Dmo. Marconi et al., NUCLEOPHILICALLY ASSISTED DEACYLATION IN SODIUM DODECANOATE AND DODECYL-SULFATE MICELLES - QUANTITATIVE EVIDENCE ON PREMICELLAR COMPLEXES, Journal of physical chemistry, 98(47), 1994, pp. 12415-12419
Hydrolyses of 2,4-dinitrophenyl acetate and octanoate (DNPA and DNPO,
respectively) and benzoic anhydride (Bz(2)O) in the pH range 8.9-10.2
are inhibited by anionic micelles of sodium dodecyl sulfate (SDS), and
reactions of fully micellar-bound substrates are very slow. The effec
t of micellized sodium dodecanoate, SDOD, depends on pH. At high pH re
actions of DNPA and Bz(2)O involve OH- and are inhibited by SDOD, but
there are significant rates at high [SDOD]. At low-pH reactions of DNP
A and Bz(2)O are inhibited at low [SDOD] and assisted at high [SDOD].
The inhibition is due to formation of kinetically ineffective premicel
lar complexes and rate-surfactant profiles can be fitted quantitativel
y in terms of this. model. When the substrates are fully micellar-boun
d rate constants in mixtures of SDOD and SDS follow the mole fraction
of SDOD and second-order rate constants of nucleophilic attack by the
dodecanoate ion at micellar surfaces are similar to those for the reac
tions of OAc- in water.