Bulletin of the Chemical Society of Japan
Online ISSN : 1348-0634
Print ISSN : 0009-2673
ISSN-L : 0009-2673
Volume 64 , Issue 8
Showing 1-50 articles out of 68 articles from the selected issue
  • Vlastimil Fidler, Takashi Ogura, Shin-ichiro Sato, Katsuhiro Aoyagi, T ...
    1991 Volume 64 Issue 8 Pages 2315-2322
    Published: 1991
    Released: June 07, 2006
    JOURNALS FREE ACCESS
    Photoreduction of Fe(OEP) (OEP: octaethylporphyrin) in organic solvents by visible light was demonstrated to be a ligand-aided process in which simultaneous coordinations of a base such as 2-methylimidazole (2MeIm) and of an aliphatic alcohol to two axial positions of the iron ion were required. Coordination of an alcohol was evidenced from the observation of the Fe–alcohol stretching (νFe–alcohol) resonance Raman (RR) band. Since this band exhibited an appreciable frequency shift between ROH and ROD, coordination of the alcohol in a protonated form was suggested. When a primary or secondary alcohol was added to the CH2Cl2 solution of FeIII (OEP)Cl in the presence of 2MeIm, a new absorption band appeared around 560–590 nm and the νFe–alcohol RR band was most intense for excitation at the maximum of the new absorption band. The new absorption was therefore assigned to the alcohol to FeIII charge transfer (CT) band. A tertiary alcohol gave neither the CT band nor the νFe–alcohol RR band, although some spectral changes were noticed after long laser illumination at 441.6 nm, and the photoreduction as seen for other alcohol solutions did not take place. This photoreduction was not apparently recognized in the presence of oxygen. However, flash photolysis experiments demonstrated that the photoreduction occurs irrespective of the presence or absence of oxygen but rapid reoxidation results in apparent no effect.
  • Takahiro Fukuzumi, Keiji Nakashima, Teiichiro Ogawa
    1991 Volume 64 Issue 8 Pages 2323-2327
    Published: 1991
    Released: June 07, 2006
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    The fluorescence emission spectra of fluorobenzene, p-difluorobenzene and hexafluorobenzene excited in collisions with electrons were measured for the study of the dynamics of the exciting aromatic system. These spectra showed a band assignable to the S1→S0 transition of the parent molecule. The bands of fluorobenzene and p-difluorobenzene were intense and showed a pronounced vibrational structure and the intense vibrational transitions were optically allowed. Whereas, that of hexafluorobenzene was broad and weak and did not show any clear vibrational structure.
  • Seishiro Fukutani, Yasuhiro Uodome, Nílson Kunioshi, Hiroshi Ji ...
    1991 Volume 64 Issue 8 Pages 2328-2334
    Published: 1991
    Released: June 07, 2006
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    In this work the combustion mechanism of silane–air flames is elucidated through a simulation employing a detailed chemical scheme. Two different pathways for the consumption of silane were found: SiH4→SiH3→SiH2O→HSiO, which proceeds in low-temperature regions, and SiH4→SiH2→HSiO, occurring at high temperatures; this supports results previously reported in the literature. It was also found that some reactions occur over wide ranges of temperature and that the governing step for the whole silane combustion is the reaction of silane with hydroxyl radicals. A least square fitting to the burning velocities and adiabatic flame temperatures obtained for the four investigated mixtures, with equivalence ratios of 2.0, 1.43, 1.0, and 0.5, indicated that a mixture with equivalence ratio of about 1.2 would have the largest burning velocity and the highest flame temperature.
  • Seishiro Fukutani, Nílson Kunioshi, Yasuhiro Uodome, Hiroshi Ji ...
    1991 Volume 64 Issue 8 Pages 2335-2340
    Published: 1991
    Released: June 07, 2006
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    A detailed chemical reaction scheme and a full set of governing equations for fluid dynamics were used to elucidate the chemical and physical phenomena involved in a silane–air counterflow diffusion flame, where the fuel and air issue from the lower and upper nozzles, respectively. It was found that a stagnation surface, where the axial velocities fall down to zero, is kept in a position slightly shifted to the upper side, dividing the system into two zones: the upper air side and the lower fuel side; after leaving the nozzle silane begins to dissociate itself into SiH2 and H2 when it reaches the region of rising temperature; oxygen penetrates into the fuel side by diffusion and reacts with H2 forming OH radicals and H atoms. The produced SiH2 is further dehydrogenated to SiO via HSiO; comparing with premixed flames, the diffusion flames have large local equivalence ratios, so that the combustion reactions in the latter flames occur through a different mechanism.
  • Taro Tsubomura, Iwao Ohkouchi, Makoto Morita
    1991 Volume 64 Issue 8 Pages 2341-2348
    Published: 1991
    Released: June 07, 2006
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    Luminescence and circularly polarized luminescence (CPL) spectra were investigated at low temperatures in order to clarify the chiroptical and electronic structures of monomeric and dimeric chromium(III) alaninato complexes. In the monomeric complexes, [Cr(L-(or D-)ala)3]·H2O, R1 and R2 lines of opposite spectral signs were found in the CPL spectra. The signs and relative intensities of the peaks were found to be comparable with circular dichroism (CD) spectra by employing theoretical arguments based on a strong crystal field theory. In the case of hydroxo-bridged dimeric complexes, [Cr2(OH)2(L-(or D-)ala)4]·3H2O, although the luminescence spectra of exchange-coupled pair states were clearly observed with a deduction of reasonable exchange interaction parameters, the CPL spectral components were not discernible because of the meso-type structure.
  • Yoshinori Ihara, Yasuhiro Satake, Yumi Fujimoto, Hitoshi Senda, Masata ...
