bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Hydration on the Thermal Stability of Protein as Measured by Differential Scanning Calorimetry. Lysozyme–D2O System
Authors: Fujita Yukihisa , Noda Yukinao 
Published: July 2006

Abstract
The thermal denaturation of the deuterated lysozyme has been investigated by differential scanning calorimetry in the range of deuterium oxide (D2O) content from 0.03 to 1.6 g of D2O per g of protein. At D2O contents above 0.55 g/g, the temperature, Td, and enthalpy change, ΔHd, of denaturation were almost independent of the degree of hydration. At lower D2O contents, however, both Td and ΔHd showed marked dependence on the degree of hydration. The values of Td increased with a decrease in the D2O content. Whereas the values of ΔHd decreased with a decrease in the D2O content in the same region. The degree of hydration dependency of ΔHd exhibited a break at approximately 170 mol/mol, which indicates that at least two types of hydration contributes to the thermal stability of the protein. The conformational enthalpy change of the protein and the enthalpy change of the hydration layer have also been estimated from the degree of hydration dependency of ΔHd. The results have been compared with those of the Iysozyme–H2O system.
Solvolysis in Carboxamides. VI. Kinetic, Product, and Deuterium Tracer Studies on the N,N-Dimethylacetamide Solvolysis of threo-2-(p-Methoxyphenyl)-1-methylpropyl Brosylate. Nature of the kΔ Pathway
Authors: Saito Seiki , Doihara Kenji , Moriwake Toshro , Okamoto Kunio 
Published: July 2006

Abstract
Solvolysis of threo-2-(p-methoxyphenyl)-1-methylpropyl brosylate (1) and its deuterium derivative (1-2-d) has been carried out in N,N-dimethylacetamide (DMA) as solvent at 50.0 and 75.0 °C. Product examination revealed that in the presence of water (0.17 mol/dm3) the main product is threo-2-(p-methoxyphenyl)-1-methylpropyl acetate (73% at 50 °C), but in the absence of water (Z)-2-(p-methoxyphenyl)-2-butene (5) (ca. 70% at 50 °C). Both of these products are derived from a threo-imidatonium ion [threo-R-Amide]+ which is produced by DMA capture of the tight ion-pair [R+OBs−] (2) from the front-side. A part (ca. 14% yield) of the (Z)-olefin 5 is directly led from the tight ion-pair 2. The formation of the olefin 5 can not be explained by intervention of the phenyl-bridged ion. Although the rate of the brosylate 1 exhibits the kΔ portion deviating upwards from the Hammett plot for a series of threo-2-aryl-1-methylpropyl brosylates, the Schleyer’s kΔ-ks treatment for the rate-(retained)product correlation was unsatisfactory. The classical simple SN1 mechanism can preferably elucidate the product distribution, including the isotope distribution, without intervention of the phenyl-bridged ion intermediate.
The Transformations of Terpene Eetones by Oxygen. II. The Base-catalyzed Autoxidation of Pulegone and Fukinone and Their Dihydro Compounds
Authors: Horinaka Akio , Yo Eiyu , Mori Otoji , Naya Keizo 
Published: July 2006

Abstract
Upon autoxidation in alkaline media, pulegone and fukinone (2) gave pairs of hydroxy ketones respectively as the major products; also, hydroxyeremophilone was isolated as its acetate from 2. On the other hand, their dihydro compounds afforded hydroxy ketones, diosphenols, and acids.
Preparation of Chlorophyll-a and Chlorophyll-b by Column Chromatography with Sephasorb HP Ultrafine
Authors: Yoshiura Masahiko , Iriyama Keiji , Shiraki Masaru , Okada Akira 
Published: July 2006

Abstract
A method for the preparation of chlorophyll-a (Chl-a) and chlorophyll-b (Chl-b) by column chromatography with Sephasorb HP Ultrafine has been developed. The partially purified chlorophyll preparation containing Chl-a, Chl-b and nonsorbed carotenes was applied to a Sephasorb HP Ultrafine column and good separation of Chl-a and Chl-b achieved with a solvent program of (I), a diethyl ether/hexane mixture (1:9, volume ratio) followed by 0.2 and 0.5 vol % isopropyl alcohol in (I). 13.1 mg of Chl-a and 7.6 mg of Chl-b were obtained from 24.7 mg of the partially purified chlorophyll using the above method.
A Simple Synthesis of α-Ylidene γ-Lactones from γ-Trimethylsiloxy Nitriles
Authors: Matsuda Isamu , Murata Shizuaki , Izumi Yusuke 
Published: July 2006

