bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lithium Salt Effects on Extractions of 15-Crown-5, 18-Crown-6, or Their Silver(I) Complexes as Picrates
Authors: Hasegawa Yuko , Nakano Takahisa , Odori Yoshihiro , Ishikawa Y\={u}k\={o} 
Published: July 2006

Abstract
The extractions of 15-crown-5, 18-crown-6, or their silver(I) or lithium(I) complexes as picrates from lithium salt solutions into chloroform have been studied at 25 °C. The extractions of these crown ethers were impaired by an increase in the lithium perchlorate or nitrate concentration. A small salting-out effect was observed in the presence of lithium chloride. The extraction of silver(I) was also impaired by the addition of lithium perchlorate or nitrate. In the lower-concentration region of the lithium salts, the extraction of silver(I) was affected more markedly than that of crown ether itself.
A Synthetic Route to the Morphan Ring System by Skeletal Transformation of Norbornadiene
Authors: Inoue Hiroo , Origuchi Toshiki , Umano Katsumi 
Published: July 2006

Abstract
The morphan skeleton was prepared from 2-phenylsulfonyl-2-azabicyclo[3.2.1]oct-6-ene (2), derived from norbornadiene, through the addition of dichlorocarbene to the monoene 2 and the subsequent thermal isomerization of the adduct obtained. The isomerization products, 2-phenylsulfonyl-6,7-dichloro-2-azabicyclo[3.3.1]non-7-ene and 2-phenylsulfonyl-7,8-dichloro-2-azabicyclo[3.3.1]non-6-ene, which are mutually convertible in the presence of lithium chloride, were converted into various morphans by reductive dechlorination and alkylation. Furthermore, the 6,7-pyridazino-annelated morphan was synthesized by the cycloaddition of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate to 2-phenylsulfonyl-2-azabicyclo[3.3.1]non-6-ene.
Asymmetric Hydrogenation of Dehydrodipeptides with Rhodium(I)–Chiral Diphosphinites. Selective (S,S)- and (R,R)-Product Formation by Double Asymmetric Induction
Authors: Yatagai Masanobu , Yamagishi Takamichi , Hida Mitsuhiko 
Published: July 2006

Abstract
In the hydrogenation of dehydrodipeptides, the effect of chiral center of the substrate ((S) or (R)) on the asymmetric induction was examined using the catalysts of Rh(I)–chiral diphosphinite containing pyrrolidine moiety (POP). The catalysts with POP’s having the ω-(dimethylamino)alkyl group indicated an extremely large double asymmetric induction to give (S,S)- or (R,R)-product in high stereoselectivities, depending on the chiral center of the substrates. This result was ascribed to the electrostatic interaction between the ligand and substrate. POP’s without ω-(dimethylamino)alkyl group gave (R,R)-product for (R)-substrate in a high stereoselectivity by the steric effect between the ligand and substrate, while for (S)-substrate, (S,S)-product was obtained in a low stereoselectivity.
Studies on the Electronic Absorption Spectra of Some Selected Furan Derivatives. Molecular Orbital Calculations
Authors: Abu-Eittah Rafie Hassan , Hammed Maher Mohamed 
Published: July 2006

Abstract
The electronic absorption spectra of three groups of furan derivatives: 2-formyl, 2-acetylfuran, and 2-furoic acid, N-(2-furylmethylene)amines and phenylfurans were investigated. The predominant conformation as well as the polarity of the molecule could be predicted from its spectrum. The investigated molecules were proved to be “all planar” configuration which led to substantial interaction between the electronic states of the subsystems. The preferred conformations of N-(2-furylemthylene)methylamine and N-(2-furylemthylene)aniline were predicted with the aid of molecular orbital calculations.
Efficient Synthesis and Structure of Bis[acetonitrile(11,13-dimethyl-1,4,7,10-tetraaza-10,13-cyclotridecadien-12-ylidene)nickel(II)] Perchlorate
Authors: Mochizuki Katsura , Toriumi Koshiro , Ito Tasuku 
Published: July 2006

Abstract
The titled binuclear nickel(II) complex has been synthesized by the oxidation of 11,13-dimethyl-1,4,7,10-tetraaza-10,13-cyclotridecadienatonickel(II) perchlorate with iron(III) perchlorate in deoxygenated CH3CN in ca. 70% yield and its structure has been determined.
Photoreductive Dehalogenation of Organic Halides in the Presence of Lithium Aluminum Hydride
Authors: Shimizu Nobujiro , Watanabe Kenji , Tsuno Yuho 
Published: July 2006

