Reactions of p-Nitrophenyl Diphenyl Phosphinate with Fluoride and Hydroxide Ion in Nonionic Micelles: Kinetic Salt Effects

Effects of Nonionic Micelles on Dephosphorylation and Aromatic Nucleophilic Substitution

“…• C by monitoring the absorbance of p-nitrophenoxide ion at 400 nm on HP 8450 or 8451 diode-array spectrometers in glass cuvettes (9). The formation of ethers and 2,4-dinitrophenoxide ion from DNCB was monitored by following the increasing absorbance at the isosbestic point (323 nm) and the subsequent, slower formation of 2,4-dinitrophenoxide ion was monitored at 358 nm.…”

“…The surfactants, C 12 E 10 (Sigma) and C 12 E 23 (Aldrich) were as used earlier (9,12) and DNCB was a sample used earlier, or was from ACROS and was recrystallized (EtOH). p-Nitrophenyl dimethylphosphate was prepared from dimethyl chlorophosphate (Aldrich) and dried sodium p-nitrophenoxide in benzene as described (41) and was vacuum distilled.…”

“…Polyoxyethylene-derived micelles inhibit, but do not suppress, reactions of OH − or F − with p-nitrophenyl diphenylphosphate and phosphinate ( pNPDPP and pNPDP, respectively) (9). There is no reaction with the terminal hydroxyethyl group, even at a pH where there should be partial deprotonation (7a, 12) because the pK a should be similar to that of ethane diol, or its monomethyl ether, i.e., approximately 14.8 (13).…”

“…The extended polyoxyethylene, palisade, layer does not exclude water, which may penetrate deeply (8), and ions should not be excluded, although their local concentrations may be lower than that in water, and ion penetration is least for the more hydrophilic ions (9). The terminal hydroxy groups should be partially deprotonated at high pH, making the alkoxide ions effective nucleophiles because in water they are more reactive than OH − , despite their lower basicities (10).…”

Aromatic nucleophilic substitution in nonionic alkylglucoside micelles

“…The reaction of 2,4-dinitrochlorobenzene (DNCB) with nonionic ethylene oxide surfactants (EO) at high pH initially gives a surfactantdinitrophenyl ether, which [12][13][14] slowly reacts with OH − giving 2,4-dinitrophenoxide ion (Eq. (1) [12][13][14]:…”