The Corey reaction is suppressed in the presence of excess of base, and 1,3-terminal dienes form instead (we term this reaction the Yurchenko diolefination). Our mechanistic proposal involves the deprotonation of the betaine that forms after the attack of dimethylsulfoxonium methylide on the carbonyl group of the ketone. The key step of the diolefination reaction involves a [2,3]-sigmatropic rearrangement of the ylide to a gamma-unsaturated sulfoxide with a barrier of 9.9 kcal/mol (DeltaH298, MP2/cc-pVDZ, for the cycloheptane derivative). The elimination of sulfenic acid from the gamma-unsaturated sulfoxide in the terminal step of the diolefination is associated with a higher barrier (17.3 kcal/mol) but is strongly accelerated in the presence of base. The reactivity of cyclic ketones in the Yurchenko reaction depends on the ring size; medium-sized cyclodecanone is less reactive than either cycloheptanone or cyclododecanone.     

Photoionization mass spectra of alicyclic compounds with various substituents,and their ionization energies and appearance energies

Conclusions We measured the ionization energies, the appearance energies, and the photoionization mass spectra of the oximes of cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and cyclododecanone and of some other compounds of the cyclooctane and cyclododecane series.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2602–2605, November, 1979.     

Screening of a minimal enriched P450 BM3 mutant library for hydroxylation of cyclic and acyclic alkanes

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%).     

Atmospheric chemistry of C3-C6 cycloalkanecarbaldehydes

The rate coefficients for the gas phase reaction of NO3 and OH radicals with a series of cycloalkanecarbaldehydes have been measured in purified air at 298 +/- 2 K and 760 +/- 10 Torr by the relative rate method using a static reactor equipped with long-path Fourier transform infrared (FT-IR) detection. The values obtained for the OH radical reactions (in units of 10(-11) cm3 molecule(-1) s(-1)) were the following: cyclopropanecarbaldehyde, 2.13 +/- 0.05; cyclobutanecarbaldehyde, 2.66 +/- 0.06; cyclopentanecarbaldehyde, 3.27 +/- 0.07; cyclohexanecarbaldehyde, 3.75 +/- 0.05. The values obtained for the NO3 radical reactions (in units of 10(-14) cm3 molecule(-1) s(-1)) were the following: cyclopropanecarbaldehyde, 0.61 +/- 0.04; cyclobutanecarbaldehyde, 1.99 +/- 0.06; cyclopentanecarbaldehyde, 2.55 +/- 0.10; cyclohexanecarbaldehyde, 3.19 +/- 0.12. Furthermore, the reaction products with OH radicals have been investigated using long-path FT-IR spectroscopy and proton-transfer-reaction mass spectrometry (PTR-MS). The measured carbon balances were in the range 89-97%, and the identified products cover a wide spectrum of compounds including nitroperoxycarbonyl cycloalkanes, cycloketones, cycloalkyl nitrates, multifunctional compounds containing carbonyl, hydroxy, and nitrooxy functional groups, HCOOH, HCHO, CO, and CO2.     

Selective oxidation of cyclooctane to cyclootanone with molecular oxygen in the presence of compressed carbon dioxide

The oxidation of cyclooctane (1) to cyclooctanone (3) with molecular oxygen and acetaldehyde (2) as a co-reductant occurs efficiently in the presence of compressed CO2. Up to 20% yields of 3 are obtained under optimised multiphase conditions.     