Abstract
α-Cyano carbanions which are generated from γ-trimethylsiloxy nitriles have been found to react with aldehydes to give α-(1-hydroxyalkyl)-γ-trimethylsiloxy nitriles (6). α-Ylidene γ-lactones (5) are derived from 6 in two steps; hydrolytic lactonization to α-(1-hydroxyalkyl) γ-lactones and dehydration. The stereochemistry of the lactones 5 with one exception have been found to be of the E form on the basis of the NMR spectra.
The Difference in Solvolytic Reactivity between Diastereomers in α-(trans-2-Arylcyclopropyl)arylmethyl 3,5-Dinitrobenzoates
Authors: Takata Toshimasa , Matsusaki Hajime , Ohkata Katsuo , Hanafusa Terukiyo 
Published: July 2006

Abstract
Each diastereoisomeric pair of α-(trans-2-p-tolylcyclopropyl) benzyl and α-(trans-2-phenylcyclopropyl)-p-tolylmethyl 3,5-dinitrobenzoates (I-4a, b, II-4a, b) has been synthesized. The relative solvolytic rates of I-4b to I-4a and of II-4b to II-4a in 80% aqueous acetone have been found to be 3.59 and 1.86 respectively at 25 °C. In the presence of 2,6-lutidine, the major products in the solvolysis were homoallylic alcohols.
The Nucleophilic Reaction of Electron-deficient Pyridone Derivatives. I. The Ring Transformation of 1-Substituted 3,5-Dinitro-2-pyridones with Sodio β-Keto Esters
Authors: Matsumura Eizo , Ariga Masahiro , Tohda Yasuo 
Published: July 2006

Abstract
A novel ring transformation is found in a series of reactions of 1-substituted 3,5-dinitro-2-pyridones, electron-deficient substrates, with monosodium salts of β-keto esters. A variety of 1-substituted 3,5-dinitro-2-pyridones are treated with diethyl sodio-3-oxopentanedioate and ethyl sodioacetoacetate to give, in addition to N-substituted nitroacetamides (3), 2,6-bis(ethoxycarbonyl)-4-nitrophenol (2), and 2-ethoxycarbonyl-4-nitrophenol (4) respectively. The bicyclic intermediates, 2-azabicyclo[3.3.1]nona-3,7-dienes, can be isolated on the reaction of 3,5-dinitro-1-methyl-2-pyridone at room temperature. The phenol derivatives (2 and 4) may consist of the reagent and a C4–C5–C6 moiety of the parent pyridone, while N-substituted nitroacetamides, 3, may result from the other fragment, N–C2–C3, of the pyridone. A probable course of the reaction, involving the step-by-step nucleophilic attack of the ambident nucleophiles, sodio β-keto esters, at the ambident electrophilic centers of 2-pyridones to form bicyclic intermediate, is proposed.
Sesquiterpenoids. LIV. Absolute Configuration of Eudesma-4(14),7(11)-dien-8-one
Authors: Endo Katsuya , Hikino Hiroshi 
Published: July 2006

Abstract
(+)-Eudesma-4(14),7(11)-dien-8-one (1)isolated from Atractylodes rhizomes has been degraded with basic alumina to the trisnor ketone (3). From the CD spectra of 1 and 3, the absolute configuration of 1 has been established to be 5S, 10R, which has so far been allocated to the (−)-enantiomer.
Oxidation-Reduction Equilibrium between Cation Radicals. An Approach to Determine Ionization Potentials of Electron Donor Molecules
Authors: Iida Yôichi , Yamagishi Akihiko 
Published: July 2006

Abstract
For several electron donor molecules, the adiabatic ionization potential and the oxidation-reduction potential in the formation of cation radical from its parent molecule were estimated by using the equilibrium constant of a preferred electron transfer reaction from neutral donor molecule to another cation radical molecule in solution.
Structural Interconversions of Dichlorobis(triphenylphosphine)nickel(II) in Various Solvents
Authors: Katô Hajime , Yorita Kazuko , Kato Yoshifumi 
Published: July 2006

