Solvent equation

It is unrealistic to expect that a single universal parameter would successfully predict the variation of a rate or equilibrium for solvents that have grossly different structures. The best that can be expected 

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In a binary liquid solution containing one noncondensable and one condensable component, it is customary to refer to the first as the solute and to the second as the solvent. Equation (13) is used for the normalization of the solvent s activity coefficient but Equation (14) is used for the solute. Since the normalizations for the two components are not the same, they are said to follow the unsymmetric convention. The standard-state fugacity of the solvent is the fugacity of the pure liquid. The standard-state fugacity of the solute is Henry s constant. 

The three properties e, p., and / m are related. One way to determine p. is by means of measurements of the dielectric constant of dilute solutions of the molecule in an inert solvent. Equation (8-6) was derived by Debye. ... 

Sinee ir, a, and (3 are approximately normalized seales, the coeffieients s, a. and b are measures of the relative weights of the dipolarity/polarizability, HBD ability, and HBA ability of the solvent. Equation (8-77) has been extended to take aeeount of the eavity effect and certain anomalies, as we will see later in this seetion. 

Braverman and Sredni20 have reported that p-methoxybenzyl trichloromethanesulfe-nate (1) undergoes a facile thermal rearrangement to the corresponding sulfoxide (2) on heating in highly nonpolar solvents (equation 1). 

The most common way to generate sulfonyl radicals for spectroscopic studies has been the photolysis of solutions containing di-t-butyl peroxide, triethylsilane and the corresponding sulfonyl chloride in a variety of solvents (equations 4-6). The slowest step in this sequence is the reaction between t-butoxyl radicals and triethylsilane (ks = 5.3 x 106m 1s-1)26 since that for chlorine abstraction (equation 6) is extremely efficient (cf. Table 4). 

The Z scale developed by Kosowct and Mohammad [48,49] is based by the chaige-transfer absorption of Af-ethyl methoxycarbonyl) pyridinium iodide molecule. The wavelength of maximum adsorption (A in nm) is measured and the energy (kcal/mol) of this transition becomes the actual polarity measured for a given solvent (Equation 4.17) ... 

Amino 4-oxo 4//-pyrimido[l,2-4]pyridazin-3-diazonium tetrafluoroborates 73 underwent ring transformation into l-(pyridazin-3-yl)-l//-l,2,3-triazole-4-carboxylates 74 on heating in dry MeOH. Yields dropped drastically when EtOH, instead of MeOH, was used as solvent (Equation 6) <2002ARK143>. 

Compounds (L)AuR have been used as precursor molecules for the in situ preparation of the strong nucleophiles [(L)Au]+ X- by treatment with strong acids HX (X = CF3S03, CF3C02, BF4, PF6, SbF6 etc. L = tertiary phosphine R = alkyl) in polar solvents (Equation (2)). The solutions are used as catalysts for the activation of alkenes and alkynes for addition of water, alcohols, and amines (Sections 4 and 10). 

Kinetic studies by Butts and Richmond indicate that both the monomer and dimer of dichloroacetic acid promote the reaction in an aromatic solvent, equations 12a and 12b, (20). 

As with other reactions, silyl esters of phosphorus acids constitute an important and useful category of reagents for conjugate addition reactions. With aldehydes, ketones, and esters, the silyl ester linkage is transferred to the carbonyl oxygen, facilitating the completion of the reaction, generating the free carbonyl or ester upon workup with a protic solvent (Equation 3.25). 

In competition experiments with benzaldehyde, allyltantalum reagent 124 was found to add selectively to an imine, when THF was employed as the solvent (Equation (17)). 

We will later further analyze the members of (3.7) as they stand, but it is useful for our subsequent discussion to now simply add a generalized dissipative term to the solvent equation of motion to obtain the stochastic equation of motion set... 

Whereas methyl 5-(3-methyl[l,2,4]thiadiazolyl)diazoacetate 56 shows no tendency to cyclize to 7-methoxycarbonyl-3-methyl[l,2,3]triazolo[3,4-A][l,2,4]thiadiazole 57, the 5-(l-diazoalkyl)substituted [l,3,4]thiadiazoles 58 are in equilibrium with the fused bicyclic form, the [l,2,3]triazolo[5,l-A]][l,3,4]thiadiazoles 59 <1988BSB795, 1992JHG713>. The latter ring-closed form 59 prevails in the solid state as indicated by infrared (IR KBr disk). The chain/ring equilibrium of the diazoimine/triazole forms is shifted toward the open-chain diazo form 58 by raising the temperature and by using less polar solvents (Equations 8 and 9). 

R is the radius of the cavity, p and a are the dipole moment and polarizability of the solute, and s the dielectric constant of the solvent. Equation (35) does address the polarization of the solute molecule by the reaction field, although not carrying this to self-consistency. (It is interesting that Onsager s paper, the sixth-most-cited in the history of the Journal of the American Chemical Society, was rejected by the Physikalische Zeitshrift, to which it had initially been submitted.)89... 

Iminium ions can be generated from tertiary amines and the free radical chlorine dioxide, a gas, which can be stored in aqueous solvents (equation 48)137. 

Only in certain atypical cases are a-diones obtained (41). However, the converse is true under phase transfer conditions where the reactions are carried out in nonaqueous solvents (Equation 2). 

Equation 13 can be extended to non-6 conditions by multiplying by an expansion parameter Since it is known that the expansion paramenter is greater than unity for good solvents and less than unity for poor solvents. Equation 13 would predict that the slope of the D/Dq versus c line for c >c would decrease in good solvents and increase in poor solvents, in agreement with predictions from... 

The presence of organolithium compounds in etheric solvents at temperatures above 0°C may lead to extensive decomposition of the solvent and solute a slow electron transfer side reaction of lithium naphthalene or sodium naphthalene with the THE solvent (equation 5) has been reported . The three isomeric forms of BuLi were shown to induce extensive decomposition of THE. The main path for this process is metallation at position 2 of THE, leading to ring opening and elimination of ethylene. An alternative path is proton abstraction at position 3, followed by ring opening. The presence of additives such as (—)-sparteine (24), DMPU (25), TMEDA and especially HMPA does not prevent decomposition but strongly affects the reaction path. ... 

In contrast, oxime ethers and esters are usually stable in solution but the E/Z isomerization can be induced by acids " or by irradiation ". Recently, Narasaka and colleagues"" "" studied the equilibration-isomerization of (E)-O-acyl oximes 239 in the presence of an acid in a nucleophilic solvent (equation 71). Isomerization probably proceeds via protonation of the oxime nitrogen followed by addition-elimination of a nucleophilic solvent until the equilibrium of E and Z isomers is achieved. The isomerization of the more labile 0-acyloximes occurs either by an Sjv2 substitution at the oxime nitrogen with acids and/or by acyl exchange through the formation of a mixed anhydride and the free oxime. 

Metal salts of 5-substituted tetrazoles (83) undergo ready alkylation on heating with alkyl halides in a wide range of solvents (Equation (9)). The products are mixtures of 5-substituted-1 A- and 2N-... 

The azathio isatoic anhydride 99 has been prepared by the reaction of 2-aminonicotinic acid 303 and thionyl chloride in ecu <2001JOC4413>, benzene, or cyclohexane as the solvent (Equation 40) <2004TL1377>. 

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