To water-acetone mixtures

Figure 4. Thermodynamic transfer functions for n-Bu NBr from water to water-acetone mixtures at 298.15°K...

Table IV. Standard Free Energy, Enthalpy, and Entropy of Transfer of n-Bu4NBr from Water to Water—Acetone Mixtures at 298.15°K...

Figure I. Single-ion standard Gibbs free energy of transfer from water to water + acetone mixtures based on S.F.T. calculations for the tetrabutylammonium ion (mole-fraction...

We know from S.P.T. calculations that the cavity term will be negative for the transfer from water to water + acetone mixtures (Table IV). According to the Bom Equation AGt° (EL) is positive. Insofar as the separate consideration of a specific and and an electric term is not arbitrary we may note that in order to have AGt° (SPEC) < 0 (preferen-... 

Water-acetone mixtures offer a sufficiently polar medium that certain alkyl halides can dissociate into a halide anion and a carbocation. The latter then reacts with water to give an SnI substitution product. 

Acetone is used as a solvent in a laboratory. There is some concern about the fire hazards associated with the acetone. One solution is to dilute the pure acetone with water, thus providing an increased flash point. What mole fraction of water in a water-acetone mixture is required to increase the flash point of the mixture to 100°F Acetone is completely soluble in water. 

The photoelastic behavior of nonionized PAAm network and ionized P(AAm/MNa) network prepared by the copolymerization of AAm with MNa ( MNa = 0.05) was investigated in water-acetone mixtures [31]. For a pure PAAm network, the dependences of all photoelastic functions (see Eqs. (15) and (16)), i.e. modulus G, strain-optical function A and stress-optical coefficient C, on the acetone concentration in the mixtures are continuous (Fig. 17). At ac = 54 vol %, the ionized network undergoes a transition which gives rise to jumpwise change in G, A and C also the refractive index of the gel n8 changes discontinuously. While in the collapsed state the optical functions A and C are negative, in the expanded state they are positive. 

JHNMR spectra of zirconyl perchlorate in water-acetone mixtures at —70°C indicate that ZrIV has an average hydration number of —four.151 This is in accord with [Zr4(0H)8(H20)i6]8+ if it is assumed that only the bound water molecules are observed the lack of an NMR signal for the hydroxy protons could be due to rapid proton exchange. 

Hudson et a/.151,152 have concluded that the bimolecular solvolysis of ethyl chloroformate involves heterolysis of the carbon-chlorine bond and not heterolysis of the carbon-oxygen bond. Their data shows that the hydrolysis of ethyl chloroformate is a second-order reaction in water/acetone mixtures, methyl chloroformate reacting about 2.2 times as fast in 65% water/acetone at 50°C. Hydroxide ion accelerates the reaction (3.1 x 107 in 18% water/ acetone and 3.4 x 108 in 85% water/acetone) and catalysis by hydroxide ion was observed with pure water as solvent by Hall118. There is some disagreement about the value for the hydrolysis rate coefficient for ethyl chloroformate in water and in other solvents (Table 21). To date, the data of Queen153 (for pure water), Kivinen92 (for ethanol) and Liemiu101 (for methanol) must be considered the most accurate. 

Hydrolysis of alkoxysilanes in water is reported to follow a first-order rate law [8, 13]. In the water-acetone mixture required for solubility of TMMS, there is a 15-fold molar ratio of water to TMMS. However, a plot of In ([TMMS],) vs. time does not result in a linear plot. This is because the consumption of water is significant. Therefore, a bimolecular, second-order rate law was employed as shown in equation (1) ... 

More recently, this method has been successfully extended by us18 to form the inverse systems, i.e. water core/polymer shell particles dispersed, initially in oil, but then transferred to an aqueous continuous phase. Clearly, whether one needs an oil or a water core depends on the nature of the active material to be released. Now one starts with a water/oil emulsion, rather than an oil/water emulsion, but the basic principles are very similar. A variety of shell polymer systems were prepared, including PMMA and poly(tetrahydrofuran) [PTHF]. The high vapor pressure liquid used in this case was in general, acetone. It turned out, however, that these water core systems are intrinsically more difficult to make than the equivalent oil core systems, because large amounts of acetone were required to dissolve the polymers initially in the water-acetone mixtures. An oil was then required which did not mix too well with acetone. In general, mineral oil worked reasonably well. In order to transfer the water core capsules into an aqueous continuous phase, the particles were centrifuged in... 

In the vast majority of cases reported where a streak camera has been used to measure fluorescence lifetimes, the measurements have been made from a single laser shot. Since a high fluorescence efficiency is necessary for single shot experiments, most of these studies have been concerned with measuring the lifetimes and quenching of organic dye molecules in solution. For example, Yu etal. [67] have made a study of the fluorescence lifetime of malachite green as a function of solvent viscosity and the lifetime and relative yield of erythrosin as a function of water concentration in a water—acetone mixture. The fluorescence lifetimes of these dyes are... 

In the laboratory of R. Bihovsky, a series of peptide mimetic aldehyde inhibitors of calpain I was prepared in which the P2 and P3 amino acids were replaced with substituted 3,4-dihydro-1,2-benzothiazine-3-carboxylate-1,1-dioxides. The synthesis began with the diazotization of the substituted aniline substrate using sodium nitrite and hydrochloric acid. The aqueous solution of the corresponding diazonium chloride product was added dropwise to the solution of acrylonitrile in a water-acetone mixture, which contained catalytic amounts of copper(ll) chloride. This Meerwein arylation step afforded the chloronitrile derivative, which was subjected to sulfonation with chlorosulfonic acid, and the resulting sulfonyl chloride was treated with the solution of ammonia in dioxane to give the desired 3,4-dihydro-1,2-benzothiazine-2-carboxamide. 

Pant and Levinger [187] studied solvation dynamics of C343 in a suspension of nanodimensional zirconia particles of radius 2 nm in a water-acetone mixture (95 5, v/v). They observed two subpicosecond components similar to those in bulk but having different amplitudes resulting in a relaxation time faster than that in bulk solution. They also showed that the maximum Stokes shift is three times smaller for the dye molecules adsorbed on the zirconia particles compared to those in bulk solution. 

Herbicides are components with relatively low Kow values and high solubilities. This means that they can be extracted from soil with a water/acetone mixture. To enable the measurement of low concentrations, the herbicides have to be transferred to a volatile solvent, which is not miscible with water, like petroleum ether or dichloromethane. If the original acetone/water extraction medium is concentrated (evaporation), the water percentage will increase during the concentration and the extracted components will precipitate or adsorb to the equipment. It is therefore necessary to add a solvent like petroleum ether to the system. There will be a distribution between the soil and the acetone/water mixture and one between the acetone/water mixture and the petroleum ether. If the water content is low the system is very effective for non-polar components. With a higher water content it will be more effective for more polar components. With a too high water content the accessibility increasing properties of acetone are lost and the efficiency of the extraction process decreases. 

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