    1991 Volume 64 Issue 8 Pages 2349-2352
    Published: 1991
    Released: June 07, 2006
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    The structures of two diaquabis(N,N-dialkylethylenediamine)nickel(II) chlorides ([Ni(H2O)2(diamine)2]Cl2·nH2O) were determined by X-ray crystallographic studies, where diamine is N,N-dimethylethylenediamine(NN-dmen) or N,N-diethylethylenediamine (NN-deen). Both complexes are trans and crystallize in the monoclinic space group P21n. The unit cell parameters of the NN-dmen complex, NiCl2C8N4O2H32, are a=7.531(1), b=13.092(1), c=9.591 Å, β=107.76(1)°, and Z=2, and those of the NN-deen complex, NiCl2C12N4O2H36, are a=9.154(1), b=8.692(1), c=12.395(2) Å, β=104.46(1)°, and Z=2. In trans-[Ni(H2O)2(NN-dmen)2]Cl2·2H2O and trans-[Ni(H2O)2(NN-deen)2]Cl2, the Ni–NMe2 and Ni–NEt2 bond distances (2.183 and 2.271 Å) are much longer than the Ni–NH2 distances (2.078 and 2.064 Å), forming tetragonally distorted octahedrons with four close in-plane neighbors(N2O2) and two remote axial ones(N2). It is apparent that this distortion originates from the steric requirement of N-substituted groups. Such a distortion significantly affects the electronic spectra of these complexes.
  • Hiroyuki Nariai, Itaru Motooka, Mitsutomo Tsuhako
    1991 Volume 64 Issue 8 Pages 2353-2355
    Published: 1991
    Released: June 07, 2006
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    The effect of water vapor on the formation of lithium cyclo-hexaphosphate Li6P6O18(P6m) from trilithium hydrogenpyrophosphate monohydrate Li3HP2O7·H2O was investigated by means of DTA-TG, X-ray diffraction analysis, isothermal heating with electric furnace, and HPLC. Li3HP2O7·H2O lost the water of crystallization at about 180°C to give anhydrous Li3HP2O7. At 300°C the disproportionation of Li3HP2O7 anhydride to Li4P2O7 and Li4P4O12 (P4m) proceeded faster under humid conditions than under dry air, and subsequently P4m increased with a decrease in P2 and soluble polyphosphates (Ppoly). At 400°C, P4m changed largely to P6m under humid conditions. In these reaction processes, water plays an important role as catalyst in the cyclization by dehydration of the end group and in ring opening by attacking the P–O–P bond. At 450°C, the amounts of P2 and P6m were almost equal under both humid and dry conditions, because all of P4m thermally changed to P6m.
  • Norio Koine
    1991 Volume 64 Issue 8 Pages 2356-2361
    Published: 1991
    Released: June 07, 2006
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    Column chromatographic optical resolutions of twenty-six typical univalent anionic cobalt(III) complexes, e.g., [Co(edta)] and fac-[Co(NO2)3(edma)], were carried out, using as a chiral eluent an aqueous solution of [Sb2(d-tart)2]2− on a strongly basic anion exchanger, where edta=ethylenediamine-N,N,N′,N′-tetraacetate(4-), edma=ethylenediamine-N-acetate(1-), and d-tart=d-tartrate(4-). The racemates were resolved with separation factors comparable to those obtained in conventional resolutions by use of cationic selectors. From a comparison of elution orders of enantiomers and separation factors obtained for the racemates, a chiral discrimination mechanism without direct contact between the racemate and selector was proposed.
  • Toshiaki Taura
    1991 Volume 64 Issue 8 Pages 2362-2371
    Published: 1991
    Released: June 07, 2006
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    The d–d transition spectra of K[Co(edta)]·2H2O, K[Co(mal)2en]·H2O, K[Co(ox)2en]·1.5H2O, K2[Co(ox)2gly]·3H2O, and K3[Co(ox)3]·3H2O (edta=ethylenediaminetetraacetate, mal=malonate, en=ethylenediamine, ox=oxalate, and gly=glycinate) were measured in a variety of solvents: H2O, HOCH2CH2OH, CH3OH, HCONH2, C2H5OH, i-C3H7OH, CHCl3, CH3NO2, CH2Cl2, (CH3)2SO, CH3CN, HCON(CH3)2, C6H5CN, C6H5NO2, CH3CON(CH3)2, (CH3)2CO, and [(CH3)2N]3PO. The 59Co NMR spectra of K[Co(edta)]·H2O and K3[Co(ox)3]·3H2O were also recorded at 25°C in these solvents. It was found that the peak positions (λmax) of the first and second d–d transition bands were greatly influenced by solvent molecules; the peak positions (λmax) of all the cobalt(III) complexes were linearly correlated to the electrophilic ability (Gutmann’s acceptor number) of the solvent and those of K[Co(edta)]·2H2O and K3[Co(ox)3]·3H2O were linearly correlated to the 59Co NMR chemical shifts in the corresponding solvents. This suggests that the d–d transition energy (ΔE) is influenced by solvent molecules as electron acceptors since 59Co NMR chemical shifts are theoretically correlated linearly to the peak positions in the first d–d transition (A1g–T1g). The 13C NMR measurements indicated that solvent molecules directly interact with the carboxyl groups of cobalt(III) complexes. Therefore, the influence of the solvent on the d–d transition energy of the carboxylatocobaltate(III) complex is due to the electron-withdrawing effect of solvent molecules on the carboxyl oxygens of the cobalt(III) complex. A spectrochemical series for the outersphere coordination of the cobalt(III) complex with solvent molecules is proposed.
  • Kazuo Kashiwabara, Minho Jung, Junnosuke Fujita
    1991 Volume 64 Issue 8 Pages 2372-2377
    Published: 1991
    Released: June 07, 2006
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    Twelve new cobalt(III) complexes of the types, cisα-[Co(L)(rac(P)-323 or 333NPPN)p+ (L=2,4-pentanedionate (acac) and oxalate (ox) ions) (four complexes) and cisβ-[Co(L)(rac(P)- or meso(P)-323 or 333NPPN)p+ (eight complexes) were prepared and characterized by 1H NMR and absorption spectra, where rac(P)- and meso(P)-323NPPN denote rac(P)- and meso(P)-NH2(CH2)mP(C6H5)(CH2)mP(C6H5)(CH2)mNH2 with m=3 and n=2, and 333NPPN the ligand with m=3 and n=3. Reactivities of the complexes towards hydrochloric acid were examined and compared with those of the corresponding 222NPPN (m=2, n=2) and 232NPPN (m=2, n=3) complexes. All the cisα isomers yield the cisα-dichloro complexes, the 333NPPN and 222NPPN complexes being more reactive than the 232NPPN and 323NPPN complexes in which five- and six-membered chelate rings of NPPN are involved. For the cisα isomers, the acac complexes afford [Co(acac)(Cl)(mnmNPPNH+)]2+ except the rac(P)- and meso(P)-333NPPN complexes which give the trans-dichloro complexes, while all the ox complexes liberate the ox ion to yield the dichloro complex of the cisα, cisβ, or trans configuration. For both cisα-acac and -ox isomers, the 222NPPN and 232NPPN complexes are more reactive than those of 323NPPN and 333NPPN, and the meso(P)-complexes are more reactive than the rac(P)-complexes.