Rearrangements in cobaltic fluoride fluorinations of cycloalkanes with seven or more ring carbons

Cyclo-heptane, -octane, -decane, -dodecane and -octadecane have been fluorinated in the vapour phase with cobaltic fluoride. The perfluorocarbons obtained revealed varying degrees of skeletal rearrangements. Thus, cycloheptane gave perfluoro-cycloheptane and -methylcyclohexane; cyclooctane gave at least eight fluorocarbons including-bicyclo(3,3,0)octane and -cyclooctane; cyclodecane gave a complex mixture from which were isolated perfluoro cis- and trans-bicyclo(4,4,0)decanes but no perfluorocyclodecane; cyclododecane and cyclooctadecane gave complex fluorocarbon mixtures in which none of the fluorocarbons with the original cycloalkene skeleton could be detected.Tetradecafluorobicyclo(3,3,0)octane gave dodecafluorobicyclo (3,3,0)oct-1(5)-ene and decafluorobicyclo(3,3,0)octa-di-1(5), 2-ene when pyrolysed over iron gauze.The fluorination of cyclooctane also afforded 1$\text{H}$-pentadecafluorocyclooctane which was dehydrofluorinated to tetradecafluorocyclooctene. This was converted to a range of derivatives including dodecafluorosuberic acid, 1,2-dichlorotetradecafluorocyclooctane, 1-methoxy tridecafluorocyclooctene and tetradecafluorocyclooctanone.     

Synthesis of Some Novel Cyclooctane‐Fused‐Heterocycles with Anticipated Biological Activities

Claisen‐Schmidt condensation of furan‐2‐carboxaldehyde 1 with cyclooctanone 2 afforded smoothly the bischalcone: 2,8‐bis((furan‐2‐yl)methylene)cyclooctanone 3 . Compound 3 was allowed to react with different organic reagents through 1,2 and 1,4 cycloaddition reactions to afford the cyclooctane‐fused heterocyclic compounds 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 and 17a , 17b , 17c in good yields. The structures of all the new compounds were elucidated and deduced from their elemental analyses as well as the spectral data.     

Thermodynamics of Mixtures Excess Volumes and Energies of Mixing of Cycloalkane Mixtures (Cyclopentane to Cyclooctane)

The volumes of mixing for the systems cyclopentane + cyclohexane, cyclopentane + cycloheptane, cyclohexane + cycloheptane (at 20°C), and cyclopentane + cyclooctane, cyclohexane + cyclooctane, cycloheptane + cyclooctane (at 30 °C) have been measured with a dilatometer. All systems show volume contractions, except the first. The energies of mixing are also given. They vary from 7 to 55 J/mol for equimolar solutions.     

FRIEDEL-CRAFTS-Reaktionen der C7-, C8- und C12-Cycloalkane mit Kohlenmonoxid

The reaction of cycloheptane, cyclooctane, and cyclododecane with carbon monoxide under pressure in the presence of anhydrous aluminium chloride has been investigated. Cycloheptane leads to acetylcyclohexane and trans-2-methyl-cyclohexane carboxylic acid as main products. Cyclooctane yields 3- and trans-4-acetyl-methylcyclohexane and various dimethylcyclohexane carboxylic acids. From cyclododecane a mixture of numerous ketones has been obtained besides a mixture of acids.     

Functionalization of alkanes and cycloalkanes by superelectrophiles. 15. Carbonylation of cycloheptane,cyclooctane, and isomeric monoalkylcyclohexanes with CO in the presence of CBr4·2AlBr3 to form individual esters of tertiary carboxylic acids of the cyclohexane series

Cycloheptane, methylcyclohexane, cyclooctane, and ethylcyclohexane were selectively carbonylated with CO. The reactions of cycloalkanes with CO at –40 °C in the presence of the superelectrophilic system CBr₄·2AlBr₃ in CH₂Br₂ followed by treatment of the reaction mixtures with alcohols afforded esters of 1-methylcyclohexanecarboxylic acid (in the reactions of cycloheptane and methylcyclohexane) or esters of 1-ethylcyclohexanecarboxylic acid (in the reactions of cyclooctane and ethylcyclohexane) in 70—80% yields with respect to CBr₄·2AlBr₃. The reaction of 1,3-dimethylcyclohexane at –40 °C and the reactions of cyclooctane and ethylcyclohexane and at –20 °C proceeded nonselectively to form four isomeric esters C₈H₁₅COOR.     

