Reaktivita p-substituovaných benzaldoximů při štěpení p-nitrofenyl-acetátu: Kinetika a mechanismus

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60461373%3A22310%2F04%3A00012342" target="_blank" >RIV/60461373:22310/04:00012342 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216275:25310/04:00003452

Výsledek na webu

—

DOI - Digital Object Identifier

—

Jazyk výsledku

angličtina

Název v původním jazyce

Reactivity of p-substituted benzaldoximes in the cleavage of p-nitrophenyl acetate: Kinetics and Mechanism

Popis výsledku v původním jazyce

Eleven p-substituted benzaldoximes (p-XC6H4CH=NOH where X = H, CH3, CF3, F, Cl, Br, OCH3, N(CH3)2, COOCH3, CN, NO2) have been synthesized and their dissociation constants determined in 10% (v/v) aqueous dioxane at 35 °C. Under the same conditions, the pseudo-first order rate constants kobs of their reactions with p-nitrophenyl acetate (PNPA) were measured at pH values from 7.8 to 10.8 and at concentrations coxime ranging from zero to 4.00#10-4 mol l-1. The kinetic model and mechanism of the said reaction was proposed by means of mathematical statistical modelling of the dependences of kobs on pH and coxime. The mechanism involves a pre-equilibrium (k-1/k1) in which PNPA forms a tetrahedral intermediate (THI) with the deprotonated form of oxime. In thegiven medium, THI is in equilibrium with the non-reactive conjugated acid THIH (dissociation constant Ka,THIH) which is stabilized by intramolecular hydrogen bond. Depending on pH, the rate-limiting step consists either in formation of TH

Název v anglickém jazyce

Reactivity of p-substituted benzaldoximes in the cleavage of p-nitrophenyl acetate: Kinetics and Mechanism

Popis výsledku anglicky

Eleven p-substituted benzaldoximes (p-XC6H4CH=NOH where X = H, CH3, CF3, F, Cl, Br, OCH3, N(CH3)2, COOCH3, CN, NO2) have been synthesized and their dissociation constants determined in 10% (v/v) aqueous dioxane at 35 °C. Under the same conditions, the pseudo-first order rate constants kobs of their reactions with p-nitrophenyl acetate (PNPA) were measured at pH values from 7.8 to 10.8 and at concentrations coxime ranging from zero to 4.00#10-4 mol l-1. The kinetic model and mechanism of the said reaction was proposed by means of mathematical statistical modelling of the dependences of kobs on pH and coxime. The mechanism involves a pre-equilibrium (k-1/k1) in which PNPA forms a tetrahedral intermediate (THI) with the deprotonated form of oxime. In thegiven medium, THI is in equilibrium with the non-reactive conjugated acid THIH (dissociation constant Ka,THIH) which is stabilized by intramolecular hydrogen bond. Depending on pH, the rate-limiting step consists either in formation of TH

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

CC - Organická chemie

OECD FORD obor

—

Projekt

<a href="/cs/project/GA203%2F01%2F1093" target="_blank" >GA203/01/1093: Vliv elektronové distribuce na reaktivitu oximů vůči esterům</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2004

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Collection of Czechoslovak Chemical Communications

ISSN

0010-0765

e-ISSN

—

Svazek periodika

69

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

CZ - Česká republika

Počet stran výsledku

17

Strana od-do

397-413

Kód UT WoS článku

—

EID výsledku v databázi Scopus

—