Abstract
Lithium aluminum hydride markedly accelerates photoreductive dehalogenation of cyclopropyl, aromatic, and olefinic halides carried out in ether.
Restricted Rotation Involving the Tetrahedral Carbon. LII. Rotational Barriers in 1,2,3,4-Tetrafluoro- and 1,4-Dimethoxy-9-(1-cyano-1-methylethyl)triptycenes
Authors: Yamamoto Gaku , Tanaka Akira , Suzuki Masahiko , Morita Yasuji , Oki Michinori 
Published: July 2006

Abstract
Kinetic measurements of rotamer isomerization of the title compounds show that the rotational barriers in these compounds are considerably higher than those in the peri-unsubstituted and the peri-chloro or peri-methyl compounds, affording a support to our earlier finding that the rotational barrier increases and then decreases as the peri-substituent becomes bulkier in 9-t-alkyltriptycenes.
Regioselective Hydrogenation of Unsymmetrically Substituted Cyclic Anhydrides Catalyzed by Ruthenium Complexes with Phosphine Ligands
Authors: Ikariya Takao , Osakada Kohtaro , Ishii Youichi , Osawa Shoichi , Saburi Masahiko , Yoshikawa Sadao 
Published: July 2006

Abstract
Regioselective hydrogenation of unsymmetrically substituted cyclic anhydrides catalyzed by ruthenium complexes with mono-, di-, or triphosphine ligands produced the corresponding two isomeric lactones, where the regioselectivity was influenced by the bulkiness of the substituent(s) on the anhydrides and of the phosphine ligands of catalyst.
Conformation et Configuration en Solution d’une Serie d’Oxo Aldoximes Aliphatiques
Authors: Bernadou Jean , Fayet Jean Pierre , Bonnafous Monique , Mauret Pierre 
Published: July 2006

Abstract
La stéréochimie de cinq α-oxo aldoximes R–CO–CH (NOH) (R=Me 1, Et 2, n-Pr 3, i-Pr 4, t-Bu 5) a été étudiée : la configuration connue est E dans tous les cas mais les deux conforméres s-cis et s-trans peuvent exister en différentes proportions lorsque varient la taille de R, la température ou le pH.
Chemical-state Analysis by Means of Soft X-Ray Spectroscopy. I. L2,3-Emission Spectra for Phosphorus, Sulfur, and Chlorine in Various Compounds
Authors: Taniguchi Kazuo 
Published: July 2006

Abstract
The phosphorus-, sulfur-, and chlorine-L2,3 emission spectra in various compounds are obtained using secondary excitation. The spectra are discussed from the point of view of chemical-state analysis. It should be noted that the spectra of a highly ionic bond reveal scarcely no influence of the cations. However, the spectra with a covalent character are complex as a result of the molecular orbital generated with the covalent bond. The spectral features are influenced by the chemical condition of the surrounding atoms and are sensitive to oxygen and hydrogen.
Chemical-state Analysis by Means of Soft X-Ray Spectroscopy. III. O Kα Emission Spectra for Oxyanions in Different Salts
Authors: Taniguchi Kazuo 
Published: July 2006

Abstract
The oxygen Kα spectra of the oxyanions in different salts are obtained by secondary excitation. The obtained spectra are affected by the cations, the central atom, and the chemical-bond condition. Generally, there are four components in the spectra, but one small component may originate from the anomalous reflection of an analyzing crystal. The spectra are discussed from the point of view of chemical-state analysis.
Determination of Formal Potentials of Multihemoprotein, Cytochrome c3 by 1H Nuclear Magnetic Resonance
Authors: Kimura Keisaku , Nakajima Shinsuke , Niki Katsumi , Inokuchi Hiroo 
Published: July 2006

Abstract
Macroscopic redox potentials of tetrahemoprotein, cytochrome c3 from D. vulgaris, Miyazaki strain, were derived from 400 MHz 1H NMR measurements. The formal potential, E1o′, was determined to be −0.245±0.005 V vs. NHE compared with a value of −0.240 V obtained electrochemically. The distributions of the intermediate states from the NMR spectra during a redox titration are in good agreement with those previously determined by electrochemistry.
Comparative Studies of Anionic Molecular Assemblies as Mediums for Electron Transfer Quenching of Excited Ru[(bpy)3]2+ by Cationic Quenchers
Authors: Shioyama Hiroshi , Takami Akihiro , Mataga Noboru 
Published: July 2006

