Transfer in water

As mentioned earlier, surfactants and ionic solutions significantly affect mass transfer. Normally, surface affects act to retard coalescence and thus increase the mass transfer. For example, Hikata et al. [Chem. Eng. J., 22, 61-69 (1981)] have studied the effect of KCl on mass transfer in water. As KCI concentration increased, the mass transfer increased up to about 35 percent at an ionic strength of 6 gi7i/l. Other investigators have found similar increases for hquid mixtures. 

Tong, L. S., 1967b, Heat Transfer in Water-Cooled Nuclear Reactors, Nuclear Eng. Design (5 301. (3) Tong, L. S., 1968a, An Evaluation of the Departure from Nucleate Boiling in Bundles of Reactor Fuel Rods, Nuclear Sci. Eng. 33 7-15. (5)... 

The pK of tyrosine explains the absence of measurable excited-state proton transfer in water. The pK is the negative logarithm of the ratio of the deprotonation and the bimolecular reprotonation rates. Since reprotonation is diffusion-controlled, this rate will be the same for tyrosine and 2-naphthol. The difference of nearly two in their respective pK values means that the excited-state deprotonation rate of tyrosine is nearly two orders of magnitude slower than that of 2-naphthol.(26) This means that the rate of excited-state proton transfer by tyrosine to water is on the order of 105s 1. With a fluorescence lifetime near 3 ns for tyrosine, the combined rates for radiative and nonradiative processes approach 109s-1. Thus, the proton transfer reaction is too slow to compete effectively with the other deactivation pathways. 

Temperature and pressure effects on rate constants for [Fe(phen)3] +/[Fe(phen)3] + electron transfer in water and in acetonitrile have yielded activation parameters AF was discussed in relation to possible nonadiabaticity and solvation contributions. Solvation effects on AF° for [Fe(diimine)3] " " " " half-cells, related diimine/cyanide ternary systems (diimine = phen, bipy), and also [Fe(CN)6] and Fe aq/Fe aq, have been assessed. Initial state-transition state analyses for base hydrolysis and for peroxodisulfate oxidation for [Fe(diimine)3] +, [Fe(tsb)2] ", [Fe(cage)] " " in DMSO-water mixtures suggest that base hydrolysis is generally controlled by hydroxide (de)hydration, but that in peroxodisulfate oxidation solvation changes for both reactants are significant in determining the overall reactivity pattern. ... 

The influence of p-toluidine [68], 1,5-diaminonaphthalene (DAN), and N,N -diphenylthiourea (DFTU) [69] in water-organic mixtures on the two-step electroreduction of Zn(II) was also examined. The presence of p-toluidine accelerated the first electron transfer in water —90 vol % DMF and water —91 vol % methanol [68]. DAN and DFTU had no effect on Zn(II) electroreduction in aqueous solutions but they also catalyzed this process in water-methanol mixtures [69]. 

Bimodal intermolecular proton transfer in water photoacid-base pairs studied with ultrafast infrared spectroscopy... 

General relationships for LFERs and isotope effects 104 Application to methyl transfers in water 105 Values of a 109... 

Marcus league table for methyl transfers in water... 

Scheme 5.1. Approximate relative rates of proton transfer in water at thermoneutrality (ApKa = 0) [35, 39, 51].

Oxidation of alcohol by hydrogen transfer in water under microwave irradia-... 

Figure 2.18 Schematic of the Grotthus mechanism of long-range proton transfer in water molecules. In this, hydrogen bonds and covalent bonds interchange, releasing a proton from one end of the chain as a new proton is introduced at the start of the chain...

Collin, A., Boulet, P., Lacroix, D., and Jeandel, G. On radiative transfer in water spray curtains using the discrete ordinates method. Journal of Quantitative Spectroscopy Radiative Transfer, 2005. 92, 85-110. 

Hostikka, S. and McGrattan, K. Numerical modeling of radiative heat transfer in water sprays. Fire Safety Journal, 2006. 41(1), 76-86. 

Examples of catalysis involving concerted cyclic proton transfer in water have recently been reported in the hydrolysis of N-phenyl-iminotetrahydrofuran (Cunningham and Schmir, 1966, 1967). There is no effect of H2PO, HCO3, and CH3COOH on the rate of hydrolysis, but the type of product obtained, butyrolactone or 7-hydroxybutyranilide is dependent on their concentration. The following scheme was proposed [equation (8)]. 

A SCF CNDO calculation [108] for the HsOJ species similarly suggests that proton transfer in water occurs by tunnelling, the estimated rate coefficient being of the order of 1014 sec-1. 

Fig. 2. (a) Proton transfer in water, (b) Proton transfer from strong acid to strong base, (c) Proton transfer from weak acid to weak base. 

There are no data available on the rate of formation of dialkyloxonium ions like protonated 1,3-dioxolane in Eq. (16). It is remarkable that the rate constants of formation of secondary onium ions from linear ethers, acetals, sulfides etc. are also utdcnovra. These should however be lower than the rate constants of proton transfer in water (an upper limit) being close to 10 mole 1 s but certainly higher than the rate constantsof protonation of olefins... 

R. Contreras and J. S. Goraez-Jeria, /. Phys. Chem., 88, 1905 (1984). Proton Transfer in Water Polymers as a Model for In-Time- and Solvent-Separated Ion Pairs. 

Wraight CA. Chance and design—Proton transfer in water, channels and bioenergetic proteins. Biochim. Biophys. Acta 2006 1757 ... 

D.E. Sagnella and M.E. Tuckerman, An empirical valence bond model for proton transfer in water, J. Chem. Phys., 108(1998), 2073-2083. 

Samalam [43] modeled the convective heat transfer in water flowing through microchannels etched in the back of silicon wafers. The problem was reduced to a quasi-two dimensional non-linear differential equation under certain reasonably simplified and physically justifiable conditions, and was solved exactly. The optimum channel dimensions (width and spacing) were obtained analytically for a low thermal resistance. The calculations show that optimizing the channel dimensions for low aspect ratio channels is much more important than for large aspect ratios. However, a crucial approximation that the fluid thermophysical properties are independent of temperature was made, which could be a source of considerable error, especially in microchannels with heat transfer. 

Glycine (intramolecular proton transfer in water) Okuyama-Yoshida 1998 Guanosine triphosphate and imido/ methylene analogs Cannon 1994... 

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