ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The first-order rate constants, k1, for 1,2-ethanediolysis (within the content of 1,2-ethanediol of 5% to 90%, v/v) and 2-ethoxyethanolysis (within the 2-ethoxyethanol content of 5% to 60%, v/v) of phenyl salicylate, PSH, in alkaline aqueous mixed solvents, fit to a relationship: k1 = k[ROH]T/(1 + K[ROH]T) where k and K represent the secondorder rate constant for the reaction of alkanol, ROH, with ionized phenyl salicylate, PS-, and association constant for the dimerization of ROH, respectively, and [ROH]T is the total concentration of ROH. Similar relationship between k1 and [ROH]T has been found for 1,2-ethanediolysis of PS- studied in mixed solvents containing 1,2-ethanediol and MeCN. In the alkaline aqueous mixed solvents containing 2-ethoxyethanol, the k1-[ROH]T profile reveals the change in the solvent structure of the reaction medium at 〉60% (v/v) of ROH content. It is proposed that alkanols exist in polymeric form, (ROH)n, and the alkanolysis of PS- involves the pre-equilibrium formation of monomeric ROH from (ROH)n, followed by an intramolecular general base-catalyzed nucleophilic attack at carbonyl carbon of ester. A slight negative KCl salt- and slight positive n-Bu4NI salt-effect are obtained for 1,2-ethanediolysis while a significant positive n-Bu4NI salt-effect is obtained for 2-ethoxyethanolysis of PS-.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.550200604
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