Abstract
Structural interconversions, ligand exchange, the temperature- and concentration-dependent equilibrium of configurational isomers, and the solvolysis of NiCl2(Ph3P)2 in various solvents have been studied. The MCD and absorption spectra were employed, together with the calculation based on ligand-field theory and the NMR spectra. Paramagnetic tetrahedral NiCl2(Ph3P)2 and the solvated paramagnetic octahedral NiCl2(Ph3P)2(dmso)2are in equilibrium in the coordinating solvent DMSO. The ratio of the former to the latter increases with the rise of concentration and temperature. Configurational isomers of NiCl2(Ph3P)2, a paramagnetic tetrahedral one and a diamagnetic square-planar one, are found in a non-coordinating solvent CHCl3. The former species decreases gradually and a yellow precipitate is formed. The same two species, and two other solvated paramagnetic tetrahedral and octahedral species, NiCl2(CH3CN)2 and NiCl2(CH3CN)4, are found to be in equilibrium in CH3CN.
An Ultrasonic Absorption Study of the DMF–Water System
Authors: Kawaizumi Fumio , Nomura Hiroyasu , Ohno Makoto , Miyahara Yutaka 
Published: July 2006

Abstract
Using the pulse method, the ultrasonic absorption was measured for binary mixtures of water and N,N-dimethylformamide (DMF) at 5.5 and 57 MHz in the temperature range of 5–45 °C. At lower temperatures α⁄f2 as a function of the concentration produces a plateau up to x (x is the mole percent of DMF in solution)=1.5, a minimum point at x=6, and a maximum point at x=25. An increase in the temperature causes these characteristic features of α⁄f2 to disappear. At 45 °C the values of α⁄f2 increase monotonically. No relaxation process is observed in the frequency range of this work. The general features of the concentration dependence of α⁄f2 resemble those of the urea–water system in a water-rich region and those of the dioxane–water system in a DMF-rich region. The mechanism of the plateau can be explained by the cooperative nature of the formation and breaking of water clusters. The maximum of α⁄f2 is ascribed to the complex formation between DMF and water molecules, while the minimum of α⁄f2 arises from the competition between the breaking-down of the water structure and the complex formation in solution. The maximum behavior in the ultrasonic absorption can be interpreted in terms of a kinetic model, DMF+mH2O\ightleftharpoonsDMF·(H2O)m. m is determined to be 3, and the following values have been obtained for the model mentioned above: ΔVm\simeq1 cm3/mol, Km=10±2.
Effect of Diffusion Layers on Bi-ionic Potentials across Liquid Ion-exchange Membranes
Authors: Yoshida Nobuo 
Published: July 2006

Abstract
In a bi-ionic system in which a liquid membrane is interposed between aqueous solutions containing different counterions, the solution composition is often not maintained uniform right up to the membrane–solution interface owing to the presence of diffusion layers adjacent to the interface. Taking the effect of the diffusion layers into account, an expression is derived for the bi-ionic potential across a membrane having completely dissociated ion-exchange sites and counterions. The expression contains as an empirical parameter the ratio between the thicknesses of the diffusion layers at the solution and membrane sides of the interface. The expression is found to agree with experimental data, with the parameter given a single value.
Film Dichroism. II. Linearly-polarized Absorption Spectra of Acridine Dyes in the Stretched Poly(vinyl alcohol) Films
Authors: Matsuoka Yukio , Yamaoka Kiwamu 
Published: July 2006

Abstract
The linear dichroic absorption spectra of the protonated and quaternized acridine dyes were measured in the UV and visible regions by the stretched film technique. The dyes examined were acridine, 10-methylacridine, Proflavine, Trypaflavine, Acridine Yellow, 10-Methylacridine Yellow, Acridine Orange, and 10-Methylacridine Orange, all of which belong to the C2v point symmetry group. Poly (vinyl alcohol) was used as a film matrix. The absorption spectrum of each dye was resolved into the long-axis and short-axis polarized components. Two orthogonally-polarized electronic transitions (the 1La and 1Lb bands) of 3,6-disubstituted acridine dyes were reduced to overlap in the visible region of the spectra. The orientation factors Ky and Kz of each dye were evaluated at a constant degree of stretching and were related to the geometry of the dye molecule.
The Determination of the Formation Constant of Triiodide Ion in Micellar Solution of Dodecyltrimethylammonium Chloride
Authors: Hayakawa Katumitu , Kanda Mitsuo , Satake Iwao 
Published: July 2006

