Detail of "959-22-8"

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Medium effects on the a-effect in DMSO-H2O mixtures - Comparative studies of p-nitrophenyl benzoate and acetate - Dissection of ground-state and transition-state effects

All Rights Reserved. Medium effects on the a-effect in DMSO-H2O mixtures - Comparative studies of p-nitrophenyl benzoate and acetate - Dissection of ground-state and transition-state effects. Um, Ik-Hwan; Shin, Young-Hee; Han, Jeong-Yoon; Buncel, Erwin ( Division of Nano Sciences and Department of Chemistry, Ewha Womans University, Seoul 120-750, S. Korea). Canadian Journal of Chemistry, 84(11), 1550-1556 (English) 2006 National Research Council of Canada. CODEN: CJCHAG. ISSN: 0008-4042. DOCUMENT TYPE: Journal CA Section: 22 (Physical Organic Chemistry) In a study of the origin of the a-effect and its dependence on the nature of the reaction medium as well as structural effects, we report herein a kinetic study of the reactions of p-nitrophenyl benzoate (PNPB) with butane-2,3-dione monoximate (Ox-, a-nucleophile) and p-chlorophenoxide (p-ClPhO-, the ref. nucleophile) in DMSO (DMSO)-H2O mixts. of varying compns. at 25.0 ± 0.1 °C. The second-order rate consts. (kN) decrease modestly on addn. of DMSO to the medium up to 10 mol% DMSO but increase significantly beyond that point for both nucleophiles. Ox- is more reactive than p-ClPhO- in all solvent mixts. studied (i.e., the a-effect).There are some commonly used reagents with their cas registry numbers 42331-34-0 and 959-22-8 in this article. The a-effect increases as the DMSO content in the medium increases up to 40 mol% DMSO and then decreases beyond that point resulting in a bell-shaped a-effect profile. The bell-shaped a-effect profile obtained for the current reaction is similar to that found previously for the corresponding reaction of p-nitrophenyl acetate (PNPA), differing notably however, in the magnitude of the a-effect beyond 40 mol% DMSO. The PNPB/p-ClPhO- reaction gains greater rate enhancement than the PNPA/p-ClPhO- reaction in the DMSO-rich region, resulting in the smaller a-effect for PNPB beyond 40 mol% DMSO. It is proposed that the obsd. modulation of the a-effect by the solvent medium is explicable as a ground-state effect in the H2O-rich region and a transition-state effect in the DMSO-rich region. .

Acid hydrolysis of p-nitrophenylbenzoate

Acid hydrolysis of p-nitrophenylbenzoate. Jagdale, M. H.; Pawar, V. B. (Dep. Chem., Shivaji Univ., Kolhapur, India). J. Shivaji Univ., 7(14), 147-50 (English) 1974. CODEN: JSHUBH. 959-22-8 is also in the experiment. DOCUMENT TYPE: Journal CA Section: 22 (Physical Organic Chemistry) The acid-catalyzed hydrolysis of p-O2NC6H4O2CPh (I) in EtOH-H2O at 60.degree. occurs by a bimol. nucleophilic attack of H2O on protonated I. Kinetic data were detd. .