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http://nopr.niscpr.res.in/handle/123456789/18247| Title: | Studies on reactions of organic bases and nucleophiles with bis-(p-nitrophenyl) methylphosphonothionate |
| Authors: | Saxena, Sherali Purnanand |
| Issue Date: | Apr-2002 |
| Publisher: | NISCAIR-CSIR, India |
| Abstract: | Bis-(p-nitrophenyl) methylphosphonothionate (b-p-NPMPT) (I) reacts with amines in aqueous medium via general base catalysis of water attack. The rate is first order each in [substrate] and [amine]. Solvent deuterium isotope effect, k2(H2O) / k2(D2O), is greater than 2 for amine reactions. Different classes of amines follow Bronsted relation with a slope of 0.40. Fluoride and phosphate ions react with (I) by nucleophilic mechanism. At higher fluoride ion concentration, 2 mol of p-nitrophenol (p-NP) is released by a first order process. At lower fluoride ion concentration less than 2 mol of p-NP is produced. k2(H2O) / k2(D2O) for the reaction of fluoride and phosphate ions with b-p-NPMPT≡ 1. It is believed that steric crowding in the transition state causes reaction of (I) with amine to proceed via general base mechanism and that of fluoride ion, oxyanions and phosphate anions through a nucleophilic mechanism. |
| Page(s): | 718-722 |
| ISSN: | 0975-0975(Online); 0376-4710(Print) |
| Appears in Collections: | IJC-A Vol.41A(04) [April 2002] |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| IJCA 41A(4) 718-722.pdf | 1.05 MB | Adobe PDF | View/Open |
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