Trajectory of the spectral/structural rearrangements for photo-oxidative reaction of neat ketoprofen and its cyclodextrin complex

Journal of Inclusion Phenomena and Macrocyclic Chemistry - Ketoprofen is a nonsteroidal anti-inflammatory drug used as mohrus tape which causes unwanted photosensitivity due to UV irradiation. In...     

Photoactive, covalent attachment of deoxyribonucleic acid on gold with double-strand specificity using self-assembled monolayers containing psoralen

Taking advantages of psoralen photochemistry, we have developed a new method of immobilizing DNA on gold substrate surfaces. A psoralen derivative having an alkylamine function was synthesized, and was self-assembled on gold substrate surfaces in a combined use of a thiol-derivatized molecule, 3,3′-dithiobis(succinimidyl propionate) forming amide bonds on the surface. We found that by irradiating with long wavelength ultraviolet light (320-400 nm), DNA molecules added in the solution phase were covalently immobilized on the monolayer surface through the photoadduct formation of the psoralen molecules with the DNA nucleobases. The present method has its advantage that is applicable to native DNAs, no chemically modifying DNAs, in spite of its covalent immobilization principle. We have examined 12 mer synthetic oligonucleotide immobilizations and have found that the surface concentration thus attained was to be 20 pmol cm⁻², which is consistent with saturated surface coverage. Interestingly, the immobilization occurred double-stranded-DNA-preferentially; no immobilization for single-stranded DNAs. Characterization of the immobilization chemistry has been achieved using atomic force microscopic imaging, infrared absorption, X-ray photoelectron spectroscopy, electrochemistry, and quartz-crystal microbalance and their results were described.     

Dopamine selective molecularly imprinted polymers via post-imprinting modification

A novel synthetic dopamine receptor bearing bidentate binding sites were prepared by covalent imprinting using a disulfide linkage which is cleaved and oxidized to a non-covalent sulfoxide recognition group. The used templates have dopamine-like structures connected to an allyl moiety via a disulfide and to a 4-vinylphenyl group via a cyclic boronic diester. After the polymerization, the ester bonds were hydrolyzed and the disulfide bond was reduced to remove the template moiety from the polymer matrix, followed by the oxidation to transform the thiol residues into sulfonic acid (post imprinted process). The imprinted polymer adsorbed dopamine selectively in aqueous solution with the two-point interaction, i.e. the formation of cyclic boronic diester and electrostatic interaction with the sulfonic acid residue.     

Role of added Lewis base and alkylaluminum halide on living cationic polymerization of vinyl ether

In the living cationic polymerization of isobutyl vinyl ether (IBVE) by the CH₃CH (OiBu) OCOCH₃ ( 1 )/EtAlCl₂ initiating system in the presence of the added base in hexane at +40°C, the stability of the initiating system 1 /EtAlCl₂, which form initiating species CH₃CH^⊕ (OiBu) derived from 1 , was investigated. In the presence of the Lewis base such as ethyl acetate or 1,4-dioxane, the active species was stable for 300 min even at +40°C in the absence of IBVE, and the living polymers were quantitatively obtained by adding IBVE. However, the active species was partly consumed by side reactions during the standing time for 60 min in the presence of a less basic additive such as ethyl benzoate, and about 50% of the active species was deactivated in the presence of methyl chloroacetate. Consequently, in the case of a less basic additive such as methyl chloroacetate (which was effective for the fast living polymerization), it can be seen that the careful selection of polymerization conditions was required. The living polymerization rate was dependent on the second order of EtAlCl₂ concentration. EtAlCl₂ induced the cleavage of 1 into CH₃CH^⊕ (OiBu) and EtAl^?Cl₂(OCOCH₃), and the reactivity of CH₃CH^⊕ (OiBu) and propagating carbocation may be controlled by EtAl^?Cl₂(OCOCH₃) with the aid of other EtAlCl₂. Et_1.5AlCl_1.5 exists as a bimetallic complex of EtAlCl₂ and Et₂AlCl, and it is expected that the polymers having a bimodal molecular weight distribution will be obtained due to two kinds of counteranions coming from EtAlCl₂ and Et₂AlCl. However, in the cationic polymerization of IBVE by 1 /Et_1.5AlCl_1.5 in the presence of ethyl acetate, the living polymer exhibiting a unimodal and very narrow molecular weight distribution was obtained. Thereby, it was suggested that the counteranions, EtAl^?Cl₂(OCOCH₃) and Et₂Al^?Cl(OCOCH₃), exchange rapidly with each other. © 1994 John Wiley & Sons, Inc.     

Studies directed towards total synthesis of saframycin: I. A synthesis of hexahydro-1,5-imino-3-benzazocin-7,10-dione.

A short-step synthesis of $\text{2}$, the right-hand half of antibiotic saframycin ($\text{1}$), is described. The key steps of this synthesis are the acid catalyzed intramolecular double cyclization of $\text{4}$ and the oxidative demethylation of $\text{7}$ to the quinone ($\text{2}$).     