4-Methyl-3,4-dihydrospiro[cycloheptane-1′,2(1H)-quinoline] and 4-methyl-3,4-dihydrospiro[cyclooctane-1′,2(1H)-quinoline]. synthesis of derivatives and chemical transformations

New derivatives of 3 ,4-dihydrospiro[cycloalkane-1′,2(1H)-quinolines] were obtained from cycloheptanone and cyclooctanone via facile three steps hetero spiro annulation process. Their nitro derivatives were prepared through electrophilic substitution reactions.     

Reactivity of cycloalkanes in hydrogen abstraction with different acceptors

The reactions of some acceptors (^?CH₃, ^?OOH, ^?CCl₃, O₃, and Br^?) with saturated cyclic hydrocarbons, viz., cyclohexane, cycloheptane, and cyclooctane were studied by the DFT methods based on B3LYP and PBE0 functionals, the method based on the double hybrid functional B2PLYP, a combined ONIOM approach (CCSD:B3LYP)) and the coupled-cluster method (CCSD) using the 6-31+G**, aug-cc-pVDZ, Midi-X, and SVP basis sets. A specific feature of these reactions is that their rates depend on the excess ring energy, although no ring opening occurs in all cases.     

C4-C14-alkyl nitrates as organic trace compounds in air

The long chain alkyl nitrates (C _n >5) form a complex spectrum of natural and anthropogenic organic trace compounds in air. HRGC/ECD and HRGC/MSD using 56 amu as the signal reveal a standard pattern of isomeric n-alkyl nitrates in semi-rural air. This is regulated by the input of the corresponding alkanes, their rate constants for the reaction with OH, the rate constant of the alkylperoxy radicals for the reaction to alkyl nitrates, the atmospheric concentrations of NO/NO₂ and by the rate constants of the alkyl nitrates for the reaction with OH radicals as the major removal reaction. The complex pattern of signals given by the ECD in the retention index range between 700 and 2000 has been observed before but this is the first time that it has been assigned to a defined group of chemical compounds.The environmental impact of the occurrence of the different groups of alkyl nitrates has yet to be evaluated. Their general property as organic stabilizers for NO/NO₂ and therefore as precursors of NO ₃ ^- ions in rain and their biological potentials are also known. The long chain alkyl nitrates act as lipophilic carriers for nitric acid.     

Catalytic ketonisation over oxide catalysts

Activity of pure Al₂O₃ has been studied in cycloketonisation of various dialkyl alkanodiates of general formula (CH₂)_n(COOR)₂, where n = 4, 5, 6, 7, 8 and 10 and R = Et, s-Bu and t-Bu at the temperature range 598-723 K in a flow system. The yields of cycloalkanones strongly depend on the size of the ring formed, the structure of alkyl group in ester molecule and on the reaction temperature. Cyclopentanone, cyclohexanone and cycloheptanone were obtained with yields 50-60% from the appropriate diethyl esters. The only low yields (<8%) of cyclooctanone, cyclononane and cycloundecanone were achieved. An increase in the order of the ester alkyl group leads in some cases to higher yields of ketones - di t-butyl hexanodiate yielded 88% of cyclopentanone. This revised version was published online in August 2006 with corrections to the Cover Date.     

Reaction of cyclic ketones with KOH-DMSO

Upon reaction of cycloalkanones with a KOH-DMSO system 2-methylenecycloal-kanols are formed, the yield (10–37%) of which decreases in the series: cyclohexanone > cycloheptanone > cyclooctanone > cyclododecanone.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1601–1605, July, 1990.     

