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  • 1
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 1011-1018 
    ISSN: 0006-3592
    Schlagwort(e): phenol ; tyrosinase ; chitosan ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: The goal of this work was to explore the technical feasibility of an enzymatic approach as an alternative to traditional approaches for phenol separations. Specifically, we examined a two-step approach to selectively remove phenols from mixtures containing nonphenolic isomers. Our model solutes, of molecular formula C7H8O, were the phenol, cresol; the alkyl aryl ether, anisol; and the alcohol, benzyl alcohol. The first step is this two-step approach employed the enzyme mushroom tyrosinase to selectively convert the phenolic, presumably to an o-quinone product. The tyrosinase was specific for the phenol and was not observed to react with either the ether or the alcohol. The second step of this two-step approach employed a sorbent of an appropriate surface chemistry to bind the products of the tyrosinase-catalysed reaction of phenols. The sorbent used for this study was chitosan. Chitosan was observed to be unable to adsorb either nonphenol and was unable to adsorb unreacted cresol. However, Chittosan effectively adsorbs UV-absorbing reaction products of the tyrosinase-catalysed reaction of phenols. When mixtures of cresol and either anasol or benzyl alcohol were studied, the two-step approach was effective for completely removing the phenolic without loss of either the ether or alcohol or the ether (i.e., phenols were removed with high separation factors).
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 51 (1996), S. 79-86 
    ISSN: 0006-3592
    Schlagwort(e): phenol ; tyrosinase ; chitosan ; immobilized enzyme ; waste minimization ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: There are a series of examples in which phenols appear as contaminants in process streams and their selective removal is required for waste minimization. For the selective removal of a phenol from a mixture, we are exploiting the substrate specificity of the enzyme tyrosinase to convert phenols into reactive o-quinones which are then adsorbed onto the amine-containing polymer chitosan. To effectively package the enzyme and sorbent, tyrosinase was immobilized between two chitosan gel films. The entrapment of tyrosinase between the films led to little loss of activity during immobilization, while tyrosinase leakage during incubation was limited. The chitosan gels rapidly adsorb the tyrosinase-generated product(s) of phenol oxidation while the capacity of the gels is substantially greater than the capacity of chitosan flakes. The performance of tyrosinase-containing chitosan gels significantly depends on the ratio of tyrosinase-to-chitosan. High tyrosinase-to-chitosan ratios result in less efficient use of tyrosinase, presumably due to suicide inactivation. However, the efficiency of chitosan use increases with increased tyrosinase-to-chitosan ratios. © 1996 John Wiley & Sons, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 567-573 
    ISSN: 0894-3230
    Schlagwort(e): Organic Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 1-Alkoxycarbonylbenzotriazoles on thermolysis lose carbon dioxide; the decarboxylation is accompanied by the formation of a mixture of 1- and 2-alkylbenzotriazoles, with the N-1 isomer predominating over the N-2 isomer in all cases. A cross-over experiment, in which heating equimolar amounts of 1-benzyloxycarbonylbenzotriazole and 1-(4-methylbenzyloxycarbonyl)-5,6-dimethylbenzotriazole gave almost all the cross-over products, supports the proposed intermolecular mechanism for this decarboxylation and the formation of 1- and 2-alkylbenzotriazoles. No decarboxylation was observed for 1-phenoxycarbonylbenzotriazole.
    Zusätzliches Material: 7 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    ISSN: 0941-1216
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A variety of 2,4,6-tri- and 2,4,5,6-tetrasubstituted 4H-1,3-oxazines (7a - i) were synthesized in excellent yields by the reaction of acetylens (5) in the presence of aluminum chloride with N-[1-(benzotriazol-1-yl)alkyl]amides 4, themselves readily prepared from benzotriazole (1) with amides (2) and aldehydes (3).
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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