Abstract
Behaviors of excited [Ru(bpy)3]2+ bound to anionic molecular assemblies such as polymer electrolytes, vesicles and micelles together with electron-acceptor quencher MV2+ have been investigated by measurements of [Ru(bpy)3]2+ luminescence quenching and radical yields in electron-transfer quenching using a dye laser photolysis apparatus. Quenching behavior characteristic to each molecular assembly has been observed. A remarkable enhancement of quenching was observed in the presence of poly(vinyl sulfate). Such an effect was observed also in sodium dihexadecyl phosphate solution though it is less pronounced. However, no such specific quenching behavior was observed in sodium dodecyl sulfate micellar solution.
Formation Constants of Cyclodextrin Inclusion Complexes with Iodine in Aqueous Solutions
Authors: Sanemasa Isao , Kobayashi Toyohisa , Deguchi Toshio 
Published: July 2006

Abstract
Formation constants of cyclodextrin (CyD) inclusion complexes with iodine were determined by measuring solubilities of iodine vapor in water. The formation constants at 25 °C are 8.3×103 (α-CyD), 1.0×102 (β-CyD), and 13 dm3 mol−1 (γ-CyD). The temperature dependence of α-CyD–I2 complexation was studied. ΔH and ΔS, being 9.52 kJ mol−1 and 107 J K−1 mol−1 at 25 °C, respectively, are both largely dependent on temperature even within a rather small temperature range 15–35 °C studied. For the complexation with α-CyD, contribution of dehydration of iodine was estimated. The method proposed here is useful to study the formation of CyD association complexes with such substrates as are slightly soluble in water and easily vaporize from the aqueous phase.
Solubility and Synergistic Extraction Equilibria for [4-(2-Pyridylazo)resorcinolato] Nickel(II) Complexes
Authors: Hoshino Hitoshi , Yotsuyanagi Takao 
Published: July 2006

Abstract
The nickel(II) complex of 4-(2-pyridylazo)resorcinol (PAR, H2L) is known to show somewhat anomalous and complicated behavior in solution. In this regard, the solubility and the synergistic extraction equilibria of the above complex are studied in connection with acid dissociation reactions. The intrinsic solubility and the acid dissociation constants are determined to be, S0=[[Ni(HL)2]]=10−6.2±0.1 mol dm−3, Ka1=[[Ni(HL)L]−][H+][[Ni(HL)2]]−1=10−6.2±0.1, and Ka2=[[NiL2]2−][H+][[Ni(HL)L]−]−1=10−7.1×0.1, respeactively in the solution with the ionic strength of 0.10 (Na2SO4) at 298 K. Using the above constants, the extraction constant of the neutral complex with trioctylphosphine oxide (TOPO) into chloroform is evaluated as Kex=[[Ni(HL)2(TOPO)2]]o[[Ni(HL)2]]−1[TOPO]o−2=103.1±0.2, where the subscript o denotes the organic phase. An equilibrium diagram for the nickel(II)–PAR complexes is proposed.
Synthesis and Properties of a New Photoresponsive Crown Ether with a Fluorescent Stilbene-cap
Authors: Shinkai Seiji , Miyazaki Kiminori , Nakashima Mikio , Manabe Osamu 
Published: July 2006

Abstract
A new photoresponsive crown ether 2 with a stilbene-cap was synthesized. The crown trans-2 could extract Li+ and Na+ into the organic phase, and UV light irradiation which produces photoisomerized cis-2 enhanced the extractability. Thus, the stilbene-cap induces the conformational change in the crown ether moiety by photoirradiation.
Sterically Controlled Synthesis of Aspartic Acid by Addition of Dialkyl Malonate to N-Benzyloxycarbonyl-l-alanyl-2-chloroglycine Methyl Ester
Authors: Shiono Shozo , Harada Kaoru 
Published: July 2006

Abstract
Aspartic acid was synthesized stereoselectively by addition of dialkyl malonate to N-benzyloxycarbonyl-l-alanyl-2-chloroglycine methyl ester, followed by hydrolysis. Substituent effect of the alkyl group of dialkyl malonate on the stereoselectivity was observed. Higher optical purity of aspartic acid was obtained as the alkyl group of dialkyl malonate became bulkier.
Preparation and Conversion of Aminodiphenylcyclopropenium Salts to 1,2,3-Triazines
Authors: Yoshida Hiroshi , Yagi Kohnosuke , Tamai Tomoji , Sano Hiroe , Ogata Tsuyoshi , Matsumoto Kiyoshi 
Published: July 2006

