Simultaneous purification and reversible immobilization of d-amino acid oxidase from Trigonopsis variabilis on a hydrophobic support

Purification and reversible immobilization of d-amino acid oxidase from Trigonopsis variabilis could be simultaneously accomplished by hydrophobic interaction on Phenyl Sepharose CL-4B in the presence of 50 mM pyrophosphate buffer (pH 8.5). The presence of a high salt concentration of 2M, which is generally required for the hydrophobic interactions, was not essential for the hydrophobic immobilization. The enzyme in free as well as immobilized form was optimally active between pH 7.0 and 9.0. The immobilized preparation could be reused in a batch process for the conversion of d-amino acids to α-keto acids. When the activity of the preparation dropped below practical limits, the gel could be regenerated by water wash and recharged with fresh crude extract from yeast.     

Photochromic dihetarylethenes. 11. Synthesis and photochromic properties of diarylethenes containing furan or furopyrimidine bridges

Procedures were developed for the synthesis of substituted bis(2,5-dimethyl-3-thienyl)furans based on 1,2-bis(2,5-dimethyl-3-thienyl)-2-hydroxyethanone. Dithienylethene structures in which the ethene fragment is involved in the furan or furopyrimidine system possess photochromic properties and their open forms exhibit fluorescence.     

Low-Temperature CH4 Total Oxidation on Catalysts Based on High Surface Area SnO2

Pure SnO₂, sulfated SnO₂-SO₄ ^2- and Pd supported on SnO₂ and SnO₂-SO₄ ^2- were prepared from SnO₂ precursor with high surface area, and used for CH₄ deep oxidation. The catalysts were characterized by means of N₂-BET, XRD, TG-DTA, XPS and TPD. SnO₂-SO₄ ^2- shows higher activity than SnO₂, due to the presence of more active oxygen species, superacid sites and its higher BET surface area. Pd/SnO₂ and Pd/SnO₂-SO₄ ^2- display essentially the same activity to each other, while it is much higher than the activity on SnO₂ and SnO₂-SO₄ ^2-. The main reason is ascribed to the concerted action between Pd and the supports.     

Novel Stereoselective Synthesis and Molecular and Crystalline Structure of 3-Allyl-4-(4-bromophenyl)-3-cyano-6-oxopiperidine-2-thione

The stereoselective synthesis of 3-allyl-4-(4-bromophenyl)-3-cyano-6-oxopiperidine-2-thione has been carried out by refluxing N-methylmorpholinium 5-[1-(4-bromophenyl)-2-cyano-2-thiocarbamoylethyl]-2,2-dimethyl-1,3-dioxa-6-oxo-4-cyclohexen-4-olate with allyl bromide in ethanol. The structure of the product was confirmed by X-ray investigation.     

Solubility Study of Nimodipine Inclusion Complexation with α- and β-Cyclodextrin and some Substituted Cyclodextrins

The solubility of nimodipine was measured in aqueous solutions of the following cyclodextrins: -cyclodextrin (-CD), hydroxypropyl--CD (HP--CD), -cyclodextrin (-CD), random substituted methyl--CD (M--CD), three hydroxypropyl--CDs (HP--CD) with mutually different average degree of substitution, and hydroxypropyl--cyclodextrin (HP--CD). From the determined linear solubility diagrams the values of the binding constant K₁₁ of the inclusion complexes of nimodipine with the respective CDs were evaluated. The -CDs efficiently solubilized sparingly soluble nimodipine, the highest value of K₁₁ was found for M--CD (1680 M^-1), followed by -CD (550 M^-1) and HP--CDs, where the higher degree of substitution lowered K₁₁. Only slight solubilization of nimodipine was observed in the solutions of the -CDs and HP--CD.     

Synthesis of ω- and (ω – 1)-acetylenic acids from five-, six-, or seven-membered cycloalkanones

A convenient method for the synthesis of - and ( – 1)-acetylenic acids involves free-radical oxidative scission of cycloalkanones containing five-, six, or seven-membered cycles to give the corresponding -olefinic acids followed by bromination of the latter and subsequent dehydrobromination under the action of alkalis.     

Synthesis of Pyrrolo[a]- and Pyrrolo[c]phenanthridine Derivatives and Indolinyl and Indolylsubstituted 6-Phenanthridines

The corresponding Mannich bases have been synthesized by the aminomethylation of 6-methyl-1H-pyrrolo[2,3-a]- and 4-methyl-3H-pyrrolo[3,2-c]phenanthridinium iodides. The interaction of 6-chloro-phenanthridine with indoline and with 5-amino-N-acetylindoline gave the corresponding derivatives of phenanthridine. 6-(1-Indolyl)phenanthridine has been obtained by the dehydrogenation of 6-(1-indolinyl)phenanthridine with manganese dioxide.     

Thioureas from 3-aminoquinazolin-4(3H)-one. 2. Unusual alkaline recyclization of 3-(N",N",S-trialkylisothioureido)quinazolin-4(3H)-ones into new 1,3,4-oxadiazoles

3-(N",N",S-trialkylisothioureido)quinazolin-4(3H)-ones obtained by the reactions of 3-(N",N"-dialkylthioureido)quinazolin-4(3H)-ones with alkyl halides undergo unusual recyclization into 5-(2-aminophenyl)-2-dialkylamino-1,3,4-oxadiazoles under the action of aqueous solutions of alkali, hydrazine, and primary aliphatic amines. A plausible mechanism of the recyclization was proposed.     

Condensed Thienopyrimidines. 14. Synthesis of 10H-Thiopyrano[4',3':4',5']thieno[2',3':4,5]pyrimido[2,3-c]-1,2,4-triazines

Reaction of a substituted 2-aminothienothiopyran with methyl(phenyl) isothiocyanate, intramolecular cyclization of the obtained N'-methyl(phenyl) thioureido derivatives, and work up of the cyclization products with hydrazine hydrate gave 2-hydrazinodihydrothiopyranothienopyrimidines. Treatment of the latter with pyruvic acid gave the novel 10H-thiopyrano[4',3':4',5']thieno[2',3':4,5]pyrimido[2,3-c]-1,2,4-triazines.     

Rate Coefficient for Self-Association Reaction of CF2 Radicals Determined in the Afterglowof Low-Pressure C4F8 Plasmas

We have analyzed decay kinetics of CF₂ radicals in the afterglow of low-pressure, high-density C₄F₈ plasmas. The decay curve of CF₂ density has been approximated by the combination of first- and second-order kinetics. The surface loss probability evaluated from the frequency of the first-order decay process has been on the order of 10^–4. This small surface loss probability has enabled us to observe the second-order decay process. The mechanism of the second-order decay is self-association reaction between CF₂ radicals (CF₂+CF₂C₂F₄). The rate coefficient for this reaction has been evaluated as (2.6–5.3)×10^–14 cm³/s under gas pressures of 2 to 100 mTorr. The rate coefficient was found to be almost independent of the gas pressure and has been in close agreement with known values, which are determined in high gas pressures above 1 Torr.