  • Keiichi Tsukahara, Kazuyo Ishida
    1991 Volume 64 Issue 8 Pages 2378-2382
    Published: 1991
    Released: June 07, 2006
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    The kinetics of the reduction by dithionite ions of metmyoglobins reconstituted with porphinatoiron(III) complexes containing the protoporphyrin IX dimethyl ester, the deuteroporphyrin IX dimethyl ester, and octaethylporphyrin were studied at 25°C and pH 6.3–9.2 in aqueous solution. Esterification of the heme propionate groups accelerated the reduction rate by SO2\divdot as well as the case of octaethylporphyrin (which does not contain the propionate groups); it also affected the redox potential of metmyoglobin, but much less so the rate of the self-exchange reaction. The reaction mechanisms are discussed.
  • Katsuhiro Saito, Kazuaki Ito, Chizuko Kabuto, Kensuke Takahashi
    1991 Volume 64 Issue 8 Pages 2383-2387
    Published: 1991
    Released: June 07, 2006
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    Reactions of tropone derivatives with 4,5-bis(benzoylthio)-1,3-dithiole-2-thione (2,3,6-trithiafulvene derivative) afforded 1,3,5-cycloheptatriene derivatives doubly substituted by trithiafulvene and S–S groups (10aH-cyclohepta[c]-1,3-dithiolo[e][1,2]dithiin-2-thione). The structure of the 1,3,5-cycloheptatriene derivative and its crystal structure were investigated by single crystal X-ray analysis to show the existence of a unique three-dimensional network of the molecules through S···S contacts.
  • Shinsaku Shiraishi, Yukihiko Inoue, Kiyoshi Imamura
    1991 Volume 64 Issue 8 Pages 2388-2392
    Published: 1991
    Released: June 07, 2006
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    N,α-Diarylnitrones reacted with 2,5- or 2,6-dialkyl-p-benzoquinones at their C=C bond regioselectively to give fused isoxazolidine cycloadducts. These cycloadducts were proved to undergo retrocycloaddition. p-Benzoquinones having electron-withdrawing substituents did not give any cycloadduct.
  • Noritaka Abe
    1991 Volume 64 Issue 8 Pages 2393-2397
    Published: 1991
    Released: June 07, 2006
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    2-Aminoazulene (1a) reacted with dimethyl acetylenedicarboxylate (DMAD) to give dimethyl 1,2-azulenedicarboxylate, tetramethyl 2,2′-(2-amino-1,3-azulenediyl)bis[fumarate], and dimethyl 2-(4-methoxycarbonyl-2-oxo-l,2-dihydroazuleno[2,1-b]pyridin-10-yl)fumarate. The reaction of ethyl 2-amino-1-azulenecarboxylate (1b) with DMAD gave dimethyl 2-(2-amino-3-ethoxycarbonyl-1-azulenyl)fumarate and 10-ethyl 4-methyl 2-oxo-1,2-dihydroazuleno[2,1-b]pyridine-4,10-dicarboxylate (8a). The treatment of 8a with phosphoryl chloride gave the 2-chloroazuleno[2,1-b]pyridine derivative. Reactions of 1a and 1b with methyl propiolate gave corresponding Michael adducts and the azuleno[2,1-b]pyridin-3(4H)-one derivatives. Reactions of 1a and 1b with dibenzoylacetylene gave 4-benzoyl-2-phenylazuleno[2,1-b]pyridine derivatives.
  • Tadashi Hanaya, Akihito Akamatsu, Heizan Kawamoto, Margaret-Ann Armour ...
    1991 Volume 64 Issue 8 Pages 2398-2401
    Published: 1991
    Released: June 07, 2006
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    (5R and 5S)-3-O-Acetyl-5-deoxy-1,2-O-isopropylidene-5-[(methoxy)phenylphosphinyl]-6-O-(tetrahydro-2-pyranyl)-α-D-xylo-hexofuranoses (7) were prepared from 3-O-acetyl-5,6-dideoxy-6-nitro-α-D-xylo-hex-5-enofuranose in 4 steps. Reduction of 7 with sodium dihydridobis(2-methoxyethoxy)aluminate followed by acid hydrolysis provided the title compounds, among which the 5-deoxy-5-phenylphosphino-D-glucoses are the first example of hexopyranose analogs having a phosphinidene group in place of hemiacetal ring-oxygen. These compounds were converted into 1,2,3,4,6-penta-O-acetates, whose structures were established by spectroscopy.
  • Kentaro Okuma, Yasuo Komiya, Hiroshi Ohta
    1991 Volume 64 Issue 8 Pages 2402-2406
    Published: 1991
    Released: June 07, 2006
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    The reaction of phosphonium ylides with elemental sulfur gave thioaldehydes, which changed to the corresponding thioamides in good yields when treated with amines. When thioaldehydes containing α-hydrogens were treated with secondary amines, the corresponding enamines or reduction products were obtained.
  • Seizi Kozuka, Hisashi Nakamura
    1991 Volume 64 Issue 8 Pages 2407-2410
    Published: 1991
    Released: June 07, 2006
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    A kinetic study has been conducted on the reaction of (arylthio)trimethylstannanes with 1-aryl-1-bromoethanes. The reaction of the arylbromoethane bearing an electron-donating substituent was found involving unimolecular ionization of the arylbromoethane. The other reactions, however, were found to be second-order reactions. The nature of the second-order reactions was shifted from one involving unimolecular ionization as the minor process, to a clear bimolecular nucleophilic reaction, according to the electron-withdrawing nature of the substituents on the arylbromoethanes.
