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Effects of Li + and K + ions on the rate of intramolecular general base‐catalysed methanolysis of ionized phenyl salicylate in the absence and presence of cationic micelles in mixed H 2 O‐CH 3 CN solvents
Author(s) -
Niyaz Khan M.,
Arifin Zainudin
Publication year - 1996
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/(sici)1099-1395(199605)9:5<301::aid-poc784>3.0.co;2-7
Subject(s) - chemistry , aqueous solution , reaction rate constant , cationic polymerization , bromide , medicinal chemistry , acetonitrile , nuclear chemistry , inorganic chemistry , kinetics , organic chemistry , physics , quantum mechanics
Pseudo first‐order rate constants ( k obs1 ) for methanolysis of ionized phenyl salicylate (PS − ) show a decrease of 3–5‐fold with increase in CH 3 CN content from 2 to 60 or 70% (v/v) in mixed aqueous solvents containing 0·01 mol dm −3 LiOH and a constant content of CH 3 OH. At 0·01 mol dm −3 KOH, the rate constants, k obs1 , reveal a decrease of 15–20% and an increase of 70–130% with increase in the CH 3 CN content from 2 to 30% (v/v) and from 30 to 60 or 70% (v/v) respectively. The values of Δ H ‡ and Δ S ‡ are not significantly affected by the presence of 2, 30 and 70% (v/v), CH 3 CN in mixed aqueous solvents containing 10% (v/v) CH 3 OH and 0.01 mol dm −3 KOH. The presence of 0.01 mol dm −3 LiOH causes the increases in Δ H ‡ and Δ S ‡ of 3·82 kcal mol −1 and 10·3 cal K −1 mol −1 , respectively, with increase in CH 3 CN content from 2 to 60% (v/v) in mixed aqueous solvents containing 20% (v/v) CH 3 OH. An increase in the total concentration of cetyltrimethylammonium bromide ([CTABr] T ) from 0·0 to 0·01 mol dm −3 decreases k obs1 by 3·6‐ and 4·0‐fold in the presence of 0·01 mol dm −3 Li + and K + ion, respectively, in mixed aqueous solvents containing 2% (v/v) CH 3 CN and 10% (v/v) CH 3 OH.