Kinetics and products of the gas-phase reactions of divinyl sulfoxide with OH and NO3 radicals and O3

Using relative rate methods, rate constants for the gas-phase reactions of divinyl sulfoxide [CH 2CHS(O)CHCH 2; DVSO] with NO 3 radicals and O 3 have been measured at 296 +/- 2 K, and rate constants for the reaction with OH radicals have been measured over the temperature range of 277-349 K. Rate constants obtained for the NO 3 radical and O 3 reactions at 296 +/- 2 K were (6.1 +/- 1.4) x 10 (-16) and (4.3 +/- 1.0) x 10 (-19) cm (3) molecule (-1) s (-1), respectively. For the OH radical reaction, the temperature-dependent rate expression obtained was k = 4.17 x 10 (-12)e ((858 +/- 141)/ T ) cm (3) molecule (-1) s (-1) with a 298 K rate constant of (7.43 +/- 0.71) x 10 (-11) cm (3) molecule (-1) s (-1), where, in all cases, the errors are two standard deviations and do not include the uncertainties in the rate constants for the reference compounds. Divinyl sulfone was observed as a minor product of both the OH radical and NO 3 radical reactions at 296 +/- 2 K. Using in situ Fourier transform infrared spectroscopy, CO, CO 2, SO 2, HCHO, and divinyl sulfone were observed as products of the OH radical reaction, with molar formation yields of 35 +/- 11, 2.2 +/- 0.8, 33 +/- 4, 54 +/- 6, and 5.4 +/- 0.8%, respectively, in air. For the experimental conditions employed, aerosol formation from the OH radical-initiated reaction of DVSO in the presence of NO was minor, being approximately 1.5%. The data obtained here for DVSO are compared with literature data for the corresponding reactions of dimethyl sulfoxide.     

Kinetics of the gas-phase reactions of OH radicals with alkyl nitrates at 299 ± 2 K

Relative rate constants for the gas-phase reactions of OH radicals with a series of alkyl nitrates have been determined at 299 ± 2 K, using methyl nitrite photolysis in air as a source of OH radicals. Using a rate constant for the reaction of OH radicals with cyclohexane of 7.57 × 10^?12 cm³/molec·s, the rate constants obtained are (× 10¹² cm³/molec·s): 2-propyl nitrate, 0.18 ± 0.05; 1-butyl nitrate, 1.42 ± 0.11; 2-butyl nitrate, 0.69 ± 0.10; 2-pentyl nitrate, 1.87 ± 0.12; 3-pentyl nitrate, 1.13 ± 0.20; 2-hexyl nitrate, 3.19 ± 0.16; 3-hexyl nitrate, 2.72 ± 0.22; 3-heptyl nitrate, 3.72 ± 0.43; and 3-octyl nitrate, 3.91 ± 0.80. These rate constants, which are the first reported for the alkyl nitrates, are significantly lower than those for the parent alkanes, and a formula, based on the numbers of the various types of C? H bonds in the alkyl nitrates, is derived for rate constant estimation purposes.     

Gas-phase reactions of brominated diphenyl ethers with OH radicals

A small volume reaction chamber coupled to a mass spectrometer was used to study the gas-phase kinetics and mechanism of the reaction of OH radicals with diphenyl ether and seven polybrominated diphenyl ethers (PBDEs) with 1-2 bromines. Relative rate constants for these reactions were determined using isopropyl nitrite photolysis in He-air mixtures at approximately 740 Torr between the temperatures of 326-388 K. The Arrhenius expression for each compound was used to extrapolate the following OH rate constants at 298 K (in units of 10(-12) cm3 molecule(-1) s(-1), with 95% confidence intervals): diphenyl ether, 7.45 +/- 0.13; 2-bromodiphenyl ether, 4.7; 3-bromodiphenyl ether, 4.6; 4-bromodiphenyl ether, 5.7; 2,2'-dibromodiphenyl ether, 1.3; 2,4-dibromodiphenyl ether, 3.8; 3,3-dibromodiphenyl ether, 3.2; and 4,4'-bromodiphenyl ether, 5.1. The measured OH rate constants are in reasonable agreement with those predicted by structure activity relationships. Positive temperature dependences of these OH rate constants are observed for all compounds measured except for diphenyl ether and 4,4'-dibromodiphenyl ether. Bromophenols (in yields up to 20% relative to the amount of PBDE consumed) and Br2 were characterized as products of these reactions, suggesting that OH addition to ipso positions of these brominated aryls may be an important reaction pathway.