  • Haruo Watanabe, Jun’etsu Seto
    1991 Volume 64 Issue 8 Pages 2411-2415
    Published: 1991
    Released: June 07, 2006
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    The catalytic activities of maghemite on the aldol condensation of acetone and on the retro-aldol condensation of diacetone alcohol are found to be higher than those of hematite. Further, the catalytic activity of maghemite on the formation of mesityl oxide is significantly higher than that of hematite. The active sites are considered to be surface hydroxyl groups which behave as a Brønsted base and acid points. Maghemite has more basic surface hydroxyl groups than does hematite, and far more acidic surface hydroxyl groups than does hematite they are sufficiently strong to make its average surface acidity greater than that of hematite. The basic surface hydroxyl groups of maghemite are speculated to be those which bond to the iron ions of the octahedral sites the acidic ones are those of the tetrahedral sites of the spinel lattice of the surface.
  • Takahiro Ueda, Hiroshi Ohki, Nobuo Nakamura, Hideaki Chihara
    1991 Volume 64 Issue 8 Pages 2416-2421
    Published: 1991
    Released: June 07, 2006
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    13C CP/MAS NMR, 23Na powder NMR, and 23Na two dimensional nutation NMR were applied to complexes of Nal with polyethylene glycol (PEG) and tetraethylene glycol (TEG) to study the conformation of the polyethers and local structure around the Na+. 13C chemical shift data suggest strongly that the polyether chains assume the gauche conformation in the complexes. 23Na NMR spectrum of TEG–Nal complex gave a broad asymmetric line; simulation of the line shape led to e2Qqh=590 kHz and η=0.7. No significant temperature dependence of the line shape was observed between 200 K and room temperature. For PEG–Nal complex e2Qqh and η were estimated to be about 320 kHz and 0.7, respectively, from the nutation spectrum. On the basis of the above results, new model structures of PEG–Nal complex were presented.
  • Kohki Ebitani, Hideshi Hattori
    1991 Volume 64 Issue 8 Pages 2422-2427
    Published: 1991
    Released: June 07, 2006
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    Successive temperature-programmed desorption (TPD) after temperature-programmed reduction (TPR) (Combined TPR-TPD) was performed in order to characterize supported platinum catalysts (Pt/SiO2, Pt/Al2O3, Pt/ZrO2 and Pt/TiO2) as well as to judge the validity of the apparent TPR profiles. In successive H2-TPD runs obtained after cooling in the absence of hydrogen from 450°C to room temperature, the hydrogen desorption peak was observed only for the Pt/TiO2 sample, indicating that the hydrogenic species were kept on Pt/TiO2 sample, while no hydrogenic species were retained on the other samples after TPR up to 450°C. For both Pt/Al2O3 and Pt/TiO2 samples, hydrogen spillover seemed to proceed. Hydrogen incorporation during TPR was greater for Pt/TiO2 than for the others. This hydrogen spillover causes an overestimation of the consumed H2/Pt value determined by the apparent TPR profile for Pt/TiO2. For Pt/SiO2 and Pt/ZrO2 samples, the apparent TPR profiles were mostly due to a reduction of the supported Pt oxides. For the Pt/TiO2 sample, the hydrogen incorporation/emission at different temperatures during TPR was investigated. To generate SMSI states, desorption of the spiltover hydrogen is suggested to play a significant role; the role of hydrogen incorporation/emission in the generation of SMSI states is also discussed.
  • Hirotoshi Nakabayashi, Noriyoshi Kakuta, Akifumi Ueno
    1991 Volume 64 Issue 8 Pages 2428-2432
    Published: 1991
    Released: June 07, 2006
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    The acid properties of anatase having different crystalline sizes were estimated by measuring the temperature-programmed desorption (TPD) of ammonia as well as the infrared spectrum of adsorbed pyridine at elevated temperature. The size-controlled anatase was prepared by hydrolysis of the titanium tetraisopropoxide dissolved in propyl alcohol using various amounts of distilled water. The acid properties of the anatase were confirmed to be strongly affected by the crystalline size. Especially, the strength of acid sites was found to remarkably increase with a decrease in the crystalline size. The specific activity and the activation energy for 1-butene isomerization on the anatase also depended on the crystalline size. The generation of strong acid sites on the surface is discussed in terms of the crystalline size.
  • Norio Kimura, Setsuo Takamuku
    1991 Volume 64 Issue 8 Pages 2433-2437
    Published: 1991
    Released: June 07, 2006
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    A one-electron reduction of 1-benzoyl-ω-haloalkane (Cl, Br, I) by solvated electrons and a subsequent intramolecular reaction of the radical anions, thus formed, have been investigated by using a pulse radiolysis technique. The reaction mechanism, electron transfer (ET) or SN2, and the rate constants were found to change as a function of the nature of the halide and the methylene chain length of the substrate. Although the order of reactivity based on leaving halogen atoms was I, Br, and Cl, the ease of the SN2 reaction was found to be in the order Cl>Br>I. In addition, the reaction rates were also affected by the polarity of the solvent used. On the basis of these results, it is discussed how the ET–SN2 dichotomy takes place.
  • Norio Nishimura, Yoshihiro Osawa, Kohji Kuramoto, Kazuo Sukemichi
    1991 Volume 64 Issue 8 Pages 2438-2443
    Published: 1991
    Released: June 07, 2006
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    The effects of temperature and pressure on the formation of charge-transfer (CT) complexes between 2,6-dibromo-4-[(3,5-dibromo-4-hydroxyphenyl)(2-ethoxycarbonylphenyl)methylene]2,5-cyclohexadien-1-one (TBPE) and amines in nonpolar solvents have been studied, and the thermodynamic parameters estimated. It was found that the heat of formation (ΔH°) as well as the reaction volume (ΔV°) are largely negative, compared with those for ordinary CT complex formation. The electronic spectra in the visible region due to the outer CT complexes are well-characterized for primary and secondary amines in nonpolar solvents that have no proton-donating/-accepting nature. In other cases, the CT spectra are broad. Ionization of TBPE in polar solvents takes place as evidenced by the electronic spectrum of TBPE anion. However, ΔH° as well as ΔV° are unusually small. When Proton Sponge is used in nonpolar solvents, ion pairs are formed. In this case, ΔH° and ΔV° are largely negative as expected.
  • Prafulla Mahapatra, Moni Mohan Bhattacharyya, Mihir Sengupta
    1991 Volume 64 Issue 8 Pages 2444-2448
    Published: 1991
    Released: June 07, 2006
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    The density data reported by Wirth for aqueous solutions of KCl, KBr, and K2SO4 in NaCl solutions of five different fixed concentrations at 298.15 K have been used to calculate the apparent molal volumes of the mixtures; the results have been compared with those calculated by the Pitzer formalism as also the Young and Smith’s mixture rule.