Abstract
Spectrophotometric measurements were undertaken at 360 nm in order to estimate the formation constant of triiodide ion in micellar solution of dodecyltrimethylammonium chloride. The absorption spectra of the solutions suggested that both iodine molecule and triiodide ion are solubilized in a hydrophilic surface region of the surfactant micelle. The apparent formation constant of triiodide ion, Ka, was found to be much larger in micellar solution than in water. It was also shown that the value of Ka decreases regularly with increasing surfactant concentration. A tentative estimation based on a lamellar micelle model led to the intrinsic formation constant of triiodide ion of 650 mol−1 dm3 or less at 30 °C, which is comparable with that in water. The thermodynamic consideration revealed that the formation reaction of triiodide ion from iodine and iodide ion in micellar solution is accompanied by an anomalous entropy decrease.
Metathesis of 1,5-Cyclooctadiene over Supported Rhenium Oxide Catalysts
Authors: Saito Kaizaburo , Yamaguchi Tsutomu , Tanabe Kozo , Ogura Toshimasa , Yagi Misao 
Published: July 2006

Abstract
The metathesis of 1,5-cyclooctadiene (COD) was investigated over supported rhenium oxide catalysts in terms of carrier effects, acid properties of the catalysts, product distributions, and the reversibility of the reaction. Only alumina plays an effective role as a support. The reaction of COD over rhenium oxide–alumina catalyst yields oligomers, C8n, sesqui-oligomers, C8n+4, and polymers. The important results are as follows: 1) The product distribution in terms of the carbon number of the products shows a decay curve with maxima around C12, C16, and C20. 2) The reaction of oligomers gives COD and some products similar to those of COD. 3) The reactivity of 1,5,9-cyclododecatriene (CDT) was low compared with COD, 1,5,9,13-cyclohexadecatetraene (CHT), and 1,5,9,13,17-cycloeicosapentaene (CEP). 4) A reaction of a mixture of macrocyclic polyenes and polymers gave appreciable amounts of CDT, CHT, and CEP, whereas no COD was obtained. On the basis of the results, we conclude that the products, oligomers, sesqui-oligomers, and polymers, are formed independently from the active intermediary polymers which are formed from COD.
A Thermodynamic Study on the Hydrolysis of Beryllium Ion in Dioxane–Water Mixed Solvents
Authors: Ishiguro Shin-ichi , Ohtaki Hitoshi 
Published: July 2006

Abstract
The hydrolytic reactions of beryllium(II) ions were calorimetrically studied at 25 °C in aqueous solution and dioxane–water mixtures, both containing 3.0 mol dm−3 (Li)ClO4 as a constant ionic medium. On the basis of the formation constants previously determined, the enthalpy and entropy changes for the reaction, qBe2++pH2O=Beq(OH)p(2q−p)++pH+, were estimated for the Be2OH3+ and Be3(OH)33+ complexes in aqueous solution and 0.1 mole fraction dioxane–water mixture and for Be2OH3+, Be3(OH)33+, and Be2(OH)22+ complexes in 0.2 mole fraction dioxane–water mixture. The enthalpy and entropy changes of formation of the Beq(OH)p(2q−p)+ complex obtained in solutions of various mole fractions of dioxane were as follows: 2Be2++H2O=Be2OH3++H+; ΔH12 (mole fraction: 0.0)=18.6±0.2 kJ mol−1, TΔS12(mole fraction: 0.0)=1.3±0.2 kJ mol−1, ΔH12(0.1)=15.2±0.2 kJ mol−1, TΔS12(0.1)=−3.4±0.2 kJ mol−1, ΔH12(0.2)=8.4±0.4 kJ mol−1, TΔS12(0.2)=−12.4±0.4 kJ mol−1, 3Be2++3H2O=Be3(OH)33++3H+; ΔH33(0.0)=61.7±0.2 kJ mol−1, TΔS33(0.0)=12.2±0.2 kJ mol−1, ΔH33(0.1)=59.4±0.2 kJ mol−1, TΔS33(0.1)=10.0±0.2 kJ mol−1, ΔH33(0.2)=59.0±0.4 kJ mol−1, TΔS33-(0.2)=9.1±0.4 kJ mol−1, 2Be2++2H2O=Be2(OH)22++2H+; ΔH22(0.2)=42.3±0.4 kJ mol−1, TΔS22(0.2)=1.3±0.4 kJ mol−1. The enthalpy and entropy changes of the reaction, H2O=H++OH−, in the solutions of the same compositions were also determined as ΔHw(0.0)=56.6±0.1 kJ mol−1, TΔSw(0.0)=−22.6±0.1 kJ mol−1, ΔHw(0.1)=58.1±0.1 kJ mol−1, TΔSw(0.1)=−25.3±0.1 kJ mol−1, ΔHw(0.2)=61.2±0.1 kJ mol−1, TΔSw(0.2)=−26.6±0.1 kJ mol−1. These results were discussed in connection with interactions between the hydroxo complexes and the solvent molecules and with those between solvent molecules in the mixed solvents.
An Interpretation of the “Molecular Space” on the Basis of Quantum Chemical Calculations of Hydrated Ions
Authors: Fujiwara Shizuo , Rode Bernd M 
Published: July 2006

