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981.
982.
Apparent molar volumes of glycine, DL--alanine, L-valine, L-leucine, and L-phenylalanine in 0.5, 1.0, 2.0, 3.5, and 5.0 m
B (mol-kg–1) aqueous solutions of glycerol have been obtained from solution densities at 25°C using precise vibrating-tube digital densimeter. The estimated partial molar volumes at infinite dilution V
o
2 have been used to obtain the corresponding transfer volumes tr
V
2
o from water to different glycerol–water mixtures. The transfer volumes are positive for glycine and DL--alanine, and both positive and negative for the other amino acids over the concentration range studied. Interaction coefficients have been obtained from McMillan–Mayer approach and the data have been interpreted in terms of solute–cosolute interactions. 相似文献
983.
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. 相似文献
984.
Krayushkin M. M. Ivanov S. N. Martynkin A. Yu. Lichitsky B. V. Dudinov A. A. Uzhinov B. M. 《Russian Chemical Bulletin》2001,50(12):2424-2427
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. 相似文献
985.
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. 相似文献
986.
S. G. Krivokolysko V. D. Dyachenko V. N. Nesterov V. P. Litvinov 《Chemistry of Heterocyclic Compounds》2001,37(3):315-319
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. 相似文献
987.
František Kopecký Božena Kopecká Pavol Kaclík 《Journal of inclusion phenomena and macrocyclic chemistry》2001,39(3-4):215-217
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. 相似文献
988.
E. K. Starostin A. V. Ignatenko M. A. Lapitskaya K. K. Pivnitsky G. I. Nikishin 《Russian Chemical Bulletin》2001,50(5):833-837
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. 相似文献
989.
E. P. Baberkina V. N. Buyanov M. E. Zhukova A. E. Shchekotikhin V. E. Zhigachev N. N. Suvorov 《Chemistry of Heterocyclic Compounds》2001,37(10):1234-1237
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. 相似文献
990.
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. 相似文献