  • Gulabshankar Ramkhelawan Dube, Vishnu Shivram Darshane
    1991 Volume 64 Issue 8 Pages 2449-2453
    Published: 1991
    Released: June 07, 2006
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    The system Co1+xFe2−2xTixO4 has been studied with a view to investigating the cation distribution and to correlate the catalytic behavior of spinel with electrical and structural properties. To investigate cation distribution, techniques like X-ray diffraction, electrical conductivity, and thermo emf. have been used. The catalytic evaluation was carried out in the temperature range of 473–673 K using benzyl alcohol as a probe molecule. Our results show CoFe2O4 to be better catalyst for benzyl alcohol decomposition compared to Co2TiO4 or pure oxides of the system.
  • Subhasis Chakrabarti, Tridibendra Narayan Misra
    1991 Volume 64 Issue 8 Pages 2454-2457
    Published: 1991
    Released: June 07, 2006
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    Raman phonon spectroscopy in the 10–170 cm−1 range has been used to study phase transition in trans-stilbene crystal. At 77 K, eight distinct phonon modes and an internal mode are observed whereas at 300 K the spectrum shows only four phonon bands and an internal mode. The temperature dependence of spectral pattern and some phonon band width suggest that the phase transition in this crystal is quasi-continuous over a small temperature range 215–225 K. The absence of a soft mode and a strong increase of the phonon band width, when approaching the Tc from below, suggest that the phase transition is of order-disorder type. The well established disordered structure of trans-stilbene crystal at room temperature attains an ordered structure at low temperature at least through one, possibly two order–disorder transitions.
  • Norikazu Ueyama, Naoto Yoshinaga, Atsushi Kajiwara, Akira Nakamura, Ma ...
    1991 Volume 64 Issue 8 Pages 2458-2463
    Published: 1991
    Released: June 07, 2006
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    An oxomolybdenum(V) complex with two chelating ligands of alkane- and arenethiolate parts, (NEt4)[MoVO(α,2-toluenedithiolato)2], was prepared and characterized by visible, ESR, IR, and Raman spectroscopies. Four distinct ligand-to-metal charge transfer absorption bands were observed in visible region. The complex crystallizes in the space group P21 with a=9.535(2), b=16.582(9), c=8.085(1) Å, β=90.757(4)°, V=1278.3(8) Å3, Z=2, and dcalcd=1.431 g cm−3. The structure was solved and refinement based on 2102 reflections converged at R=0.089 and Rw=0.100. The complex takes an apical oxo and trans bis(α,2-toluenedithiolato) structure with a distorted MoOS4 core from a tetragonal-pyramidal geometry.
  • Hu Huang, Fumiaki Kai, Yoshifumi Asai, Masaaki Hirohata, Masaaki Nakam ...
    1991 Volume 64 Issue 8 Pages 2464-2469
    Published: 1991
    Released: June 07, 2006
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    Reaction of nickel(II) perchlorate with the title ligand (Hpahqs) in aqueous solution followed by standing for about six months produces a complex having the formulation [Ni4(pahqs)4(H2O)4]·20H2O. A single crystal X-ray analysis revealed that the complex contained the four nickel(II) and four ligand molecules and showed a novel structure of oxygen bridged tetranuclear nickel(II) complex. Crystal data: triclinic, space group P\bar1, a=17.884(7), b=22.071(8), c=12.819(8) Å, α=100.77(4)°, β=92.55(4)°, γ=71.46(4)°, Z=2. Except one N atom in each azo-group, all the other donor atoms in the ligand were fully used in coordination to nickel(II), forming either N,N,O- or N,O-chelate rings, simultaneously. The geometry around each of the four nickel(II) was distorted octahedron. The bond lengths of N1–N(N atoms in N,N,O-terdentate moieties) were elongated compared with those of the corresponding complex, and the lengths of N1–N(N atoms in quinoline rings) were kept almost similar values to those of the Ni(II)-8-hydroxyquinoline complex. The bond lengths of Ni–O were elongated compared with those of the nickel(II) complexes with either N,N,O- or N,O-chelate rings, resulting in the contraction of the angles of N–Ni–N or N–Ni–O. The angles of Ni–O–Ni around four nickel(II) sites were ca. 140°. The antiferromagnetic exchange interaction was operating between the four nickel(II) via bridging oxygen atoms.
  • Shoichi Katsuta, Hisanori Imura, Nobuo Suzuki
    1991 Volume 64 Issue 8 Pages 2470-2474
    Published: 1991
    Released: June 07, 2006
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    The liquid–liquid partition behavior of tris(acetylacetonato)chromium(III) ([Cr(acac)3]) between heptane and 0.10 mol dm−3 aqueous sodium perchlorate solutions has been studied in the presence of a series of chlorinated phenols (HA) at 298.2 K. A large enhancement of the partition coefficient of [Cr(acac)3] with HA has been observed, e.g., it rises by about 1000-fold in the presence of 0.02 mol dm−3 3,5-dichlorophenol in the organic phase. This effect is ascribable to the association of [Cr(acac)3] with HA in the organic phase. From a partition-equilibrium analysis, the association complexes have been identified as being [Cr(acac)3iHA (i=1,2), and the association constants (βass,i) determined. The βass,i, value increases with an increase of the acid-dissociation constant of HA in the family of HA with the same combination of substituents at the 2,6-positions, i.e., the association is due to hydrogen bonding of the hydroxyl hydrogen atom of HA to [Cr(acac)3]. A linear free-energy relationship has been found between the βass,i, values of [Cr(acac)3] and those of [Co(acac)3] previously reported.
