Kinetics of base‐catalyzed cyclization of 2,6‐dinitrophenylsulfanyl ethanenitrile and 2,4,6‐trinitrophenylsulfanyl ethanenitrile |
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Authors: | Jiří Černý Jiří Hanusek Vladimír Macháček |
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Affiliation: | Department of Organic Chemistry, Faculty of Chemical Technology, University of Pardubice, Nám. ?s. legií 565, CZ‐53210 Pardubice, Czech Republic |
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Abstract: | The kinetics of base catalyzed cyclization of 2,6‐dinitrophenylsulfanyl ethanenitrile and 2,4,6‐trinitrophenylsulfanyl ethanenitrile giving 2‐cyano‐7‐nitrobenzo[d]thiazole‐3‐oxide and 2‐cyano‐5,7‐dinitrobenzo[d]thiazole‐3‐oxide respectively was studied in methanolic methoxyacetate, acetate, trichlorophenoxide, N‐methylmorpholine, and N‐methylpiperidine buffers at 25 °C and I = 0.1 mol L?1. It was found that reaction involves both general acid and general base catalyses whose manifestation depends on the pKa of the acid‐buffer component and the ratio of both buffer components. In weakly basic buffers the rate‐limiting step is C? H bond breaking in the cyclic intermediate, while in strongly basic buffers the rate‐limiting step is the general acid‐catalyzed elimination of hydroxyl group from the intermediate. Copyright © 2008 John Wiley & Sons, Ltd. |
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Keywords: | cyclization reactions acid– base catalysis reaction kinetics mechanism N‐oxides |
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