Role of the Liquid/Liquid Interface in a Phase-Transfer Catalytic Reaction As Investigated by in Situ Measurements Using the Quasi-Elastic Laser Scattering Method

Abstract

The relationship between the concentration of a phase-transfer catalyst, tetrabutylammonium bromide (TBAB), and the rate of its cyclic reaction was investigated using the quasi-elastic laser scattering (QELS) method. TBAB forms an ion pair (TBA + C6H5O -) with sodium phenoxide (C6H5ONa) at the interface. This ion pair moves from the interface to the organic phase where it reacts with diphenylphosphoryl chloride and produces triphenyl phosphate. During this reaction, tetrabutylammonium chloride, which is generated simultaneously with the product, returns to the water phase. An increase in the concentration of the phase-transfer catalyst (TBAB) dose not promote the cyclic reaction. The QELS study indicates that this is because some of the TBAB catalyst adsorbs on the interface and disturbs mass transfer of the other chemical species (TBA + C6H5O -). Interfacial coverage of the catalyst should be taken into account to find the optimum concentration of the catalyst. This paper shows for the first time that the interfacial catalyst promotes the reaction and at the same time disturbs mass transfer of the other chemical species.

Facilitated Sulfate Transfer across the Nitrobenzene-Water Interface as Mediated by Hydrogen-Bonding Ionophores

“…All chemical shift values (δ) were reported in parts per million (ppm), using the residual solvent signal of 7.67,7.50) as a reference. A series of NB-d5 solutions which contain target anions (HPO4 2-or SO4 2-, as a TBA + salt) and ionophore 1 was prepared.…”

Analysis of a Quasi-Elastic Laser Scattering Spectrum Using the Maximum Entropy Method

“…[2][3][4][5][6][7][8] We fabricated a conventional laser heterodyne QELS measurement system using a diffraction grating as a local oscillator, and have reported on the dynamics of the mass transfer of surfactants at a liquid/liquid interface. [9][10][11][12][13] Furthermore, we devised a new principle of the QELS method using a monoluminous flux detection technique in a beam divergence, and have achieved 50 -100 times higher S/N ratios than the conventional heterodyne system. 14 Although the S/N ratio was substantially improved by a new technique, averaging of 20 -100 power spectra was necessary to estimate the capillary wave frequency.…”

Induced-current-generated System Using the Chemomechanical Transduction at a Nitrobenzene/Water Interface

“…[1][2][3] Spontaneous oscillations by alcohol transfer through water/alkane interface 4,5 and at water/nitrobenzene interfaces have much in common. [6][7][8] Sha et al have reported that those spontaneous oscillation stably continued for 120 h and that the period was controllable by the interface area.…”