  • Kazushi Mashima, Nozomu Sakai, Hidemasa Takaya
    1991 Volume 64 Issue 8 Pages 2475-2483
    Published: 1991
    Released: June 07, 2006
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    Titanacyclic compounds of the formula Cp*2Ti(CH2CH2C(CH2CHR)CH2) (5a; R=H and 5b; R=C6H5, Cp*=pentamethylcyclopentadienyl), the first stable titanacyclopentanes, have been prepared by the reaction of bis(pentamethylcyclopentadienyl)titanium–ethylene complex (3) with methylenecyclopropanes (4), and their structures were determined based on both spectroscopic data and X-ray crystallography. Complex 5b crystallized in space group P21a(Z=4) with cell constants, a=21.832(3), b=8.580(1), c=14.759(2) Å, β=96.81(1)°, U=2744.9(6) Å3 (4261 reflections, R=0.053). The reaction of 5 with carbon monoxide afforded spiro[2.4]heptan-5-ones in 98% yield. The thermal decomposition of 5 has been investigated, and possible mechanisms of the reactions have been proposed based on deuterium-labeled experiments. A novel formal reductive elimination of organic ligands giving 1-phenylspiro[2.4]hexane has been observed in the thermolysis of 5b. A structure–reactivity relationship has been discussed.
  • Sarat Kumar Sahoo
    1991 Volume 64 Issue 8 Pages 2484-2487
    Published: 1991
    Released: June 07, 2006
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    Germanium was extracted from 0.005 mol dm−3 citric acid at a pH between 2.5 and 6.5 on a column of silica gel coated with Aliquat 336S as the stationary phase. Germanium was then stripped with 0.5 mol dm−3 hydrochloric acid and determined spectrophotometrically as its complex with phenylfluorone. Germanium was separated from alkali and alkaline earths, manganese, iron, cobalt, nickel, copper, and zinc in binary mixtures by the exploitation of difference in pH for formation of citrato complexes. It was separated from antimony, bismuth, tin, gallium, indium, and thallium by taking advantage of stability of chloro and sulfato complexes. This method was applied to the determination of germanium in coal fly ash.
  • Enrico Leporati, Gianluca Nardi
    1991 Volume 64 Issue 8 Pages 2488-2496
    Published: 1991
    Released: June 07, 2006
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    The complex-formation equilibria and relative stability constants of species present in aqueous solution of copper(II) and iron(III) with “L-leucinehydroxamic acid” (2-amino-4-methylpentanehydroxamic acid, ahmpe) have been determined by using potentiometric and spectrophotometric titrations in 0.5 mol dm−3 KCl solution at 25°C. Their acid-base reaction stoicheiometries have been evaluated and the protonation constants calculated from potentiometric data with the aid of the GAUSS Z and SUPERQUAD programs. The complex formation constants have been determined by using SQUAD (absorbance data), SUPERQUAD and STBLTY (potentiometric data) programs. The ligand is bound to the metal ions through the coordination of the N atoms of the α-amino group and the deprotonated –NHO group in copper(II)–ahmpe system. For iron(III)–ahmpe system the coordination is referred to oxygen atoms of carboxylate and hydroxamate moieties. The UV-visible studies provide important evidence for the formation of several complex species depending on the pH. The experimental curves [ε=f(λ)], deduced from refinement of absorbance data with the program SQUAD, have been split up into precisely positioned absorption bands by Gaussian analysis using a nonlinear least-squares computer program NLIN. So the solution electronic spectra have been also employed to estimate the coordination sphere and have let us to suppose a weak tetragonal coordination [CuL2(H2O)2] and octahedral for Fe3+ complexes. The determination of formation constants and the coordination pattern proposed have a great interest in terms of metal chelate structures and their important role in biological systems.
  • Mahammad Ali, Swapan K. Saha, Pradyot Banerjee
    1991 Volume 64 Issue 8 Pages 2497-2501
    Published: 1991
    Released: June 07, 2006
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    The oxidation of sulfite and thiosulfate by Co(dipic)2 (where H2dipic=2,6-pyridinedicarboxylic acid) was studied in aqueous medium. The reactions were carried out by varying reagent concentrations, pH, and ionic strength. For thiosulfate oxidation, the rate is zero order in complex and second order in thiosulfate. The reaction rates were found to increase with the acidity and the general rate law is expressed as kobs={k0+k1[H+]}[S2O32−]2 where k0 and k1 denote the acid independent and dependent paths respectively. The values of rate parameters are k0=(2.87±0.20)×10−8 mol dm−3 s−1 and k1=(0.57±0.02) mol−2 dm6 s−1 at 30°C. A plausible mechanism is suggested by considering the formation of an intermediate active species in the rate-determining step. The sulfite oxidation was, however, first order both in complex and reagent. An inverse dependence on [H+] was obtained for this reaction indicating a higher reactivity of the anionic species in solution. The general rate law is given by kobs=2(k1[SO2·H2O]+k2[HSO3]+k3[SO32−]) and the evaluated second-order rate constants are: k1=(5.60±0.04)×10−5 mol−1 dm3 s−1, k2=(3.02±1.21)×10−3 mol−1 dm3 s−1 and k3=(4.91±0.05)×10−2 mol−1 dm3 s−1 at 60°C. The reactivity order SO32−>HSO3>SO2·H2O has been explained successfully by considering the two isomeric structures for these species in solution. An overall rate law has been derived to interpret these results over the whole range of pH. The theoretical pH rate profile calculated from the different rate parameters shows an excellent agreement with the experimental one suggesting the validity of the proposed mechanism.
  • Ratnakar Balkrishna Lanjewar, Amar Nath Garg
    1991 Volume 64 Issue 8 Pages 2502-2507
    Published: 1991
    Released: June 07, 2006
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    Mössbauer spectra of alkyl- and arylamine coordinated pentacyanoferrate(II) complexes, Na3[Fe(CN)5L]·xH2O where L=(CH3)3N, (CH3)2CHNH2, (CH3)2CHCH2NH2, (CH3)3C–NH2, C6H5NH2, C6H5NHCH3, C6H5N(CH3)2, C6H5NHC2H5, o-ClC6H4NH2, and p-ClC6H4NH2 have been studied. All compounds exhibit a well-resolved quadrupole doublet. An unusually high quadrupole splitting is observed for isobutylamine coordinated complex (ΔEQ=1.75 mm s−1). Other complexes show ΔEQ=0.67–0.86 mm s−1. A correlation of δ vs. ΔEQ suggests a positive sign of electric field gradient for isobutylamine coordinated complex and negative for all other complexes. Partial isomer shift (p.i.s.) and δ have been correlated with partial quadrupole splitting (p.q.s.). Also characteristic CN and Fe–N stretching frequencies have been correlated with δ to derive information on σ-donor and π-acceptor properties of the ligands.
  • Hideyuki Kuno, Makoto Shibagaki, Kyoko Takahashi, Ichiro Honda, Hajime ...