Adsorption of egg albumin onto methylated yeast biomass

A new biosorbent, methylated yeast (MeYE), was prepared for the adsorptive separation of proteins from aqueous solutions. Yeast was methylated in a 0.1 M HCl methyl alcohol solution at room temperature. About 80% of the carboxylic groups of yeast could be methylated within 9 h. The adsorption of egg albumin onto MeYE was studied to evaluate the protein adsorption ability of MeYE. At near neutral pH, egg albumin was scarcely adsorbed onto unmethylated yeast and the adsorbed amount of egg albumin increased with increasing methylation degree. The amount of egg albumin adsorbed onto MeYE increased with increasing pH from 4 to 7 and steeply decreased above pH 7. The Langmuir isotherm was applied to determine the apparent adsorption constant and the saturated adsorbed amount of egg albumin on MeYE. Both the apparent adsorption constant and the saturated adsorbed amount increased with the degree of methylation. The saturated adsorbed amount of egg albumin onto MeYE having methylation degree 77% was 8.41 x 10(-6) mol g(-1) or 0.378 gg(-1) at near neutral pH.     

Tishchenko Reaction Over Solid Base Catalysts

Catalytic behavior of solid bases for mixed Tishchenko reaction in which an equimolar mixture of two different aldehydes is allowed to react was investigated employing the combinations of benzaldehyde and pivalaldehyde, pivalaldehyde and cyclopropanecarbaldehyde, and cyclopropanecarbaldehyde and benzaldehyde. The reactions were performed at 353K for 4h in vacuo without solvent using 5mmol of each aldehyde and 100mg of solid base catalyst. For all the combinations, the catalytic activity of alkaline earth oxides increased in the order of BaOMgO2O₃, ZrO₂, ZnO, -alumina, hydrotalcite, KF/alumina, and KOH/alumina produced either no amount or very small amounts of cross-esterification and self-esterification products. Quantum chemical calculations carried out at the PM3-MO level for the positive charges on the carbonyl carbon atoms of aldehydes and the structure parameters of the active species for the ester formations indicated that the selectivities to four Tishchenko dimers over MgO and CaO are determined primarily in the step of the nucleophilic addition of the active species (PhCH₂O^-, ^tBuCH₂O^-, and C₃H₅CH₂O^-) to the carbonyl carbon atoms of aldehydes. The reaction of the aldehyde having more positively charged and sterically less hindered carbonyl carbon atom with the active species having less hindered oxygen atom proceeds faster.We also attempted the application of solid base catalysts to the challenging Tishchenko reaction of furfural, and excellent results were obtained with CaO and SrO. For instance, when furfural (10mmol) was treated with SrO (100mg) without solvent at 353K for 6h in vacuo, almost quantitative conversion to the corresponding ester was accomplished. Furthermore, application of SrO to the Tishchenko reaction of 3-furaldehyde was carried out successfully. The catalytic systems were also successfully applicable to the intramolecular Tishchenko reaction (lactonization) of o-phthalaldehyde to phthalide. For example, treatment of o-phthalaldehyde (1mmol) with CaO (50mg) in benzene (1mL) solvent at 313K under N₂ produced phthalide quantitatively in a short time of 15min. We finally refer to the perspective of application of solid base catalysts to Tishchenko reaction.     

Oxidative Methylation of Toluene with Methane over K-exchanged Y Type Zeolite Catalyst Promoted with Alkali Metal Bromide and Alkali Metal Oxide

IntroductionManyresearchgroupsareconductingextensiveresearchtoreplacecrudeoil-basedchemicalswithnaturalgasandcoal-basedchemicals.Itisknownthatstyreneisoneofthemostimportantindustrialmonomers.Currently,styreneisproducedbycatalyticalkylationofbenzenewithethyleneoverA1Cl,-HClcata-lyst,followedbyoxidativedehydrogenationoftheresultantethylbenzeneoverpotassium-promotedironoxidecatalystsL'l.However,thisprocessinvolvestheutilizationofbenzeneandethylene,obtainedfromcrudeoilandpetroleumgas,whichareexp…     

X-ray absorption spectral analysis with a 9 V battery X-ray generator.

X-ray absorption spectral (XAS) analysis is performed with a combination of a 9 V dry electric battery X-ray generator and a portable Si PIN X-ray detector. The calcium K edge (4.0 keV) in paper is measured with a grazing incidence geometry, which suppressed the artifact due to the Kalpha X-ray fluorescence peak at 3.5 keV. The 9 V dry battery X-ray emitter is useful for portable XAS measurements.     

Drag coefficient and upstream influence in three-dimensional stratified flow of finite depth

A numerical study of the three-dimensional stratified flow past a vertical square flat plate in a channel of finite depth is described. Particular attention is paid to the anomalous dependence of the drag coefficient C_D on parameter K( = ND/-πU), where N is the Brunt-Väisälä frequency, D is the half depth of the channel and U is the upstream velocity. It is shown that C_D generally increases with K, while it decreases locally at integral values of K. Time development of the upstream columnar disturbance and the corresponding variation of C_D reveals that the periodic variation of C_D with time for K > 1 comes from the successive upstream radiation of the columnar disturbances of the first internal wave mode. Although the propagation speed of the columnar disturbance is consistent with the prediction of linear theory, its time-dependent structure is different from the weakly nonlinear theory as has been shown by laboratory experiments.