Abstract
Diphenylcyclopropenone gave aminodiphenylcyclopropenium fluorosulfate (3) by ethylation with ethyl fluorosulfate, followed by treating with secondary amine in one-pot operation. The salt 3 reacted with sodium azide to afford 1,2,3-triazine in a good yield.
Palladium Catalyzed Coupling Reaction of α-Bromo Ketones with Hexabutylditin
Authors: Kosugi Masanori , Koshiba Mamoru , Sano Hiroshi , Migita Toshihiko 
Published: July 2006

Abstract
Palladium-catalyzed reaction of α-bromo ketones with hexabutylditin in the presence of trimethylsilyl chloride gave enol trimethylsilyl ether in moderate to good yields.
The Determination of a Small Amount of Biological Constituent by the Use of Chemiluminescence. IV. A Highly Sensitive Detector for the HPLC of Protein
Authors: Hara Tadashi , Toriyama Motohiro , Ebuchi Takashi 
Published: July 2006

Abstract
A highly sensitive detector for the HPLC of protein has been manufactured by making use of the phenomenon that the catalytic activity of copper(II) against the chemiluminescence between luminol and hydrogen peroxide is lowered in the presence of protein. According to the present detector, 2×10−4–1×10−1 g/dm3 protein could be determined, with the detection limit of 10 ng. By combining the present detector with a TSK-GEL G3000SW column, 2×10−3–1×10−1 g/dm3 ovalbumin could be determined, with the detection limit of 50 ng. The ovalbumin in 2×10−2 g/dm3 could be determined by the internal-standard method with a coefficient of variation of 8.65% (n=5). Care had to be taken in the detection of the protein acting as a chemiluminescent catalyst.
Synthetic Inorganic Ion-exchange Materials. XXXVIII. Acid-base Properties of a Cryptomelane-type Hydrous Manganese(IV) Oxide and Some Chromatographic Applications
Authors: Tsuji Masamichi , Abe Mitsuo 
Published: July 2006

Abstract
The pH titration curves of a cryptomelane-type hydrous manganese(IV) oxide(CRYMO) apparently showed a dibasic Brönsted-acid towards Li+, Na+, K+, and Rb+ ions and a monobasic Brönsted-acid towards Cs+ ions, instead of an amphoteric character, using a mixed solution of alkali metal nitrate and nitric acid or each hydroxide with the ionic strength of 0.1. The apparent ion-exchange capacities(meq/g) of alkali metal ions increased in this order: Li+(0.50)&lt;Na+(0.55)&lt;Cs+(0.85)&lt;Rb+(1.00)&lt;K+(1.10) at pH 2 and Cs+(1.20)&lt;Rb+(1.72)&lt;Na+(1.78)&lt;Li+(1.80)&lt;K+(1.81) at pH 10. The point of zero charge(PZC) of CRYMO was estimated to be much lower than 2. The unusual selectivity for K+ and Rb+ ions can be successfully applied to some ion-exchange separations: e.g., the removal of K+ ions from NaNO3 and NaMnO4 solutions, the removal of Rb+ ions from a CsNO3 solution, and the selective uptake of K+ ions from seawater.
Atomic Absorption Spectrophotometric Determination of Copper(I) After Extraction of Its Ternary Complex with 3-(4-Phenyl-2-pyridyl)-5,6-diphenyl-1,2,4-triazine and Tetraphenylborate into Molten Naphthalene
Authors: Nagahiro Tohru , Uesugi Katsuya , Satake Masatada , Puri Bal K 
Published: July 2006

Abstract
A preferable atomic absorption spectrophotometric method has been established for trace determination of copper(I) via extraction of its ion-associated complex with 3-(4-phenyl-2-pyridyl)-5,6-diphenyl-1,2,4-triazine and tetraphenylborate into molten naphthalene. The optimum pH range for the extraction is 1.6–8.2. Solid naphthalene containing the copper(I) complex is separated by filtration and dissolved in N,N-dimethylformamide. The absorbance is measured at 324.7 nm. Beer’s law is obeyed in the concentration range 2.5–80 μg of copper in 10 cm3 N,N-dimethylformamide solution. Ten repeat analyses on a sample containing 35 μg of copper give a mean absorbance of 0.205 with a standard deviation of 0.0017 and a relative standard deviation of 0.83%. The method has been successfully applied to determination of copper in standard reference materials and biological samples.
Preparation and Some Properties of Bis(trimethylenediamine)cobalt(III) Complexes with a Bidentate-N,S or -N,Se Ligand
Authors: Konno Takumi , Okamoto Ken-ichi , Einaga Hisahiko , Hidaka Jinsai 
Published: July 2006