    1991 Volume 64 Issue 8 Pages 2508-2512
    Published: 1991
    Released: June 07, 2006
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    A platinum-support zeolite coupled with a silica layer was prepared by Chemical Vapor Deposition (CVD) of tetraethoxysilane, and was investigated in order to determine the catalytic characterization in an analysis of the surface. With this catalyst system, it was demonstrated that the terminal carbon–carbon double bond is preferentially hydrogenated in the case of several unsaturated hydrocarbons. Further, it was elucidated that a highly regioselective hydrogenation of compounds which possess plural double bonds was achieved over this catalyst system. As a result, a reaction model regarding this catalyst system has been put forward.
  • Toshihiro Takai, Eiichiro Hata, Tohru Yamada, Teruaki Mukaiyama
    1991 Volume 64 Issue 8 Pages 2513-2518
    Published: 1991
    Released: June 07, 2006
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    Tris[1,3-bis(p-methoxyphenyl)-1,3-propanedionato]iron(III) (Fe(dmp)3) was found to be an excellent catalyst for oxygenation of a number of olefinic compounds including styrene analogues and olefinic alcohols into the corresponding epoxides in good to quantitative yields with combined use of molecular oxygen and an aldehyde at room temperature.
  • Hiroshi Sakamoto, Yasuyuki Shimohigashi, Tomohisa Ogawa, Keiichi Kawan ...
    1991 Volume 64 Issue 8 Pages 2519-2523
    Published: 1991
    Released: June 07, 2006
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    A series of dipeptides with the sequence of H–D-Leu–L-Phe–R, where R denotes 4-phenylpiperidide, 4-phenylpiperazide, and their derivatives, have been synthesized to examine their ability to inhibit chymotrypsin. Dipeptide phenylpiperidide and phenylpiperazide inhibited chymotrypsin fairly strongly (Ki=7.5×10−4 M and 1.4×10−3 M, respectively) (1 M=l mol dm−3), while their phenyl-substituted analogs were inactive. In high resolution 3H NMR measurements, it was found that the proton signals of D-Leu γ-CH and β-CH2 shifted considerably to the upfield when compared with those of H–D-Leu–L-Ala–OH, suggesting that these upfield shifts are due to the magnetic anisotropy effect by the benzene ring of the Phe residue. This was confirmed by measuring NOE between D-Leu–isobutyl and L-Phe–phenyl groups. These NMR data indicate that the side chains of both D-Leu and L-Phe are in close proximity, resulting in formation of a hydrophobic complex. It was suggested that, in the inhibitory conformation of dipeptides against chymotrypsin, the phenyl group of phenylpiperidide or phenylpiperazide moiety fits the S1 site, while the side chain-side chain hydrophobic complexing core fits the S2 site.
  • Teruaki Mukaiyama, Takashi Ohno, Takashi Nishimura, Jeong Sik Han, Sh\ ...
    1991 Volume 64 Issue 8 Pages 2524-2527
    Published: 1991
    Released: June 07, 2006
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    O-Trimethylsilyl monothioacetals, which are generally difficult to activate under acidic conditions due to their rapid disproportionation, smoothly react with triethylsilane in the presence of a novel catalyst system, trimethylsilyl chloride and indium(III) chloride, to afford the corresponding sulfides in good to high yields. One pot synthesis of sulfides from aldehydes is also attained in high yields by successive treatments of aldehydes with trimethylsilyl alkyl (aryl) sulfides and triethylsilane in the presence of the above catalyst system under extremely mild conditions.
  • Masuo Funabashi, Toshimori Hasegawa
    1991 Volume 64 Issue 8 Pages 2528-2531
    Published: 1991
    Released: June 07, 2006
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    Deuterium was effectively introduced into the title sugar (1a) at C-1, C-3, C-5, and C-6 to afford 1,5-anhydro-D-[1-2H1], -[3-2H], -[5-2H], -[1-2H2], -[6-2H2], and -[5,6-2H3]glucitols respectively as primary targets for a basic study of the unknown metabolism of 1a, which had been suggested to be a candidate of metabolic indexes for insulin-dependent diabetes mellitus.
  • Abhijit Saha, Parikshit Chandra Mandal, Sudhindra Nath Bhattacharyya
    1991 Volume 64 Issue 8 Pages 2532-2538
    Published: 1991
    Released: June 07, 2006
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    Flavin-adenine dinucleotide (FAD) and flavin mononucleotide (FMN) were irradiated with 60Co γ-ray and G-values for their decomposition under aerated, argon and nitrous oxide saturated conditions at pH 6.5 were determined by spectrophotometric, fluorescence and HPLC measurements. Among the water-borne radicals the hydroxyl radical (OH) was found to be responsible for causing permanent changes in FAD and FMN. The striking similarity between the difference spectra of irradiated FAD and FMN in N2O saturated conditions shows that the OH radicals attack at the isoalloxazine moiety. A plausible mechanism for the reaction of the OH radicals with the isoalloxazine moiety has been discussed. The rate constant for the reaction of isoalloxazine moiety of FAD with OH radicals was determined to be 4.7×109 dm3mol−1 s−1 by competition kinetic studies using glucose as the reference solute. From the kinetic consideration and G-values it is evident that ca. 50% of the OH radicals attack at the AMP (adenosine monophosphate) portion of FAD apart from isoalloxazine moiety. The attack at the AMP portion of FAD is supported by the observed phosphate release in the irradiated FAD solution. Effect of Fe3+ ion on the radiolysis of FAD and FMN was also studied.
  • Ingeborg Csöregh, Mátyás Czugler, Alajos Kál ...
    1991 Volume 64 Issue 8 Pages 2539-2543
    Published: 1991
    Released: June 07, 2006
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    The crystal structures of the inclusion compounds of the 2c,4t-diphenylcyclobutane-1r,3t-dicarboxylic acid (α-truxillic acid) host (1) with methanol [MeOH] (1 : 2) and with dimethylacetamide [DMA] (1 : 2) have been determined by single crystal X-ray diffraction. The substantial difference between the effects of the protic (MeOH) and aprotic (DMA) guests on the molecular packing is discussed. Crystal data: 1 · 2MeOH: monoclinic (P21n), a=12.528(4), b=5.589(1), c=13.715(4) Å, β=101.16(4)°, Z=2, R=0.064 for 1300 reflections; 1 · 2DMA: monoclinic (P21c), a=6.151(1), b=26.586(2), c=7.938(1) Å, β=105.32(6)°, Z=2, R=0.056 for 1488 observations. In both clathrates, half of the rigid α-truxillic acid molecule occupies the asymmetric unit together with one guest molecule. The hydrogen bonds between the trans-positioned functional groups of the host acid and the guest molecules in 1 · 2MeOH give rise to infinite layers parallel with the crystallographic ac diagonal. In contrast, the only one-way hydrogen bond from host to guest in 1 · 2DMA leads to discrete 1 : 2 host–guest aggregates. In this latter case, the hosts and guests are stacked separately, along the c axis direction.
