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Micellar rate effects on reactions of hydroxide ion with phosphinate and thiophosphinate esters
Author(s) -
Blaskó Andrei,
Bunton Clifford A.,
Hong Young S.,
Mhala Marutirao M.,
Moffatt John R.,
Wright Sallyanne
Publication year - 1991
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/poc.610041006
Subject(s) - chemistry , micelle , phosphinate , hydroxide , reaction rate constant , bromide , aqueous solution , pulmonary surfactant , inorganic chemistry , medicinal chemistry , organic chemistry , kinetics , biochemistry , physics , fire retardant , quantum mechanics
Cationic micelles of cetyltrimethylammonium chloride, bromide and mesylate (CTACl, CTABr, CTAOMs) speed reactions of OH − with phosphinate and thiophosphinate esters: Ph 2 PO.OPh (1a), Ph 2 PO.OC 6 H 4 NO 2− p (1b), Ph( i ‐Pr)PO.OC 6 H 4 NO 2− p (1c), Ph 2 PO.SEt (2a), Ph 2 PO.SPh (2b), (EtO) 2 PO.SPh (2c) and (EtO) 2 PS.OC 6 H 4 NO 2− p (Parathion, 3). First‐order rate constants go through maxima with increasing [surfactant]. The rate—surfactant profiles are fitted quantitatively in terms of a kinetic model that treats the distribution of OH − between aqueous and micellar pseudo‐phases in terms of coulombic and non‐coulombic ion‐micelle interactions. Second‐order rate constants at the micellar surface are lower than in water by factors that range from 0.035 for 1a to 0.7 for 1c. The thiophenyl derivative (2b) is more reactive than the corresponding phenoxy derivative (1a) and it is more reactive than the corresponding thioethyl derivative (2a). Parathion (3) is the least reactive substrate in both water and micelles.