Rapid interfacial reaction

The fast reaction rate between Zn(II) ion with Hocqn at the 1-butanol-water interface was measured by two-phase sheath flow method [33]. The formation of a fluorescence complex at the interface was measured in the period less than 5 ms after the two-phase contact as shown in Fig. 18. By the help of digital simulation, the initial process of the interfacial reaction between Zn(II) and Hqn was analyzed (Fig. 18). This approach is promising for the measurement of rapid interfacial reactions such as protein folding and luminescence lifetime as well [36]. 

By the total internal reflection condition at the liquid-liquid interface, one can observe interfacial reaction in the evanescent layer, a very thin layer of a ca. 100 nm thickness. Fluorometry is an effective method for a sensitive detection of interfacial species and their dynamics [10]. Time-resolved laser spectrofluorometry is a powerful tool for the elucidation of rapid dynamic phenomena at the interface [11]. Time-resolved total reflection fluorometry can be used for the evaluation of rotational relaxation time and the viscosity of the interface [12]. Laser excitation can produce excited states of adsorbed compound. Thus, the triplet-triplet absorption of interfacial species was observed at the interface [13]. 

In the liquid acid-catalyzed processes, the hydrocarbon phase and the acid phase are only slightly soluble in each other in the two-phase stirred reactor, the hydrocarbon phase is dispersed as droplets in the continuous acid phase. The reaction takes place at or close to the interface between the hydrocarbon and the acid phase. The overall reaction rate depends on the area of the interface. Larger interfacial areas promote more rapid alkylation reactions and generally result in higher quality products. The alkene is transported through the hydrocarbon phase to the interface, and, upon contact with the acid, forms an acid-soluble ester, which slowly decomposes in the acid phase to give a solvated... 

Tributyltin carboxylates undergo rapid chemical exchange, as evidenced by NMR. As a consequence, even the interfacial reaction between tributyltin carboxylate and chloride is fast. IR, mass spectra, gas chromatographic retention time and chloride assay show that the product of the reaction is tributyltin chloride. 

Controlled release epoxy formulations in which tin is chemically anchored as tributyltin carboxylate to the polymer chain are discussed. NMR evidence is presented to establish that rapid exchange exists in tributyltin carboxylates. Consequently, even the interfacial reaction between tributyltin carboxylates and chloride is very fast equilibrium constants are reported for the reaction between tributyltin acrylate in hexane and sodium chloride in water. IR spectra, gas chromatographic retention time, chloride assay, and the complex intensity pattern of the molecular ion peaks in the mass spectrum show that the product of the reaction is tributyltin chloride, suggesting that it is the chemical species responsible for antifouling activity in marine environment. 

When chemical reactions occur in an extraction process, the effective mass transfer coefficient may be higher or lower than that expected from purely physical considerations, e.g., Eqs. (10) and (11). For example, the slow interfacial reaction of Eq. (5) will tend to reduce the mass transfer rate. On the other hand, a rapid irreversible reaction can enhance the mass transfer rate. 

Therefore, heterogeneous catalysts present a greater potential for the application of HT and Combinatorial methods, because they involve diverse compositional phases that are usually formed by interfacial reactions during their synthesis, which in turn produce a variety of structural and textural properties, often too vast to prepare and test by traditional methods. In this respect the HT and Combinatorial methods extend the capabilities of the R D cycle, which comprises the synthesis, the characterization of physicochemical properties and the evaluation of catalytic properties. The primary screening HT method gives the possibility of performing a rapid test of hundreds or thousands of compounds using infrared detection methods [27-29]. Alternatively, a detection method called REMPI (Resonance Enhanced Multi Photon Ionization) has been used, which consists of the in situ ionization of reaction products by UV lasers, followed by the detection of the photoions or electrons by spatially addressable microelectrodes placed in the vicinity of the laser beam [30, 31]. 

The chemical methods for the preparation of nanomaterial could be categorized as either template-directed or template-free. The template synthesis methods commonly used for the production of one-dimensional nanostructured PANI are further subdivided into hard template (physical template) synthesis and soft template (chemical template) synthesis approach according to the solubility of the templates in the reaction media. Non-template routes for the synthesis of one-dimensional nanostructured PANI such as rapid-mixing reaction method, radiolytic synthesis, interfacial polymerization, and sonochemical synthesis have also been reported [56], Other approaches like combined soft and hard template synthesis are also known. An overview of hard-template, soft-template, and template-free procedures are presented in the following paragraphs. 

Before a protein molecule can adsorb and exert its influence at a phase boundary or take part in an interfacial reaction, it must arrive at the interface by a diffusion process. If we assume there is no barrier to adsorption other than diffusion, simple diffusion theory may be applied to predict the rate of adsorption. Under these conditions, after formation of a clean interface, all the molecules in the immediate vicinity will be rapidly adsorbed. The protein concentration in a sublayer, adjacent to the interface.and of several molecular diameters in thickness, will thus be depleted to zero. A diffusion process then proceeds from the bulk solution to the sublayer. The rate of adsorption, dn/dt, will be simply equal to the rate of this diffusion step given by classical diffusion theory (Crank, 1956) as... 

A comparative study of the thermal reactions in oxygen of the above three reactants [118], together with nickel formate, showed that the shapes of the ar-time curves were comparable with those for vacuum decompositions. The magnitudes of the Anhenius parameters (with the exception of the decomposition of the formate which does not give carbide product) were diminished. It was concluded that the initiation of reaction was unaffected by the presence of oxygen, so that the geometry of each rate process was unchanged. In the presence of Oj, interfacial reactions on the nickel oxide product (-+ COj + HjO) proceeded appreciably more rapidly by a common mechanism and all values of E, were close to 150 kJ mol. ... 

The formation of compatibilizer frequently occurs by interfacial reaction of the modified polymers. An example is the use of maleic anhydride grafted to a polyolefin elastomer (EPM/EPM-g-MA) as the interfacial additive for reactive blending with a polyamide, nylon-6 (Van Duin et al., 2001), in a twin-screw extruder. It was found that the consumption of MA occurred rapidly and different blend morphologies were produced. However, it was found that the nylon-6 degraded during processing, due to the reaction of anhydride with the... 

Synthesis of polyethers by polycondensation of alcohols can also be performed by the classical interfacial reaction between functionalized monomers. By this procedure, an organotin polyether was synthesized in a rapid (15 s) and high yield reaction (>80%) [26]. 

Kojima H, Bard AT (1975) An A.C. technique for determining the rates of rapid electrode reactions of aromatic compounds in aptotic media. J Electroanal Chem Interfacial Electrochem 63(2) 117-129. doi 10.1016/S0022-0728(75)80285-3... 

We surmised that our previous failures were caused by the rapid hydrolysis of the phosphorus acid chloride mainly from the following two observations. First, phosphorus acid chlorides are rapidly hydrolyzed in the presence of water. Second, classical interfacial reactions employing fully charged Lewis Bases such as R-0 and RCO are found to occur within the... 

Predictions for HF/hydrocarbon dispersions at 10°C were also made using VisiMix 2000 (see Table 1). Droplet diameters were smaller by factors of about 7-11 than those for sulfuric acid/hydrocarbon dispersions. The HF phase has a much lower viscosity and also a lower density than those of sulfuric acid. The much greater interfacial areas with HF/hydrocarbon dispersions are thought to be a major factor affecting the much more rapid alkylation reactions that occur when HF is used as the catalyst plus the significant differences in products obtained. 

---