Document Details

Document Type : Article In Journal 
Document Title :
Solvent effects on ester linkage of 4-nitrophenyl acetate in aqueous and ethanol solutions with imidazole and hydroxide ion as nucleophiles
Solvent effects on ester linkage of 4-nitrophenyl acetate in aqueous and ethanol solutions with imidazole and hydroxide ion as nucleophiles
 
Subject : Chemistry 
Document Language : English 
Abstract : The reaction of 4-nitrophenyl acetate in aqueous and ethanol solutions with imidazole as a nucleophile has been monitored spectrophotometrically. The second order rate constants of these reactions are 10 times higher in water than in alcoholic solutions. This is attributed to better solvation of the initial state and less solvation of the excited state in the alcohol medium. The entropy of activation in water is more negative indicating the greater structuredness of the excited state in water. In addition to the above, the base hydrolysis reaction of the ester using OH- as a nucleophile in buffered aqueous solutions has been followed spectrophotometrically as a function of pH The observed pseudo first order rate constant obeys the relationship k obs=ko+kOH [OH-] where ko represents the water reactions and the buffer dependent rate constant, and kOH is the rate constant for the OH- catalyzed (specific base) reaction. For both cases, a mechanism involving a tetrahedral intermediate and in which the nucleophile attacks at the electrophillic carbon of the ester C=O is proposed. 
ISSN : 0376-4710 
Journal Name : Indian Journal of Chemistry - Section A Inorganic, Physical, Theoretical and Analytical Chemistry 
Volume : 47 
Issue Number : 10 
Publishing Year : 2008 AH
2008 AD 
Number Of Pages : 6 
Article Type : Article 
Added Date : Thursday, October 15, 2009 

Researchers

Researcher Name (Arabic)Researcher Name (English)Researcher TypeDr GradeEmail
سهام سليمان ابراهيم الطريريAl-Terairy, Seham SResearcherDoctoratealterary_seham@yahoo.fr
سالم أحمد صالح باسيفBasaif, SResearcherDoctoratesbasaif@yahoo.com
عباس عباس محمدالسعيد العوضيEl-El-Awady, A.AResearcherDoctorateabbaselawady@hotmail.com

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