  • Eiji Kubota, Satoru Takizawa, Wataru Kashiwagi, Masatoki Yokoi
    1991 Volume 64 Issue 8 Pages 2544-2546
    Published: 1991
    Released: June 07, 2006
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    The molar conductivity of manganese(II) sulfate, MnSC4, in aqueous solution was measured in a temperature range of 10–45°C. The acquired data were analyzed by the Quint-Viallard equation, and the resulting ion association constant, KA, was used in the Bjerrum equation to determine the contact ion size, RB. The limiting ionic molar conductivity λ0 (1/2 Mn2+) for the manganese ion at 15, 25, 35, and 45°C are 40.8, 53.1, 65.2, and 79.8 S cm2 mol−1, respectively. The resulting thermodynamic properties for the ion association reaction are: ΔG°298=−13.5 kJ mol−1, ΔH°=7.91 kJ mol−1, and ΔS°298=74.1 JK−1 mol−1.
  • Takehiro Abe
    1991 Volume 64 Issue 8 Pages 2547-2548
    Published: 1991
    Released: June 07, 2006
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    The excited-state dipole moment of nitrobenzene has been estimated to be 33.7×10−30 Cm from solvent spectral frequency shifts. This value agrees well with that ((31.7±3.3)×10−30 Cm) determined from an electrooptical absorption measurement.
  • Mamoru Shimoi, Shigeru Miyamoto, Hiroshi Ogino
    1991 Volume 64 Issue 8 Pages 2549-2550
    Published: 1991
    Released: June 07, 2006
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    Potassium, sodium, and ammonium salts of [V(cydta)(H2O)] complexes were prepared, where cydta denotes trans-1,2-cyclohexanediamine-N,N,N′,N′,-tetraacetate. Crystal structure analysis of Na[V(cydta)(H2O)]·5H2O revealed that the vanadium(III) atom adopts a capped trigonal-prism structure, a cydta acting as a sexidentate ligand and an aqua ligand occupying the capping position.
  • Tomoharu Ama, Takaji Yasui, Jinsai Hidaka
    1991 Volume 64 Issue 8 Pages 2551-2553
    Published: 1991
    Released: June 07, 2006
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    Ci-trans(O)-[Co(C(S)-edma-d1)2]+ was prepared by way of the stereospecific deuteration of the facially coordinated edma (ethylenediamine-N-acetate) in (−)543CD-C2-trans(O)-[Co(edma)2]+. The vicinal CD spectrum due to the C(S)-edma-d1 in the Ci-trans(O) complex was investigated in connection with the D→H exchange in the ligands, suggesting a two-step mechanism.
  • Masanobu Tsuchimoto, Masakazu Kita, Junnosuke Fujita
    1991 Volume 64 Issue 8 Pages 2554-2556
    Published: 1991
    Released: June 07, 2006
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    A new tetraaza-macrocyclic complex involving a ten-membered chelate ring, trans-[Co(NO2)2(N410)]BF4(N410=1,4,7,10-tetraazacycloheptadecane) was prepared and the structure was determined by the X-ray diffraction method. The ten-membered chelate ring takes a distorted boat–chairboat form with the N–Co–N bite angle of 105.4(1)°.
  • Yasuhiro Tanoue, Akira Terada, Yasuo Umezu
    1991 Volume 64 Issue 8 Pages 2557-2559
    Published: 1991
    Released: June 07, 2006
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    An isomer of fusarubin, 2-acetonyl-5,8-dihydroxy-7-hydroxymethyl-3-methoxy-1,4-naphthoquinone, was prepared from 2-hydroxymethyl-7-(2-hydroxypropyl)-1,4,5,6,8-pentamethoxynaphthalene.
  • Tetsuo Miyakoshi, Hidenori Kobuchi, Noriyasu Niimura, Yoshiro Yoshihir ...
    1991 Volume 64 Issue 8 Pages 2560-2562
    Published: 1991
    Released: June 07, 2006
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    Two phenolic lipids, 3-[(8Z,11Z)-8,11,14- and 3-[(8Z,11E,13E)-8,11,13-pentadecatrienyl]catechol, which are the major constituents of the sap from a Japanese or Chinese lac tree, Rhus vernicifera, have been synthesized via the Wittig reaction of ylides derived from 3,6- and 3,5-heptadienylphosphonium salts with 3-(8-oxooctyl)catechol diacetate.
  • Yasushi Yokoyama, Yuji Terada, Hideyuki Kawashima
    1991 Volume 64 Issue 8 Pages 2563-2565
    Published: 1991
    Released: June 07, 2006
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    The treatment of (2E,4S)- and (2Z,4S)-1-benzyloxy-5-ethenyloxy-2,4-dimethyl-2-pentene with borane both with and without a catalytic amount of Rh(Ph3P)3Cl gave 2,3-anti-3,4-anti-(2R,3R,4S)- and 2,3-anti-3,4-syn-(2R,3R,4R)-5-benzyloxy-2,4-dimethyl-1,3-pentanediols, respectively, with fair to good diastereoselectivity.
  • Tsuyoshi Okamoto, Takaaki Kakinami, Hiroshi Fujimoto, Shoji Kajigaeshi
    1991 Volume 64 Issue 8 Pages 2566-2568
    Published: 1991
    Released: June 07, 2006
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    The reactions of thiophene derivatives with benzyltrimethylammonium tetrachloroiodate, benzyltrimethylammonium tribromide, and benzyltrimethylammonium dichloroiodate in acetic acid or in acetic acid–zinc chloride under mild conditions gave chloro-, bromo-, and iodo-substituted thiophene derivatives, respectively, in satisfactory yields.
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