Abstract
Seven optically active cobalt(III) complexes of [Co(bidentate-N,S or -N,Se)(tn)2] type were prepared for the first time; bidentate-N,S or -N,Se denotes 2-aminoethanethiolato (aet), 2-aminoethaneselenolato (aes), 2-aminoethanesulfenato (aese), 2-aminoethanesulfinato (aesi), 2-(methylthio)ethylamine (mea), and 2-(methyl-seleno)ethylamine (mseea). These complexes were characterized from their absorption, CD, and 1H NMR spectra. All complexes obtained were assigned to the Λ configuration. The (+)550CD mea isomer took selectively the Λ-(R) configuration in solution, while the (+)550CD mseea isomer a mixture of the Λ-(R) and Λ-(S) ones. The absorption and CD spectra of the complexes are discussed in comparison with those of the corresponding bis(ethylenediamine)cobalt(III) complexes. The Λ-(R)- and Λ-(S)-[Co(aese)(tn)2]2+ isomers showed the CD spectral change with time and it was suggested that the epimerization at sulfur was accompanied by the racemization of the skew pair of chelate rings.
Flavin Mononucleotide Chemiluminescence for Determination of Traces of Copper(II) by Continuous Flow and Flow Injection Methods
Authors: Yamada Masaaki , Kanai Hideshi , Suzuki Shigetaka 
Published: July 2006

Abstract
Flow injection analysis, with chemiluminescence detection, is used to determine traces of copper(II) by means of the flavin mononucleotide–hydrogen peroxide–phosphate buffer system. This permits the determination of copper(II) more selectively than any other chemiluminescence system with a detection limit of 0.03 ng(20-μl sample injection) or 0.06 ng ml−1 (continuous sample flow). The linear range is 3 orders of magnitude, the sampling rate is 120 h−1, and the relative standard deviation is 3.1% for 1 ng Cu(II)(n=10). Iron(II) and chromium(III and VI), the strongest enhancer after copper(II), provide signals 2–3% of that for copper(II). Effect of surfactant micelles on the signal for copper is also discussed. The method is successfully applied to real samples.
Synthesis of O-β-d-Glucopyranosyl-(1→2)-O-β-d-glucopyranosyl-(1→6)-d-glucopyranose; Dehydrative β-d-Glucosylation Using 2-O-Acetyl-3,4,6-tri-O-benzyl-d-glucopyranose
Authors: Koto Shinkiti , Morishima Naohiko , Sato Hiroko , Sato Yuko , Zen Shonosuke 
Published: July 2006

Abstract
A step-by-step synthesis of O-β-d-glucopyranosyl-(1→2)-O-β-d-glucopyranosyl-(1→6)-d-glucopyranose through the dehydrative β-d-glucosylation using 2-O-acetyl-3,4,6-tri-O-benzyl-d-glucopyranose and the ternary system of p-nitrobenzenesulfonyl chloride, silver trifluoromethanesulfonate, and triethylamine is described.
Copper(II)-Catalyzed Transamination between Pyruvate and Hydrophobic Pyridoxamine Embedded in Synthetic Bilayer Membranes
Authors: Murakami Yukito , Kikuchi Jun-ichi , Akiyoshi Kazunari 
Published: July 2006

