Selective and sensitive spectrophotometric determination of copper(II) and benzoylperoxide with N-ethyl-2-naphthylamine

Spectrophotometric determinations of benzoylperoxide (BPO) and copper(II) were, respectively, investigated by using the colour reaction for N-ethyl-2-naphthylamine (NENA), BPO and copper(II) as a metal ion in various concentrations of acetonitrile-water mixed solution as acidic media. The calibration graphs were linear in the range of 0-200 mug BPO with apparent molecular coefficient (epsilon) of 8.5 x 10(3)M(-1) cm(-1) at 530 nm, and 0-2.4 mug per 10 ml copper(II) with epsilon = 1.72 x 10(5)M(-1) cm(-1) at 533 nm, respectively. Additionally, the FIA method for copper(II) was proposed with NENA-BPO. The calibration graph for FIA was linear in the range of 0-7.9 ng copper(II) per 5 mul at 533 nm. These proposed methods were selective and simple in comparison with previous methods such as cuproin kinetic reactions, especially the spectrophotometry for copper(II) with NENA-BPO was very specific, and the effect of foreign ions was negligible.     

Synthesis of eight-membered ring compounds using enyne metathesis

[reaction: see text] A novel procedure for synthesizing eight-membered ring compounds was developed using ruthenium-catalyzed enyne metathesis. When a CH2Cl2 solution of enyne connected with catechol, o-amino phenol, or o-phenylenediamine was stirred in the presence of benzylidene ruthenium carbene complex (10 mol %) at room temperature overnight, an eight-membered ring compound was obtained in high yield. In a similar manner, monocyclic 1,4-diaza- or 1-oxa-4-azacyclooctene derivative was obtained in high yield.     

Structure and reactivity in cationic polymerization of butadiene derivatives. III. 2-phenylbutadiene

Cationic polymerization of 2-phenylbutadiene (2-PBD) has been investigated. Polymerization were performed by SnCl₄·TCA, WCl₆, and BF₃·OEt₂ as catalysts in methylene chloride. 2-PBD polymerized easily and gave low molecular weight polymers. The polymerization proceeded to give a polymer having 1,4-structure without 1,2- or 3,4-structure. The double bonds of the polymer were partially consumed, probably owing to cyclization and chain-transfer reactions. 2-PBD was 0.66 times as reactive as styrene and 1.2 times as reactive as isoprene in the copolymerization at ?78°C by SnCl₄·TCA in methylene chloride. Reactivities of ring-substituted 2-PBD obeyed the Hammett relation with ρ⁺ = ?2.04. The ¹³C chemical shift of ring-substituted 2-PBD was measured. Chemical shift values for C₁ and C₃ were correlated with Hammett σ, but those for C₂ and C₄ were almost unaffected by the substituents. On the basis of experimental results, the transition state of the cationic polymerization of 2-PBD was depicted as a benzylic cation rather than a phenylallylic one.     

Chiral synthesis of (R)-( -)-mellein and (3R,4aS)-( + )-ramulosin

By employing an intramolecular Diels-Alder reaction as the key-step, (R)-(—)-mellein 1a (a metabolite of Aspergittus melleus) and (3R,4aS)-( +)-ramulosin 2 (a metabolite of Pestalotia ramulosa) were synthesised from ethyl (R)-3-hydroxybutanoate 3a.     

Anti-plasmin inhibitor. V. Structures of novel dimeric eckols isolated from the brown alga Ecklonia kurome OKAMURA

6,6'-Bieckol (1), 2-O-(2,4,6-trihydroxyphenyl)-6,6'-bieckol (4), and 8,8'-bieckol (2), bispolyphenols with a dibenzo-1,4-dioxin skeleton, have been isolated as potent anti-plasmin inhibitors from the brown alga Ecklonia kurome OKAMURA. Their structures have been determined to be dimers of eckol linked at the C-6 or C-8 positions, through an aryl-aryl bond on the basis of spectral data. Their inhibitory actions on anti-plasmins (alpha 2-macroglobulin and alpha 2-plasmin inhibitor) and some proteases have been examined.     

The knoevenagel condensation of ethyl acylpyruvates

Extensive studies of the Knoevenagel condensation of aromatic aldehydes and active methyl-lene compounds have been reported (2). In 1894, Knoevenagel reported (3) the reaction of benz-aldehyde with ethyl benzoylpyruvate in the presence of piperidine to give ehtyl benzyl-(bis-benzoyl)pyruvate, m.p. 162°, but no yield of the product was reported. This paper deals with the interesting results of the reactions of ethyl acetylpyruvate ( 2 ) ( 4 ) and ethyl benzoylpyruvate ( 3 ) (5) with some aromatic aldehydes ( 1a-f ).     

Liquid imidazole-borane complex

Physical properties of liquid imidazole-borane complex were investigated to demonstrate their utility as aprotic polar solvents or liquid electrolytes appropriate for selective ion transport.     

Regioselective oxygenations of s-trans dienes, silyl dienol ethers (SDEs), by triphenyl phosphite ozonide (TPPO) and its mechanistic study

The direct oxygenation of s-trans dienes, silyl dienol ethers (SDEs) 2, by triphenyl phosphite ozonide (TPPO) has been examined in detail. The regioselective oxygenation was found to give hydroperoxide 3, alcohol 4, ketone 5, dimer 6, and peroxy phosphate 7 with concomitant formation of triphenyl phosphate 8 and diphenyl trimethylsilyl phosphate 10. The formation of peroxy phosphate 7 was found for the first time in TPPO oxygenation reactions. The low temperature (31)P and (1)H NMR spectroscopic analyses proved the direct reaction of SDEs with TPPO without generation of singlet oxygen. The formation of the oxygenated products 3-7 is reasonably explained by the intervention of the zwitterion ZI, which can be formed by the nucleophilic attack of SDE to the central oxygen of the ozonide. The regioselective attack of SDE to the central oxygen of the ozonide was supported by the quantum chemical calculation (B3LYP/6-31G).     

Study on functionalization of metal surfaces. III. Photopolymerization of monomer films on metal surfaces

The three kinds of monomer films on metal surfaces were deposited by adsorption from a solution of 6-polymerizable substituents-1,3,5-triazine-2,4-dithiol monosodium salts (RTDN); the polymerizable substituents such as cis-9-octadecenylamino, di(cis-9-octadecenyl)amino, and p-vinylbenzyl(cis-9-octadecenyl)amino groups were selected in view of the polymerization activity of unsaturated groups in the substituents and the packing degree of monomer molecules. The monomer films were estimated to consist of mainly 6-substituents-1,3,5,-triazine-2,4-dithione (3H, 5H) and to be multimolecular layers that are considerably cross-packed and ordered. The monomer films on metal surfaces were polymerizable under a UV light irradiation in air atmosphere to give polymer films. In the photopolymerization, azobis(isobutyronitrile) (AIBN) was very effective for increasing the monomer conversion and the polymerization rate. The optimum concentration of AIBN in monomer films was very small, about 0.025 mol %. The monomer conversion was influenced by the kind of monomers, namely, the polymerization activity and the packing degree. The effect of the packing degree was especially remarkable. The monomer conversion decreased with an increase in the thickness of monomer films. This is because the polymerization was initiated by oxygen and AIBN, which were diffused into the inner of monomer films. The possibility of polymerization of the unsaturated groups and the thione groups in monomer molecules under UV light irradiation is discussed.