Abstract
Quantum chemical calculation has been made for the sizes of the hydration shells of the metal ions as well as for the binding energies of water molecules in the hydration shells. The results of the both calculations give the basis of the size of the molecular space. Although the experimental value of the molecular space, (20±5A)3, does not exactly agree with the calculated value, we assume that the quantum chemically obtained hydration sphere refers to the molecular space.
Photoelectron Spectra of Hydrogen-bonded Complexes
Authors: Utsunomiya Chikatoshi , Kobayashi Tsunetoshi , Nagakura Saburo 
Published: July 2006

Abstract
The photoelectron spectra of typical hydrogen-bonded complexes, CF3COOH–(C2H5)2NCH3, CF3COOH–(n-C3H7)3N, CF3CF2COOH–(C2H5)2NCH3, and CF3CF2COOH–(n-C3H7)3N were observed in the gas phase. It was found that the nonbonding orbital of the proton acceptor is stabilized significantly by hydrogen-bond formation while the three higher occupied orbitals of the proton donor are destabilized. The large orbital energy changes due to hydrogen-bond formation strongly support the charge-transfer model for the hydrogen bond.
Vibrational Distribution of CS(X1Σ+) Fragments Formed in the UV Flash Photolysis of CS2
Authors: Ebata Takayuki , Kawasaki Masahiro , Obi Kin-ichi , Tanaka Ikuzo 
Published: July 2006

Abstract
The vibrational distribution of the CS(X) fragment has been studied by the UV flash photolysis and kinetic spectroscopic technique. The CS fragment was generated by the flash photolysis of CS2 at ≈200 nm. The vibrational distribution is well represented by a sum of two modified Poisson distributions with different mean values. This distribution is explained by assuming the following two photodissociation processes of CS2; one is a predissociation through a triplet state and the other is a direct photodissociation.
(Remark: Graphics omitted.)
Pressure Effects on the Base Hydrolysis Reaction Rates of α-, β-[Co(edda)(NH3)2]+ and α-[Co(edda)(NO2)2]− in a Carbonate Buffer
Authors: Kitamura Yoichi 
Published: July 2006

Abstract
The pressure effects on the base hydrolysis reaction rates of α-, β-[Co(edda)(NH3)2]+ and α-[Co(edda)(NO2)2]− in a carbonate buffer were measured up to 1500 kg/cm2 (1 kg/cm2=98.0665 kPa). The activation volumes at normal pressure were found to be 16.6, 22.3, and 11.9cm3/mol respectively. These values are consistent with those expected from the SN1 CB mechanism, where the conjugate bases dissociate via the Id mechanism.
The Thermal Decomposition of Vanadium(III) Chloride Oxide and Its Reaction with Oxygen
Authors: Yajima Akimasa , Matsuzaki Ryoko , Saeki Yuzo 
Published: July 2006