Abstract
The copper(II)-catalyzed transamination of 4-aminomethyl-5-[(dihexadecylamino)methyl]-2-methyl-3-pyridinol [(PM)2C16] with sodium pyruvate was investigated in an aqueous medium at pH 6.9, μ 0.10 (KCl), and 30.0±0.1 °C in the presence of single-walled bilayer vesicles of N,N-dihexadecyl-Nα-[6-(trimethylammonio)hexanoyl]-l-alaninamide bromide [N+C5Ala2C16] and N,N-dihexadecyl-Nα-[6-(trimethylammonio)hexanoyl]-l-histidinamide bromide [N+C5His2C16]. The binding mode of the pyridoxamine moiety in the vesicles was clarified by comparing the reaction behavior of the (PM)2C16–pyruvate–CuII system with that of the 4-aminomethyl-5-dodecylthiomethyl-2-methyl-3-pyridinol [(PM)C12]–pyruvate–CuII system. The pyridoxamine moiety of (PM)2C16 was more tightly anchored in the hydrogen-belt domain of the membranes than that of (PM)C12 as confirmed by fluorescence polarization spectroscopy. The difference in binding mode between (PM)2C16 and (PM)C12 is reflected on the copper(II)-coordination equilibria for the formation of the copper(II)–ketimine intermediates. The copper(II)-catalyzed transamination of (PM)2C16 with pyruvate in the N+C5His2C16 vesicle was most enhanced among related reaction systems treated here. The rate enhancement was attributed to the favorable formation of the reactive 2:1 ketimine–copper(II) chelate and the general-base catalysis by the coordination-free imidazolyl group of the lipid.
Phase Transition Behavior and Membrane Structure of Monoalkyl Amphiphiles
Authors: Kumano Atsushi , Kajiyama Tisato , Takayanagi Motowo , Kunitake Toyoki , Okahata Yoshio 
Published: July 2006

Abstract
Membrane structure and crystal-liquid crystal phase transition behaviors were investigated for two kinds of artificial amphiphiles with single alkyl chain and N-benzylideneaniline moiety. These artificial amphiphiles showed both thermotropic and lyotropic mesomorphisms in a similar manner to biological lipids. Artificial amphiphile with one polar head group formed the multilayer liposome even in a low concentration region of amphiphile/water system. Artificial amphiphile with two polar head groups at both ends of the molecule does not form the multilayer liposome but forms monomolecular lamellae. Addition of cholesterol to the two polar-headed amphiphile changed its aggregated structure drastically from monomolecular lamellae to large single liposomes composed of monomolecular layer. In the case of two polar-headed amphiphile/water system, two endothermic peaks were observed, which were assigned to gel I to gel II and gel II to mesophase transitions. These transitions may correspond to meltings of partial and whole part of hydrophobic portion in amphiphilic molecule, respectively.
Conformation Analyses of Poly(l-lysine) Induced by Various Surfactants
Authors: Takeda Kunio 
Published: July 2006

Abstract
The relative proportion of α-helix, β, and random-coil structures in each conformation of poly(l-lysine) (PLL) caused by surfactants was computed by simulating a mixed spectrum of typical circular dichroism(CD) spectra for these structures to the experimentally obtained spectrum. Simulation was done in both the 190–250 nm and 200–250 nm regions at 1-nm intervals. The results show that PLL assumed 52 and 75% α-helix (at largest) in sodium octyl sulfate (SOS) and sodium 1-octanesulfonate solutions, respectively. The α-helical structure was found to coexist with considerable amounts of β and random-coil structures in these surfactant solutions. For instance, 51% α-helical structure coexisted with 29% β-structure and 20% random-coil structure in 6.0 mmol dm−3 SOS. In contrast, PLL did not assume any α-helical structure in the concentration range of 0 to 10 mmol dm−3 sodium dodecyl sulfate(SDS). Rather, the random-coil structure was transformed to a β-structure when SDS was added to PLL. The effects of NaCl and of 1-octanol on the relative proportions of the three structures in PLL were also examined.
The Arrhenius Parameters for the Reactions of O Atoms with Ethene and Five Fluoroethenes
Authors: Umemoto Hironobu , Sugiyama Koichiro , Tsunashima Shigeru , Sato Shin 
Published: July 2006

Abstract
The rate constants for the reactions of ground-state oxygen atoms with ethene and five fluoroethenes have been measured over the temperature range of 240–450 K, using a pulse radiolysis-resonance absorption technique. The rate constants were well expressed by the following Arrhenius expressions: k(O+C2H4)=8.4×106 exp(−712⁄T); k(O+C2H3F)=3.1×106 exp(−622⁄T); k(O+CH2=CF2)=2.4×106 exp(−638⁄T); k(O+cis-CHF=CHF)=1.9×106 exp(−500⁄T); k(O+C2HF3)=3.0×106 exp(−544⁄T); k(O+C2F4)=8.1×106 exp(−634⁄T), in units of m3mol−1 s−1. The change in the preexponential factors with the degree of fluorination is discussed in terms of the conventional transition-state theory.