دورية
Deacylation of 4-nitrophenyl acetate by 6A-(ω-aminoalkyl)amino-6A-deoxy-β-cyclodextrins
| العنوان: | Deacylation of 4-nitrophenyl acetate by 6A-(ω-aminoalkyl)amino-6A-deoxy-β-cyclodextrins |
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| المؤلفون: | Redman, Kahlee, May, Bruce L., Kean, Suzanna D., Clements, Philip, Easton, Christopher J., Lincoln, Stephen F. |
| المصدر: | Journal of the Chemical Society, Perkin Transactions 2; August 1, 1999, Vol. 1999 Issue: 8 p1711-1718, 8p |
| مستخلص: | The deacylation of 4-nitrophenyl acetate ( pNPA) in aqueous solution to give 4-nitrophenolate is significantly accelerated by the 6A-(ω-aminoalkyl)amino-6A-deoxy-β-cyclodextrins [βCDNH(CH2)nNH2] which are themselves acylated to give predominantly βCDNH(CH2)nNHCOCH3. The deacylation is characterised by kdK = 27.4, 35.5, 24.5 and 16.0 dm3 mol−1 s−1 at 298.2 K in aqueous 0.05 mol dm−3 borate buffer and I = 0.10 mol dm−3 (NaClO4) when n = 2, 3, 4 and 6, respectively, where kd (s−1) is the rate constant for pNPA deacylation through a βCDNH(CH2)nNH2·pNPA complex characterised by a stability constant K (dm3 mol−1). The inhibition of the deacylation by adamantane-1-carboxylate (AC−) is consistent with a mechanism where AC− competes with pNPA in entering the βCDNH(CH2)nNH2 annulus through the formation of a βCDNH(CH2)nNH2·AC− complex. The latter complex has been qualitatively studied by 1H NMR ROESY methods, and its structure and that of βCDNH(CH2)nNH2· pNPA have also been force-field modelled. The possibility of the operation of an SN2 mechanism as an alternative explanation for the deacylation data is also considered. |
| قاعدة البيانات: | Supplemental Index |
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