Abstract
The thermogravimetry and differential thermal analysis of VClO in an argon stream were carried out. The products obtained by heating VClO in an argon stream at various temperatures were examined by chemical analysis and X-ray analysis. Also, the reaction between VClO and oxygen was examined in the same manner. When VClO is heated in an argon stream, it decomposes above about 400 °C to form V2O3 and VCl3, 3VClO(s)→V2O3(s)+VCl3(s). Subsequently, the resulting VCl3 disproportionates to form VCl2 and VCl4, 2VCl3(s)→VCl2(s)+VCl4(g). VClO reacts with oxygen above about 120 °C to form V2O5 and VCl3O, 6VClO(s)+3O2(g)→2V2O5(s)+2VCl3O(g); this reaction is accompanied by the 4VClO(s)+3O2(g)→2V2O5(s)+2Cl2(g) reaction.
A Proton Conductive Coordination Polymer. I. [N,N′-Bis(2-hydroxyethyl)dithiooxamido]copper(II)
Authors: Kanda Seiichi , Yamashita Kenichi , Ohkawa Kuwako 
Published: July 2006

Abstract
In a family of catena-μ-N,N′-disubstituted dithiooxamidocopper(II) complexes which have been assumed as two-dimensional coordination polymers, one complex with HOC2H4- substituents is an electronic conductor as well as others, and also a protonic conductor uniquely. The latter property was proved both by spectroscopic detection of the hydrogen molecules evolved from d.c. electrolysis of pressed pellets of the powder specimen and by observation of the anomalous increase (three orders of magnitude) of the electric conductivity as an effect of 103 Pa of H2O or D2O vapor on the dehydrated specimen in an evacuated conductivity cell. A novel conduction mechanism was suggested for such a solid system with both conjugated double bonds and extended hydrogen bonds.
Studies of Unusual Amino Acids and Their Peptides. XI. The Resolution of β-(2-Furyl)-β-alanine and β-(2-Thienyl)-β-alanine and Their Absolute Configurations
Authors: Kuwata Shigeru , Yamada Takashi , Shinogi Tatsuya , Yamagami Naoki , Kitabashi Fumio , Miyazawa Toshifumi , Watanabe Hiroshi 
Published: July 2006

Abstract
(+)-β-(2-Furyl)-β-alanine and (+)-β-(2-thienyl)-β-alanine were obtained by resolving the N-benzyloxycarbonyl-Dl-amino acids with quinine and by removing the protecting group from them. It was concluded, from the changes in their ORD curves depending on the pH, and also from the sign of the Cotton effects of their DCHA salts of the N-ethylthiocarbonothioyl derivatives, that both the compounds belong to the l-series. This conclusion was supported by the fact that the aspartic acid obtained by the oxidation of these amino acids belongs to the d-series.
Acyl Cyanide. VI. The Synthesis of 1-Cyano-1-alkenyl Esters by the Reaction of Acyl Cyanides with Acid Chlorides. Synthesis and Mechanism
Authors: Oku Akira , Arita Shingo 
Published: July 2006

Abstract
The reactions of enolizable acyl cyanides (acetyl, propionyl, isobutyryl, and diphenylacetyl cyanide) with acid chlorides (acetyl, propionyl, benzoyl, p-nitrobenzoyl, diphenylcarbamoyl, and dimethylcarbamoyl chloride) in the presence of tertiary amines gave the corresponding 1-cyano-l-alkenyl carboxylates or carbamates in good yields. Among several solvents and amines examined in the reaction of acetyl cyanide with propionyl chloride, benzene and pyridine seem to be most appropriate. The maximum yield (98%) of the ester was attained in benzene when both the chloride and pyridine were used in excess amounts (1.2–1.4 times the amount of the cyanide). The rate of reaction depended little on the concentration of the chloride but on both the cyanide and the amine being of first order in each reactant; it was also influenced by the basicity of tertiary amines and, in the case of weak bases, additionally by their nucleophilic power.
Halogenated and Non-halogenated Aromatic Sesquiterpenes from the Red Algae Laurencia okamurai Yamada
Authors: Suzuki Minoru , Kurosawa Etsuro 
Published: July 2006

Abstract
The taxonomic reexamination of the red alga ‘L. intermedia Yamada,’ previously collected at Oshoro Bay, Hokkaido, showed that this alga consistd of a mixture of L. intermedia Yamada, L. capituliformis Yamada, and L. okamurai Yamada. Within the Japanese species of genus Laurencia, laurinterol and debromolaurinterol were found to be characteristic metabolites of L. okamurai, not of L. intermedia. In the course of this examination, dibromophenol and debromoaplysinol were newly isolated.